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General Meeting 1965 of the German Chemical Society and Kekul Celebration.

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tration reaches a limiting value, whereupon the reactions
proceed according to Equation 11. When the H N 0 3 or NO@
and NO30 concentrations are very high, Reaction (e)becomes
important and the dissolution proceeds according to the
overall Equation 111. At the highest HNO3 concentrations,
direct discharge of the N 0 2 “ ion is probably also an important
factor in the reaction.
[GDCh-Ortsverband Aachen (Germany),
July 16th, 39651
cycloheptapeptides with a-linked side chains and with a Damino acid in the ring ( I ) . The e,y-diaminobutyric acid
groupings all have the L-configuration. Structure ( I ) has
now been proved by synthesis of polyrnyxin B1 and colistin
I*?
[VB 944/251 IE]
German version: Angew. Chem. 77,975 (1965)
The Chemistry of Polymyxins
K . Vogler, Basel (Switzerland)
The chemistry of polymyxins, a class of basic polypeptide
antibiotics, began in I954 when polymyxin B1 was first purified
by countercurrent distribution (1;. C . Craig). Partial hydrolysis with mineral acid led to the conclusion that this w2s
a cyclohepta- or cyclooctapeptide with side-chains containing a,y-diaminobutyric acid (Dab) ( W. Haussmnnn).
An amide linkage of the side chain with a fatty acid (+)-6-methyloctanoic acid (MOA) or 6-methylheptanoic acid
(IOA) - confers the properties of a n invert soap on these
antibiotics. They are particularly active against Gramnegative bacteria. Difficulties were encountered in elucidating the point of attachment of the side chain and in finding
Polymyxin R ,
Polymyxin BZ
Colistin A
(=Polymyxin El)
Colistin B
(=Polymyxin E2)
Circulin A
a n answer to the question whether the rest of the molecule
also contained a D-a,y-diaminobutyric acid residue. Syntheses with D-Dab led to highly active products which were
not however identica1 with natural polymyxinB1. Degradation
experiments with nagarase (T. Suzuki), which specifically
degrades the side chain, revealed that the polymyxins are
H-C-CHz-CHz-NHz
FO
t-Dab
I
H!
! FO
L-Thr
H,C- C-FH
OH YH
FU
H-C-CH,-CH,-NH,
L-Dab
Y;R
MOA
IOA
-CH:-CsH5
--CHZ-C~H~
-CH2-CH(CH&
-CHz-CH(CH3)2
Phe
Phe
Leu
Leu
MOA
--CH2--CH(CH3)2
-CHZ-CH(CH&
Leu
Leu
IOA
MOA
-CHz-CH(CH&
-CHZ-CH(CH~L
-CH2-CH(CH3)z
-CH(CH+CzH5
Leu
Leu
Leu
Ileu
A, which is identical with polymyxin El. Circulin A, which
was previously thought to be a cyclodecapeptide, is also a
cycloheptapeptide according to the results of new analytical
and synthetic experiments.
[GDCh-Ortsverband Aachen (Germany),
July 30th, 19651
[VB 9511259 IE]
German version. Angew. Chem. 77, 974 (1965)
General Meeting 1965 of the German Chemical Society and KekulC Celebration
This year’s general meeting of the German Chemical Society
in conjunction with the Kekulk Celebration commemorating
the 100th anniversary of the benzene formula took place in
Bonn (Germany) from 13th to 18th September. The following
report contains abstracts of the discussion papers, but is confined to those papers which have not yet been published.
Abstracts are arranged alphabetically according to the
names of the authors. For a subject index, see page 1003 of
this issue.
1
Reactions of ”Hot” Carbon Atoms in
NitrogenjAlkane Systems
H . J . Ache and P . WofL Upton, L.I., New York (U.S.A.)
Reactions of “hot” carbon atoms [generated by 14N(p,a)lrC,
JzC(p,pn)IfC, or by llB(p,n)ifC processes] in nitrogen/
alkane mixtures give rise to 1 IC-labelled hydrocarbons (e.g.
acetylene), and H l l C N as the only compound containing
nitrogen. The reaction of a n energetic carbon atom with a
nitrogen molecule presumably leads to an IICN. radical,
966
which is stabilized to H I C N in a second rapid step by
abstraction of hydrogen from a hydrocarbon molecule.
Further insight into the formation of the second main
product, viz. [11C]acetylene, was obtained o n mixtures of
protonated and deuterated hydrocarbons by the “double
tracer” technique. The fact that more than 90 % of the
[11C]acetylene in 1 : 1 mixtures of protonated and perdeuterated hydrocarbons is found as HlIC=CH or D I ~ C E C D
shows that it is formed by an intramolecular process in which
the first step is the insertion of an energy-rich carbon atom
into a C-H bond. The highly exited complex formed can
decompose to acetylene and other by-products.
In the reaction of hot 11C-atoms with hydrocarbon molecules
containing both primary and secondary C-H bonds (e.g.
propane), preferential formation of [11C]acetylene by C-insertion into C-H bonds of methyl groups is observed in the
ratio of about 1.3: 1.
In mixtures of protonated and perdeuterated hydrocarbons,
the acetylene formation shows isotope effects ranging from
for alicyclic compounds to 1.28 for
C Z H ~ / C ~=D 1.08
~
methane.
Angew. Chem. iirternat. Edit. 1 Vol. 4 (1965)
1 No.
II
2
Radiometric Determination of the Self-Diffusion
Coefficient of the Pertechnetate Ion in A q u e o u s
Solutions
L. Astheimer and K . Schwochau, Koln (Germany)
In the polarographic determination of electron transfer by
the IlkoviE equation, ionic diffusion coefficients calculated
from the limiting equivalent conductivity of the ion are
generally used. This method assumes the absence of added
foreign electrolytes, in disagreement with the conditions
used in polarography. Thus at the usual depolarizer concentrations, the self-diffusion coefficient should be used [ ] ] .
We determined the self-diffusion coefficient D of the Tc04ion by the capillary method. The long-lived, @--active
99gTc was labelled with 95mTc, which is formed on bombardment of natural molybdenum with deuterons. The equation
D
=
presence of specific adsorption, sharp maxima may still OCcur with solutions of very high conductivity as surface tension
gradients may persist due to reactant concentration gradients
at the drop surface arising from lack of spherical symmetry in
the diffusion systems for the oxidized and reduced forms of
the depolarizer.
Specific adsorption of inorganic depolarizers is largely confined to ions of the heavy metals and is most pronounced with
halide supporting electrolytes. Approximate values of the adsorption coefficient at potentials close to the half-wave potential can be deduced from changes in wave shape and height produced by specificadsorption in a.c. andpulsepolarography. But
the most powerful technique for studying specificadsorption of
inorganic depolarizers is R.F. polarography as measurements
can be made with low depolarizer concentration and with solutions containing insufficient of the adsorption-promoting
anion to affect the half-wave potential. Such measurements
suggest that leadisadsorbedfromperchloric acidsolutions containing small amounts of bromide ion in the forms PbBr+
and PbBr2.
(412/x2t)ln[(8/~~2)
Ao/At]
was used to obtain D from the fraction At/Ao of the activity
remaining in the capillary after a time t, where 1 is the length
of the capillary. At 10-3 M Tc04- in 1 M aqueous NaOH,
D = 1.27~
lO-5cm2/sec, in 1 M LiCl: 1 . 2 4 ~
10-5 cm2/sec. In
the absence of supporting electrolyte, D = 1 . 4 9 10-5
~
cmz/
sec, which almost coincides with the value D = 1 . 4 7 ~
10-5
cm2/sec obtained from the limiting ionic conductance.
Although the supporting electrolytes noticeably affect the
self-diffusion of T C 0 4 - , the consequent effects on rate of
electron transfer can be neglected. The self-diffusion coefficient of 10-3 M perrhenate was also determined in 1 M
NaOH and found to be 1 . 2 7 10-5
~
cm2/sec, i.e. the same as
that of Tc04- under the same conditions.
4
N e w C o m p o u n d s of Lithium Oxide with
Europium Oxide
H . Barnighausen, Freiburg (Germany)
The compound LiEu304 was intensively studied. It is readily
prepared by reduction of Eu304Br with LiH or by treatment
of Eu2O3 with LiH in a LiCl melt. In the latter procedure
evaporation of the LiCl in a high vacuum (600OC) affords
single crystals, examination of which by means of Weissenberg and precession diagrams leads to the following crystal
data :
[ l ] R . J . Bearman, J. physic. Chem. 66, 2072 (1962).
Orthorhombic; a = 11.565 A, b = 11,535 21, c = 3.480 A;
space group Pbnm; Z = 4; pR = 1.539 g/cm3.
3
Effects in Polarography Attributable to the
Specific Adsorption of Reactants
G . C . Barker and J. A. Bolzan, Harwell, Berks. (England)
Maxima in d.c. polarography are known to be caused by
tangential motion of the surface of the mercury drop and the
accompanying streaming of solution near the drop. It has
been believed that this tangential motion is due to surface
tension gradients connected solely with non-uniformity in
the interfacial potential arising from the finite electrical
conducitivity of the solution and the non-spherical flow of
diffusion current through the solution surrounding the
shielded drop. An explanation based on this non-uniformity
of potential, however, cannot account for sharp maxima,
neither is it consistent with the tendency in many cases for
the maximum to increase as the supporting electrolyte concentration is raised. The latter facts become understandable
when regard is given to the effect of specific adsorption of a
reactant on the electrocapillary curve. If either the oxidized
or the reduced form of the depolarizer is strongly adsorbed
at the electrode-solution interface, there is a sharp break in
the electrocapillary curve at the half-wave potential which
greatly affects the rate of change of surface tension with
potential in the neighbourhood of this potential. Streaming
then tends to be most pronounced close to the half-wave
potential and hence a sharp maximum is observed. The height
of the maximum may increase along with the supporting electrolyte concentration as the integral adsorption coefficient
may be proportional to a power of the anion concentration
greater than unity. Although non-uniformity of interfacial
potential often plays some part in causing maxima in the
Angew. Chem. internat. Edit. Vol. 4 (1965)
No. I 1
According to the formula LiEu304 found analytically, the
formula unit must contain two Euz+ ions and this is indirectly
confirmed by formation of the isotypic compound LiSrzEuO4
from the stoichiometric amounts of LiEuOz and SrO a t
7OO0C (lattice constants: a = 11.611 A, b = 11.540 A, c =
3-4846 A).
Heating of LiEu304 in air affords the compound LiEuOz, as
well as Eu203 (C form). The new substance occurs in two
modifications, which are each obtained in pure form when
Eu2O3 is treated with Liz0 o n slight modification of the reaction conditions. The crystal data of the orthorhombic modification have been reported previously [I]. Crystals of the monoclinic modification belong to space group P2&, with lattice
constants a = 5-6815 A, b = 5.9885 A, c = 5.6211 A, @ =
103.17 ( Z = 4, p~ = 6-807 g/cm3).
[I] H . Barnighausen, Acta crystallogr. 16, 1073 (1963).
5
Ternary Compounds and Solid Solutions in the System
Calcium Oxide/Phosphorus(V) Oxide/Boron(III) Oxide
Helmut Bauer, Karlsruhe (Germany)
The ternary system CaO/P205/B203 has previously been investigated only with regard to the formation and properties
of glasses. Investigations confined mainly to the CaO corner
show the existence of two compounds with incongruent melting points having the formulae 15Ca0.2P205.3Bz03 111 and
2CaO.P20~.B203[2J. The former compound is stable only
967
between about 1300 and 14OO0C, but can be obtained in a
metastable state by rapid quenching. The structure of the
compound is not yet known; powder diagrams, however, indicate wide occurrence of the structure type. Thus isostructural phases of wider stability range and a certain range of
compositions are found in the systems SrO/PzO5/B2O3 and
BaO/Pz05/B203, and compounds of the type 6MO.Pz05B2O3 (M = Mg, Zn, Cd, Cr, Mn, Co, Ni) show similar powder
diagrams. 2 CaO.P2O5.B203 crystallizes in the hexagonal
system and is a member of an isotypical series 2MO-Xz05.
B203, of which the compounds with M = Ca, Sr, Ba, and
X = P, As have been prepared.
Besides the ternary compounds, two ranges of solid solutions
were found in the system CaO/Pz05/B203. These can be assigned structures of the apatite type and the p-tricalcium
phosphate typeL31. The solid solutions of apatite structure are
based on a combination of substitution (of B045- for P o &
groups) and addition (insertion of B3+ in interstitial sites and
of 0 2 - on the two-fold positions of the apatite lattice); those
with the p-tricalcium phosphate structure are formed by
pure addition. Both types of solid solutions are also found in
other systems MO/X205/B203 : the apatite type in systems
with M = Ca, Sr, Ba, and X = P, As, as well as M = Ca, X =
V; the p-tricalcium phosphate type in the system CaO/Asz05/
B203.
[I 1 H. Bauer, Habilitation Thesis, Technische Hochschule Karlsruhe, 1963.
[2] H. Eauer, Z . anorg. allg. Chem. 337, 183 (1965).
[ 3 ] H. Eauer, Neues Jb. Mineralog., Abh. 102, 68 (1964).
6
Optical Investigations of the Surface Chemistry of
Germanium and Silicon
K . H. Beckmunn, Hamburg (Germany)
The state of polarization of polarized light reflected from a
solid having a thin surface coating depends on the refractive
index and the thickness of the film, and can therefore be used
to determine these parameters. Thickness measurements on
very thin layers (d < 100 A) can be made with particular accuracy. This method was used to follow the growth of a copper layer on a germanium surface formed by electrode position.
It was further shown that during the anodic dissolution of
p-germanium in a weakly alkaline electrolyte solution, thin
layers of presumably GeOz are reversibly formed at certain
potentials.
In chemical reactions between a semiconductor surface and
the surrounding medium, some of the reaction products often
remain on the surface in the form of very thin films. HurrickL1l has described a method of determining the infrared
spectrum, and thus the composition, of such films in which
the radiation is made to traverse the layer 100 times or more
by total internal reflections. The infrared spectrum of
15 b layers of GeOz on Ge and the constitution of layers
which form on the surface of germanium in various etching
solutions were determined by this method.
If in this arrangement the sample in an electrolyte is irradiated with continuous light and an alternating potential is applied between sample and counter electrode at 13 C/S (the
modulation frequency of the infrared spectrometer), only the
change in the infrared absorption due to the alternating electrochemical polarization is recorded. Such a change occurs,
e.g., when the number of absorbing particles changes with
the electrochemical polarization. By this means the infrared
spectra of free electrons and defect electrons in the space
charge zone immediately beneath the semiconductor surface
were measured and used to calculate the concentration
changes of these charge carriers due to the electrochemical
polarization.
111 N. J. Harrick, Physic. Rev. 125, 1165 (1962).
968
7
The Mode of Action of the Antibiotic Chromomycin
W. Behr, K. Koschei, and G. Hartrnann, Wiirzburg (Germany)
The antibiotic chromomycin is a very effective inhibitor of
DNA-dependent nucleic acid synthesis [ * I . Comparative experiments showed that it inhibits the DNA-dependent RNA
synthesis as strongly as does actinomycin. The glycosidically
bound chromose groups in the chromomycin molecule are
essential for this activity. On stepwise cleavage of the sugar
residues, a considerable decrease of inhibition efficiency is
observed. The sugar-free rest has no effect o n RNA synthesis
under the conditions used.
As in the case of actinomycin, the reaction of chromomycin
with DNA is accompanied by a change in absorption spectrum (red-shift of the maximum in the visible region by about
25 mp). This indicates that this antibiotic also blocks the
DNA. The association indicated by the spectral displacement is, however, significantly slower than that with actinomycin. The apparent enthalpy of activation is about 7 kcall
mole. In the presence of an excess of chromomycin, on the
average 29 nucleotides of the DNA bind one molecule of the
antibiotic. For actinomycin this ratio is 11:1.
In contrast to actinomycin
chromomycin associates not
only with DNA and apyrimidinic acid, but also with apurinic
acid and transfer-RNA (t-RNA). The spectrum of these associates differs from that of the complex with DNA. With an
excess of chromomycin, three t-RNA nucleotides suffice to
bind one chromomycin molecule. The antibiotic has no effect
on the enzymatic aminoacylation of t-RNA with arginine.
Free nucleosides and nucleotides of comparable concentration do not alter the spectrum of chromomycin.
[I 1 G. Hartrnann, H. Goiler, K. Koschel, W. Kersten, and H. Kersten, Biochem. 2. 341, 126 (1964).
[21 M. Liersch and G. Hartmann, Angew. Chem. 77, 731 (1965);
Angew. Chem. internat. Edit. 4, 707 (1965).
8
Experiments in Chemical Documentation
G. Bergerhoff, Bonn (Germany)
On the bibliography of a very specialized field as an example
it is shown that the requirement of completeness increases
considerably the number ofjournals to be scanned. The information material must therefore be condensed. Resolution of
publications into words screened with respect to import and
redundance can be accomplished by data processing equipment, which can also answer requests for information by
logical combination of the stored concepts. The enquirer is
led to the original reference without noticing the condensed
nature of the stored information.
A randomly selected set of information comprising about
10000 words in 36 publications was processed with a programme of the Deutsches Rechenzentrum. With the aid of a
cumulative thesaurus synonyms, foreign words, chemical
formulae, and conjugated and declined words can be related
to their basic forms, superfluous words can be eliminated, and
a reduction to about 10 % is possible. The relatively frequent
homonyms are included with all their meanings.
The “ballast” in answers to detailed questions is slight, for
general questions stimulating. A logically constructed notation taking into account the expressive power of words would
help to reduce ballast and to obtain relations which are not
evident in the formalism based on the usual language.
9
Reactions with Potassium Dihydrogen Phosphide
G . Bergerhoff and F. Knoll, Bonn (Germany)
Although alkali diorganyl phosphides have become extremely
versatile reagents, little is known of the chemistry of the
parent compound KPHz. In oxidation experiments and reAngew. Chem. internat. Edit. / Vol. 4(1965)
/ No. I I
actions with halides, secondary reactions at the P-H bond
always occur. Pure addition reactions can so far be obtained
only on elementary phosphorus in dimethylformamide. These
can be regarded as nucleophilic cleavage of the P4 molecule.
By following this reaction conductometrically, several intermediate stages were observed, of which the red-brown, amorphous product KP5H2 was precipitated with benzene. Attempts to obtain phosphanes by reactions with alkyl halides
always resulted in polymers formed by cleavage of P-H bonds
as shown by the formation of triphenylmethane from KPHz
and chlorotriphenylmethane.
0
P
ep< I)P-PHz
P
P\
0
0
/P\
/P\
-P\ ,P-P, /P-P, ,PP
P
P
I
I
PH2
PH2
I
disodium adducts polymerize acrylonitrile and methyl methacrylate, whereas styrene is not affected. Both the radical ions
and the dianions give rise to an anionic polymerization mechanism.
The polymerization of styrene by alkali metal ketyls of benzois actually initiated by the
phenone described by Smith
disodium derivative formed by the addition of two sodium
atoms to benzophenone and is not stereospecific, in contrast
to earlier reports 111.
Polymers obtained by free-radical polymerization and copolymerization of p-vinylbenzophenone, p-vinylbenzophenone
anil, and p-vinyl-1,I-diphenylethylene can be converted into
the corresponding poly-radical ions and polydianions ; they
are suitable for ionic graft polymerization.
[l] S. Smith, J. Polymer Sci. 38, 259 (1965).
PH2
12
Whereas solutions of KPHz in dimethylformamide show
well-defined 31P- and 1H-NMR spectra with chemical shifts
8p = 255.3 ppm (vs. 85 % H3P04) and 8~ = 1.12 ppm (vs.
tetramethylsilane) and coupling constants JPH of 139 and
136.8 cps, the complicated KP5H2 gives no IH-NMR spectrum and only a poor 31P-NMR spectrum. From the course
of the reaction the structure of a monomeric pentaphosphide
ion ( I ) or of a polyphosphide ion (2) is proposed. The structure ( I ) is supported by molecular-weight determinations. A
route to defined polyphosphanes via degradation is thus indicated.
Synthesis and Structure of Insecticidal
Polychlorotetrahydromethanoindanes
K. H. Biichel, Birlinghoven (Germany)
Little has hitherto been known about the numerous possible
stereoisomers in the cyclodiene series of insecticides of the type
of heptachlor [1,4,5,6,7,8,8-heptachloro-3a,4,7,7a-tetrahydro4,7-methanoindene]. The isomeric dihydro-compounds (2)
of heptachlor seem to be of particular interest because after
removal of the double bond from the five-membered ring its
biological epoxidation to toxic products cannot come into
effect.
C1,Cl
10
Reactions at the N = N Double Bond of
Azodiphosphoric Acid Derivatives
1oooc, too atrn,
FeCI,
c1
(21, a - D H C
H. Bock and E. Kinzel, Miinchen (Germany)
i
The energy levels of orange azodicarboxylic acid derivatives
differ from the corresponding levels of violet azodiphosphoric
acid derivatives by up to 20 kcal/mole. Comparison of the
reactivity of the two types of compounds was therefore of
interest.
