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Ions and Radicals from Aromatic Hydrocarbons and Amines.

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to the active complex after addition of a Lewis base. In the
presence of relatively large amounts of highly substituted
aromatic compounds. e. g . mesitylene or hexamethylbenzene,
the polymerization is inhibited, the butadiene being displaced
from the catalyst complex by the stronger x-electron donor.
Since this displacement is an equilibrium reaction, minutest
amounts of these stronger x-electron donors have only a retarding effect on the rate of polymerization; x-electron donors
also redure the molecular weight of the resulting polymer.
The kinetics of the polymerization of butadiene with the
catalyst system Co-(111) acetylacetonate/ethylaluminum
sesquichloride were investigated with the aid of adiabatic
calorimetry. The rate equation for the polymerization is
= k'x[Mlx(Col
o c
= 144.1)
The concentration of ethylaluminum sesquichloride does not
enter into the rate equation. The fraction on the right
side of the equation takes into consideration the partial,
reversible inactivation of the catalyst by the benzene solvent.
Here [v] is the benzene concentration and K is a constant,
the x-electron donor constant, by means of which the tendency of benzene to form a x-complex with cobalt is expressed numerically, taking butadiene as unity. If still other
x-electron donors (substituted aromatics, Lewis bases,
acetylenes, etc.) are present during the polymerization, then
additional, similar correction terms must be introduced into
the rate equation. By adding small quantities of substituted aromatics to the polymerization mixture, the xelectron donor constants for these compounds were determined from the decrease in the rate of polymerization:
I Aromatic
Using a combination of continuous and discontinuous multiplicative counter current distribution [2] and chromatographic techniques with a new method of assaying inflammatory and co-carcinogenic action, two colourless, amorphous
substances A and B were recently [3] separated from croton
oil which accounted completely for its toxic, inflammatory
and co-carcinogenic properties. Both substances appeared
to be chromatographically pure; their RF values are 0.6 and
0.7; [ a ] =~ 47" and 46", respectively. According to their
ultraviolet and infrared spectra, they contain free hydroxyl
and ester groups and double bonds [4]. When treated with
4-nitroazobenzene-4'-carbonyl chloride [5], substance A
produced a deep red crystalline ester [m.p. 86-87 "C, infrared absorption in KBr 2.95 p (OH); 3.43, 3.51 p (CH);
5.8-5.85 P (CO);6.1-6.15~ ( C s C ) ; Amax (230). 330.5, (345),
(460) mp; Emax in ethanol (15000), 30880, (26800), (634)l.
Analyses and molecular weight determinations agreed best
with the molecular formula c51 H64-66 0 1 2 N3 @I.
The DL50 of both substances was 10 y/50 g with frogs and
the inflammatory level was about 10-2 y/mouse ear. In skin
tests, a single dorsal application of 300 y/mouse of 9,lOdimethyl-1,Zbenzantrhacene (DMBA) followed by two
treatments per week for 12 weeks with each 0.5 y of substances
A or B produced benignant tumours (mean: 10 or ll/mouse,
resp.) in all of the mice. After further 16 weeks without
treatment, some of the tumours developed into malignant
proliferating, plate-epithelial carcinoma. Sarcoma and
leukemia were also observed. Oral administration of DMBA
and dorsal application of substance A or B produced epithelial carcinoma and sarcoma in a similar way. Application of
300 y DMBA alone or application of substance A or B alone
did not result in malignant tumours.
The isolation of the co-carcinogens A and B offers a first
chance of elucidating the structure of these highly active
compounds as well as of testing the two stage hypothesis
of carcinogenesis and subjecting it to biochemical analysis.
[Colloquium, Max-Planck-Institut fur Medizinische Forschung, Heidelberg (Germany), June 18th, 19621
[VB 608/41 IE]
Ions and Radicals from Aromatic Hydrocarbons
and Amines
The butadiene concentration does not enter into the rate
equation for catalyst formation. The rate-determining step
is the reduction of cobalt from a valence of f 2 to +l.
[GDCh-Ortsverband Ruhr, Miilheim/Ruhr (Germany)
[VB 599/43 1El
June 27th, 19621
The Toxic, Inflammatory, and Co-carcinogenic
Components of Croton Oil
E. Hecker, Munich (Germany)
Richard Kuhn, Heidelberg (Germany)
It has proved possible to prepare aza analogues (F. A. Neugebauer) of "strongly acidic" hydrocarbons [7]. Like the
corresponding hydrocarbons, many of these analogues, e. g .
IV, yield strongly colored anions in suitable solvents when
treated with even dilute aqueous sodium acetate solution.
These anions may be oxidized, with formation of free radicals,
by treatment with K#e(CN)6 (Electron Paramagnetic
Resonance spectra, K . H. Hausser). Examples [8] :
I (Biph)C=N-CH(Biph)
Croton oil is a pharmaceutical laxative oil which is obtained
from the seeds of the tropical plant Croton tigZium L. (Euphorbiaceae). The laxative as well as the toxic and inflammatory or vesicant properties of the oil have long been known
and have frequently induced various groups of workers to
investigate the chemistry of the oil. It was found [l] that croton
oil can cause the development of large tumors from potential
tumor cells. This co-carcinogenic action of the oil has
acquired considerable importance in cancer research, since its
study might provide a dearer understanding of the complicated mechanism of carcinogenesis. The so-called Two Stage
hypothesis of carcinogenesis based on the results of corresponding investigations is still in dispute since, despite numerous attempts, it has not been possible to isolate the co-carcinogenic component of the oil in a pure state.
