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Colloquium in Honor of G. Scheibe

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The following observations confirm this course of reaction:
1 . Reduced pyridine nucleotide (DPNH) is formed only in
presence of cis-p,y-enoyl hydrase, racemase and HOADH.
D-( -)-$-Hydroxylauroyl-CoA (2) is dehydrogenated to ( 4 )
only in presence of racemase and HOADH.
2. After incubation of 35 pmoles of [5-14C]-cis-3-dodecenoylCoA ( I ) with cis-$,y-enoyl hydrase and racemase, 3.0 mg
of methyl rat.$-hydroxylaurate (m.p. 27 "C) were isolated
by saponification, esterification and gas-chromatographic
separation. The optical rotation of methyl D+)- or L-(+)-$19.5'; c = 1 in CHCl3)did not
hydroxylaurate ([a]ko =
change in the blank under the conditions of isolation.
Through these reactions the unsaturated fatty acids are
connected with the metabolic cycle of the saturated fatty
acids [4], so that o u r knowledge of the $-oxidation of all the
fatty acids occurring in the animal kingdom is thereby
complete.
Received, March 25th. 1964
[Z 717/542 I € ]
German version: Angew. Cheni. 76, 4 4 0 (1964)
[I] J . R. Stern and A . Del Caiiipillo, J. biol. Chemistry 218, 985
( 1956).
[2] S . J. Wakil and H. R. Malpler, J. biol. Chemistry 207, 215
(1954).
[3] D. E. Green in: Progress in the Chemistry of Fats and other
Lipids. Pergamon Press, London 1963, p. 102.
[4] W . Seiibert, G. Greull, and F. Lynen, Angew. Chem. 69, 359
( 1 957).
New Syntheses of Pyrylium Salts
By Dr. Richard Schmidt
lnstitut fur Organische Chemie
und Organisch-Chemische Technologie
der Technischen Hochschule Stuttgart (Germany)
Dedicuted to Professor H . Rredereck
on the occrrsioti of his 60th birthday
By reacting phenylacetylene with aromatic acid chlorides i n
the presence of Lewis acids, pyrylium salts ( I ) could be
obtained i n good yields:
The reactions went best with excess acid chloride acting as
both reactant and diluent at -5 to + 15 "C. The pyrylium
salts prepared are shown in Table 1.
Table I. Properties of the pyryliurn salts i l l .
I
I Hexachlorostannatel
Ar
m. p. [ ' C ]
yield
(decornp.)
1 %I
Phenyl
290-298
73
0-C hloro phenyl
p-Chlorophenyl
p-Tolyl
294-298
290-294
273-277
72
81
55
Perchlorate
log
Emax
~
287-290
360
(288-290 [I]) 408 [2]
209
3 I4
200-202
320
230--232
325
415
(224 131)
SnC14 has been the most suitable Lewis acid. The hexachlorostannates could be converted to perchlorates with perchloric
acid in dimethylformamide/water. The pyrylium salts are
yellow and fluoresce strongly in solution. The ultraviolet
spectra were taken in methanol. By comparison of ( I n ) with
authentic 2,4,6-triphenylpyrylium perchlorate [I] and by
conversion of ( I n ) to 2,4,6-triphenylpyridine [4] the course
of the reaction was clarified.
Received, March 31st. 1964
[Z 711/537 IE]
German version: Anpew. Chenl. 76. 437 (1964)
[ I ] C. G. LeF3vre and R. J . IY. LeFi.iw, I . chem. SOC.(London)
1932, 2894.
121 R . Wizinger, S. Losinyer, and P. Ulrirli, Helv. chim. Act3 3Y,
5 (1956).
[3] K. Diinroth, G. Neiibauer, H . Mollenkamp, and G. Oosterloo.
Chem. Ber. 90, 1668 (1957).
[4] W . Difthey, J . prakt. Chem. (2) 94, 53 (1916).
C O N F E R E N C E REPORTS
Colloquium in Honor of G. Scheibe
On thc occasion of Prof. G . Scheibe's 70th birthday a colloquium was held in Munich (Germany) on November 29th
and 30th, 1963. The following is a selection from the papers
read.
Influence of Heavy Atoms on the Polarization of
Triplet/Singlet Phosphorescence of Organic C o m p o u n d s
F. D 6 w , H . Gropper, and N . M i k a , Miinchen (Germany)
The triplet/singlet phosphorescence of organic molecules in
isotropic solid solution, when excited with linearly polarized
light, is itself partially polarized. On theoretical grounds, a
degree of polarization p = 0.5 is to be expected in the plane
perpendicular to the electric vector of the exciting light
source, if the absorbing and the emitting transition moments
in the molecule are parallel. If they are perpendicular to each
other, p = 0.33 [l]. The x-TCabsorption transitions of planar
molecules are all polarized in the plane of the molecule. For
numerous aromatic hydrocarbons, the triplet/singlet phosphorescence consists essentially of only one intense com[I
1
W . L. Leivschin, Z . Physik 32, 307 (1925).