Reactions of Ph20P-N=N-POPhZ include Diels-Alder cycloadditions, metalation, electrophilic substitution, and addition of proton-active compounds, f.e. the same broad
reactivity spectrum as the azodicarboxylic ester.
Whereas azodicarboxylic esters oxidize hydroquinones
smoothly and without detectable intermediates to quinones
the reactions with azobis(dipheny1phosphinic acid) gave
rise to new 1 : 1 adducts.
[I J H. Bock, G. Rudolph, E. Baltin, and J, Kroner, Angew. Chem.
77, 469 (1965); Angew. Chem. internat. Edit. 4, 457 (1965).
11
Initiation of Polymerization by Radical Ions and
by Dianions
D . Braun and W. Neumann, Darmstadt (Germany)
Mono- and disodium adducts of 1,I-diphenylethylene, transstilbene, and tetraphenylethylene in tetrahydrofuran initiate
polymerization of styrene, methyl methacrylate, and acrylonitrile. The corresponding derivatives of benzophenone, pbiphenylyl phenyl ketone, bis(p-biphenylyl) ketone, and
benzophenone anil are initiation for methyl methacrylate
and acrylonitrile, but styrene is only initiated by the disodium
derivatives. The monosodium adducts of azobenzene,
p-dimethylaminoazobenzene,
azoxybenzene, and nitrosobenzene initiate the polymerization of acrylonitrile; the
Angew. Chem. internat. Edit.
/ VoI. 4 (I965) / No. I 1
y-DHC
P-DHC
Addition of HCI under pressure and in presence of a Lewis
acid catalyst to the unsaturated hexachloro-analogue ( I ) affords ct-, @-, and y-dihydroheptachlor (DHC) 111, whose configuration has been proved by independent syntheses and
1H-NMR spectra. The addition is an equilibrium reaction.
The relative amounts of the isomers produced can be influenced by varying the conditions (solvent, pressure, temperature), so that the synthesis can be caused to yield, for instance, almost homogenous p-isomer. a- and y-DHC can be
isomerised to 8-DHC under the conditions of the addition.
p-Dihydroheptachlor [I’ is an insecticide whose spectrum of
activity is comparable with that of chlordane or DDT and
which has a very low toxicity to warm-blooded animals
(LD50 > 9000 mg/kg mouse). Moreover, it has given no sign
of possessing chronic toxicity 121.
In the octachlorotetrahydromethanoindane (chlordanes)
series (5), (6), the number of possible isomers is still larger.
On chlorination of hexachlorotetrahydromethanoindane (3)
one obtains a crystalline product (4) from which, by chromatography on silica gel (n-hexane), have been isolated pDHC and @-chlordane,the new isomers y-, a-, and E-chlor[ I ] K . H . Biichel, A, E. Ginsberg, R. Fischer, and F. Korte.
Tetrahedron Letters 1964, 2267.
[2] P . L. Chamber, C . G . Hunter, J . Robinson, and D . E. Stevenson, Med. Pharmacol. exp. 12, 289 (1965).
969
14
c1-c1
Cl.,Cl
Formation of Ferrocene
c1
c1
c1
dl
(3)
(4)
(6), 6-Chlordane
(S), ?-Chlordane
dane, and a nonachloro-derivative. The symmetrical y- and
8-chlordane have the best insecticidal properties. The structures of all the known chlordane isomers have been confirmed
by independent syntheses and IH-NMR spectra.
15
Automatic Determination of Molecular Weights by
L i g h t Scattering
H.-J. Cantow, Freiburg (Germany)
The reciprocal absolute scattering intensity (Rayleigh ratio)
R multiplied by the concentration C and the characteristic
optical constant K of a dissolved substance can be recorded simultaneously with the measurements versus the
consPC by a combination of anaangle function sin23/2
logue computing elements.
+
The reciprocal Rayleigh ratio is formed by a servo-controlled
potentiometer. The geometrical correction factor sin8 is introduced and the scattering angle is converted to sinz3/2 by
function potentiometers coupled to the rotating optical system. The solvent scattering is eliminated by a n opposing potential.
and the dimensions
The weight-average molecular weight
of the dissolved macromolecules as well as the thermodynamic solution paramters can then be obtained in the usual way
from the resulting Zimm diagram. The angular range of
30 '-150' can be scanned in 12 sec for each concentration.
The recorded curves have the further advantage that errors
made in point-by-point measurements are smoothed out.
mw
A system is proposed which instantaneously indicates the
molecular weight (at a single concentration in a theta-solvent
where the effects of solute-solvent interactions are cancelled)
by sacrificing information about the molecular dimensions.
The method consists in determining the Rayleigh ratio Ro
at zero angle, which is independent of shape and dimensions
of the molecule, by measuring the intensity scattered at two
angles in alternation with a rotating-sector system. For monodisperse and polydisperse randomly coiled molecules, angles of
45 O and 70' are suitable. The signals are combined so that the
alternating component of the resulting signal is 2 R45-R70r
which practically equals Ro. Such measurements at fixed angles
are possible with a n average accuracy (independent of the
molecular dimensions) of 2 % in Ro o r Mw.
H . Cordes, Ludwigshafen (Germany)
The four processes in the formation of dicyclopentadienyliron (ferrocene) from ferrous chloride and cyclopentadiene
in presence of alkali alkoxide, i.e. the preparation of FeC12,
the reaction with alkoxide, the reaction with monomeric
cyclopentadiene, and the isolation of the ferrocene, were investigated.
Anhydrous FeClz is formed rapidly and quantitatively by reduction of sublimed FeCIx in organic solvents, such as alcohols, in which both chlorides are sufficiently soluble, with
metals such as Fe, Zn, or A1 in the presence of acid, which is
essential for the process. Acid is often autogenically produced
by partial hydrolysis of the very hygroscopic FeC13 ; small
amounts of water are removed via the insoluble oxide hydrates.
On the addition of methoxide, the remaining acid is neutralized and white to light grey Fe(I1) methoxide is then precipitated. An excess of at least 100 % of methoxide should be
added to obtain good yields of ferrocene. At 4O-5O0C,
addition of monomeric cyclopentadiene gives ferrocene in
yields of over 80 % within a few minutes. Derivatives such as
methylcyclopentadienyl react more slowly.
When a water-soluble solvent is used, hydrolysis of the reaction mixture gives crude ferrocene in better than 95 %
purity, particularly if a n excess of Fe(I1) methoxide is used,
since all components except ferrocene are soluble in weakly
acidified water. Analytically pure ferrocene is obtained by recrystallization, sublimation, or steam distillation.
The main side reaction is the hydrolysis of the iron salts to
oxide hydrates, which, presumably owing to their extreme insolubility (even when freshly precipitated), d o not react with
cyclopentadiene. Therefore the presence of more than traces
of water decreases the ferrocene yield considerably, and even
anhydrous alkali hydroxides are not suitable as bases in place
of alkali alkoxides.
15
Interpretation of the Spectra of
Monoamino-p-benzoquinones
S. Dahne, D . Leupold, H . Paul, and J. Ranft,
Berlin and Leipzig (Germany)
The spectra of many disubstituted quinone dyes can, like
those of indigo dyes, be explained by the assumption that
two polymethine elements of the structure ( I ) are coupled
within one moleculerll:
.....( n + 3 ) n.____
I I/
X-( CR),-X'
X,X' = Elements of group IV, V. or VI;
R = any substituents; n = 1,3,5. .. .
For example, 2,5-diamino-p-benzoquinones(2) can be regarded as coupling products of two trimethinemerocyanines
( I ) , X = NRz, X' = 0, n = 3.
*
A gas laser with h = 6328 8, is a suitable light source. The refractive index increment can be measured simultaneously
with the same light source. A simple circuit then allows the
direct recording of Ro/CK, which in theta-solvents is equal
to Mw.
It thus appears possible to follow rapid processes as well as
continuous fractionations, e.g. those using Baker-Williams
columns. The method should also be suitable for rapid routine determinations of Rw.
970
(3)
[I] S. Dahne, D. Leupold, H . Paul, and J. Ranff, Mber. dtsch.
Akad. Wiss. 7, 25 (1965); D . Leupold and S. Dahne, Theoret.
chim. Acta 3, 1 (1965).
Angew. Chem. internat. Edit. I Vol. 4(196S)
1 No. I I
Analogously the properties of monosubstituted quinone
dyes, e . g . 2-amino-p-benzoquinone (3), are ascribed to a
polyene-polymethine coupling. The term schemes, calculated
by a supplemented LCAO-MO method, of the uncoupled
polyene ( 4 ) and the uncoupled polymethine ( 5 ) can be combined to that of the monoaminoquinone (3) by a stepwise approach of the separate molecules, i. e. by stepwise increase of
the resonance integral of the coupling bonds C(I)-C(2) and
C(4)-C(5).
-CH=CH-C=O
(4)
a?... 6 r.......ttQ
:O-(CR)~-N:
(5)
These ideas were confirmed by measurements of infrared and
N M R spectra. The C=O stretching frequency of the polyene
part of the molecule is higher than that of the polymethine
part. The chemical shifts of the protons in (3) after correction
for the ring current are essentially the same as in the separate
polyene and polymethine.
Because of the asymmetry of the polyene-polymethine coupling, the x +r* transition of longest wavelength of the monosubstituted benzoquinones is allowed. They therefore absorb
considerably more strongly in the visible than the centrosymmetric compounds of type (2), in which this symmetryforbidden transition is only slightly allowed by a HerzbergTeller mixture [2].
[2] S. Dahne and D. Leupold, 2. Naturforsch. 206, 76 (1965);
D. Leupofd and S. Dahne, J. molecular Spectroscopy, in press.
16
Specificity and Mode of Action of Pepsin in t h e
Condensation of Oligopeptides
H . Determann, Frankfurt/Main (Germany)
In the pepsin-catalysed plastein reaction, the terminal amino
acids of the peptides play a decisive part. The specificity of
pepsin is more marked in condensation than in hydrolysis
reactions. Thus pentapeptides with C-terminal L-Leucine, Lphenylalanine, and L-tyrosine can be condensed, whereas
those with L-valine, L-isoleucine, and D-phenylalanine are n o
substrate of the enzyme. Theamino-end appears to be less important to the reactivity. Here L-tyrosin can be replaced by
r-alanine; the reaction does not take place with D-phenylalanine on either end. A D-amino acid in the peptide interior
does not affect the reactivity (experiments with J. Heuer and
D. Jaworek).
The mechanism of pepsin-catalysed peptide hydrolysis is still
unknown. The specificity shown by pepsin in our condensation experiments suggests that the carboxy group is activated.
Attempts to capture a reactive intermediate by the addition of
various acceptors were, however, not successful. Neither inhibition of the plastein reaction, nor inclusion of the additives into the polypeptide, were observed when various
amounts of aniline, phenylacetic acid, alanine amide, or
acetyltyrosin where present in the reaction mixture.
17
Chelation of Neptunium, Plutonium, and Americium
b y Derivatives of 8-Hydroxyquinoline
S. H. Eberle and C. Keller, Karlsruhe (Germany)
Ter- and quadrivalent ions of the transuranium elements form
compounds ML3and ML4 (HL= ligand) with 8-hydroxyquinoline (Hox) and its 5,7-dihalo derivatives. Only basic substances
Angew. Chem. internat. Edit. Vol. 4 (1965) 1 No. I 1
are obtained from aqueous solutions with 2-methyloxine; the
neutral neptuniumcompoundisformed in themelt under water.
Similarly to Ce(ox)3, Pu(ox)3 is very sensitive to oxidation
and is only obtainable under strict exclusion of oxygen. Neptunium(\/) forms the neutral chelate Np02(ox).(H20)2, difficultly soluble in water and organic solvents, and a watersoluble anion [Np02(ox)yaq]-. Plutonium(V) gives only
chelates of the type PuOz(L)(HL)Z.aq. Both ions give compounds of composition MO2(Mox)(Hmox)~aqwith 2-methyloxine (Hmox). No chelation was observed with 6-valent actinides, since they are reduced by all the ligands used.
The extraction behavior and the stability constants are very
similar to those of complexes of the rare earths, thorium, and
uranium(1V); the stabilities of the actinide chelates are however always higher than those of the analogous elements. The
h a l e n t ions stepwise form 1 :1 and 1 :2 complexes with 8hydroxyquinolinesulfonic acids, which for neptunium and
plutonium have the same stability constants. The measurements show that the tendency to form chelates with oxine
derivatives decreases in the sequence M(1V) > M(I1I) >
WV).
18
Transport and Phase-Boundary Reactions of Defect
Electrons in Silver Bromide
E. Eisenmann and W. Jaenicke, Erlangen (Germany)
The mobilities of defect electrons as determined by diffusion
and Hall-effect measurements, respectively, differ by a factor
of about lo4 at room temperature. To determine whether this
discrepancy is caused by reactions at the phase boundary,
trapping reactions inside the crystal, or space-charge limited
transport, an electrochemical cell with an AgBr single crystal
as diaphragm between a bromine and a bromide solution
was polarized. The mobility was determined by the rate of
migration of the resulting boundary. Current-potential
measurements in both directions of polarization allowed the
study of rate determining phase-boundary reactions. The
mobility from the moving-boundary method agrees with that
obtained by diffusion.
Between 0 and 150 "C the mobility has a n activation energy
of 0.71 eV. At 175 "C it passes through a maximum and maintains a negative temperature coefficient to higher temperatures (measurements to 250 "C). This part of the curve agrees
with the curve obtained by extrapolation of the Hall-effect
data (measurements to 140 "C). A trapping mechanism is
proposed to explain the results.
19
Effect of Ultraviolet Radiation and of Carcinogenic
Nitrosamines on Constituents of Nucleic Acids 11 1
E . Fahr, R. Kleber, and E. Boebinger, Wurzburg (Germany)
The carcinogenic activity of nitrosamines [21 has been ascribed 131 to a conversion into diazoalkanes. This explanation is
supported by the fact that di-t-butylnitrosamine and diphenylnitrosamine, which can give no diazoalkanes, are not
carcinogenic.
From the relatively high reactivity of the N-NO group in
nitrosamines it may be expected that these can also effect directly chemical reactions in living organisms. We found that
in aqueous solution (pH 4.2 and 3.0 at 3OoC, nitrosamine:
111 For the part of this lecture dealing with the effects of UVirradiation, cf. Naturwissenschaften 52, 513 (1965).
[2] H. Druckrey, R . Preussmacn, G. Blum, S. Ivankovic, and
J. Afkham, Naturwissenschafteh 50, 100 (1963).
[3] D . F. Heath, Nature (London) 192, 170 (1961); P . N. Magee
and E. Farber, Biochem. J. 83,114 (1962); H. Druckrey, R. Preussmann, D. Schmahl, and M. Miiffer, Naturwissenschaften 48, 134
(1961).
97 1
pyrimidine = 200: 1) dimethylnitrosamine reacts with cytosine, cytidine, and cytidylic acid, but not with adenosine and
guanosine. The reaction is first order with respect to the
pyrimidine with half-lives at p H 4.2 of 13000 min (cytosine),
18800 (cytidine), and 6800 (cytidylic acid). The obvious assumption that the reaction is a deamination is incorrect, since
the expected products uridine and uridylic acid could not be
detected.
Model experiments with the nitrosamines ( 1 a)-(l e) and (2)
showed that the carcinogenic nitrosamines ( I d ) , ( 1 b ) , and
(2) react with urea and cytidine, whereas the non-carcinogenic
compounds ( I c)-(1 e) d o not. These results show that the dialkane hypothesis is not necessary to explain the different
behavior of the nitrosamines.
spectively. 1H-NMR studies show that (2) and (3) ionize in
liquid sulfur dioxide to chlorotropylium chloride and 1chIoro-4,5-benzotropylium chloride, respectively. With
SbC15, (1)-(3) form the hexachloroantimonates.
With phenols, (1) gives hydroxyarylcyclopropenylium salts [I].
The cyclopropenylium salt formed from (1) and anthrone
can be deprotonated with triethylamine to the methylenecyclopropene derivative (4). Contrary to previous assumptions C21, the reaction of diphenylcyclopropenylium perchlorate with anthrone in glacial acetic acid/pyridine leads
not to (4),but to I0-(2,3-diphenylallylidene)anthrone.
4,6,8-Trimethylazulene is also electrophilically substituted by
(1) ; the isolatable perchlorate (7) reacts with ethanol in the
presence of bases to l-(l-ethoxy-2,3-diphenylcyclopropenyl)4,6,8-trimethylazulene.
R,
N-NO
R''
(4):
x=
0)
a: R
=
R
=
b:
c: R
R' = CH,
R' = CzH,
= CH3;
R'
4c6H5
C6H5
d: R = CH3; R' = (CH3)3C
e: R
=
(SA
R' = ( P ) C H , - C ~ H ~
x=
= c6H5
(6): X =
;o
a
CH3
20
The Electronic Structure of Metal
Tri(cyclopentadieny1) Complexes
R . D . Fischer, Munchen (Germany)
The bonding in lanthanide and actinide complexes containing three equivalent, centrally attached C5H5 ligands was investigated with a simple LCAO-MO method. The qualitative one-electron approximation already shows that each complex (C5H5)3M has one unoccupied, non-bonding molecular
orbital of rotational symmetry along the molecular axis.
This essentially covalent model explains the unexpectedly
strong Lewis acidity of most tri(cyclopentadieny1)-lanthanide
complexes and the ready formation of many surprisingly
stable adducts :
(CsHs)sM+ :B
C6H5
(7)
Anthrone with (2) and (3) gives the heptafulvene derivatives
(5) and (6), respectively, corresponding to (4). With phenol,
2,6-dimethylphenol, and 2,6-diethylphenol, (2) reacts in fair
salts (8). Comyields to x-chloro-(p-hydroxypheny1)tropylium
parison of the vC=,, frequencies and the dipole moments of
(4)-(6) [ ( 4 ) : 1630 cm-1, 9.4 D ; ( 5 ) : 1655 cm-1, 3.8 D;
(6) : 1655 cm-l,3.7 D] shows that the methylenecyclopropene
system is a stronger electron donor than the heptafulvene
system.
[I] B. Fiihlisch and P . Burgle, Tetrahedron Letters 1965, 2661.
[2] B. Fiihlisch and P. Burgle, Angew. Chem. 76, 784 (1964);
Angew. Chem. internat. Edit. 3, 699 (1964).
+ (CsHhMB
A satisfactory explanation can also be given for the low
magnetic moment and the relatively high dipole moment of
(C5H5)3U [21. The MO treatment further enables the U-BH4
linkage in (C5H5)3UBH4 [21 to be understood, as well as the
green colour of (C5H5)3Yb, which is unusual for Yb(lI1)
complexes.
[l] E. 0. Fischer and H . Fischer, Angew. Chem. 77, 261 (1965);
Angew. Chem. internat. Edit. 4, 246 (1965).
[21 Y. Hristidu, Dissertation, Universitat Munchen, 1962.
21
Cyclopropenylium and Tropylium Systems
B. Fohlisch, P. Burgle, and D . Krockenberger,
Stuttgart (Germany)
The strongly polarized ketones diphenylcyclopropenone,
tropone, and 4,5-benzotropone react already at 0-20 O C with
phosgene almost quantitatively to 3,3-dichloro-1 ,Zdiphenylcyclopropene ( I ) , 7,7-dichlorocyclohepta- 1,3,5-triene (2),
and 7,7-dichIoro-3,4-benzocyclohepta-1,3,5-triene
( 3 ) , re-
972
&c6
22
The Influence of the Crystal Field on the Acidity of
Protons in the Crystal and on the Surface
F. Freutzd, Gottingen (Germany)
In hydroxides the proton is situated within the electron cloud
of the oxygen ion. When optical excitation is excluded, it
vibrates in the zeroth energy level of a potential energy well,
the form, position, and connection to neighboring potential
wells of which is determined by the gradient of the electric
field and the electron density "p(H)" at the proton position.
The proton in the electron cloud of the oxygen ion and the
cations partly bound covalently to the OH- group perturb
the charge distribution of the oxygen ion: the more covalent
the cation-oxygen bond, the weaker the oxygen-proton bond,
i.e. p(H) is decreased and the proton becomes more acidic.
The component of the coulomb field of the cation along the
0 - H direction causes a n additional loosening of the 0-H
bond.
If 0 2 - ions are present as ligands in addition to OH- groups
(as in many oxide hydroxides), the cation is polarized preferably towards the more electronegative 0 2 - ligands, so that
Angew. Chem. internat. Edit.
Vol. 4 (1965) No. 11
the cation-hydroxyl bond is weakened. This releases electron
density from the oxygen ion of the hydroxyl group, which becomes available for firmer binding of the proton: p(H) is increased, the proton acidity decreased. The magnitude of this
effect increases with increasing polarization of the cations by
0 2 - compared to OH-.
