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Meeting of French and German Chemists.

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Solution of Organic Chemical Problems b y Nuclear
Magnetic Resonance Spectroscopy
arrangement, to the doubly labelled phenol (7) proceeds via
the spirodienone (6) postulated by Marveli.
The rearrangement of the deutcrated phenol (8) in D20 leads
to a phenol (9) whose proton and deuterium resonance
spectra show that deuterium is attached only in the CH3- and
=CHZ-group of the side chain i n agreement with the proposed
mechanism. Quantitative eval tiation by electronic integration gave a ratio of l : 2 betweeii the degrees of deuteration in
the CH3- and =CH2 groups. This result proves the intramolecular path of the rearrangement, since a prototropy
could apparently be possible only from the methyl group in
the cis-position to the carbonyl group.
W. von Philipsborn, Zurich (Switzerland)
Applications of nuclear magnetic resonance spectroscopy to
solve problems of tautomery, to clarify a reaction mechanism
with the aid of deuterium substitution, and the significance of
proton spin-spin coupling for the analysis of complicated
spectra were discussed.
Derivatives of P-hydroxyfuran ( I ) occur to over 99 % in the
Az-furenid-4-one form (2). The single exception known up
to now is 2-acetyl-3-hydroxyfuran (isomaltol), which exists
exclusively in the enol form (3), being stabilized by hydrogen
bonding, as can be proved by its nuclear magnetic resonance
spectrum.
CH3
(2)
(1 )
13)
It was proved that 7-methylxanthopterine has the monoprotonized lactam structure ( 4 ) in CF3COOH. The spectrum
shows four separated absorptions of five (1x2 and 3x1)
protons bound to nitrogen.
CH,
c H3
(Y,
The configuration of the side chain of fulvoplumierin (10)
can be determined unequivocally from its proton resonance
spectrum by use of the spin-spin coupling method. Coupling
of the methyl group in the ABCX3 system under discussion
simplifies this to an ABC-(A HX)-system, from which the
trans-configuration of the 7,8-double bond follows on the
basis of JAB = 13.9 t 0.7 cps. The configuration of the 5,6double bond can also be deduced inter ulia from the resonance
position [7.87 ppm of TMS (total magnetic susceptibility)] of
the proton at the C-6 poqition.
14)
The enone structure =CH-CO-COOH was deduced for the
C3-side chain of the red butterfly dyestuff erythropterine
instead of the -CH=C(OH)-COOH enol structure previously
postulated. Thus the ultraviolet spectrum of the dye, which
is unusual for a pteridine acquires a rational explanation.
COOCH3
The thermal rearrangement of 2-(cr-[14C]-methyl-allyl)-4methylphenol (5), known as the anomalous Claisen re-
(10)
[VB 695/85 IE]
German version: Angew. Chem. 75, 477 (1963).
Meeting of French and German Chemists
Tubingen (Germany), April 25-27thY 1963
From the agenda:
Enrichment of Binary Gas Mixtures b y Removal of the
Adsorbates
C . Eyraud, Lyons (France)
When applied to adsorbed phases, static investigation methods do not render it possible to predict all the effects that are
caused by dynamic processes, e.g. the permeability to vapors
of micro-porous solids or enrichment effects produced by
removal of the adsorbate.
The permeability minima of a porous body in relation to a
condensable vapor at a pressure corresponding to a monomolecular coating are explained as being due to “diminution
of the pore diameter” or “solidification” of the adsorbate.
Angew. Chem. internat. Edit. 1 Vol. 2 (1963) / No. 8
The lecturer dealt mainly with Ihe influence of the removal of
the adsorbates o n the separation effect of gas diffusion
membranes. Experiments with hydrocarbon isomers show
the importance of molecular structure for the surface mobility
of the molecules. The enrichment observed in the mixture
H20/DHO is attributed to thc different types of interaction
between molecule and solid, i. e. to a specific differential
mobility of HzO and DHO. If (here is any mass effect, it will
probably be of the next lower order of magnitude in this case.