Arigen;. Chem. internut. Edit.
Vol. 3 (1964)
No. 5
ponent, which is polarized perpendicularly to the plane of
the molecule [2]. However, halogeno substituents, r . g . in
naphthalene, intensify other components of the phosphorescence that are polarized in the plane of the molecule. The
resulting intensification of emission is known as the heavy
atom effect [ 3 ] . The superimposition of differently polarized
components is also manifest in the degree of polarization.
which becomes increasingly positive with increasing atomic
number of the substituting element [4]. A similar influence
has now been observed in the series fluorene, dibenzofuran,
carbazole, and dibenzothiophene, i n which i; rises from --0.32
to +0.04.
The theory of triplet/singlet transitions [51 provides selection rules for the mixing of singlet and triplet states via
[21 H. Cropper and F. Diirr, Ber. Bunsenges. physik. Chem. 67,
46, 193, 202 (1963).
[31 D. S . McClure, N. W. Blake, and P. L. Hanyt, J . chem.
Physics 22, 255 (1954).
[41 F. Di;rr, H . Cropper, and N. Mika, Z. Naturforsch. 18tr. 1025
(1963).
[51 D.S. McCliire, J . chem. Physics 17, 665 (1949); 20, 682 (1952).
387
3.90
3.98
4.09
2.89
the different components of the spin orbit operator {LS}. On
the assumption that for the compounds under examination,
only the lowest triplet state To of the symmetry 3La or 3 L b
is noticeably influenced by spin orbit coupling, the following
combinations result as the most probable ones. (Coordinates:
x = longitudinal axis. z = transverse axis, y = normal to
plane of molecule).
1. If To E 3La (z-symmetry), the following states mix:
(a) via {Ls},, an S(qn*)-state; polarization along y;
(b) via {LS},, a n Sx-state (probably ‘ L b ) ; polarization along x.
2. If To E 3 L b (x-symmetry), the following states mix:
(a) via {LS},, an &-state (probably lLa); polarization along z ;
(b) via {LS),, a n S(a,x*)-state; polarization along y.
analytical methods for non-metals also, which have their
analytically most sensitive lines in the vacuum ultraviolet
region. In this way, iodine can be detected with certainty
down to 10-8 g. Traces of oxygen can be detected indirectly
by means of the CO spectrum.
13
i
t
56
7 8 91011
12
.f
1
II
16
n
The Boltzmann Occupation of the Energy Terms of
Atoms and Molecules
1 : contact and adjustment pivot of
H . Krempl, Munchen (Germany)
It is known from Boltzmann statistics that
(a) for absorption, the cross-sectional area of a band represented by the extinction coefficient EA obeys the law
EA = log Id1 = E
~
c ’. exp(-U,/kT).d
and
the hollow cathode
2 : standard tapered joint
3; 18: O-rings
4: 13; 20; 2 3 : outlet and inlet tubes
for coolant
5 : cathode block
6; 7 : gas channels
8 : actual hollow cathode
10; 1 1 : Pyrex glass iiisiilation
12: anode block
14: joint for connecting to
spectrograph
1 9 : I.iF window
16: LiFlens
17; 21; 22: vacuum sealing wax
19; 24: outlet and inlet for
carrier gas
(b) for emission, the intensity EE of any line obeys the law
EE = EE . c . exp(-Ua/kT).d
Photochemistry and Spectroscopy of Acridines
,
V. Znnker, F. Mnder, and W. Korber, Miinchen (Germany)
where c is the concentration of the materials concerned, d is
the thickness of the layer, and Ua is the appropriate height
of the term above the ground state. EA and EE are atomic
and molecular constants, respectively (transition probability
functions).
Both these laws were examined over a wide range of temperature (a) for the first band of benzene, A = 2700 A, over
the range of -176 to 100°C; (b) for the atoms and ions of
C, Mg, Al, Zn, Pb over the range of 8000 to 40000”C, by
means of spectrochemical thermoanalysi? in an electrically
heated plasma.
At moderate concentrations, i. e. as long as Beer’s law holds
(a) or in optically thin plasmas (b), the law predicted statistically by Boltzmann proved t o be valid.
For initial terms close to the ionization limit, a lower degree
of occupation was observed in the case of emission than is
to be expected theoretically; this may be ascribed to the
action of the surrounding plasma fields on the undisturbed
term system.