23
of the INH concentration in the plasma after injection of
INH with the specific activity of the enzyme proteins determined spectrophotometrically in the acetylation reaction,
where INH is determined colorimetrically as the coupling
product with vanillin.
Differences in the specific activity indicate enzyme variants of
INH-acetylase and genetically determined polymorphism for
the INH-acetylation in these species similar to that observed
in man.
The Interaction of Pigments and Binders
in Solid Paint Films
W. Funke, Stuttgart (Germany)
Infrared-Spectroscopic Investigation of Barbiturates
From the dependence of water absorption and water permeability of paint films on the volume concentration of pigment, the behavior of the pigment/binder interface in the
presence of water can be determined. If the adhesion of the
binder to the pigment is maintained on uptake of water, the
water uptake is, relative to the amount of binder, independent
of pigment volume concentration, whereas the water permeability decreases with increasing pigment volume concentration. If the adhesion is lost on water uptake, this
uptake increases with pigment volume concentration corresponding to the expansion (swelling) of the binder. Since
in this case the water vapor need not diffuse through the
binder, but can make its way through the crevices on the
surface of the pigment particles, the vapor permeability
increases with increasing pigment volume concentration.
When soluble subszdnces are present on the pigments or at the
interfaces, osmotic processes can lead to increased water absorption if the permeation of these soluble substances through
the binder is retarded. As soon as the pigment volume concentration becomes sufficiently large, the binder becomes
permeable and the water uptake decreases again.
Electron-microscopic investigations showed that in solid
paint films relations exist between both water uptake and permeability to water vapor and the state of agglomeration.
24
Enzymatic Reactions of Isonicotinic Hydrazide
H. W. Goedde, W. Schloot, and A . Valesky,
Freiburg (Germany)
The tuberculostaticum isonicotinic hydrazide (INH) is converted mainly into acetyl-INH in animals and excreted as
such in the urine. Enzyme preparations were made from liver
homogenates of Cercopithecideae ( C . aethiops sabaeus). By
the use of 14C-labelled acetyl-coenzyme A it was shown according to the reaction
Acetylase
INH + [14C]-acetyl-S-CoA __
25
S. Goenechea, Bonn (Germany)
The following characteristic absorption bands were found in
the infrared spectra of 21 barbiturates:
The N-H stretching vibrations give rise to two strong bands
at 3220-3200 and 3100-3080 cm-1. Some of the compounds
show a third band in this region; only for Luminal does this
band appear at 3310 cm-1.
In all spectra three carbonyl bands are observed: at 1750,
1730, and 1690 cm-1 (amide I-band). The derivatives which
are not N-methylated show an additional absorption between 1540 and 1515 cm-1 (amide 11-band). This band is absent from the spectra of N-methylated barbiturates, whereby
they can be distinguished.
Substituents at C-5 have the following effects: The asymmetric CH3 stretching vibration of alkyl groups gives rise to definite absorption at 2975-2960 cm-1. If the substituent is
small (e.g. ethyl, isopropyl, or n-propyl), then, depending on
the nature of a second substituent, additional bands can appear at 2990-2980 cm-1 and 2960-2950 cm-1. This splitting
occurs when the second substituent is ethyl, allyl, bromoallyl,
phenyl, or cycloalkenyl. The symmetric CH3 stretching vibrations are assigned the absorption at 2875 5 10 cm-1. The
asymmetric CH2 stretching frequencies (2950-2930 cm-1) become noticeable only when many CH2 groups are present.
The absorptions due to the symmetric CH2 stretching vibration are generally very weak.
Ally1 groups absorb at 1640-1637 cm-1; the bromoallene residue absorbs at 1620 cm-1 and can readily be recognized in
the presence of the allyl group. Vinyl substituents give a band
at 1630-1628 cm-1. Al-Cycloolefins as substituents on C-5,
on the other hand, do not absorb between 1680 and 1600
cm-1. In allylcyclopentenylbarbituric acid the allyl absorption also is missing.
Alcoholic OH groups on C-5 give a strong absorption band
around 3470 cm-1. Phenyl substitutents can best be recognized by the three sharp bands at 1590, 1575, and 1490 cm-1. In
the spectrum of Luminal the band at 1590 cm-1 occurs only
as an uncharacteristic shoulder.
[14C]-acetyl-INH
+ COA-SH
that acetyl-coenzyme A is the acetyl-group donator in this
reaction.
The acetylation of INH with acetyl-coenzyme A and with the
model substance N,S-diacetylcysteamine can be followed
spectrophotometrically at 303 m p and p H 9.0.
The activity of acetylase preparations from liver homogenates
of Macaca mulatta rhesus can be increased twenty-fold by
precipitation with acid and acetone. At 5OoC the enzyme is
largely deactivated.
The substrate specificities towards INH, p-nitroaniline, p aminosalicyclic acid, and sulfanilamide were studied as a
function of acetyl-coenzyme A or N,S-diacetylcysteamine
concentration, and the inhibition by Hg(I1)Cl-benzoate and
N-ethylmaleinimide were tested.
Further studies with the acetylases of Macaca rnulafta rhesus
and Cercopithecus aethiops sabaeus showed a close correlation
Angew. Chem. internat. Edit. VoI. 4(1965) /No. I 1
26
The Charge Distribution in Phosphazines
H. Goetz, Berlin (Germany)
The controversial problem of possible dx-px conjugation was
studied on phosphazines of the type
(p-X-C6H4)(C6H~)*P=N-N=(9-fluorenyl)
(1)
with X = H, C1, Br, OCH3, and N(CH&, and the corresponding alkyldiphenyl and trialkyl compounds, and on
phosphazines of the type
(p-X-C6H4)(C,H,),P=N-N=C(p-Y-c6H4)(p-z-~H4)
(2)
with Y = Z, C1, and Y = H, Z = NO2 by measurements of dipole moments and ultraviolet absorption spectra.
973
The dipole moments vary between 5 and 10 D, depending on
the substituent. This indicates the resonance
for the ground state, with high participation of the ionic
form, for which in type (2) there is a stronger dependence on
the substitutents Y and Z than on X. The influence of X cannot be explained purely on the basis of its inductive effect.
The ultraviolet spectra of all the compounds show a x + x*
transition at long wavelengths, which can be assigned to the
P=N-N=C chromophore. Solvatochromic effects indicate
a n isoenergetic point [*I, confirming the results of the dipole
moment studies. No n + x* transitions can be recognized.
The x + x* band is considerably shifted towards the blue
with respect to that in symmetrical and asymmetrical diketazines :C=N-N=C :. This is however not due to conjugation across the phosphorus, but to a strong decrease of the excitation energy by the resonance of the ground state. The substituents X in type (2) have less influence on the position of
this x + x* transition than the substituents Y and Z . The
phosphorus atom terminates the conjugation. Further, in the
ground state (x)there is an interaction (in the sense of a qualitative LCAO-MO model) of the pz orbitals of the p-phenyl
substituents with the d, or the d,, orbital of the phosphorus
atom. N o such interactions can be detected in the excited
states (x*).
FCHz
@OzK
FC 2
FCH
H-C,' L C H 2 0 H
H
(61
(7 )
FCHz
FCH
+ H-C, A C H 2 O H + &zOH
F
(S), cis
+ trans
(9)
Esters containing olefinic fluorine (10) can be reduced without elimination of fluorine[II.
[*I At the isoenergetic point the participation of the two resonance forms is equal.
6-Fluorogeraniol(16) can be obtained in five stages from ( I ! )
27
Fluoroisoprenols
W. Grell, If. Machleidt, J. Piek, and H. Schumacher,
Bonn (Germany)
FIuoroisoprenols and their pyrophosphates deserve interest
as antimetabolites of squalene and steroid biosynthesis.
LiAIH4 reduces ethyl (3-fluoromethyl)crotonate ( I ) at + 50 "C
to a mixture of 60-70
of (2), 20-10 % of ( 3 ) , and 20 %
of ( 4 ) ; at -78 "C to 86 % of cis/frans-3-fluoromethyl-2butenol(5), 14 % of ( 4 ) , and a trace of (2).
In contrast to (13), the acetylacetic ester (17) is unstable. It
rearranges to the dihydrofuran derivative (18) under elimination of HF.
(4)
+
[l] H . Machleidt and R . Wessendorf, Liebigs Ann. Chem. 674,
1 (1964).
(51, cis
+
trans
(4)
The cyclopropane derivative (4) is formed, essentially independently of temperature, via the adduct ( I a) by SNi substitution. Compounds (2) and ( 3 ) are probably formed by
SNI and/or S N reactions
~
from (Sa), and (3) possibly also
via the adduct (Sb).
Ethyl 4-fluoro-3-fluoromethylcrotonate (6) is reduced by
Li41H4 at -78 OC to 3-fluoromethyl-3-butenol (7), a little
cis/trans-(8), and a trace of (9).
974
28
The Biosynthesis of Nicotinic Acid by
Mycobacterium tuberculosis
D.GroB, HalIe/Saale (Germany)
Nicotinic acid is formed in some fungi and in mammals as a
product of tryptophan degradation. This degradation does,
however, not occur in most bacteria and i n higher plants. In
Angew. Chem. internat. Edit.
Vol. 4 (1965)
1 No. I 1
Mycobacterium tuberculosis (BCG strain), tryptophan is also
not a precursor of nicotinic acid. However, here 14C-labelled
aspartic acid is incorporated into the nicotinic acid molecule.
After application of [4-14C]-aspartic acid, the radioactivity
occurs only in the carboxy group of nicotinic acid, whereas
on application of [u-l4C]-aspartic acid, 14C-activity is found
in the ring carbon atoms, too. By application of [1-14C,4-15N]aspartic acid it was shown that the carboxy group C-1 of
aspartic acid is eliminated in the biosynthesis of nicotinic
acid, that the carboxy group C-4 of aspartic acid supplies the
carboxy group of nicotinic acid, and that the carbon atoms
?,3 and 7 as well as the nitrogen atom of the nicotinic acid are
derived from aspartic acid.
After application of 14C-labelled C3-compounds such as
[2-14C]-glycerol, [1,3-14C&glycerol, [l-14C]-glyceraldehyde,
[ 1-14C]-glycerate, and [3-14C]-pyruvate, the radioactivity recurs in the pyridine ring of nicotinic acid. [2-14C]-Glycerol
and [1,3-*4C]-glycerol are preferably incorporated into C-4,
C-5, and C-6 of nicotinic acid. These results show the following biosynthesis route for nicotinic acid in M . tuberculosis:
Secondary amines or diacylimides react with (1) to give ONacetals of type (2), which can be condensed with CH-acidic
compounds or added to vinyl ethers.
CH3O\
CHCOOCH,
RI2N/
+
R-H
R-CH-COOCH3
I
NR '2
+
(2)
+
RO-CH=CUz
+
RO\
CH-CH2-CH-COOCH3
I
cH30'
NR'2
From (2) and acetyl chloride or thionyl chloride, immonium
salts of type (3) are formed, which give the substituted glycine
C P
R'ZN-CH-COOCH~+ A r - H
@
+
(3)
+
Ar-CO-CH,
+
Ar-CH-COOCH3
I
NR'2
Ar-CO-CH2-CH-COOCH,
I
NR'2
CYc+ YHz-COOH
C H2N,CH-COOH
.--)
+
The pyridine ring apparently is synthesized in the same way in
higher plants and in other bacteria.
29
Syntheses with Methyl Methoxychloroacetate
P(OR)3
+
RO\ 40
fP\
R O CH-COOCH,
derivatives with aromatic or heterocyclic compounds, and
aroylalamine derivatives with ketones. Aliphatic diazo compounds add to (3) ; trialkyl phosphites react by rearrangement
to phosphonic esters as with ( I ) .
H. GroJ and J. Freiberg, Berlin-Adlershof (Germany)
With aromatic compounds in the presence of Friedel-Crafts
catalysts, methyl methoxychloroacetate ( I ) gives either methyl
methoxyarylacetate or methyl diarylacetate:
30
NMR-Spectroscopic Studies of the Equilibrium and
Kinetics of Benzene Oxide - Oxepin Conversions
H . Giinther, Koln (Germany)
ArH
i
CH3O\
CH-COOCH3
C i
AICI,
_ _ f
C HCOOC H3
CH~O'
or
The hypothesis that substituted oxepins are in equilibrium
with the isomeric benzene oxides was confirmed"] on crmethyloxepin synthesized by Vogel and Schubarth.
C H.
A r\
CHCOOCH3
A;
Compound ( I ) adds to unsaturated compounds to give
methyl cr-methoxycarboxylates:
R-CH=CHp
+
(1)
4
R-CH-CHZ-CH-COOCH~
1
t.1
OC H3
From enamines and ( I ) , methyl cr-methoxy-y-ketocarboxylates are obtained after hydrolysis:
HO
R-CO-CR2-CH-COOCU3
I
OC H3
With a n excess of Grignard reagents, ( I ) reacts to glycol
monomethyl ethers; with trialkyl phosphite ( I ) eliminates
alkyl chloride and rearranges to the corresponding dialkyl
phosphonate:
R-CH-7-RCH30 OH
RMgX
(1)
P(OR),
RC1
+
RO\ 00
P
RO' 'YH-COOCH,
OCH3
Angew. Chem. internat. Edit. 1 Vol. 4(1965)
No. I 1
In the N M R spectrum of this compound in CF3Br solution
at about -1 10 "C, the methyl signal is split into a doublet with
chemical shifts TA 8.45 and tg 8.09. The equilibrium con) 4.0 at -90 'C. The temperature-dependstant K (= ~ B / Y A is
ence of K between -74 and -123 "C yields the enthalpy dif0.4 kcal/mole. The activation
ference AH =- H g O - HA
energies (9.3 5 1.0 kcal/mole) of the forward and reverse reaction are the same within the limits of error. The introduction of the methyl group thus lowers the enthalpy difference
between monocyclic and bicyclic isomers relative to the unsubstituted compound. The position of the equilibrium at
higher temperatures is determined essentially by the entropy
term, as in the oxepin case.
[ l ] In collaboration with H . Friebolin, Freiburg.
31
Free-Radical Reactions on Thermolysis of Methyl
Oleate in the Absence of Oxygen
A . K. Sen Gupta, Hamburg (Germany)
*
When methyl oleate is heated to 280 5 "C in a n atmosphere
of argon, homolytic cleavage of the C-C single bonds adjacent to the double bond occurs as well as dimerization. The
975
free radicals are stabilized by recombination, hydrogen abstraction, or addition to the chain end of another molecule.
The main products isolated were 9-octadecene, 9,17-hexacosadiene, methyl decanoate, methyl 9,17-hexacosadienoate,
and dimethyl 9,ll-hexadimethyl 9-octadecene-l,l8-dioate,
cosadien-l,26-dioate.
32
Biochemical Difference Between Fresh and
Frozen Meat
R. Hamm and L. Kormendy, Kulmbach (Germany)
It could previously not be decided with certainty whether a
sample of meat is fresh or had been frozen and thawed. Since
there is no reliable histological test, a biochemical method was
sought. Previous work [1,21 had shown that two isozymes of
glutamate-oxalacetate transaminase occur in the skeletal
muscle of beef and pig. One of these (GOTM) is localized in
muscle mitochondria; the other (GOT,) occurs in the sarcoplasm. The isozymes can be separated by high-voltage electrophoresis on cellulose acetate membranes and determined [21
by spraying the strip with cc-ketoglutarate/malate dehydrogenase/NADH/pyridoxal phosphate [31. The centrifuged
juice of fresh meat shows the GOT, band only. After freezing
(-10 to -4OOC) and thawing, however, GOTM enters the
sarcoplasm, evidently because of damage to the mitochondrial structure. A strong GOTM band is then found in electrophoresis together with the GOTs band. The method is not
affected by the duration of the cold storage nor by the normal
time of aging of the meat.
[l] G. Gantner and R. Hamm, 2. Lebensmittel-Unters.u. Forsch.
126, 1 (1964).
[2] L. Kormendy, G. Gantner, and R . Hamm, Biochem. 2. 342,
31 (1965).
[3] Commercially available as “GOT-Test-Kombination” from
C. F. Boehringer & Sohne GmbH., Mannheim (Germany).
33
Rearrangements of Homoallylic Carbonium Salts
M . Hannck and H. J. Schneider, Tiibingen (Germany)
From 1-bromo-3-butene and I-bromo-3-pentene in nitromethane or dichloromethane, the corresponding tetrafluoroborates were prepared with silver tetrafluoroborate, and the
rearrangements of the carbonium ions were studied as a function of reaction time and temperature. To this end the solutions were hydrolysed rapidly with an excess of sodium
hydrogen carbonate solution, and the alcohols formed were
analysed.
Cyclopropylcarbinols, cyclobutanols, homoallylic alcohols,
and ally1 alcohols were found, the proportions of which
depended on the rearrangement time and temperature. The
roughly equimolar mixture initially formed from the butenyl
tetrafluoroborate of about equal amounts of cyclopropylcarbinyl and cyclobutyl cations first alters its composition
in favor of the cyclobutyl cation, which then is converted
into the ally1 cation. In the rearrangement of the pentenyl
system, the cyclopropylcarbinyl cation is found to be the
more stable. From this it is concluded that the rearrangements
proceed via different ionic intermediates. The results give
indications of the stabiltities and rearrangement rates of the
ions involved.
34
Hydrocyanic Acid in Some Prunoideae Seeds and in their
Products such as Marzipan and Marzipan Substitutes
E. Hanssen and W. Sturm, Hannover (Germany)
The hydrocyanic acid contents of bitter almonds and of apricot and peach kernels are often higher than has been assumed.
On processing of these prunoideae seeds to persipan, es-
976
pecially on soaking in water and by the dehydrating process,
a stepwise decrease of the HCN content takes place, so that
the amounts remaining in the final product are slight and
toxicologically insignificant.
When bitter almonds are baked the hydrocyanic acid is only
expelled in part (depending on the conditions of baking), and
on cooking as well as on burning of bitter almonds practically
no HCN is set free. This is because the emulsin required for
the liberation of HCN is inactivated by heat.
At the optimum pH-value (4-6) the hydrocyanic acid can be
quantitatively liberated at room temperature in 3 hours if
it is distilled directly and titrated. It is warned against acid
hydrolysis (PH < 3) as well as against acid addition before
distillation because the amount of HCN liberated is reduced
by lowering pH. - This method of determination also can be
used to estimate the amount of bitter almonds mixed with
sweet almonds.
35
Non-stationary Processes in the Reduction of Zinc
Oxide with Hydrogen
W. Hirschwold, Berlin (Germany)
The kinetics of the reduction of zinc oxide with hydrogen:
+ Hz(g)
znO(s>
+ Znk)
+ H20k)
was studied between 280 and 500 “C at hydrogen partial pressures of 0.1-0.01 mm. The rate-determining step then becomes the reaction at the phase boundaryinstead of diffusion
in the gas phase.
On sintered samples of almost the theoretical density, a lag
period was observed during which the phase boundary reaction increased to a stationary value. From the temperature
dependence, a change in activation energy is found in the nonstationary initial phase of the reaction.
The following relations were obtained for the rate constants
ki and kst of the reduction of fresh samples and those in the
stationary period, respectively:
ki = lx 1Oa e--195WRT [cm,/sec]
kst = 5 x 104 e--139WRT [cmlsec]
Although under the conditions used solid zinc is not thermodynamically stable, zinc can remain interstitially in the solid
oxide phase and considerably alter the degree of lattice disorder near the surface. Simultaneous measurement of electrical conductivity showed a proportionality of the latter to the
reaction rate. On the basis of this result, chemisorption of
hydrogen as rate-determining step is excluded by the boundary-layer theory.
The results are interpreted with the assumption of catalytic
activity of the interstitial zinc. Pretreatment of the samples in
air and with oxygen ions causes an “extraction” of interstitial
zinc; this supports the assumption made.
36
Determination of Pilocarpine in the Aqueous H u m o r of
the Eye by Polarographic Adsorption Analysis
0.Hockwin, Bonn (Germany)
Pilocarpine, CllH16N202, an alkaloid occurring in jaborandi
leaves (Pilocarpus pennatifolius), is used in ophthalmology to
decrease the pressure within the eye.
In a study of the influence of pilocarpine on the metabolism
of the eye lens, a decrease of oxygen uptake was observed.
At a pilocarpine concentration of 10-3 M in the nutrient
medium of the lens, 02-uptake was completely inhibited.
The usual methods of determining pilocarpine fail in the study
of the aqueous humor because of the small volume (0.1 to
Angew. Chem. internat. Edit. 1 VoI. 4 (1965) / N o . I 1
0.15 ml) of the sample. In polarographic adsorption analysis,
the diminution or suppression of maxima by surface-active
substances is measured. Von Stackelberg and Schiitz measured
instead the displacement of the break-off potential, which is
directly proportional to the concentration of surface-active
agent. This method is suitable for the determination of pilocarpine.