Production of Fine-Grain Metal Carbides
R. A . Puris and E. Clur, Lyons (France)
Metal carbides are usually prepared at high temperatures by
fusion in an annular kiln or hy solid-state reactions. These
techniques, as well as that of electrolytic fusion, lead to the
487
production of more or less pure, but always crystalline,
carbides. Conversions into carbides of finely-divided metals
or metal oxides using carbonaceous gases, such as carbon
monoxide or hydrocarbons, have been attempted in only a
few cases. The authors studied carbide formation from
reactive oxides and CH4 or Hz/CH4 mixtures, since in this
way finely-divided carbides can be produced at lower temperatures. Transition metal carbides of groups IVa, Va, and
VIa of the periodic table can also be prepared - particularly
those of Mo, W, V, Cr, Ti, Ta, and Nb. An H2/CH4 mixture
at 700- 1000 "C will completely convert pyrolysis residues
of less stable organic complexes or ammonium salts into the
carbides. The carbides were identified by analysis and by
their X-ray diagrams. The latter display long lines in most
cases, indicating particle sizes of less than one micron. The
specific surface area of these powders is of the order of
several m2/g.
Mercuration of Tertiary Amines and Enamines
K. Brodrrsen, Aachen, and G . Opitz, Tiibingen (Germany)
Mercuration of triethyl-, tripropyl-, and tributylamine with
HgClp or HgBr2 in ether leads to the ammonium salts (1).
Properties of Secondary y ,$-Unsaturated Ketones a n d
Alcohols
J. Culonge, Lyons (France)
y,&Unsaturated ketones ol type (5) are converted into
dihydrobiphenyl derivatives on treatment with polyphosphoric acid. On heating with sdfitr these hydrocarbons form
substituted biphenyls (6).
A mechanism is proposed for this cyclization: it recalls the
reversible protonization which precedes cyclization to a
tertiary alcohol with subsequent elimination of water.
f5J
161
Secondary y,s-unsaturated alcohols of type (7) are converted
into saturated ketones (8) by polyphosphoric acid. It is
possible that this isomerization proceeds via a polyhydroxytetrahydropyran, for the act ion of polyphosphoric acid on
2,2,6-trimethyltetrahydropyr~nleads to 2-methylheptan-6one.
It\,(' =~'II-Ci12-CIl(It~)-CIIOII-C~13
It'
L r'w
i71
J
'I\
(2)
In polar solvents such as acetonitrile or nitromethane, dehydrogenation to the immonium salts (2) then occurs. These
exhibit characteristic C=N bands in the 6 p region of the
infrared spectrum. Hydrolysis yields the corresponding aldehydes.
Simple tertiary vinylamines (3) react with HgC12 or HgBrz
in ether to yield a,P-unsaturated ammonium salts (4) by Nmercuration.
R2.;-CII=CI~2
f3)
-
I
l ~ 2 > ! - ( ~ l l = c ~ l t 21Igxp
2-";
HgX
(4)
The conversion of the vinylamines into (4) is accompanied by
a bathochromic shift of the double bond band in the infrared
spectrum in contrast to the hypsochromic shift on immonium
salt formation.
( ' Il-~'112-cIJ2-cII(II"-co-cII,
This isomerization resembles the rearrangement of 2,6,6-trimethyltetrahydropyran-2-carboxylicacid (cinenic acid) to
2,2-dimethylheptan-6-one-l-cnrboxylic
acid (geronic acid)
PI.
Elimination Reactions
W. Hiickel, Tubingen (Germany)
The most important types of elimination reaction involve
either monomolecular or pseudo-monomolecular elimination
of an anion with subsequent climination of a proton (E 1-) or
bimolecular elimination (E 2'), where the attack of the
reagent is directed at a proton.
The scheme formulated by H//x/ze.sin 1935 for E 1 elimination
requires supplementation, because anomalous eliminations
often occur which proceed with intramolecular anionic
migration of hydrogen and a double bond shift, accompanied
by anomalous substitution which leads to tertiary alcohols or
The Reaction of B-Ketols and Molecules with a
Reactive Hydrogen Atom
It2 It'
J. Dreux and M. Longeray, Lyons (France)
Condensations of the type
were studied in order to elucidate the reaction mechanism.