+
The Hollow Cathode as a Light Source for Emission
Spectrography in the Vacuum Ultraviolet Region
G. Miluzzo, Rome (Italy)
The hollow cathode (Fig. 1) is based on the principle of
cathode sputtering and is superior as a light source to arc
and spark discharges mainly for two reasons. Through
cooling and by its mode of construction, the Doppler and
Stark effects are largely avoided, so that background-free
spectra with very sharply defined lines are obtained. By combining the hollow cathode with a vacuum spectrograph,
spectra of nonmetals (e.g. Br, 1) and metalloids (e.g. Si, Ge,
As) can be measured in the vacuum ultraviolet region simply
and with great accuracy. (An atlas of the spectra of several
elements in the vacuum ultraviolet region is under preparation, in collaboration with the Vatican Astronomical Observatory.) Where possible, the cathode itself is made from
the material under examination. Alternatively (CI, Br), it
suffices to introduce the sample into a carrier material (Al,
Mg). In this very simple way it is possible to employ spectro-
385
Earlier investigations [6] of the photochemical behavior of
acridine proved that the same end products, viz. the sparingly
soluble dimer 9,9’-diacridanyl and, presumably, the more
soluble 9,lO-dihydro derivative acridan, occur in H-containing solvents, both in the presence and absence of 0 2 . Our
investigations showed in addition that on photolysis in
ethanol saturated with nitrogen, acridine (conc. > 5x 10-4 M)
forms a colorless product, (purified by recrystallization from
dimethyl sulfoxide) m. p. 262 ” C under nitrogen. This
substance exhibits a split acridan band in the ultraviolet - an
indication of substitution a t C-9 - and a weak band at 360
mp, which is characteristic for diacridanyls. Its infrared spectrum is identical with that of synthetic 9,9’-diacridanyl prepared from acridine with Na/Hg. The results of its elemental
analysis also correspond to the formula of diacridanyl. The
mass spectrum yields fragments of mass number 180. This
shows that the 9,9’-bond is the weakest one and that the
compound dissociates into acridiniuin ions. By analogy to
N,N‘-dimethyl-9,9’-diacridanyl, the molecular weight of which
(388) can be determined as a result of its superior solubility,
and the mass spectrum of which yields ostensibly similar
fragments with mass number 194, it must be assumed that
the photochemical reduction product obtained from acridine
is 9,9’-diacridanyl (mol. wt. 360).
At acridine concentrations of < 5r 10-4 M in H-containing
solvents, a “soluble acridan” is formed as photochemical
product and could be isolated from dioxan and cyclohexane.
The ultraviolet spectra again point to acridans substituted at
C-9 (split acridan band), and the elemental analyses and
molecular weights tally with 9-dioxanylacridan and 9-cyclohexylacridan, respectively. The conclusion is that acridans
substituted at C-9 are formed from acridine also in other
H-containing solvents. On the basis of these results, we
explain the reaction in terms of radicals, the primary reaction
consisting of hydrogen transfer from the solvent with the
formation of a 9-acridanyl radical. It was possible to prove
spectroscopically the presence in solutions containing oxygen,
of an 02-adduct, probably diacridanyl peroxide, :md its stable
decomposition product, acridone. The spectra of some
acridans and diacridanyls were analysed by fluorescence and
fluoresccnce polarization. The characteristic acridan band
devoid of fine structure at 300 m!J. is a superimposition O f the
Atigew. Cheni. ititerntr!. Edit.
Vol. 3 (1964)
No. 5
I Lb-band upon the IL,-band. The splitting of the acridine
band in the 9-substituted derivatives is to be explained by a
bathochromic shift of the ILb-band.
The preband, occurring at about 360 m p with the diacridanyls is markedly influenced by temperature and disappears
almost completely at -183 "C. This implies the existence of
two different conformations of diacridanyl, the conformer
richer in energy absorbing at the longer wave length (at 360
mp). I n the frozen state, the diacridanyls undergo a n interesting photolysis involving sp!itting of the 9,9'-bond and
electron detachment, acridinium cations being formed. On
melting the solution, diacridanyl is reformed.
Studies of the Tetrahydrate o f Hydrogen
Bromide H904 Br"
@
H . Zimmerrnnnn, d . Rudolph, and G . Henning,
Munchen (Germany)
At low temperatures, hydrogen bromide forms a crystalline
tetrahydrate, m.p. --56 "C [7]. Its infrared spectrum was
examined at - - 170 "C.In contrast to that of the corresponding
acid solutions at room tempcrature, it exhibits a fine structure
[8]. In particular, the long-wave infrared spectrum shows
groups of sharply defined bands, for which it was possible t o
set up a term series for the vibrational states. This term system
indicates that the substance IS present in the form H904+Rr .
The H 9 0 4 +complex consists of a pyramid-shaped H30+ ion
that is linkec! to three further water molecules by exceptionally strong hydrogen bonds. This complex has therefore ii
structure similar to that of the H904' ion, which is present
in aqueous solutions of acids, according to Wicke, Ei.yc,n.
and Ackernitrnn [9].