Studies of the aqueous humor of human and rabbits' eyes
showed that 20 min after the administration of pilocarpine,
to 1'10 of the amount taken occurs in the aqueous humor.
The resulting concentration of pilocarpine is sufficient to completely suppress oxygen uptake by the eye lens.
37
Reactions of Tetramethoxyethylene
R . W. Hoffmann, Heidelberg (Germany)
As a particularly electron-rich olefin, tetramethoxyethylene
( I ) is very sensitive to oxidation. With oxygen it gives
methyl trimethoxyacetate (3) (39 %), as well as dimethyl
carbonate (51 %), probably by way of the epoxide (2).
Oxidation with iodine affords dimethyl oxalate (5) (61 %)
and a small amount of dimethyl tetramethoxysuccinate
(6). Occurrence of a radical cation cannot be excluded,
but formation of (5) and (6) is most simply formulated
as involving the tetramethoxyethylene dication ( 4 ) . Attack
of iodide o n (4) gives (5), and attack of (4) on ( I ) gives
(6). In conformity therewith, oxidation by iodine in the
38
Relations between Rotational Isomerism, Hydrogen
Bonding, and Substituent Effects
H. Hoyer and M. Chua, Bonn (Germany)
Intramolecular hydrogen bonds to rotatable carbonyl groups
are supposedly strenthened by the presence of methyl or
methylene groups ortho to the carbonyl group by bond deformation "1. This hypothesis can be tested by measurement
of the infrared spectra of solutions (in CC14) of compounds
in which an O H group is offered a second proton acceptor
besides the carbonyl group for the formation of intramolecular hydrogen bonds.
The spectrum of methyl 5,6,7,8-tetrahydro-2-hydroxy-3nitro-1-naphtoate shows that here the postulated strengthening does not occur, but that the ester group is turned out of
the plane of the aromatic system.
In compounds like N-(4-methylphenyl)-2-hydroxy-3-methoxycarbonyl-5,6,7,8-tetrahydronaphylideneimine o r N-(4methylphenyl)-2-hydroxy-3- methoxycarbonyl - 5,6 - dimethylbenzylideneimine, however, the hydrogen bond to the azomethine group is favored by the ortho methylene o r methyl
group. These groups hinder the rotation of the azomethine
group and thereby reduce the energy difference between the
conformation required for hydrogen bonding and a conformation which is more stable but unfavorable for hydrogen
bonding.
The same explanation is given for the facilitation of hydrogen
bonding to the aldehyde group in 2-hydroxy-3-nitro-5,6,7,8tetrahydro-I-naphthaldehyde.The infrared spectrum in CC14
shows two carbonyl bands. Their intensities indicate that
hydrogen bonding to the aldehyde group is less unfavorable
than in the simpler 3-nitrosalicylaldehyde.
[l] I. M . Hunsberger, H. S. Gutowsky, W. Powell, L . Morin, and
V. Bandurco, J. Amer. chem. SOC. 80, 3294 (1958); idem in
D. Hadzi: Hydrogen Bonding. Pergamon Press, London 1959,
pp. 461-474.
39
(4)
Preparation of Cyanosilanes
J. Hundeck, Miinchen (Germany)
In the presence of chlorotrimethylsilane the yield of cyanotrimethylsilane in the reaction of bis(trimethylsi1yl)amine and
hydrocyanic acid
is approximately doubled.
+
presence of AgBF4, which removes all the iodide as it
is formed, leads to a preponderating amount of (6); this
compound is also obtained from ( I ) by means of AgBF4 or
HgC12 a t a higher temperature.
Compound (6) is obtained on alkylation of (1) by (4) ; similar alkylations are readily effected by other cations, e . g . ,
those from tropylium bromide (62%), benzenediazonium
[ 'z:
CH3
RX
+
+ 3 HCN
+ NH4CI
[(H3C)sSi]zNH (H3C)3SiCI
--f
3 (H3C)3SiCN
L
(I)
-+
R-C-C,.?
CH3
X@] + R-C(OCH3)2-C02CH3
+
CH3X
chloride (88 %), triphenylmethyl chloride (30 %). The larger
the partial positive charge on the alkyl group, the easier is
alkylation of ( I ) , whereas with, e.g., n-butyl iodide there is
no reaction. This shows that ( I ) is readily attacked in a n sN1
reaction but does not function as a nucleophile in S N re~
actions.
Angew. Chem. internat. Edit. 1 VoI. 4 (1965) 1 No. I I
(a)
Adducts of iodosilane with tertiary amines react even at -20
to -70 "C with hydrocyanic acid or cyanogen iodide with the
formation of cyanosilanes, possibly according to Eq. (b).
R3SiI.NR3'+ HCN(1CN)
-+
R3SiCN
+ NR3'.HI
(NR3'.Iz) (b)
The action of cyanogen iodide on methyldialkylaminosilanes
in bulk or in ether solution at 0 to -20 "C gives methyldialkylaminocyanosilanes according to Eq. (c) ( R = C H ~ , C Z H ~ ) .
(H3C)nSi(NR2)4--n+ ICN
+
(HsC)nSi(NRz),-nCN+[NRzII
(c)
Diethylaminodimethylcyanosilane was also prepared from
diethylaminoiododimethylsilane and cyanogen iodide in
28 % yield:
+
(H~C)ZS~[N(CZHS)Z~I
ICN
-+
(H~C)ZS~"(CZH~ZICN12
+
(d)
[l] T. A . Bither, W. H. Knoth, R. V. Lindsey Jr., and W. H. Sharkey, I. Amer. chem. SOC.80, 4151 (1958).
977
Reaction of organylsilylamines with hydrocydnic acid and
cyanogen halide also gives organylcyanosilanes [Eq. (e)].
When organylsilyldialkylamines are used, dialkylcyanamides
and organylsilylcarbodiimides are formed as by-products
[Eq. (01.
+
+
2 (H~C)~S~-NRZ
XCN 2 HCN
+ 2 (H3QSi-CN
NR2(CN)
2 [(HsC)3Si]3N
+
+ XCN + 4 HCN
+ NR2H HX
(e)
+ 4 (H3C)3Si-CN
+ (H3C)3Si-N=C=N-Si(CH3)3 +- NH3.HX
(f)
Trialkylcyanosilanes R3Si-CN ( R = C H ~ , C ~ H Scan
) further
be detected in the reaction of cyanogen with trialkylmethylaminosilanes alongside cyanoformamidine derivatives.
40
Isotope Effects in the Separation of Rare Earths
on Ion-Exchangers
H . Ihie, Bonn (Germany)
Equilibria for chemical exchange of isotopes have hitherto
been measured mainly for light elements (H, Li, B, C, N, 0),
where the equilibrium constants are considerably greater or
less than unity.
For elements of medium to high mass number the equlibriuni
constants K for isotope exchange approximate to unity.
Values of 10-3 to 10-4 can be estimated for E = K - 1.
We have measured the quotients of the distribution coefficients of samarium isotopes between a cation-exchanger and
two complex-forming aqueous phases. Because of the high
selectivity of the ion-exchange chromatography, microcolumns (length 80 rnrn, inner diameter 2 mm) suffice in bandelution experiments to give enrichments that are measurable
by mass spectrometry. Values of E have been calculated from
the measured relative isotope abundances in the eluted
fractions [I]. For two neighboring samarium isotopes, with
mass numbers M and M + 1, the following values of E were
obtained at 20'C:
where r denotes cation-exchanger Dowex 50 W X 4, wl denotes
aqueous 0.4 M a-hydroxyisobutyric acid of pH 3.45, and w2
denotes aqueous 0.43 M tartronic acid of p H 2.00.
The results are lower than those estimated from current
theory. The discrepancy probably arises because the theory
requires a series of simplifying assumptions that cannot be
verified experimentally.
111 E. Glueckauf, Trans. Faraday SOC.54, 1203 (1958).
41
Alteration of the Barrier-Layer Properties of OxideProtected pn-Junctions in Silicon
D.Jahn, Baden (Switzerland)
The rectifying properties of pn-junctions in silicon can be
stabilized by covering the crystal surface with an insulating
protective coating, particularly at the intersection of the
junctions with the surface. If SiOz is used as insulator, which
can be applied to silicon in thicknesses of several p by oxydation at high temperatures, this oxidation process often has
978
unfavorable effects on the rectifying properties, i. e. redistribution of doping agents at the phase boundary Si/SiOz in accord with the distribution coefficients, rapid diffusion of impurities with high temperature coefficients of solubility into
the crystal and formation of inclusions on cooling, and
formation of inversion layers in the silicon owing to space
charges in the SiOz layer.
The blocking action of silicon samples with npn structure
(P-diffusion in p-Si of 103 ohm.cm) and mechanically and
chemically exposed pn junctions having a hard characteristic
and high blocking voltage (> 1000 volts) was lost on oxidation in dry 0 2 at 1000°C (SiOn film thickness 0.1 p). This
change is due partly to a surface effect. When the oxidized
samples were polarized for several minutes at 50-200 volts
versus a platinum cathode in an electrolyte (e.g. glycol with
2 % of H z 0 and 0.4 % of KN03), high blocking voltages
were again obtained, although the characteristic remained
soft (which indicates defects in the bulk of the material). The
same changes are observed when the oxide layer is removed
with H F or when the sample is etched with HFIHN03. The
possibility of changing the effect of the thermally produced
SiOz layer on the semiconductor by electrolysis supports the
assumption [I] that near the Si/SiO2 interface there are oxygen
vacancies in the SiOz, which represent a strong positive space
charge. In the high field prevailing during the electrolysis,
migration of ions is evidently possible already at room temperature, which leads to elimination of the space charge.
[ I ] J. E.Thomas and D . R. Young, IBM Journal 8, 368 (1964);
M. Croset, Onde Electrique 45,499 (1965).
42
Conversion of Diaziridines into Azines
A . Jankowski, Essen (Germany)
Diaziridines ( I ) are isomeric with hydrazones. Like hydrazones they are hydrolysed by acids to a hydrazinium salt and
a ketone. In contrast to hydrazones they cannot be hydroIysed in neutral o r alkaline media, which limits their applicability in hydrazine synthesis via diaziridines.
Diaziridines can be converted into azines (2) with a new reaction: Treatment of diaziridines with catalytic amounts of
acids, aqueous solutions of acid salts (e.g. hydrazine sulfate),
or acidic agents (ion exchange resins), in the presence of a
carbonyl compound and with the medium kept acidic,
opens the ring and an exothermic reaction with the carbonyl
compound takes place which yields the azine.
R, /NH
,c,l
R
NH
+
R,
c=o
'
R
H+
R,
R
R'
R
C=N-N=C:
+ H~O
The rate of conversion is strongly temperature-dependent.
At 50 "C, C-methyl-C-ethyldiaziridineis completely transformed after 30 min, whereas a t 25 OC the reaction takes 9 h.
The reaction rate is also influenced by the substituents R. It
increases in the sequence C,C-dimethyl- < C-methy1-Cethyl- < C,C-diethyl-diaziridine.
The optimum p H is 2.5. Below this, the azine is partially
cleaved to a hydrazine salt and a ketone; above it a n as yet
unexplained side reaction occurs with the formation of
ammonia and nitrogen, which lowers the azine yields. If
instead of acid a n aqueous solution of a hydrazine salt is
used and the solution is maintained at p H 2.0-2.5, hydrolysis
of the azine is prevented and it is obtained in 95 % yield.
The formation of azines is industrially interesting, since they
can be easily hydrolysed to hydrazine hydrate and can be
used as starting materials in syntheses.
Angew. Chem. internat. Edit
Vol. 4 (1968) No. I 1
42a
An Accurate and Simple Calculation of the
C-C Distance in Benzene
energiesr21, are obtained. With the aid of the segment method
delocalisation energies are calculated for the acenes, which
agree with those obtained with the MO-method. Fig. (c)
J. J . Jennen, Mortsel (Belgium)
There is a discrepancy between the observed C-C distance
in benzene (1.397 A "1) and the average value of C-C single
1.33)/2 = 1.43 A.
and double bond distances: (1.53
According to Rogowski [21 this discrepancy can be attributed
t o a shortening of the C-C single bond. According to the
author a a-delocalization, due to an electron releasing effect
from the three C-H bonds in m-position toward the aromatic ring, is responsible for said shortening. Consequently,
the Kekule structure ( I ) changes into a Thiele structure (2)
with saturated partial valencies. For structure (Z), wherein
a-electrons also are involved, the author introduces a segment
+
Ib/
/C/
111
illustrates the situation for naphthalene [surfaces 2, 3 and 8
are equivalent since the segments of the central bond are
spinless (a = O).].
(1.43)
r~
Delocalisation energies in
( 3 ) O = 0"
( 4 ) O = 60"
a = 0"
a = 30"
( 5 ) O = 120"
a
=
60"
notation[31 [see (3) to (5)]; the segment radius for single
and double bonds remains unaltered. In order to describe
the bond configurations a segment must rotate around the
z-axis of the carbon atom considered (angle 0 ) and simultaneously around the segment axis (center of the circle middle of the arc) (angle cc = 0/2). In this way only three
structures result: one Kauffmann (3) and two Thiele structures (4) and ( 5 ) ; from this it follows that the mean bond
1.43
1.43)/3 = 1.397 A, in
length in benzene is (1.33
agreement with the observed value
+
+
[ I ] A . Atmenningen, 0.Bastiansen, and L . Fernholf, Kgl. norske
Vidensk. Selsk., Skr. Nr. 3 (1958); A . Langsefh and 8. P . Stoicltef,
Canad. J. Physics 34, 350 (1956).
[2] F. Rogowski, Fortschr. chem. Forsch. 4, 44 (1962).
131 J. J. Jennen, J. prakt. Chem. 121 25, 188 (1964).
42b
A New Semiquantitative Calculation of the
Delocalisation Energy in Benzene and in the Acenes
J . J. Jennen, Mortsel (Belgium)
The ring currents generated by the mobile electrons (six
x-electrons and six a-electrons) in benzene are represented
graphically using the segment method 111. In this way Fig. (a)
is obtained, wherein for a mobile electron half of the entire
path is represented (the other half is enantiomorphic to the
plane of the benzene nucleus). By the segment spin and the
exchange in the Kauffmann structure the mobile electrons
travel alternatively above and below the ring plane. By
projection of the path shown in Fig. (a) the equivalent
surfaces of Fig. (b), which are a measure for the delocalisation
[ I ] Graphical representation with six x-electrons alone: J . J.
Jennen, Meded. vlaamse chem. Veren. 26, 208 (1964) [KekulB
issue].
Angew. Chem. internal. Edit.
V o l 4 (1965) / No. I I
Acene
segment method
I
MO-method
-----I-
Benzenz
Naphthalene
Biphenyl
Anthracene
Tetracene
6 x 113
x 1/3
13 X 1 / 3
16 x 1 / 3
21 X 1/3
11
=2
= 3.67
-4.33
= 5.33
= 7
3.68 I31
4.38 131
5.32 I31
6.93 f41
[2] For this concept cf. also A . f. Stavermann, Chem. Weekbl.
39, 344 (1942), Chem. Zbl. 1942, I1 2466.
131 H. A . Staabc Einfiihrung in die theoretische organische
Chemie. Verlag Chgmie, Weinheim/Bergstr. 1959, p. 121.
141 A . Streifwieser j r . : Molecular Orbital Theory for Organic
Chemists. Wiley, New York, 1961, p. 241.
43
Coronaphenes, a New Group of Cyclic Hydrocarbons
W. Jenny and R . Peter, Basel (Switzerland)
The influence of ring fusion on the absorption spectra and reactivity of ortho-fused benzenoid hydrocarbons has repeatedly been studied in the acene and phene series. The empirical
rules obtained can be extended only with reserve to angularly
fused phenes which are combined in a larger polycyclic ring
system. A number of new hydrocarbons was synthesized with
the aim of studying these relations. The new polycyclic compounds are related to the circo-hydrocarbons, but in contrast
to these they have an "empty" interior. The name coronaphene is proposed for these compounds, with a numerical prefix indicating the number of benzene rings fused in the molecule. All coronaphenes formally contain two concentric annulene systems and are therefore also of theoretical interest.
A synthesis leading to the skeleton of a [lo]-coronaphene is
described. Starting from l,l-di-p-tolyl-2,2-ethoxycarbonylethane, the diol ( I ) was obtained after several steps. By dehydration and dehydrogenation, this was converted into 3,lOdimethylbenzo[c]phenanthrene (2) in 50 yield. The action
of phenyl-lithium o n the dibromomethyl derivative (3) gave
di(benzo[c]phenanthren-3,10-dimethyIene) (4), the structure
of which was confirmed by N M R and mass spectra. Extensive dehydrogenation of ( 4 ) was achieved by treatment with
AlCI3/CS2 and subsequent heating in the presence of Pd:C
979
3
H3 c.
BrHzC
$
-+
H3C
BrHzC
,
(2)
J
are poorly soluble in non-polar solvents, are unstable and decompose below their melting points. Only (Ib) and ( I c )
could be obtained pure; ( I d ) was obtained only in solution.
By contrast, the fluorenyiidenedihydroquinolines(3a)-(3d)
and (4a)-(4d) are stable, deeply colored compounds of low
polarity and basicity.
(3)
(3a): n = 0 (3c): n = 2
(3b): n = 1 (3d): n = 3
c
(4a): n = 0 (4c): n = 2
(46): n = 1 (4d): n = 3
[Amax (log E) in acetonitrile: (3a) (m.p. 220 "C), 541 m p (4.30);
(3b) (m.p. 215 "C), 547 mp (4.60); (3,) (decomp. at 229 "C),
562 mp (4.68); (3d) 574 m p (4.84); (4a) (m.p. 181 "C), 523 mp
(4.34); (46) (m.p. 212 "C), 503.5 m p (4.65); (4c) (m.p. 215 "C),
539 mp (4.79); (4d) (decomp. at 214 "C), 552 m p (4.84)I.
to 320-340 "C in a current of COz. A greenish-yellow dihydro
derivative (5) was isolated by repeated column chromatography.
44
Studies on Azalogous Sesquifulvapolyenes
Ch. Jutz, R . Kirchlechner, and W. Muller,
Miinchen (Germany)
Vinylogous azalogues of sesquifulvalene (with the pyridine or
quinoline system instead of the cycloheptatrienylidene group
in sesquifulvalene) were previously unknown. For an investigation of bathochromic shifts of the principal absorption
when the polyene chain is extended, the set of compounds
(1b)-(Id) was built up by reaction of the vinylogous 1methyl-4-aminopyridines (2a)-(2c) with cyclopentadienylsodium in tetrahydrofuran.
(/ah n =
o
(lb): n = 1
111
Compounds ( 3 a ) , (3b), (4a), and (4b) were obtained by reperaction of 4-methoxy- or 2-methoxy-N-methylquinolinium
chlorate with fluorene or 9-ethylidenefluorene, respectively,
and sodium methoxide; (3c), (3d), (4c), and (4d) were
prepared from vjnylogous N-methyl-4- or N-methyl-2-aminoquinolines. Electrophilic substitution on the 4-(1 h d e n y l idene)-1,4-dihydropyridine system, (S), R = H, leads to derivatives substituted in the 5-membered ring: The action of dimethylformamide/POC13 leads via the immonium perchlorate
(Sa) (Amax = 475 my, log E = 4.64) to the aldehyde (Sb)
(Amax = 475 mp, log E = 4.97); (5) with p-dimethylaminobenzaldehyde and perchloric acid gives the dye salt ( 5 c )
(lmax
= 51 5 mp, log E = 4.67; methylation of ( 5 ) , R = H, with
dimethyl sulfate gives ( 5 d ) ; coupling of (5) with diazonium
salts leads via a cation to the azo compounds (Se) (Amax =
639 mp, log E = 4.9).
R
(Sa): R
=
R'=
(Sb): R
=
R'
R'
(lc): n = 2
(54: R =
(ld): n = 3
(Sd): R
fSe): R
(Sf): R
[hmay. (log E) in acetonitrile: ( l a ) , 438 mp (4.57); ( I b ) 542, 515
=
=
=
R'=
=
H; R ' = n-C4H9; R" = - N = N - C &
H; R' = n-C4H9; R" = -N=N-p-C6H4-N02
=
m p (4.69; 4.71); (Ic) 584 mp (4.8); (Id) 602 my].
45
Ternary Oxides of Seven- and Four-Valent Technetium
(20): n = 1, R = CH3
(26): n = 2 , R = C & ,
(2c): n = 3 , R = C6HS
[Amax (log f) in acetonitrile: (2a) 399.5 m p (4,96) (26)
483 m p (4.93); (Zc) 575 m p (4.96)J.