Experiments showed that condensation occurs when the
hydroxymethyl compound can be dehydrated (R=H), or
when there is a possibility of transhydroxymethylation,
forming a new compound that can be dehydrated.
The reaction does not take place when the hydroxymethyl
group is attached to a completely substituted carbon atom,
or when the reactive hydrogen atom of the other reactant is
attached to a tertiary carbon atom. This fact precludes an
s N 2 mechanism.
488
Thus, (+)-neomenthylamine and nitrous acid gives - in
a A3-menthene, 2/3 of
addition to 20 % Az-menthcne
which are racemized; this can be explained by intermediate
formation of a tertiary carbonium ion at C-4, which is also
indicated by the formation o f menthan-4-01 as well as a little
(-)-menthol. Further examplcs are afforded by the alcoholysis of the toluenesulfon,ltes of ol-decalols, which in
addition to the normal elimination product, viz. Al.9-octalin,
[l] H . Rupe and C . Liechtenhon, Ber. dtsch. chem. Ges. 41,1278
(1908).
Angew. Chem. internut. Edit. 1 Vol. 2 (1963) No. 8
even i n the absence of acid also gives varying quantities of
AY,Io-octalin, and, once again, also involves anomalous
substitution which results in t-9-decalyl ethers in addition
to the normal s-1-decalyl ethers.
The hydride displacement must always lead to Saytzeff
elimination; its preponderance in many cases is thus explicable. Geometrically isomeric alcohols and amines behave
differently on solvolysis of their toluenesulfonates. cisIsomers give predominantly A(-Saytzeff hydrocarbon and
much anomalous substitution, whilst trans-isomers always
give more A2-Hofmann hydrocarbon than the cis-isomers,
and often, when the neighboring group in the cyclohexane
ring is a higher alkyl group, give A l - and Az-isomers in
equal quantity. This rule is not valid for five-membered rings.
The 4-centre principle, which requires coplanarity for the
elimination process, does not hold for E 1 elimination; the
analogy to E 2 elimination required by Barton is not confirmed by the reaction products. Repeatedly there is direct
opposition; on alcoholysis, menthyl toluenesulfonate gives
68 % of a 1/4 racemised A3-menthene; reaction with alkoxide
yields almost pure A2-menthene.
1t,9C,10c-cc-Decalol (m.p. 62 “C) - as its toluene sulfonate
.~ gives 61 % A1 32-octalin by E I and 100% by E 2, whereas its
isomer 1C,9c,10t-~-decalol(m.p. = 49°C) gives I ”/, by E I ,
and at least 67 % by E 2.
The question still remains to what extent the residual 23 %
Al39-octalin (t some A9,to-octalin) result from a competitive
E 1 reaction. In general, with rapidly solvolysed toluenesulfonates, it is often difficult to decide the ratio in which E 1
and E 2 eliminations occur side by side.
Owing to its relatively rigid structure, is it impossible for
It,9c,IOc-cc-decalol to fulfil the demands of the 4-centre
principle, which requires coplanarity in the transition state
of the elimination reaction, whether it be E 1 or E 2, and
whether it be in the direction of the A1,2- or A1.9-product.
cyan ( 1 2 ~ and
) may be converted by oxidation into flavones
(130). Anomalous behaviour of the double bond would be
expected owing to the steric hindrance by the substituents in
the ortho- and peri-positions.
OR
OR
O
OR
( / 3 a ) I t = II
Or1
(Ira) R = H
Since several authors also claim Lo have isolated quercetylene
from plants, a n attempt was made to synthetize the substance. The elemental analysis of the product obtained by
the method of Malkin and Nicrensteiii is in accord with a
quercetylene hydrochloride. Chromatographic investigations
show, however, that the product is not uniform and contains
cyanidin chloride and phlobaphene, but not a trace of a
substance resembling quercetylene. For this reason, deca-omethylquercetylene was synthetir.ed as follows:
On
Rearrangements in the 5,6- and
5,8-Dihydroxyflavanone Series
J . Chopin, Lyons (France)
were
Derivatives of both 5,6- and 5,8-dihydroxyflavan-4-one
synthetized in order to examine their ability to undergo the
following rearrangement:
011
‘
It1
‘i@*rR2
0
- :::j$tl**
(9)
Oil
0
It
I t was established that the earlier compounds claimed as
quercetylene cannot be regarded as such.