From the infrared spectra of the tetrahydrate of hydrogen
bromide, it appears probable that the proton in the hydrogen
bonds under discussion moves in an asymmetrical potential
field with two minima. At low temperatures, it is fixed i i i the
lower potential trough. Proton mobility therefore is very
low, and the conductivity at -180°C amounts to K < 10-9
mho. cm-1. The conductivity varies with temperature and
shows a sharp point of inflection at -90 ' C . A discontinuous
change in the properties of the substance at - 90 "C can be
similarly proved in the wide-band nuclear resonance spectrum, but not in the infrared spectrum.
[VB 780/136 IE]
German version: Angev. Chem. 76, 305 (1964)
[6] Cf., for example, V . Zanker and P . Sehntid/, 2. physik. Chem.
N F 17, I 1 (1958); A . Kellmann, J. Chim. physique 57, 1 (1960);
M . Giurgea, V . Topa, and S. Haragea, ibid. 58, 705 (1961).
171 S . U. Piekering, Phil. Mag. V, 35, 1 I 1 (1893).
3hemical Reactions with (n, y),
Tission Recoil Atoms
9-,and
F. Baumgartner, Munchen (Germany)
Recoil atoms resulting from nuclear reactions are capable of
forming new molecules. Nuclear reactions thus represent a
means for synthetizing molecules independently of preparative chemical methods. Thus, by P-disintegration of the
parent substances, it was possible to prepare the hitherto
unknown compounds dicyclopentadienylrhodium ( I ) , dienzene technetium(1) (2), and cyclopentadienyltricarbonylxhnetium (3). These substances were purified by sublima3n. (2) is a stable Tc cation, which has also been synthetized
macroscopic amounts.
.~
-
[81 Cf. Th. Ackermann, Z . physik. Chem. N.F. 27, 269 (1961).
191 E. Wicke, M . Eigen, and Th. Ackerniann, Z . physik. Chem.
N.F. I , 340 (1954).
Chemical Synthesis of Polypeptides and the
Hydrodynamic Properties of Their Solutions
G. Spach, Strasbourg (France)
Condensation of the tripeptide L-alanylglycylglycine with
dicyclohexylcarbodiimide or ethyl metaphosphate yields
only products with a degree of polymerization < 6. In order
to obtain high molecular-weight copolypeptides with the
amino acids in a regular order, a new synthesis depending on
internal anhydride formation was considered. In a preliminary
investigation, the carbamyl chloride ( I ) was synthetized by
the action of phosgene on glycyl-L-proline. The substituted
diketopiperazine (3) containing a n intramolecular peptide
link was formed from ( I ) with the stoichiometric quantity of
triethylamine. The intermediate anhydride (2) was not isolated and is probably of low stability [l].
r
T o extend the range of syntheses with recoil atoms, i.e. in
order to be independent of specific parent substances, we
used two-phase mixtures of uranium oxide and the target
material. In the uranium phase, energy-rich recoil atoms were
produced by nuclear fission and some of these, e.g. 105Ru,
1311, 99M0, react with the target compound. The following
radioactive molecules have been prepared via uranium fission :
U (n.0
U (n,f)
+ Fe(CsH5)z
+ Fe(CsHs)2
u hf)
+ Cr(C0)6
u ( K f ) + Cr(GH6)z
u (n,f) + CI(C6Ha)z
u (n,f) f C6H5-X
1
H,
4
p
H,C'
I
'YH2
N--f
Ru(CSHS)Z
+ csH~FeCsH41
--f
OC',
H,C-NH
C H\
1-71
C
, 0
MO(C0)6
-+ Mo(CsH6)z
-+ TC(C&)z+
+c~H5-1
X =.CI, Br, or I
According to the last equation, organically bound halogen
may be substituted very selectively by fission iodine. Between
500 and 4 ° K the yields of these recoil syntheses are independent of the temperature.
[Chemische Gesellschaft Heidelberg (Germany),
January 14th, 19641
[VB 790/131 1El
German version: Angew. Chem. 76, 307 (1964)
Atr,ycw. Chem. internat. Edit. / Vol. 3 (1964) ,! No. 5
Examination of dilute solutions of the homopolypeptides
polybenzyl-L-glutamate and polycarbobenzoxy-L-lysine in
dimethylformamide showed that the molecules exist in the
form of a helix of type 3.010, with three monomers per turn,
while in the solid state they assume an a-helix configuration
with 3.6 monomers per turn [2].
Polybenzyl-DL-glutamate exists in both the A and B forms
depending on the polymerization solvent. The A form appears
[ I ] A . Braek, These 3e cycle Universite de Strasbourg, 1963.
[2] G. Spaeh, L . F r e u d , M . Dnune, and H. Benoit, J. molecular
Biol. 7, 468 (1963).
389
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