Compound (2) was obtained from N-methylpicolinium perchlorate by reaction with dimethylformamide dimethylacetal,
(2a) and (2b) by reaction of 3-(N-methylanilino)prop-l-enylidenemethylanilinium and 3-(N-methylanilino)penta- 1,3-dienylidenemethylanilinium perchlorates, respectively, and sodium methoxide. The betaine-like basiccompounds ( I ) , which
[ l ] J . A. Berson and E. M. Evleth, Chem. and Ind. 1961, 1962;
J . A . Berson, E. M , Evleth, Z . Hamlet, and L. Manatl, J. Amer.
chem. SOC. 87, 2887 (1965).
980
C. Keller, 3. Kaneifnkopulos, and M. Wassilopulos,
Karlsruhe (Germany)
Tc(VI1) and Re(VI1) are closely related crystallochemically.
Thus the alkali pertechnetates MTc04 (M = Li to Cs),
M ~ T c O(M
~ = Na, K), and M5TcO6 (M = Li, Na), the alkaline earth pertechnetates MXI(TcO4)z (M = Ca to Ba),
M3II (TcO& (M = Ba, Sr), and MsU(Tc06)2 (M = Ca to
Ba), and the quaternary oxides MI1(M1o.s, TcV" 0 . 5 ) 0 3
(MI1 = Ba, Sr; MI = Li, Na) with ordered perovskite structure, largely correspond to the analogous perrhenates. When
Sr(TcO& and Ca(Tc04)~are prepared by the evaporation of
aqueous solutions, the dihydrates are obtained, which at
9OoC (Sr) and 100°C (Ca) are transformed to the monohydrates, which are dehydrated at 21OoC (Sr) and 155°C
(Ca), respectively, to the anhydrous compounds. The pertechnetates are generally less stable than the perrhenates. Any
Angew. Chem. internat. Edit.
Vol. 4 (1965)l No. 11
phase transition temperatures are always lower in the Tc
compounds, e.g. the transformations of orthorhombic
CsXO4 and TKO4 to the tetragonal Scheelite structure occur
at 95 "C (TlTc04) and 136 OC (CsRe04), respectively. In the
compounds of the six-valent elements, the differences in
transition temperatures are considerably larger, e,g. aLi6xo6 + p-LisX06 at 3 10 "C and 620 "C for X = Tc and Re,
respectively.
In its solid-state chemistry, TcOz shows no similarity to ReOz.
Whereas only one ternary oxide, viz. NazRe03, has so far
been prepared with Re(IV) [in most cases disproportionation
of Re(IV) occurs in the reaction of Re02 with MzO or MO],
TcOz reacts to give defined compounds of Tc(IV), e.g.
LizTcO3(LizTi03 structure), Na2TcO3, Na4Tc04, MTc03
( M = Ba, Sr, Ca; perovskite structure), and MzTc04 (M =
Ba, Sr; KzNiF4-structure). BaTcO3 was obtained in two
modifications: in the direct reaction BaO + TcOz, BaTc03 is
formed in the BaTiO3-structure (a = 5.763 A, c = 14.05 A);
in the symproportionation from BaO + Tc + Ba(TcO&, cubic
BaTc03 (a = 8.140 A) is obtained. Tc(IV) thus is similar to
Mn(IV) in its solid-state chemistry.
46
Attempted Preparation of Carbenes, Nitrenes, and
Sulfenes
D . Klamann and K. Ulm, Hamburg-Harburg (Germany)
Although trihalomethanes and chloromethyl phenyl sulfide
form carbenes with ethylene oxide in the presence of tetraalkylarnmonium halides, alkyl, allyl, and benzyl halides and
p-toluenesulfonates, as well as halogen compounds activated
by neighboring groups, give the corresponding alkyl2-substituted ethyl ethers smoothly under thesame conditions. In these
reactions the reactivity, but also the concurrent p-elimination
of HX, increases along the series chlorine to iodine and with
increasing substitution of the alkyl residue. Dihalomethanes
afford bis-(2-halogenoethyl)formals.
On treatment of N-halo compounds such as N-chloroamines
and N-haloamides and -urethanes under the same conditions,
the nitrene intermediates could not be isolated. Chlorination
of the reactant (especially ethylene oxide) and polar addition
of the N-halo compound to the acceptor double bond occur.
On treatment of methane- or benzenesulfonyl chloride with
ethylene oxide in the presence of tetraalkylammonium halides
and addition to substituted butenynes or butadienes, ethylene
oxide is inserted into the SOzCI group, yielding 2-halogenated
sulfonic esters. This reaction is general for sulfonyl chlorides
and epoxides.
47
Preparation and Reactions of Dihalocyclopropanes
D . Klamann and P. Weyerstahl, Hamburg-Harburg (Germany)
Dihalocarbenes are formed when trihalomethanes are heated
with ethylene oxide in presence of tetraalkylammonium salts
at 12O-17O0C. By reaction of open-chain and cyclic monoand di-olefins numerous, mostly new, 1,l-dichloro-, 1,l-difluoro-, and 1-chloro-1-fluorocyclopropaneshave been prepared. Diolefins afford various amounts of bis-adducts.
Reaction of chloroform and ethylene oxide with tetrasubstituted ethylenes does not afford the primary product, but the
2-chlorodiene was obtained as a result of elimination of
hydrogen chloride and isomerization. One or the other product can be obtained from trisubstituted olefins, depending on
the reaction temperature.
1,l-Disubstituted olefins cannot be converted directly into
2-chlorodienes by reaction with chloroform and ethylene
Angew. Chem. internat. Edit./ Vol. 4 (1965) / No. I 1
oxide, but the resulting dichlorocyclopropanes are smoothly
cleaved to the 2-chlorodiene and hydrogen chloride by quinoline at 200 "C or by pyrolysis at about 400 "C.
48
Synthesis of Aliphatic Amines from Carbon
Monoxide, Steam, and Ammonia
H . Kolbel and J. Trapper, Berlin (Germany)
At 200 to about 270 "C, the equilibrium
3n CO
+ n HzO + NH3 +
+ 2n COZ
CnH2n+lNHz
favors the products, in which amines with many carbon atoms
predominate over those with few. The reaction is exothermic
and was studied at 11 atm total pressure of a gas consisting
of, e.g., 5 6 % of CO, 21 % of H20, 1.1 % o f NH3, and 22%
of an inert gas. An iron catalyst containing small amounts
of copper and potassium carbonate was used. In continuous
operation (for several weeks), a single passage of the gas
through the reactor gives conversions of 80 % for CO and
3 0 % for NH3 at a gas velocity of 50-60 liters per liter of
catalyst per hour.
The liquid products contain, apart from hydrocarbons, up to
23 % of nitrogen-containing compounds, mainly l-aminoalkanes from methylamine to n-dodecylamine. About 50 %
of the non-gaseous products are liquids; the rest have the consistency of soft to hard paraffin waxes. The nitrogen content
of the hard paraffin (up to 1.35 %) suggests that more than
50 % of the constituent molecules contain nitrogen. Oxygen
compounds are also formed, e.g. alcohols, carbonyl compounds, and fatty acids. It is therefore probable that amino
acids are also formed, but significant amounts were not
found. Since the melting points of the amino acids expected
lie in the range of the synthesis temperatures, they probably
decompose during the process.
If the yields can be increased, this reaction should be suitable
for the technicalproduction of the aliphatic amines mentioned.
49
A New Photochemical Reaction of Benzene and Some
of Its Homologues
G. Koltzenburg and K . Kraft, Miilheim/Ruhr (Germany)
Under direct photochemical excitation at 254 mp, benzene
reacts in even dilute solutions (in ether, n-pentane, etc.) with
isoprene to give at least ten products. The two chief products,
a 2:2 adduct (46 %, based on benzene consumed) and a 1 : 1
adduct (23%), were isolated.
The 2: 2 adduct, C22H28, forms colorless crystals melting at
164-168 OC. It contains five non-conjugated double bonds;
four cis-substituted double bonds come from benzene and
one exo-methylene group from isoprene (shown by comparison of the NMR spectra of C22H28 and the analogous adduct
of C6D6 and isoprene, CzzD12H16). One of the two methyl
groups of the isoprene molecules is retained; it is found on a
tertiary carbon atom. The compound can be hydrogenated
under pressure. After hydrogenation of the four cis double
bonds, the exo-methylene group is saturated only at 100
atm of Hz.
The 2 2 adduct isomerizes at 130 "C to a colorless, lower-meltingcompound (m.p. 82-85 "C)containing a 1,3-~yclohexadiene
partial structure (Amax = 38400 cm-1, E = 3400 in cyclohexanel
98 1
The 1: 1 adduct, a colorless oil of b.p. 55 OC/6 mm, is probably a mixture of stereoisomers ( I ) .
Crystalline 2:2 adducts were obtained from toluene (m. p.
132-138 'C),p-xylene (m.p. 170-196 "C),a-xylene (m.p. 150170 "C), hexafluorobenzene (m.p. 238-271 "C), and 1,2,4,5tetrafiuorobenzene (m. p. 230-241 "C). Benzene and butadiene
also form a 2: 2 crystalline adduct which sublimes at 195 "C.
In the presence of sensitizers such as benzophenone and benzil, n o crystalline adducts were obtained. Irradiation with electrons or with y-rays from 60Co also failed to produce adducts.
2-Alkyl- and 2-Arylisoindoles are obtained from 2-alkyl- or
2-arylisoindoline-2-oxides in the presence of acetic anhydride
and triethylamine, even at 0 "C, and can be isolated in pure
form by distillation or crystallization [21. 2-Arylisoindoles can
also be obtained from 1,2-dibromobenzocyclobutene and
primary aromatic amines.
1 -Arylisoindoles are formed on reductive cyclization of 2cyanobenzophenones with hydrogen and Raney nickel; 1,I,diaryl-3,3'-dehydrobiisoindoles are by-products which can
be regarded as diazafulvalene derivatives.
The substituted isoindoles react like isoindole itself with
philodienes as in the Diels-Alder reaction or Michael addition. According to the substituents on the nitrogen, 1: 1 o r
1 : 2 adducts are formed; their constitution and configuration
have been elucidated in several cases.
[ 2 ] R . Kreher and J. Seubert, Angew. Chem. 76, 682 (1964);
Angew. Chem. internat. Edit. 3, 639 (1964).
50
Reactions with Sulfur Ylides
52
H . K8nig, Lud wigshafen (Germany)
Dimethyloxosulfonium methylide ( I ) was acylated in usually very good yield to the crystalline mono- and diacyl derivatives (2) and (3).
ss=o
( I ) R'
( 2 ) R'
( 3 ) R'
=
H. Krimm, Krefeld-Uerdingen (Germany)
p-Isopropenylphenol dimerizes readily to ( I ) , less easily
to (2).
R," ,R'
H3C'
Reactions o f p-Isopropenylphenol
HO-&H:H2-$oOH
CH3 H2C
'cH3
R2 = H
(I)
(4)
R2 = CO-R
CO-R'; R2 = CO-R
= H;
=
The structure elucidation of the new class of compounds is
based inter alia o n the strong displacement of the carbonyl
band to longer wavelengths (A- 6.4p), on the ultraviolet and
particularly on the N M R spectrum, which shows a characteristic 6-proton singlet due to the methyl groups on the sulfur
atom.
The trimer (3) occurs in two geometrically isomeric forms.
Two further, saturated oligomers (4) and (5) have indane
structures.
The reaction of excess of benzonitrile with ( I ) gives inter
alia a crystalline heteroaromatic ylide (4).
R-8-FH
O ?
(2) +
X+Y
Y
Compounds (2) and (3) react in 40-99 % yield with simultaneous addition of a n electrophilic particle X and a nucleophilic partner Y , and elimination of dimethyl sulfoxide, to
carbonyl and I ,3-dicarbonyl compounds. Suitable combinations XY are, e.g., formally the ions X = H+, CH,+, Bri, and
Y = CI-, Br-, H-, CsHsS-, C G H ~ N H - .
The reactions of p-isopropenylphenol with phenol to 2,2-bis(p-hydroxypheny1)propaneand with aniline to 2,ZCp-aminop-hydroxydipheny1)propane (6) are reversible. In (6) the
hydroxyphenyl and aminophenyl groups are interchangeable.
This leads to 2,2-bis-(p-hydroxyphenyl)propaneand 2,2-bis(p-aminopheny1)propane in good yields.
51
N e w Syntheses and Reactions of Isoindoles
R. Kreher and J. Seubert, Darmstadt (Germany)
CH-active compounds add to p-isopropenylphenol; e.g.,
malonodinitrile gives (7).
Isoindole is formed from 2-benzyloxyisoindoline by basecatalysed elimination; however, it can be recognized only as
its adduct with maleic anhydride or N-phenylmaleimide "1.
[ i ] R. Kreher and J. Seubert, 2. Naturforsch. 206, 75 (1965).
982
Angew. Chem. internat. Edit.
Vol. 4 (1965)1 No. 11
p-Isopropenylphenol can be copolymerized ionically or freeradically with vinyl monomers. Polyfunctional esters of p isopropenylphenol are particularly suitable for radical copolymerization.
NaCH2CN CHz=C=N-Na
to be present as a mixture in which the first form predominates. The compound forms a crystalline but unstable adduct
with pyridine. It adds to carbonyl compounds according to
53
R2C=O
Geminal Nitrosoacyloxyalkanes and their Dimers
(I)
:
R
,C=N-OH
R2
R-CEN
Pb(OAc),
R\l /No
C
R2' b - C O - C H 3
(2)
(a) R' = RZ = CH3
ld) R' = CH3; R2 = C(CH&
(e) R' = CH3; R2 = C H Z - C & ,
ibJ R' = CH3; R2 = CzH5
(c) R' = R2 = n-C3H7
( f ) - ( i )R'R2 = (CH& n = 4,5,6,7
Pb(0Ac)r
'i2
?
A
( k ) R' = n-C3H7
(I) R' = n-C5HII
R' = n-C7H,,
(nj R' = CH,-C~H,
[ni)
i3)
Infrared spectra of (2) in tetrachloroethylene: C-0: 1215
to 1240 cm-1; CH3-(CO): 1360-1370 cm-1; N=O: 1550 to
1570 cm-1; C=O: 1735-1750 cm-1. Infrared spectra of (3)
in KBr: trans-NO-NO: 1185-1200 cm-1; C-0: 1205 to
1220 cm-1; CH3-(CO): 1360-1375 cm-1; C=O: 1730 to
1750 cm-1.
The structures were confirmed by N M R and mass spectra.
The gem-nitrosoacetoxyalkanes (2) are oxidized to the nitro
compounds (4) by H202/NaN02 "1. Condensation of (2) with
aniline leads to a-phenylazo-a-acetoxyalkanes( 5 ) , DielsAlder reaction with compounds R-CH=CH-CH=CH-R
leads (analogously to the reaction of gem-nitrosochloroalkanes 121) to 3,6-dihydro- 1,2-oxazines (6),whereby alcoholysis
of the alkyl group takes place.
+ NaCHzCN
+ R-C(NHNa)=CH-CN
NaCHZCN +
:CH2
+ NaCN
The doubly and triply metallated acetonitriles are formed
when a n excess of metallating agent is used. They can be detected in the reaction rnixtureL21, but not isolated. Thus the
reaction of a multiply metallated acetonitrile with a,o-dibromoalkanes Br(CH2),Br leads to carbocyclic nitriles (2)
together with compounds of type (3).
n
CH-CN
W
R,'
R'
H -,c - N=N- c:- H
H3C-CO-0
0-CO-CH,
+ R2C(ONa)-CH2CN
Compound ( I ) can function as a carbene source particularly
in the presence of cyanide acceptors:
(HzC),
(1)
+ NaCH2CN
or to nitriles according to
H . KrupL Hamburg (Germany)
Aliphatic ketoximes ( l a ) to ( l i ) are converted into gemnitrosoacetoxyalkanes (2) by lead tetraacetate 111. Some of
the products can be isolated in the monomeric form as deep
= 660-690 mp). From aliphatic aldoximes
blue oils (A,
( I k ) to ( I n ) the nitroso-bridged dimers ( 3 ) are obtained.
CHEC-NH-Na
/7 ,(CHdq
(HzC),
n
c
C
(CH2)"
'CN NC'
(3)
(2)
n = 3-6
[Z] C. Kriiger and E. G . Rochow, Angew. Chem. 75, 793 (1963);
Angew. Chem. internat. Edit. 2, 617 (1963).
55
Reactions with Isocyanide Dichlorides
E. Kiihle and 3.Anders, Leverkusen (Germany)
Zsothiocyanates are obtained in good yields from isocyanide
dichlorides with sodium sulfide solution a t room temperature
or with phosphorus pentasulfide in an inert solvent at a
higher temperature
Isocyanates are accessible from isocyanide dichlorides and
acid anhydrides. The alkoxy compounds obtained from isocyanide dichlorides and alkoxide solutions also give isocyanates with elimination of alkyl chloride.
R
.
[l] Cf. D.C . Iffland and G . X . Criner, Chem. and Ind. 1956,176.
[Z] 0. WichferIe, Collect. czechoslov. chem. Commun. 16, 33
Carbodiimides are formed by heating isocyanide dichlorides
with primary amine hydrochlorides.
Isunitriles can be prepared from isocyanide dichlorides and
organic compounds of trivalent phosphorus.
(1951).
56
54
Rheological Properties of G r i n d i n g Pastes
S o d i u m Acetonitriles, Preparation and Reactions
W. Liehr, Krefeld-Uerdingen (Germany)
C . Kruger, Mulheim/Ruhr (Germany)
Monosodium acetonitrile ( I ) can be isolated as an insoluble
salt, sensitive to air and moisture, by treating sodium bis(trimethylsilyl)amide[~1with acetonitrile in ether at -60 "C.
CH3CN
+ NaN[Si(CH3)3]2
3
NaCHzCN
+ HN[Si(CHM2
(1)
IH-NMR and infrared spectra show all three tautomers
[ l ] U.Wannagat and H . Niederprum, Chem. Ber. 94, 1540 (1961).
Angew. Chem. internut. Edit. 1 Vol. 4 (1965)
Nu. I 1
Grinding pastes rich in pigment and containing dilute solutions of binder are usually recommended for high-speed ball
mills. The method of flow-point determination of Daniel
is proposed for finding suitable compositions for the grinding
pastes. Pastes compounded in this manner are difficult to use
in sand and pearl mills. The addition of binder solution in
excess of that required to attain the flow point has been proposed, in order to obtain almost Newtonian behavior. The
flow properties of pigment-binder systems have now been
studied with a rotation viscometer.
983
It has previously been observed that the flow properties of
grinding pastes change during dispersion. We followed this
change with degree of dispersion using the hysteresis method
of determining flow curves at various constant concentrations
of binder, but with different ratios pigment: binder: solvent,
dispersed in a sand mill.
The results obtained were partly expected: the viscosity decreases with increasing proportion of binder solution; it decreases with increasing temperatures; higher structural viscosity is found with higher proportions of pigment. Some
peculiar rheological properties were, however, also observed:
if the pastes, which become warm during dispersion, are
measured immediately, they are found to be thixotropic. With increasing dispersion time and decreasing
particle size the initially high viscosities decrease.
If the measurements are made some time later dilatancy
is initially observed for the same sample, but on prolonged
shearing a structure is destroyed and thixotropy is restored.
This time dependence, which is opposite to that of rheopexic
systems, might therefore be designated “antirheopexic”. The
flow anomalies become less pronounced with decreasing proportions of pigment in the pastes, the dilatancy decreases,
and Newtonian behavior is approached. Similar observations
on polymer solutions of various concentrations have been
described.
T[”Cl
1
58
Evolution o f Fission Products f r o m Neutron-Irradiated
U r a n i u m Dioxide at H i g h Temperatures
F. Lux, D . Craw, and J . Vogel, Munchen (Germany)
The investigations, based on Hahn’s emanation method, of
the behavior of irradiation products of uranium in heterogeneous reactions of neutron-irradiated uranium compounds
with gases or liquids containing a complexing agent “1 have
been extended to reactions of solid uranium compounds with
solids. The formation of uranium carbide from neutron-irradiated uranium dioxide and graphite in a Tammann furnace under argon was studied. The argon was circulated over
copper and uranium turnings at 420 OC to remove any traces
of oxygen.
With unirradiated UOz, UCz was formed after 5 min at
1750 “C, as shown by X-ray diffraction. Neutron-irradiated
UOZ was at first heated without admixture of graphite to
1300-1900 “ C in alumina or graphite crucibles. Fission
products were given off already below the temperature for
UC2 formation (1750 “C),depending on the crucible material
(cf. Table 1).
Table 1. Fission products given off from irradiated UOz
(grain size 1 I*) after 4 h.
Crucible
material
Fraction of fission product given off [a]
Sr
Ba
Te
Mo
Ru
I
I
I
I
I La
[
Ce
I
Nd
[a1 Zr, Nb, and N p were not observed in any case.
Ibl Here the UOz reacts completely with the crucible to UCz.