Quercetylene can be converted into quercetin (13a) by
atmopsheric oxygen at 100 “C. Molecular-weight determinations at elevated temperatures indicate that (Ifb) is
dissociated. One of the limiting canonical structures for the
dissociation product would be the carbene (14). Compound
( 2 l a ) is not piezochromic, but biflavylenes which have no
substituents in the 3- and 5-positions are piezochromic; however, they do not substantially dissociate at elevated temperaOR
(10)
On treatment of 5-hydroxy-8-methoxyflavanone(9), where
R = R1 = H, R2 = OCH3, Ar = C6H5 with alkali or heat but
not, however, with acid, it is completely isomerized to 5 hydroxy-6-methoxyflavanone; however, the 5,8- and 5,6dihydroxyflavanones resist all attempts at isomerization.
This unusual resistance to cleavage of the oxygen heterocycle
disappears on introduction of a methoxyl group into the 4’position of the 2-phenyl residue (Ar = P - H ~ C O - C ~ H ~5,8).
Dihydroxy-4’-methoxyflavanone isomerizes completely on
treatment with alkali to the 5,6-dihydroxy-4’-methoxyflavanone.
ture. Instead, these substances show piezomagnetism, i. e. the
compounds sometimes become paramagnetic under pressure.
The paramagnetism disappears again on removing the pressure. This appears to be the first evidence of piezomagnetism
in organic substances.
Steric and Electronic Effects in Nucleophilic
Aromatic Substitution
fl. Suhr, Tiibingen (Germany)
Synthesis and Properties o f Quercetylenes
The rate of reaction of uncharged Lewis bases with uncharged
fluorine compounds, e . g .
E. Bayer, Tubingen (Germany)
Malkin and Nierenstein claim to have obtained quercetylene
( I r a ) from quercetin by reductive dimerization. The substance is significant as an intermediate in anthocyan metabolism since, theoretically, it is at the oxidation level of antho-
Angew. Chem. internat. Edit.
Vol. 2 (1963) No. 8
R-CeH4F
+
C S H I I N --f R - C ~ H ~ - N C ~ HfI ~ H F
was investigated. On alteration of the activating substituent
R, differences in rate of six powers of ten were found. The
489
influence of the substituent obeys the Hammet relationship,
with a p-value of 7.2. In addition, p-nitrofluorobenzene was
treated with numerous Lewis bases. It was shown that here
steric effects are in general much more strongly marked, and
hence largely determine the occurrence of reaction. Within a
group of sterically equivalent compounds, electronic effects
once again determine the rate of reaction.
Electrochemical Investigations of the Reducing
Properties of Liquid Amalgams
J . C . Merlin and M . Breant, Lyons (France)
When using liquid amalgams for the reduction of organic
compounds or inorganic ions, it is difficult to predict their
reducing power because the reaction can proceed irreversibly
as soon as equilibrium conditions are disturbed. We have
plotted current intensity vs. potential curves by both polarography and linear chrono-amperometry. Relatively concentrated amalgams of Bi, Pb, Sn, Cd, Ga, In, and T h were
investigated, but not those of alkali and alkaline-earth metals
which reduce water.
If the ions formed as a result of oxidation of the amalgamated
metal are precipitated or complexed, the half-wave potential
is displaced to a less positive value corresponding to an
increase in the reducing capacity of the amalgam. Intensity
v s . potential curves were plotted under the following conditions :
(a) at a constant ionic strength of 1.0; (b) at different p H
values so that the formation of hydroxylated ions and
hydroxides could be controlled; buffer solutions which did
not form complexes with the metal ions had to be employed;
(c) in the presence of complexing agents, so that the effect
of complex formation o n the half-wave potential could be
investigated.
It was possible to classify the reducing capacities of the
various amalgams and to predict the course of some reactions.
These predictions were tested and confirmed by the reduction
of E u ~ +and o-dinitrobenzene.
chains and -BH2 and --HH3 groups, which display typical
absorption bands, occurs. Molecular water seems to cause
cleavage of diborane with formation of two -OBI32 groups.