57
Preparation of Aryl Esters
J. Lorenz, Marienberg (Germany)
The emanation of fission products depends chiefly on whether, owing to “microscopic solid-state reactions” of the products of irradiation with other solids such as the crucible, these
products can be immediately removed from the surface of the
U02 grains, since diffusion from within the grains is sufficiently rapid at the high temperatures employed. In a graphite
crucible the BaO, for example, present in the UOz is reduced
to metallic barium which immediately evaporates. BaO-removal in a n alumina crucible occurs only at temperatures
where the vapor pressure of BaO is sufficiently high. The
oxides of e.g. Mo and Ru are however more volatile than the
metals themselves. Thus the sequences in which the fission
products are removed are found to be in the order of the
vapor pressures of the elements in graphite crucibles, and of
the oxides in alumina crucibles, except for a shift observed
with lanthanum. The rate at which the fission products are
given off is inversely proportional to the grain size.
When triphenyl phosphite is heated with a carboxylic acid at
150-250 “C, an exothermic reaction takes place to the phenyl
ester of the carboxylic acid. The phosphite loses two phenyl
groups; excess of acid acts as an “inert” solvent. The best
yields are obtained when heating is stopped when the reaction begins, or by working in a diluent such as decalin.
Aliphatic and aromatic monocarboxylic acids can be used,
with yields of 70-90 %. Oxalic, fumaric, and acetylenedicarboxylic acid decompose; phthalic acid gives mainly the anhydride. Adipic and terephthalic acid give the diphenyl esters in
yields of 72 and 40 %, respectively. Salicylic, p-chlorobenzoic,
nicotinic, and 4-thiapimelic acid can be converted into the
[I] F. Lux and F. Ammentorp-Schmidt, Radiochim. Acta 4, 1 I2
phenyl esters in yields of 68, 50, 38, and 65 %, respectively
(1965); F. LKX and F. Ammentorp-Schmidt, Angew. Chem. 77,
732 (1965); Angew. Chem. internat. Edit. 4, 707 (1965).
NHz- or SH-substituted acids can not. Phosphites made from
substituted phenols or thiophenols also give the corresponding aryl or thioaryl esters.
59
The high activation energy and the exothermic nature of the
reaction suggest as high-energy intermediates a mixed anhydride (C6H50)zP-O-CO-R
(in the first stage) and
Preparation and Properties of Diprimary
(C6H5O)(O)(H)P-O-CO-R
(in the second stage). The reAlk ylenediphosphines
action of potassium acetate with triphenyl phosphite gives
phenyl acetate, which would not be expected if the reaction
L. Maier, Zurich (Switzerland)
proceeded via a phosphonium ~ O ~ ( C ~ H ~ ~ ) ~ ( H ) P + - O - C O - C H ~ .
In the presence of one mole of pyridine, the reaction of 2
Diprimary alkylenediphosphines ( I ) can be easily prepared
moles of acetic acid with one mole of triphenyl phosphite
by reduction of alkylenediphosphonates with LiAIH4.
gives the phenyl ester (68 %) exothermically already at 100 “C.
The fact that only two of the phenyl groups are transferred is
(RO)~OP(CHZ)~PO(OR)Z
3 HzP(CH2)xPHz
due to the high acidity of monophenyl phosphite relative to
( I ) , x = 1-4
the carboxylic acids.
984
Angew. Cliem. internat. Edit. Vol. 4 (1965) 1 No. I 1
Previous reportsrll that ( I ) , x = 1 and 2, are unstable above
-78 'C are incorrect. The infrared spectra of alkylenediphosphines show a P-H absorption band at 2270-2290 cm-1; the
3IP-NMR spectrum has a triplet ofintensityratio 1 :2: 1 which
is shifted with increasing x to higher fields; e.g. x = 1 :
+121.8 ppm, x = 2: +130.8 ppm, x = 3: 1-138.6 ppm. The
1 H-N M R spectrum confirms the structure (1) of the alkylenediphasphines.
With strong acids the alkylenediphosphines give phosphonium salts, e . g . (2):
H2P(CH2)3PH2
+ H3P04
+ [H2P(CH2)3PH3Jd
HzP04-
12)
I n the presence of free-radical initiators they add onto olefins,
forming ditertiary alkylenediphosphines, which can be oxidized with H202 to the dioxides (3) and characterized as such.
they could not be completely separated 121. Thus, apart from
the thioamide resonance,
the mesityl group contributes to the hindrance of rotation around the C-N bond in ( I ) and (2). This is one of the
reasons that isomers of non-sulfur containing formamides,
acetamides, and benzamide have so far not been enriched.
For nitrosamines[3l, considerable enrichment of isomers was
achieved, e.g. of (3) and (4). The crystals, m.p. 20-22OC,
obtained directly from the synthesis of the compound consist
of about 94 % of (3).
+
HzP(CHz)xPH2 4 CH2=CHR
--f
(RCH~CH~)~P(CH~)XP(CH~CH~R)
H~Oz/Acetone
(RCH;?CH~)~(O)P(CH~)~P(O)(CH~CH~R)Z
1
(3)
( 3 a ) ,x
(36), x
n-C6H13,m. p. 145-150°C
= 4, R = n-CloH21, m.p.91-91.8'C
=
3, R
=
With N-hydroxymethyldialkylamines,prepared from formaldehyde and secondary amines, the diprimary alkylenediphosphines ( I ) give alkylenebis(dialkylaminomethylphosphines) ( 4 ) in excellent yields.
H~P(CH~)X+
P H4~RzNCHzOH
+ (R~NCH;?)~P(CH~)XP(CH~NR~);?
( 4 ) , x = 1-4, R = CzH5
The equilibrium [81 % of (3)] is attained with a half-life of
8.2 5- 2.0 min in CC14 at 36 "C. From an equilibrium mixture
of the isomers in CS2, mainly (3) crystallizes out at -60°C.
In the filtrate (4) is enriched to 75 % since at this temperature
it is converted only slowly into (3).
121 W . Walter and G. Maerten, Liebigs Ann. Chem. 669, 66
(1963); W . Walter, G. Maerten, and H. Rose, Liebigs Ann.Chem.,
in press.
[3] I n collaboration with G. Albert.
61
The 1H-NMR spectrum of alkylenebis(diethylaminomethy1phosphines) ( 4 ) contain three complex bands, quantitative
analysis of which proves the structure of the products.
[ I ] A . J . Lefl/er and E. G. Teach, 133rd ACS Meeting, San Francisco, April 1958. Abstracts of Papers, p. 29 N.
60
Separation of R o t a t i o n a l Isomers of Amides,
Thioamides, and Nitrosamines
A . Munnschreck, Heidelberg (Germany)
The thioamides, e.g. ( I ) and (2), of mesitylenecarboxylic acid
can be separated chromatographically and identified by their
N M R spectra; ( I ) : m.p. 58.5-60°C, (2): m.p. 98-99OC.
The crystalline substances are stable, but in solution a n equilibrium mixture containing 68 % of ( I ) at 5OoC is formed.
The equilibration is a first order process with a half-life of
Addition Reactions of Cyanic Esters
D . Martin, Berlin- Adlershof (Germany)
Sterically unhindered esters of cyanic acid give the following
reactions:
1. Isomerization: On being heated, or on treatment with
Lewis acids or H-acidic compounds, alkyl cyanates isomerize
to isocyanates, which react further to esters of isocyanuric
acid.
2. Trimerization: On being heated with acids or tertiary
amines, aryl cyanates isomerize to aryl cyanurates.
3 . Nucleophilic Additions:
a) At the C-atom: They proceed particularly easily because
of the neighboring electron-attracting 0 and N atoms. The
compounds (2) obtained by the addition of the nucleophile
Z - Y - H ( I ) are stable when the bonding pair of electrons between Z and Y is not available for a secondary reaction.
RO-CEN
P
")
f.
2-Y-H
2
-
R , Rz Y
RO-C-NH
1
(2)
Z-Y
=
0, S, N
If 2 is a n acyl group, the primary adduct (2) is immediately
protonated to (3) by another molecule of ( I ) . The bonding
electron pair from Z is now available for charge equalization,
and (3) reacts with Z-Yo to ( 4 ) .
S'
24.7 4. 2.8 h in CDC13 at 50 'C. The free energies of activation
of the isomers were found to be AG?; = 27.3 and AGi2; =
26.8 kcal/mole. For the corresponding oxygen compounds
the values are 22.9 and 22.3, respectively[*], i . e . they isomerize faster. In the corresponding thioformamides the equilibrium is also established faster than in ( I ) and (2), so that
*
(3)
7, =
(4)
H, Acyl, Sulfonyl, Phosphcryl, Y
= 0, S
[ I ] A . Mannschreck, Tetrahedron Letters 1965, 1341.
Angew. Chem. internat. Edit.
Vol. 4 (1965) N o . I /
985
In reactions with compounds (5) containing electron-rich
double bonds, i. e. enamines, pyrroles, aromatic hydrocarbons, carbanions, cyanide ions, CH-acidic compounds, or
Grignard reagents, cyanic esters act as nitrile group donors.
n
RO-CrN
.+I
Z-C=C-H
I
I
RO-C=N@
- 0
I .
Z-C-C-H
4 J I V
-
63
Mechanism of the Electrolytic Reduction of Hydrogen
Peroxide on Germanium
W. Mindt and H. Gerischer, Munchen (Germany)
RO-C=NH
2-C:C
I
I
1
(51
From an analysis of the current-potential curve of the electrolytic reduction of Hz02 on germanium it was deduced that
the transfer of electrons depends on a free-radical surface
state ofthe germanium. This radical state originates in a transition region between a hydroxide-like and a hydride-like surface structure as a consequence of the surface reaction:
lGeOH + 2H++ e- s 1Ge-H HzO + p+
/
/
This reaction proceeds via the radical form
Ge-, which
effects the reduction of H202 according to the reaction:
+
b) At the 0-atom: Phosphoric di- and triesters attack cyanates at the 0-atom with elimination of cyanide:
3
+ H202 + e- +
ace-OH f OH/
It was further shown that only the electrons of the conduction
band take part in this reduction.
>Ge-
64
4. Cycloadditions: In contrast to nitriles, cyanates react
smoothly with 1,3-dipoles under cycloaddition. Tetrazoles
are formed with azides, 1,2,3-triazoleswith diazo compounds,
1,2,4-triazoles with nitrilimines, and 1,2,4-oxadiazoles with
nitrile oxides.
5 . Electrophilic Additions: In the cases studied so far, these
are more difficult than with nitriles. N-Phenylnitrilium cations
add onto aryl cyanates yielding quinazolines. Triethyloxonium tetrafluoroborate yields small amounts of phenetole with
phenyl cyanate.
The Determination of Potassium and Argon in I r o n
Meteorites by Neutron Activation Analysis
0. Miiller and J. ZQkringer, Heidelberg (Germany)
Several iron meteorites were dated using the potassium-argon
method. Because of the very low potassium content of these
meteorites, potassium and argon were determined by neutron
activation analysis:
K41(n,y)
62
Injection and Extraction Processes at Semiconductor
Electrodes
R. Memming and G. Schwandt, Hamburg (Germany)
Electrons and positive holes participate in reactions at semiconductor electrode surfaces, i. e. such reactions can occur
via various energy bands of the semiconductor (conduction
or valence band). Quantitative information on this participation is obtained by the “thin slice method” described below.
On the side opposite the semiconductor surface to be studied
there is a pn-junction. When minority carriers are injected
into the semiconductor at the phase boundary (e.g . electrons
in the case of p-germanium), they diffuse into the crystal and
thence to the pn-junction. The injected charge carriers are
accelerated in the internal electric field of the pn-junction. If
the junction is short-circuited, this gives rise to a current. This
method has been frequently used to detect qualitatively the
injection of charge carriers. It is suitable for quantitative
determination of the injection current if the mean free path
of the minority carriers in the semiocnductor is known.
The “thin slice” method has been applied to germanium and
silicon in various electrolytes. Thus in solutions in methanol
(in contrast to aqueous solutions) it can be shown that the
reactions occurring at anodically polarized germanium
electrodes depend on the nature of the halide ions present.
The method is suited not only to the study of injection and
extraction processes during an electrochemical reaction, but
also to the observation of the recombination of electrons and
holes at the surface. Electron-hole pairs are generated at the
surface by illumination and detected by the pn-junction.
The short-circuit current is a measure of the rate of recombination via surface states. The position of such centers within
the forbidden zone can thus be determined.
986
K42
P-,y
--+12.4
h
Ca42
@-.Y
Ar40(n,y) Ar41 -+
K4’
1.8 b
The concentrations found were: argon 10-8-10-7 ml/g; potassium 10-8- 10-7 g/g meteorite.
The ages of iron meteorites determined by the potassiumargon method are about 6 x 109-7 x 109 years, i.e. they are
considerably older than stone meteorites (maximum age
5 x lo9 years). This points to a different history of formation
of the two types of meteorites.
65
A Simple Indene Synthesis involving
Dihalocyclopropanes
F. Nerdel and J. Buddrus, Berlin (Germany)
Dihalocyclopropanes ( I ) that carry alkyl or aryl groups condense with aromatic compounds in the presence of strong
Lewis acids, affording indenes (2), with concurrent 1,2-migration of an alkyl or aryl group. Ring closure requires a
strong Lewis acid (AIC13 is better than FeCI3), to loosen the
halogen (Cl, F) that is fairly firmly retained on the cyclopropane ring. In this way, 1,l-dichloro-2,2-dimethylcyclopropane gives 2,3-dimethylindene. The reactions occur at
room temperature. At least 1.1 moles of AlC13 are used per
mole of cyclopropane. Two layers are formed during the reaction: the Iower is a complex of indene, AICI3, HCI (HF),
and the aromatic starting compound; the upper contains
only the aromatic starting compound. Yields range from 45
to 67 %; they are highest when the aromatic compound and
dihalopropane carry several alkyl groups.
Angew. Chem. internat. Edit. / Vol. 4 (1965) 1 No. I 1
66
A N e w Method of Generating Carbenes
F. Nerdel and J. Buddrus, Berlin (Germany)
Epoxide rings can be opened with anions to form "bases" [I].
We found that the pseudobase ( I ) can eliminate hydrogen
halide from haloforms, liberating carbenes which can be
captured with alkenes.
o n thermal decomposition follows the opposite sequence. The
rate constants kl of the first-order decomposition of the azides
ArzBN3 depend o n steric and electronic parameters of the
aromatic substituents. The yields of rearrangement product,
the values of k l , the derived activation parameters, the migration tendency of the ligands o n boron in mixed azides
L2BN3 111, and the stabilizing influence of Lewis bases allow
the following conclusions to be drawn: Boron azides are the
more unstable the more electrons are withdrawn from the
azide group and the stronger the anchimeric assistance by
the migrating ligands during the elimination of nitrogen;
the neighboring-group effect becomes weaker with increasing
strength of the boron-ligand bond.
[I] P. I. Paetzold, Angew. Chem. 76, 598 (1964).
69
CCl?
3-
+
CClZ
C P
Equimolar amounts of ethylene oxide, chloroform, and alkene are heated at 150 "C in a n autoclave, and the product is
isolated by distillation. No reaction is observed in the absence of alkene. Evidently the formation of carbenes is reversible. With vinyl ethers, a-haloacrolein acetals (2) are obtained via a cyclopropane, which is unstable at high temperatures.
Carbonato C o m p o u n d s of Praseodymium(1V) and
TerbiumOV)
Sw. Pajakofl, Wien (Austria)
In the thermal decomposition of praseodymium(I11) and
terbium(I1I) carbonates in a n oxygen atmosphere at 250 to
350 "C, carbonates and oxide carbonates of the quadrivalent
metals are formed, which decompose further at higher temperatures:
--
300-320°C Pr204.C02 320-350
+
yellow-brown
(2)
111 J. N . Bronsted, Mary Kilpatrick, and M . Kilpatrick, J. Amer.
chem. SOC.51,439 (1929).
O C
,
Pr204.0.5 CO, 350-380 "C
yellow-brown
420-450 "C
Pr204 +
Pr6011
light brown
dark brown
380-400 'C
Prz04.0,5 C02Pr204 --+
brown-yellow
Tbz(C03)3-2 H20 250 "C
E02Tbz(C03)3 280-300 "'
4
white
67
yellowish white
The Reaction of Iron(II1) Chloride with LiAlH4
H. Neumaier, Miinchen (Germany)
lron(II1) chloride reacts quantitatively with LiAIH4 in ether
solution at -1 16 "C according to
FeC13
+ 3 LiAlH4
-+
Fe(AIH&
+ AlH3 + 3 LiCl + 0.5 H2
Iron(I1) aluminum hydride is reasonably stable a t room
temperature. At higher temperatures it decomposes to the
elements, with a significant increase in the rate of hydrogen
evolution at 90-100 'C. The P-T diagram of the thermolysis
shows n o break or region of constant pressure, which makes
the existence of the intermediate FeA12H6 postulated by
Schaefler [I] appear improbable.
[l] G . W. Schaeffer, J. S. Roscoe, and A . C. Stewart, J. Amer.
chem. SOC.78, 729 (1965).
68
The Stability of B o r o n Azides
P. I. Paetzold, Miinchen (Germany)
The thermal stability of boron azides L2BN3 decreases in
the sequence L = NR2 > OR > R > C l > Ar. The extent of
the rearrangement
L z B N ~ + N2
+ l/n (LB-NL)"
Airgew. Chem. internat. Edit. I VoI. 4 (1965) ,INo. I I
400-450
O C
light brown
450-600 "C
+ TbbOll -+
brown
Tb407
dark brown
In the oxidation of the oxides and hydroxides of praseodymium and terbium in alkali carbonate solutions (>2.5
M KzC03) with ozonized oxygen, hydrogen peroxide, or
alkali peroxymonosulfate, yellow, water-soluble carbonato
complexes of the quadrivalent metals are formed. From these
complexes the following compounds were synthesized:
K4[Pr(C03)4].4H20
yellowish-white
K6[Pr(C03)5].2H20
light yellow
K6mb(CO3)5].4H20
yellowish-white
Ba3[Pr(C03)5].3H20
light yellow
Ba3nb(C03)5}.2H20
yellowish-white
From these compounds new complexes with mixed ligands
were prepared:
[Pr-carbonato-oxalato]
jPr-carbonato-fluoro]
[Pr-carbonato-hydroxo]
[Tb-carbonato-fluoro]
[Tb-carbonato-hydroxo]
The carbonates and oxide carbonates of praseodymium(1V)
and terbium(1V) behave differently towards complex-forming aminopolycarboxylic acids and hydroxycarboxylic acids
than d o carbonates of the tervalent rare earths. This effect
can be used to separate praseodymium and terbium from the
neighboring rare earths.
987
70
Action of Hexarnethylenetetramine on the
Catheptic Endo- and Exopeptidases of Fish Tissues
and blue solutions in acetone and methanol. Addition of ammonia to solutions in acetone or methanol changes the color
to orange.
72
A. Purr, Miinchen (Germany)
Hexamethylenetetramine inhibits the plant endopeptidase
papain. Optimum inhibition occurs between p H 4.5 and 5.5.
The inhibition is probably due to a reaction of the SH groups
of the enzyme with formaldehyde, formed from hexamethylenetetramine in weakly acidic media.
The p H optimum for the inhibition of the catheptic endo- and
exopeptidases of fish tissues ( e . g . carp liver) by hexamethylenetetramine is 4.0, but inhibition is still strong at pH 5 . 5 . Experiments with physiologically harmless substitutes for hexamethylenetetramine show that the peptidases are inhibited
particularly by giyoxylic acid, methyl giyoxal, and sorbic
acid. The activity of the substances decreases in the sequence
glyoxylic acid > methyl glyoxal > formaldehyde > hexamethylenetetramine > sorbic acid.
71
Reactions of Dibenzo[c,f]-l,2-diazepin-ll-one
W. Ried and
sr. Piesch,
Frankfurt/Main (Germany)
The compound ( I ) 111 undergoes none of the usual carbonyl
reactions and does not react with Grignard reagents. It reacts
with acetylene in liquid ammonia and with monosubstituted
alkynes in dioxanes at 80 O C t o give the corresponding ethyn01s in good yields. Alkynols d o not react with ( I ) .
Syntheses of Cycloamides and Cyclopeptides with
Medium-Sized R i n g s
M . Rothe, K.-D. Steffen, and J. Rothe, Mainz (Germany)
N-(Aminoacy1)lactams ( I ) and ~-(dminoacy~)cyclopeptides
cyclize to various products, depending on the length of their
side group and the ring size. If a 5-, 6-, or 7-membered ring
can be formed, cyclols (2) occur as intermediates. a-Aminoacyl-(f), x = I , and o-aminoaroyl-lactams give bicyclic
amidines (3) ; glycyl- and anthranoylcaprolactam give e . g.
5-oxopentamethylenimidazoline ( 3 ) , x = 1, y = 5 , and 6-0x0pentaniethylenedihydroquinazoline, respectively. $-Aminoacyl-lactams ( I ) , x = 2 111 and -cyclopeptides are converted by
aminoacyl insertion into macrocyclic peptides (4); after
introduction of two P-alanyl groups into the cyclodipeptide
of p-alanine and rearrangement, the cyclotetrapeptide is
formed. r-Aminoacyl-lactams (l), x = 3 , cyclize by reaction
of the free amino group with the carbonyl group in the ring
or in the side chain. Medium-sized rings are thus accessible
without recourse to the dilution principle, e.g. the tenmembered cyclodi-y-aminobutyryl (4),x = y = 3. 6- and &aminoacyl-lactams ( I ) , x = 4 or 5 , eliminate the side chain;
in compounds with longer aminoacyl groups, polycondensation or, in dilute solution, ring closure occurs.
NH-CO
(1)
I \
130 C-C-R
The azo chromophore fixed in the cis-position in ( I ) reacts
with ketenes to (2).
RZ
R~~--FR~
The reaction goes best with diphenylketene, less well with
dimethylketene, and in poor yields with unsubstituted ketene.
A smooth reaction is also obtained with p-tolyldiphenylketenimine.
The azo group in (1) can be hydrogenated to the hydrazo
group with weakly active Raney nickel. The product reacts
with malonoyl chloride to (3), a deep violet substance which
gives purple solutions in chloroform and methylene dichloride
[I] R . B. Johns and K. R . Markham, J. chem. SOC.(London)
1962, 3112.
988
x
=
9 =
The aminoacyl group can be introduced by acylation of free
or trimethylsilylated lactams and cyclopeptides with N-protected amino-acid chlorides or by lactam formation from activated N-protected dipeptides with C-terminal y- or %amino
acids.
Diglycylsarcosine dimerizes to cyclo(diglycylsarcosyldigl ycylsarcosyl) (decomp. > 350°C).
[l] Cf. also V. K . Antonov, Ts. E. Apadzhanyan, T. R . Telesnina,
M. M . Shemyakin, G. G. Dvoryantsnva, and Yu. N. Sheinker
Tetrahedron Letters 1964, 727.
73
N e w Enzymatic Baking Agents
A. Rorsch, Detmold (Germany)
Malt baking agents increase the sugar content of the dough
by degradation of the starch, accelerate fermentation, increase the volume of the baked product, and improve color,
crust, storage properties, and taste of the products. Fungus
amylases have also been used as baking agents. They improve
mainly the crumb consistency and usually increase the volume. Doughs treated with these d o not tend to relax or
to Ifecome sticky, and can be readily handled by machines.
Proteolytic enzyme preparations degrade the gluten of excessively strong, gluten-rich flour and can be used particuArtgew. Cliem. internut. Edit.1 Vol. 4 (1965) No. 1I
larly in the production of baker's ware for diabetics and sometimes of hard biscuits and crackers. They sometimes have adverse effects, however, when accompanying some malt baking agents in the processing of weak German wheat flour.
After the importance of the cereal gums (water-soluble pentosans) consisting mainly of arabinose and xylose to the rheological behavior of doughs and for the adjustment of the
water content in dough and bread had been recognised, pentosanase-containing preparations were developed, which allow the controlled degradation of the gums during fermentation and in the first stage of baking, and effect improved
loosening, better crumb consistency, and volume increase.
The results obtained with such a pentosanase from Asperg i l h oryzne in wheat bread and other baked goods show it
to be valuable particularly in the processing of rye doughs. The
preparation was free from protein- or starch-degrading
enzymes.
74
Compounds (4b) and (Sb) are obtained in about 8 "/, and
3-7 %, optical purity, respectively, the latter yield depending
on the solvent. With decreasing temperature and in the presence of AIC13.O(C2H5)2 the optical yield of (4b) increases to
about 70 "/,; the amount of the catalyst has no influence on
the degree of optical induction. On reduction, (+)-(4b) and
(+)-(Sb) were always obtained; assignments of absolute configurations could be made.
In the system ( I ) + (3) the sign of the rotation of the diol
(6b) obtained by reduction of ( 6 a ) depends o n the solvent
in which the diene addition is carried out. In methylene chloride the laevorotatory form of ( 6 6 ) is obtained; in acetone,
dioxane, and in methylene chloride in the presence of
AICI3.O(C2H& the deXtrorOtdtOry enantiomer is obtained.
The induction is less marked than for the reaction of ( I ) with
(2) ;it reaches a value of 45 %,at-70 "C in methylenechloride
[I equiv. of catalyst]. Chemical determination of the absolute
configurations of the pure enantiomers of (6c), obtained by resolution of the racemate, and of the derived pure optically
active compounds (6b), ( 6 d ) , (7a), and (7.) was not possible [21.
Electrochemical and Direct Fluorination of
Substituted H y d r o c a r b o n s
&
P . Snrtori, K. P . Ehlers, and G . Steiner, Aachen (Germany)
R
Hydrocarbons can be perfluorinated by the action of elementary fluorine directly or via fluorides of metals in high oxidation states, or by electrolysis in anhydrous hydrogen fluoride.
In carboxylic acids and carbonyl fluorides, the carbonyl
group impedes substitution of neighboring H atoms to such
an extent that the action of fluorine causes almost quantitative chain cleavage to COF2 and partly and fully fluorinated
alkanes, formed by radical recombination.
Chloroalkanes, particularly 1,2-dichloropropane, can be converted into chloroperfluoroalkanes by fluorine in the gas
phase. The occurrence of more highly chlorinated products indicates intermediate elimination and readdition of chlorine.
The success of electrochemical fluorination depends decisively
on the solubility or the fineness of the dispersion of the starting material in hydrogen fluoride. Thus gaseous alkanes can
be perfluorinated by bubbling them through the electrolyte.
The carbonyl group in acid fluorides imparts sufficient solubility in H F for a perfluorination with good yield.
Chloroalkanes are poorly soluble in hydrogen fluoride. Electrochemical fluorination in suspension leads to a number of
only partially fluorinated compounds, since these are carried
out of the mixture by the electrolysis gases before fluorination
is complete. The chloro-substituent is retained.
75
Optical Induction in Six-Membered Cycloadditions
J . Snuer and J. Kredel, Miinchen (Germany)
The optical induction occuring in six-membered cycloadditions was studied using cyclopentadiene ( I ) , (-)-menthy1
acrylate (2), and (-)-menthy1 fumarate ( 3 ) . In various solvents (triethylamine, dioxane, 1,2-dimethoxyethane, acetone,
methylene chloride, methanol) (1) and (2) react t o give mixtures of the isomeric Diels-Alder adducts (4n) and (Sa),
which are reduced by LiAlH4 to (46) and (Sb), respectively.
The ratio (4a):(Sa) depends on the solvent (Berson scale).
Decreasing temperature and increasing polarity of the solvent favor the formation of (4a). At -7OoC, in the presence
of catalytic amounts of AIC13.O(C2H& in methylene chloride, practically pure (40) or ( 4 c ) , respectively, are formed
in high yields from ( I ) and (2) or from ( I ) and methyl
acrylate together with 1 of the exo-isomers (5a) or (5c) 11J.
[l J Other Lewis acids, e.g. BF3.O(C?H&, SnCI4, and TiCl4,
behave similarly.
Angew. Chem. internat. Edit. 1 Vol. 4 (1965) 1 No. I 1
(la): R = COz-Menthyl
(Sa): R = COz-Menthyl
(b): R = CHzOH
(c): R = C02CH3
(bj: R = CHzOH
(c):
R
(d): R
=
=
COzCH3
CO2H
(68): R = COz-Menthyl
(b): R = CHzOH
(c): R
COzH
(d): R = COzCH3
___
-.
R = I ; R' = COzH
(b): R = I ; R1 = COs-t-C,H,
(70):
(c):R=H;Rl=C02H
~-
[ 2 ] Note added in proof; The laevorotatory forms of (6c) and
(4d) have the same configuration.
76
Chemistry and Stereochemistry of t h e Photocycloa d d u c t s of Dichloromaleic I m i d e and Anhydride with
AcycIic 1,3-Dienes
H.-D. Schnrf and F. Korte, Birlinghoven (Germany)
Dichlorornaleimide and dichloromaleic anhydride undergo
a Diels-Alder reaction when heated with 1,3-dienes to give
derivatives of 1 ,Zdichloro- 1,2,3,6-tetrahydrophthalic acid.
Under UV-illumination the same reagents undergo exclusively
1,2-cycIoadditioii to derivatives of 3-alkenyl- I ,2-dichlorocyclobutane- 1,2-dicarboxylic acid, (la) and (Ib).
R
=
H, CH3 Z = CO2R
2-1,= CO-0-CO,
CO-NH-CO
In the dehalogenation or ( l a ) or (Ib), Z = C02CH3, with Ni
(CO)4 in C6Hs/DMF at 80 " C , the corresponding dimethyl
3-alkenylcyclobutene-1,2-dicarboxylatesor (by thermolysis)
989
the dimethyl 1,3,5-hexatriene-2,3-dicarboxylateswould be expected to be formed. Instead, a rearrangement to 4,5-disubstituted 1,4-cyclohexadiene-1,2-dicarboxylates is observed.
This novel formation of Diels-Alder products by rearrangement can also be extented to the photocycloadducts of
cyclic 1,3-dienes.
Compound ( I b) resembles (NPCIZ)~
in itsproperties; at 255 “C
it polymerizes with elimination of benzonitrile.
The unexpected reaction of (3) with twu moles of SO2 can be
explained by the formation of the oxygen-containing heterocycle (4).
77
Mechanism of C-Nitrosation of Phenol
in Various Solvents
L
Hermann Schmid, G . Muhr, and P. Riedl, Vienna (Austria)
The initial rate of C-nitrosation of phenol by nitrous acid in
aqueous solution to p-nitrosophenol was determined by stopping the reaction with sodium hydroxide and photometric
determination of p-nitrosophenol in the resulting solution.
The rate equation (at constant ionic strength) is
rate
=
(41
The transamination of dibutylboramide with tetraphenylimidodiphosphinyl diimide is a n example for a ring closure
which leads to a “hetero”-cyclophosphazene and which does
~[C~HSOH][HNOZ]
At constant ionic strength the rate is independent of hydrogenion concentration in the range 10-5-0.5 mole/l; log k is proportional to the ionic strength.
Addition of methanol decreases the rate owing to removal of
nitrous acid by the formation of methyl nitrite. This effect
was used to determine the position of the methyl nitrite equilibrium. The free energy, entropy, and enthalpy of the Cnitrosation in aqueous solution were determined and suggest the following activation process: Phenol, which in the
ground state already has a high electron density a t the 0- and
p-positions, polarizes the nitrous acid, whereby the positive
nitrosyl ion adds to the negative carbon atom of the benzene ring. The rearrangement of the activated complex to nitrosophenol takes place by proton shift from the C-atom with
the nitroso group t o the hydroxide ion.
The nitrosation of phenol by nitrous acid in 70 % sulfuric
acid, in which phenol is not oxidized or sulfonated, was followed directly by photometry. Here the nitrite acidium ion
acts as the nitrosating agent.
78
Cyclophosphazenes Containing Carbon :
Derivatives of a New Heterocyclic System
A. Schmidpeter and R. Bohm, Miinchen (Germany)
2,2,4,4-Tetraphenyl-6-dimethylamino
- 2,4 - diphospha - 1,3,5 triazine ( I u ) is formed in good yield by cyclocondensation
of N,N-dimethylguanidine
phinyl trichloride:
+
with
tetraphenylimidodiphos-
4 (CH3)2NC(NH)NHz ( N [ C ~ H ~ ) Z P C ~ ~ Z } C I
+ ~[(CH~)ZNC(NH~)~
( lIaC) ~
+
P-chlorinated derivatives ( I b) are accessible viu condensation
products (2) of an amidinium hexachloroantimonate and
PClS [l’.
(3-1
not occur directly at a phosphorus a t o m It yields the borophosphazadiene (5), the ring structure of which is shown by
its 31P-NMR spectrum.
79
Exchange Reactions in Solid Co, Rh, and Ir Complexes
Initiated Thermally and by the 80mBr Nuclear Transition
G. B. Schmidt, W. Herr, and K. Rossler, Koln (Germany)
Whereas “activated” exchange reactions occur in crystalline
rhodium and iridium pentamminebromo halides as a consequence of the 8omBr nuclear-isomeric transition [I], the
thermal exchange of Br atoms in these complex salts is very
slow even at 210°C (atout 8 % exchange in 24 hours in
[Rh(NH&Br]Brz). By contrast, there is a rapid exchange
of covalent for ionic halogen in solid cis- and trans
[Co(en)2Cl2lCl and truns-[Co(en)2Br2]Br labelled with 36CI
and 82Br, respectively, between 100 and 170 “C, as well as in
solid trans-[Rh(en)2Cl2]Cl between 170 and 300 “C. The exchange rates in the three cobalt complexes studied were almost the same, e.g. t112 zx 4 h a t 150’C. For trans[Rh(en)&l2]CI, t112 = 13 h at 25OoC. The activation energies
for these exchange reactions were found to be 30 to
34 kcal/mole.
Previous irradiation with 6OCo y-rays or with X-rays does not
noticeably affect the exchange rate in trans-[Rh(en)~CI~]CI,
whereas the rate of exchange of the corresponding cobalt
complex increases markedly with the radiation dose: thus
t1,2 at 150°C decreases after irradiation with 150 kV X-rays
(2x 104 to l x 106 R) to 60 and 6 min, respectively, from
220 min for the unirradiated compound. X-rays are about ten
times more effective than y-rays. The exchange presumably
occurs according to a jump mechanism involving lattice
defects.
[I] G. B. Schmidt and W. Herr, Z . Naturforsch. I8a, 505 (1963).
80
Basic Salts of Bivalent Tin
H. G. Schnering and H. Pelsfienke, Miinster (Germany)
[ I ] A. Schmidpefer, K. DUU, and R . Bohm, Angew. Chem. 76,
605 (1964).
990
Precipitations from heterogeneous and from homogeneous
solution, determinations of halogen 111 and tin, and chemical
and X-ray characterization show that the following compounds exist:
Angew. Chem. infernnt. Edit.
Vol. 4 (1965) 1 No. I 1
Sn9C1407 = 2SnC12-7SnO ( I ) : pale yellow microcrystalline;
isotypic with (3) ; the compound is the primary hydrolysis
product from SnC12 solutions; when kept in solution it
changes completely into compound (2), which regenerates
( I ) when heated at 230 OC (in vacuum); at 525 "C compound
( I ) decomposes endothermally into SnO and SnC12.
Sn4CI3(OH)30 = 3 Sn(OH)CI.SnO (2) : colorless hexagonal
plates; sensitive to light when moist; this is probably the only
basic chloro-compound of bivalent tin that is stable in acidic
solution; at 230 "C it decomposes endothermally into SnCl2
and ( I ) . Crystals of Sn4C13(0H)30 are hexagonal-rhombohedral with a = 10.032 8,and c = 44.092 A, belonging to space
group D:d; determination of the complicated structure is not
yet complete.
SnsBr4O-i (3) : yellow, mostly microcrystalline but also forms
six-sided platelets; compounds (3) and ( I ) are isotypic and
are strongly disordered in some directions; according to a
single-crystal photograph, compound (3) may be hexagonal,
with a = 9.23 and c = n x 9.55 A, where the value of n is uncertain.
Attempts to prepare a bromo-compound analogous to (2)
failed.
[l] Cf. H . Schafer and K . D . Dohmann, Z . anorg. allg. Chem.
300, 1 (1959).
81
Synthesis and Properties of some New
Phenyltinarsines, Stibines, and Bismuthines
Herbert Schumann and M a x Schmidt, Marburg (Germany)
Organotin chlorides o r SnC14 react with sodium diphenylarsine, -stibine, or -bismuthine in liquid ammonia to phenyltinarsines, -stibines, and -bismuthines, which can be crystallized from benzene after removal of the ammonia:
(C&5)nSnC14-n f 4-n NaX(C6H5)2 +
(C~HS),S~[X(C~H,),]~-~
4-n NaCl
X = As, Sb, Bi
n = 0-4
+
Lupinus luteus after feeding of [2-i4C]lysine. We sought the
source of the nitrogen in the biosynthesis of lupine alkaloids
in Lupinus h e u s by feeding of [2-I4C, 15NIlysine. In the sparteine isolated, the ratio 14C: 15N was about three times greater
than in the lysine used. This is expected if a symmetrical intermediate is assumed, e.g. cadaverine, in which the or-nitrogen
of lysine is uniformly distributed, and if one takes into account that there are then 6 radioactive carbon atoms [asterisks in formula (2)] to two nitrogen atoms. This finding supports previous results that lysine is incorporated into sparteine via the symmetrical intermediate cadaverine.
j2-14CILysine and [1,5-14C2]cadaverine are incorporated in
cytisine (3) by Cytisus laburnum. Oxidative degradation
showed that 20 % of the total radioactivity occurs at C-2, and
that C-3, C-4, and C-5 are not radioactive. The radioactivity
at C-13 is decisive. In the synthesis of (3) from a lupinine-like
precursor, this atom should not be radioactive, whereas in
biosynthesis by degradation of sparteine (2), 2 0 % of the
radioactivity should be found here also. Oxidation gave a
mixture of two isomeric cytisamides, in which the C-atoms 1 1
and 13 had been converted into carbonyl groups. This mixture was separated. Reaction with phenyl-lithium and subsequent oxidation led to elimination of the carbon atoms 1 1
and 13 which each contained 20 % of the radioactivity of the
original alkaloid.
Labelled cytisine was also obtained by feeding sparteine. The
methyl group of methylcytisine (4) does not become radioactive after feeding of sparteine or of cadaverine and lysine.
This group is therefore introduced subsequently by methylation.
83
Infrared Studies on Hydroxides
From triphenylstannyl-lithium and phenylchloroarsines,
-stibines, and -bismuthines, or with AsC13, SbC13, and BiCI,
in tetrahydrofuran, the compounds
[(C6H5)3SnhX, [ ( C ~ H S ) ~ S ~ ] Z X Cand
~HS,
( C ~ H ~ ) & I X ( C ~x
H=
~ )As,
~ , Sb, Bi,
are obtained in pure form after separation from precipitated
lithium chloride.
The analogous germanium and lead derivatives are obtained
by starting from organogermanium and organolead compounds. Most of the new compounds are very sensitive to air
and moisture and are immediately oxidized in air to esters of
arsinic acids or to polymers containing Sn-0-Sb o r Sn-0-Bi
linkages, respectively.
82
Biosynthesis of Lupine Alkaloids
H. R. Schiitte, Halle/Saale (Germany)
The lupine alkaloids lupinine and sparteine, as well as the
oxygen-containing derivatives of the latter, are formed from
two and three molecules of lysine, respectively, via cadaverine.
The latter, which had previously not been detected in the
plant, could be determined by reverse dilution analysis in
Angew. Chem. internat. Edit. / Vol. 4 (1965) / No. I I
E. Schwarzmann, Gottingen (Germany)
In hydroxides containing no hydrogen bonds, the O H stretching vibration occurs in the range 3700-3600 cm-1, and the
O H torsional vibration between 300 and 500 cm-I. Hydrogen
bonding gives rise to a decrease of the stretching frequency
with increasing strength of the bond (i. e. decreasing O(H)...O
distance) and to an increase in the torsional frequency (provided the bond is linear). A multiplicity of O H bands in the
infrared spectrum is therefore often due to hydrogen bonds of
various lengths.
Coupling of O H stretching vibrations with each other can also
cause a splitting of bands. The same applieito torsional vibrations. Thus the splitting of O H stretching and torsional
bands of partially deuterated hydroxides containing a
single type of OH- ion (i.e. one hydrogen bond length
only) decreases with increasing degree of deuteration
and often the bands coalesce to a single band with decreasing
coupling. In some hydroxides with very short hydrogen bonds
[e.g. InO(OH), y-MnO(OH)], a multiplicity of O H stretching
bands is observed, with a splitting of several hundred cm-1,
which cannot be explained by vibrational coupling, since it
remains in partially deuterated compounds. Resonance effects between neighboring vibrational levels, such as occur in
the tunneling motion of a proton in a potential well with a
double minimum, and a n interaction of the O H stretching
vibration with the first overtones of the O H torsional vibration, may be the cause.
99 1
84
c oocH 3
-0
A Stable Ninhydrin Reagent f o r Automatic
Determination of Amino Acids
E. Schwerdffeger, Geisenheim/Rheingau (Germany)
In the automatic amino-acid determination according t o
Spackmann et nI.[ll, difficulty is experienced owing to the
sensitivity of the ninhydrin reagent to oxygen and light. These
difficulties can be avoided if the partial reduction of ninhydrin
is carried out immediately before the color reaction with the
amino acids by means of reducing agents added to the eluting
buffer. The potassium cyanide first used for this purpose is
partly retained by the cation exchange column, so that the
color yields of the amino acids first eluted from the column
are somtimes too low. The use of ascorbic acid instead of
potassium cyanide eliminates these difficulties. The color yields
of the reactions with amino acids are constant and correspond to those obtained with the reagent described by Spackman ef al. The optimum concentration of ascorbic acid in the
elution buffer is 0.01-0.02 ”/,. The ninhydrin reagent is a 2 %
solution of ninhydrin in a mixture of 37.5 ”/, ethylene glycoI,
25.0
of 4 M acetate buffer (pH 5.5), and 37.5 % of water.