The alteration in the symmetry of the molecule is responsible
for the observed variation in the intensity of the symmetrical
absorption band.
Treatment of alumina gel with diborane at 20-150 “C results
in the formation of -0BH2 groups. Infrared spectra confirm
this hypothesis. The absorption band of diborane is much
broader and displaced towards lower frequencies than in the
case of silica gel. The bonds between the boron atoms and
the surface must be stronger. The chemical reactions and the
mass spectrum of alumina gels, which were treated at higher
temperatures, indicate incipient polymerisation. In addition
to the bands already described, the infrared spectra display
a very broad band at lower frequencies. This must be due to
polyborane chains, whose boron atoms are bound to the
surface oxygen by coordinate bonds.
Catalytic Ri n g Expansion of Cycloalkanones and
Steroid Ketones with Phenyldiazomethane
R . Heischkeil, Tubingen (Germany)
The idea of producing next higher homologues of rings using
phenyldiazomethane follows as a logical consequence of the
catalytic ring expansions with diazomethane discovered by
our research group at Tubingen. Extension of the reaction to
phenyldiazomethane attains satisfactory success only when
petroleum ether is used a s solvent instead of ether. Undesirable side reactions which occur in ether are largely suppressed in petroleum ether; simultaneously, the yields of
homologous phenylcycloalkanones obtained increase considerably. In addition, it proves possible to introduce a
second benzylidene group lo give the next higher x,w-diphenyl cyclic homologue:
Hydrolysis of Diborane on Silica Gel and Alumina Gel
M . V. Mathieu, Lyons (France)
The hydrolysis of diborane by hydrated solid particles permits both differentiation between molecular water of constitution and “free” hydroxyl groups and determination of
the number of hydroxyl groups per unit area. It is assumed
that two molecules of water of constitution react with one
molecule of diborane to form -0BH2- groups, while “free”
hydroxyl groups react with diborane to form -OBzH5 groups.
The structure of hydrolysed diborane was studied by infrared
spectroscopy to test this working hypothesis. If the surface
of the silica gel contains hydroxyl groups only, then the
formation of -OB2H5 by reaction with the hydrogen atoms
B-H...B of diborane is feasible. Formation of -B-O-B-
The products are separated by fractional distillation in V ~ C U O
and purified by several recrystallizations.
This reaction for producing cyclic homologues becomes
somewhat more complicated when applied to a$-unsaturated
ketones of the steroid series (A4-cholesten-3-one, testosterone
acetate, progesterone), both from the theoretical and practical points of view. The reaction products are separated on a
column of inactivated alumina. Analysis of the fractions by
thin-layer chromatography indicated a few isomeric reaction
products which appear to be both conjugated and unconjugated A-homophenyl steroid ketones, judging from their
[VB 699/87 IE]
ultraviolet and infrared spcctra.
German version: Angew. Chem. 75, 725 (1963)a
Meeting of the German Pharmacological Society
April 28th to May lst, 1963 in Mainz, Germany
F r o m the agenda:
Pharmacological and Biochemical Characteristics of
6-Aminonicotinamide
A . Brunnemann and H. Cuper, Berlin-Dahlem (Germany)
In rats and other mammals, 6-aminonicotinamide produces
toxic effects which become especially apparent in progressive
paralysis of the hind extremities. There is also a marked drop
in body temperature accompanied by blood-stained diarrhoea;
490
after considerable loss in weight, the animals die within a few
days. Following intraperitoneal application of 25 mg/kg of
6-aminonicotinamide, 50 y, of the animals die within 5 days.
Neither artificial feeding nor increase in external temperature
clearly influences the survival period. On the other hand, the
prolongation of barbiturate narcosis by 6-aminonicotinamide
is temperature-dependent.
The toxic action is caused by incorporation of the antimetabolite into the NAD molecule. To test this hypothesis,
the 6-aminonicotinamide analogue of NAD (6-ANAD) was
synthetized with the help of an NAD-nucleosidase from
brain microsomes and its identity checked both by spectroAngew. Chem. inivrnut. Edit. 1 Vul. 2 (1963) 1 No. 8
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