It is insensitive to air and diffuse daylight, and forms n o insoluble deposits in the tube connections.
Only the keto group to which the ester group is equatorial is
attacked on reduction, since the Clemmensen reduction of
the keto group and oxidation of the hydroxy group in (2) and
(3) gives the same P-adamantonecarboxylic acid (5).
I
(4)
H
(4)
OH
[ I ] D. H. Spackman, W.H. Stein, and 5’.Moore, Analyt. Chern. 30
1 190 ( 1 958).
85
New Reactions with Trichloromethanesulfenyl Chloride
In the ester (2) the OH group and the a-hydrogen to the ester
group are arranged 1,3-diaxially [as in the compounds (4),
(IO), and ( I ] ) ] , as the low chemical shift of the proton at
C-2 in the N M R spectrum shows.
The second P-adamantonecarboxylic acid was prepared via
the lactone (7), which is formed in 20 yield in the Clemmensen reduction of ( I ) .
A. Senning, Aarhus (Denmark)
N-Trichloromethanesulfenyl derivatives can be prepared
under mild conditions from arnides and CCI3SCI. For example, in the reaction of benzamide with CC13SCI at about
100 “C, 5-phenyl- 1,3,4-oxathiazol-2-one is formed (together
with benzonitrile), which on pyrolysis decomposes to benzonitrile, C 0 2 , and sulfur. N,N’,N”-Trisulfonylguanidines
( R S O ~ N H ) ~ C = N - S O Z are
R obtained from sulfonamides and
CCI3SCI. Cyclization attempts with CCI3SCl and 1,2-diacyIhydrazines were unsuccessful. Only the 1,2-bis(trichloromethanesu1fenyl)hydrazine derivatives are obtained; the
(8) H
mono-derivatives are accessible from the monopotassium salt
of the 1,2-diacylhydrazine.
Substantially better yields of (7) are obtained if the ester (2)
Depending on the conditions, urotropine and CC13SCI give
or (3) is reduced i n methanol with NaBH4 to (10) or (12),
two isomeric I ,3-bis(trichloromethanesulfenyl)hexahydrorespectively. Both compounds form a lactone which can be
1,3,5-triazines. With triethylamine and CC13SCI a sequence of
converted into (7) via (14).
substitution and addition-elimination reactions leading to
121
cis- or trans- l-diethylamino-l,2-bis(trichloromethylthio);
H
a
o
:
i
:
J.
ethylene is observed.
N-(Trichloromethanesu1fenyl)ketimines can be prepared by
treating the magnesium salt of the ketimine (obtained by addition of a Grignard reagent t o a nitrile) with CCI3SCI.
Sulfenimines (RS)2NH can be substituted with CCI3SCl and
other sulfenyl chlorides to give esters of trithioorthonitrous
acid N(SH)3. Nucleophilic substitution of metal acetylacet(10) H
onates with CCI3SCI leads to the corresponding fully substituted trichloromethylthioacetylacetonates.
a H
(11) H
H f
(141 H 0
ajo
J
86
(71
Synthesis of the T w o Stereoisomeric
@-AdamantanonecarboxylicAcids
G. Snatzke and D . Marquarding, Bonn (Germany)
Methyl adamantane-4,8-dione-2-carboxylate( I ) can be reduced with NaBH4 in isopropanol to two of the four possible
hydroxyketo esters.
992
(12) OH
113) 01%
t
(31
The esters (10) and (12) are also obtained directly from ( I )
by reducing the latter in methanol with a n excess of NaBH4.
Angew. Chem. internat. Edit.
Vol. 4 (1965) I No. I I
87
Surface Reactions of Gases with Semiconductors
M . J . Sparnaay, Eindhoven (Holland)
1,2,3,4-tetrahydro-4-oxo-4aH-carbazoles
(2) and 3-alkyI-2indolebutyric acids (3) to afford 3-alkyl-3-indolebutyric acid
lactams ( 4 ) ; these can be hydrolysed to (3) ( D . Cornelius,
E. Worbs). Dihydro-2,5,5-trimethylresorcinol reacts analogously ;the 2,2,5,5-tetramethyl derivative, however, gives (5).
Gas adsorption o n semiconductor surfaces often effects a
change in the surface charge distribution. Thus the negative
charge of a pure germanium surface is increased when oxygen
at about 10-6 mm pressure is admitted. The negative surface
charge is compensated by a positive space charge. The free
energy of such electrical double layers can be calculated approximately. It is of the order of 1 kcal!mole and depends on
the doping.
Surface structures can be investigated by diffraction of slow
electrons, as well as by adsorption methods. Thus Boonstrn
found that at room temperature, one HCI or HBr molecule
is adsorbed per two germanium atoms at the surface of a
powdered germanium crystal. One molecule of H20, HZSe,
and H2Se is adsorbed per four G e surface atoms, and one
molecule of NH3 or PH3 per six G e atoms. Above 100 OC the
adsorbed molecules react fairly rapidly with the G e atoms.
14j
HOOC,)
131
R
=
CH3, C2H.j. C3H7, allyl, 2-cyanoethyl, benzyl
2-Methyl-l,3-indanedioneaffords ( 6 ) . The P-keto-lactam ( 7 )
gives (8).
88
Isomerization of Thionophosphates
H. Teichmann, Berlin (Germany)
When trialkyl thionophosphates are heated for several hours
at 130 "C or higher they are converted via the isomeric trialkyl thiolophosphates into mixtures of sulfur-free trialkyl
phosphates, esters of condensed phosphoric acids, their sulfonium salts, and dialkyl sulfides.
The first stage, viz. the autocatalytic isomerization of the
thionophosphates, is a n intermolecular 0 + S transalkylation. From an equimolar mixture of trimethyl and triethyl
thionophosphate, the mixed thiol esters ( C H ~ O ) ~ P O ( S C ~ H S )
In the Beckmann or Schmidt rearrangement, tetrahydro- 1 - ,
and (C2H50)2PO(SGH3) are formed concurrently with the
-2-,-3-, or -4-oxocarbazoles[ll afford azepinoindole derivatives
isomers (CH30)2PO(SCH3) and ( C ~ H ~ O ) ~ P O ( S C Hligand
S);
[for instance, ( 9 ) + (lo), and (11) + (12)l (U.Wolcke).
exchange at the phosphorus atom of the thiolophosphates
does not occur under the conditions used. Trimethyl and triethyl thionophosphate decompose about equally fast at
130 "C over ca. 70 h, as shown by gas chromatographic analysis; the concentration ratio during this time remains at
about 1 (C2H50)2PO(SCH3): 0.5 (CH30)2PO(SCH3): 0.25
0.25
( C H ~ O ) ~ P O ( S C ~:H
S ) (C2H50)2PO(SC2H5). This shows
that thiolophosphates participate from the start in the alkylation of the thiono sulfur, preferably the methoxy-containing
esters, corresponding to their higher alkylating power.
Methyl diphenyl thionophosphate, in contrast to the trimethyl analogue, is practically stable at 130 "C, although it
is a considerably stronger methylating agent. This stability is
due to the lack of alkylating properties in the isomeric
of (CH30)2PO(SCH3) initiates
( C ~ H S O ) ~ P O ( S C Haddition
~);
2,3-Disubstituted 1-(3-0~0-2-butenyl)indoles(13) [21 are rea rapid decrease in thiono sulfur content in methyl diphenyl
arranged to (14) with opening of theindole ring by methanoand trimethyl thionophosphates.
lic HCl (U. Reinehr, D . Cornelius).
The transformation of trialkyl thionophosphates to their
(even less thermostable) thiol isomers, usually described as
"isomerization", should be interpreted as a special case of the
Pishchimuka reaction, i. e. the reaction of thionophosphates
with alkylating agents via quasi-phosphonium intermediates
R
to thiolophosphates.
I
WRS
- do
:
89
N e w Rearrangements in t h e I n d o l e Series
H.-J. Teuber, FrankfurtIMain (Germany)
.
Monophenylhydrazones ( I ) of 2-substituted 1,3-cyclohexanediones, which in accordance with Bredt's rule d o not
yield pyrazoles, react in the Fischer synthesis by way of
[ l ] Cf. H.-J.Teuber and D . Cornelius, Liebigs Ann. Chem. 671,
127 (1964).
[2] H.-J.Teuber, D . Cornelius, and H . Pfaff, Chem. Ber. 96, 2617
( I 963).
Angew. Cliem. internut. Edit.
Vol. 4 (1965) 1 No. I I
.~
993
90
of organic anions (X
Mechanism of the Reaction of Metal Hexacarbonyls
with n- and js-Electron Donors
= C6HsQ, o-, m-,or J J - C H ~ C ~ H ~ ~ ,
2,4,6-(CH3)3C6H~@etc.). Thermolysis of silyl azides leads to
resin-like, heterogeneous products. N-silylphosphazenes are
obtained by reaction with phosphines:
+ (4-n)
+
H . Werner and R . Prinz, Miinchen (Germany)
R'nSi(N&n
The kinetics of the reactions of metal hexacarbonyls of the
group VIb elements with n-donors such as amines or phosphines, and with x-donors such as aromatic six-membered
rings or oligoolefins were studied spectrophotometrically.
The substitutions with n-donors take place according to a
two-step dissociation mechanism; in the first, rate-determining step a CO group is eliminated from the hexacarbonyl,
and in the second, fast step the resulting pentacarbonyl fragment adds the donor L to form the substituted compound.
When polydentate donors (diphosphines, diamines, or triamines) are used, the substitution of further C O groups is
also rapid, since the rate constants observed agree very well
with those for the reactions of metal hexacarbonyls with
monodentate ligands. For the reaction:
The reaction of silyl azides, which are very sensitive to hydrolysis, with Grignard reagents i n diethyl ether proceeds by two
routes, which yield easily hydrolysable N-silyl-N-organylmagnesium amide bromide dietherates (d) and tetraalkylsilanes (e).
R3P
100-150
OC
R'nSi(NPR&-n
+ (4-n)
N2
(cj
MgBr
___c
+
IOOT
R'3Si-N3 + R M g B r
C,,,,0C2",
Nz
(4
R;Si-$R
RkSi-R
+
MgN3Br
(e)
Reaction (d) is an example of the general reaction (b), i. e. replacement of the azide group. This substitution is rapid and
quantitative with organic anions as Lewis bases, if they are
M(C0)6 + ( C & ~ ) Z P C & P ( C ~ H ~ ) ~
used as their lithium salts (YZ = RLi), with Bronsted acids
+
[(C~HS)~PCZH~P(C~HS)Z]M(C~)~
2Co
(YZ = YH), or according to Eq. (f) with Lewis acids ( Y Z =
Hal-EHal,, E = element).
the following activation parameters were obtained: M = Cr:
Ea = 38.5 kcal/mole, AS* = +17.3 e.u.; M = Mo: E a =
Hal-EHaln + R3Si-Hal
N3-EHaln
(f)
R3Si-N3
30.1 kcal/mole, AS+ = +1.0 e.u. ; M = W: Ea = 36.4 kcall
mole, AS* = +4.0 e.u.
The following azide-bridged, explosive azide halides were
prepared according to reaction (f), among others : (SbHal4N3)~
The reaction of molybdenum hexacarbonyl with x-donors
(Hal = F, CIrIl); (TiHalz(N3)~)n(Hal = Cl, Br); (BHal~N313
is also first order in M o ( C O ) ~and practically independent of
(Hal = CI, Br) 121; SnCI,(N3)4-, (n = 2,3), and AICIn(N3)3-n
the donor concentration. This again suggests a primary dis(n = 0,1,2).
sociation of M o ( C O ) ~to Mo(CO), and CO. Owing to the low
nucleophilicity of the 6-ring aromatic compounds, the reverse
[I] N. Wiberg and K . H. Schmid, Angew. Chem. 76, 380 (1964);
reaction
Angew. Chem. internat. Edit. 3, 4 4 4 ; (1964).
Mo(CO)S+ CO + Mo(CO)~
[2] P. I. Paetzold, M. Gayoso, and K. Dehnicke, Chem. Ber. 98,
1173 (1965).
competes in this case with the substitution
+
+
Mo(C0)s
+ Ar
+ ArMo(CO)5 (Ar = aromatic compound)
so that the rate constants depend o n the nature of the aromatic ligand. For example, for the reaction of Mo(CO), with
benzene at 112 rt 0.2"C in n-decane/cyclohexane, k = 1.92 x
10-5 sec-1; for the reaction with mesitylene, k = 2.72 x 10-5
sec-l"].
The rate constant of the reaction with x-donors depends
on the initial concentration of Mo(CO)~. With increasing
dilution the overall reaction rate increases, which can
be explained by the decreasing importance of the reverse reaction, the rate of which depends on the concentrations of
Mo(C0)5 and CO. This increase of rate on dilution is evidence against an SN2 reaction.
+
92
Infrared Spectra of 'SN-Labelled Iminophosphoranes
W . Wiegriihe and H. Bock, Munchen (Germany)
In the course of investigations of the P = N double bond [I] it
proved necessary to make a definite assignment to the P=N
stretching frequency, for which conflicting values have been
reported. To this end we synthesized the 1sN-labelled iminophosphoranes (1)-(3) by the following method:
[ l ] H. Werner and R . Prinz, J. organomet. Chem., in press.
91
The Chemistry of Silyl Azides
N. Wiherg, K . H . Schmid, and Wan-Chul Joo,
Miinchen (Germany)
The reactions of silyl azides to be described can be summarized in essence by Equations (a) and (b) (R = methyl, ethyl,
n-butyl, phenyl, dimethylamino, methoxy).
0,
R3Si-N-NsN:
+ :X
R3Si-N3 + Y-7,
0,
-+
R$i-N-X
+
K3Si-Y
+
+
Nz (a)
%-N3 ( b )
The elimination of nitrogen [reaction (a)] can be effected
either thermally above 300 OC (no group X present) or chemically with trialkylphosphines (X = R3P) or magnesium salts
994
(Ts = p-toluenesulfonyl)
The spectra were measured in the range 5000-400 cm-1 and
complete assignments could be made. P = N stretching bands
occur at 1344 ( I ) , 1147 (2), and 1199 (3) cm-1. They are
easily identified by isotope shifts of IS-20 cm-1. The S-N
stretching frequency with Av = 4-6 cm-1, is found at 784 (2)
and 762 (3) cm-1, compared to 902 cm-1 in tosyl amide,
which was also studied.
The P=N double bond is reinforced by substituents with (-I)
effect at the phosphorus and with (-M) effect at the nitrogen.
[ I ] H. Bock and W. Wiegrube, Angew. Chem. 74, 327 (1962);
Angew. Chem. internat. Edit. I , 265 (1962); Angew. Chem. 75,
789 (1963); Angew. Chem. internat. Edit. 2,484 (1963); W. Wiegrabe and H . Bock, Chem. Ber., in press.
Angew. Chem. internat. Edit. Vol. 4 (1965) 1 No. I 1
95
93
Synthesis of Pyrimidine Nucleosides via Silyl
Derivatives
Stereospecific Retention in Nuclear Reactions on
cis/trans-Isomeric Cobalt Complexes
G. K . W O K Heidelberg (Germany)
E. Wittenberg, Rostock (Germany)
In the reaction of uracil or of its 5-X derivatives ( I ) with
hexamethyldisilazane, the bistrimethylsilyl compounds (2)
are formed quantitatively. Their structures were proved by
their ultraviolet and infrared spectra.
X = H, CH3, F, CI, Br, I, -CH20CH2C&I5
Y = CH3, glucopyranosyl, galactopyranosyl, arabinopyranosyl,
ribofuranosyl, deoxyribofuranosyl.
The compounds (2) react with methyl iodide in benzene in
the presence of AgCf04 almost exclusively to N(1)-methylpyrimidines (3). In the reaction of (2) with acylated halogenosugars (glucopyranose, arabinopyranose, galactopyranose, ribofuranose, 2-deoxyribofuranose), acylated trimethylsilylnucleosides are formed, which are hydrolysed to the acylated nucleosides. The free nucleosides are obtained, usually in
good yields, by removing the acyl group with sodium methoxide or ammonia.
94
Zuber, Rauscher, et al. found some years ago that, after capture of thermal neutrons by isomeric cobalt complexes, retention and subsequent thermal healing are stereospecific,
i.c. if the neutron-activated atoms recombine with the same
ligands after the nuclear reaction, the complexes always have
the original configuration.
To elucidate this phenomenon in cis- and trans-[Co(ethylenediamine)2Cl~]NO3,recoil atoms with different recoil energies
were generated by carrying out nuclear reaction with thermal
neutrons (0.025 eV) up to 45 MeV neutrons.
The proportion of radioactive cobalt occurring as trans[Co(ethylenediamine)zCl2] @ in the irradiated target material
was determined by precipitation as the perchlorate, the cisisomer by precipitation as the nitrate, and Co*+ by extraction
with 8-hydroxyquinoline in chloroform. Thermal healing was
followed for 30 h.
In reactions with cobalt atoms of low recoil energy (10-100
eV), the parent compound is formed stereospecifically together with Co2+ and other products. The parent compound
is formed exclusively from CoZ+ o n subsequent tempering. At
high recoil energies (up to lO5eV) the other steroisomer is also
formed in smaller amounts. All other products are formed
from Co2+ o n subsequent healing.
These results suggest that in nuclear reactions with thermal
neutrons the energy transferred locally to the lattice is insufficient for positional exchange processes to occur among
the ligands. Such exchange is observed only at higher neutron
energies.
Formation of Nitrite from Nitrate in Vegetables
96
W. Wodsak, Hamburg (Germany)
Some vegetables, e.g. spinach, are rich in nitrate. The nitrate
content depends inter alia on nature and amount of fertilizer
employed. If there is a deficiency of molybdenum and manganese in the soil, insufficient nitrate reductase is formed; the
degradation of nitrate is then inhibited. Manganese favors the
formation of vitamin C, which promotes the degradation of
nitrate to amino compounds.
Nitrate is harmless even to infants. Nitrite, however, is
strongly toxic. It oxidizes hemoglobin to methemoglobin,
which cannot transport oxygen. Nitrite is practically never
formed in the organism of adults, since the nitrate is absorbed
before it can be reduced by the intestinal flora. In the infant
dyspepsia which is accompanied by proliferation of the flora
of the lower intestinal regions can lead to the reduction of
nitrate before it is absorbed.
In fresh spinach, unfavorable storage conditions (dense packing, lack of oxygen) can lead to the formation of up to 40 mg
N02/100 g. The nitrite content of deep-frozen spinach immediately after thawing is seldom above 1 mg/100 g, provided it is properly prepared. The same applies to tinned
spinach. In spinach sold in glass containers as baby food,
nitrite was never detected. The nitrite content of spinach
which has been prepared for eating may however increase
considerably on storage, especially in originally deep-frozen
spinach because of the high bacterial count. U p to 15 mg
N02/100 g were found after 24 h at 20 "C, but very little if the
sample had been sterilized.
Angew. Chem. infernat. Edit.
Vol. 4 (1965)
1 No.
I1
Structural Studies on Serine-Specific Transfer-RNA
H. G . Zachau, D . Diitting, and H . Feldmann,
Koln (Germany)
Soluble ribonucleic acid from yeast contains several serinespecific transfer ribonucleic acids (serine t-RNA). The serine
t-RNA present in largest amount was purified by repeated
countercurrent distribution and split with pancreas and TI
ribonucleases. The mono- and oligonucleotides were isolated
by column chromatography. The composition and base sequence of most of the oligonucleotides could be determined by
further enzymatic degradation. Eleven odd nucleotides were
found: one each of N(2)-dimethyl-Gp, 5-methyl-Cp, rTp, Ip,
2'-0-methyl-Gp, 2'-O-methyl-Up, two of 4,5-dihydro-Up,
and three of \T-Up. With the aid of these odd nucleotides
and the ( A P ) ~ G
sequences,
~
base sequences up to 23 nucleotides could be determined. Some of the odd nucleotides occur
in close proximity in serine t-RNA.
Comparison ofthe known fragments of serine t-RNA with the
base sequence of a n alanine t-RNA recently elucidated by
Holley et al. shows that some of the odd nucleotides and many
oligonucleotide sequences are different. There are, however,
also some striking similarities, e.g. N(2)-dimethyl-Gp and Ip
are separated by 9 nucleotides in both t-RNA's.
[VB 958/265 IE]
German version; Angew. Chem. 77, 1013 (1965)
995
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