[I] I. Berenblurn, Cancer Res. 1, 44, 807 (1941).
I1 (Biph)C=N-C@iph)
111 (Biph)C=N-e(Biph)
m.p.199 "C (decomp.) [91
olive, formsdimer of m. p. 270 "C (decomp.)
[2] E. Hecker: Verteilungsverfahren im Laboratorium. Verlag
Chemie, Weinheim/Bergstr. 1955; Z. analyt. Chem. 181, 284
(1961); Chemiker-Ztg. 86, 272 (1962).
[3] Reported at a Symposium for Cancer Research, sponsored
by the Deutsche Forschungsgemeinschaft,Jan. 2nd- 5th, 1962
in HomburgjSaar, Germany.
[4] J. G.Meyer, Ph. D. Thesis, University, Munich (1962).
[5] E. Hecker, Chem. Ber. 88, 1666 (1955).
[6] H. Bresch, Diploma Thesis, University, Munich (1962).
[7] Definition: R. Kuhn, H . Fischer, F. A . Neugebauer, and H.
Fischer, Liebigs Ann. Chem. 654, 64 (1962).
[8] (Biph) = 2,2'-biphenylene.
191 C. K. Ingoldand C.L. Wilson,J.chem. SOC.(London) 1933,1493.
Angew. Chem. internat. Edit. J Vol. I(I962) J No, 11
The dimer of I11 is identical with a substance which has been
described as tetrafluorenylhydrazine [lo] and which should
contain four more hydrogen atoms.
IV (Biph)C=CH-NH-CH=C(Biph)
V (Biph)C=CH-N-CH=C(Biph)
VI (Biph)C=CH-N=CH-&Biph)
orange-yellow. m.p. 320 OC [lf]
yellow, forms dimer of m.p.
226 “C(decomp.)
(B$h)C= CH-I?-CH=C(Biph)
If one of the two fluorene residues in VII
VII (Biph)C= CH-CH(Biph)
is replaced by a residue of 1,2;7,8-dibenzofluorene,a colorless hydrocarbon (m.p. 263 “C) results, which yields green
anions. The orange isomer (m.p. 251 “C) derived from 3,4;
5,6-dibenzofluorene is more strongly acidic and yields bluered anions. The differences in color and acidity ( D . Rewicki)
were discussed from steric points of view.
[GDCh-Ortsverband Darmstadt (Germany)
July loth, 19621
[VB 607/42 IE]
End Group Estimation in Polymer Compounds
Using Dyes
S. R. Palit, Calcutta (India)
A new technique enables small amounts of organic compounds with functional groups to be detected by colour
reactions qualitatively or quantitatively down to amounts of
the order of 1 ppm. Either (a) the change in partition coefficient of a dye between two liquid phases is determined when
a trace of the compound to be estimated is added to one
phase (“dye partition test”), or (b) the change in shade of
colour of a solution of a dyestuff in an organic solvent is
observed when a salt or a compound with acidic or basic
g r o ~ pis
s added (“dye interaction test”).Whilst method(a)[l2]
allows only qualitative estimations, as the compound under
investigation may become concentrated in the phase interface, method (b) can be used for quantitative photometric
estimations. For example, an aqueous methyl violet solution
of pH 7-12 is extracted with benzene. The benzene extract
is yellow to brown and reacts with great sensitivity to the
smallest amount of an acidic group (e.g. -COOH, -SO4H,
-SO3H) giving a violet colour. Other dyestuffs, e.g. Rhodamine 6 Gx, can similarly be used. Base-sensitive dyes, such
as Eosin H and Eosin acid L New, can be employed for the
determination of basic groups, e.g. amines, at pH 4-5.
Examples of applications, especially in macromolecular
chemistry, were mentioned, particularly the estimation of end
groups for the elucidation of starting, terminal and transfer
reactions in polymerisation, the determination of molecular
weights, and the estimation of monomer reactivities in
[TechnischeHochschule Stuttgart (Germany) July I7th, 19621.
[VB 625/47 IE]
Recent Contributions to the Chemistry
and Biochemistry of some Amino Acids
hydroxyproline which has been isolated and crystallized from
acid hydrolysates of mediterranean sponge first by separation
of the cyclic imino acids via their ether-soluble N-nitroso
derivatives and separation of the liberated imino acids on
columns of IR-120 resin [l]. Out of 64 g of dried sponge
there were obtained 62 mg of the crystalline amino acid,
C5HgNO3, [a13 = -24.4’. The proof of structure was furnished by the synthesis of the racemic 3-hydroxy-~~-proline
by hydroboration of 3,4-dehydro-~~-proline
[2] in the following manner: the methyl ester of N-carbobenzyloxy-3,4dehydro-DL-proline[3] was treated with diborane, the
resulting alkylborane oxidized with alkaline hydrogen peroxide and the product hydrogenolyzed to a mixture which on
automatic amino acid analysis separated into 68 % 3hydroxy-DL-proline, presumably trans, 10% 4 - h y d r o x y - ~ ~ proline and a trace of allo-4-hydroxy-~-proline.The pure
crystalline synthetic 3-hydroxy-~~-proh1e
proved to be
sterically homogeneous and was identical with the natural
amino acid with regard to mobility in five solvent systems,
ion exchange chromatography, high voltage electrophoresis
and infrared spectra of the N-carbobenzyloxyamino acid
methyl esters. D-Amino acid oxidase did not attack the
natural amino acid which is, therefore, considered to be
whereas the D-isomer in the
racemate was quantitatively oxidized by the oxidase, presumably t o 1,2-dehydro-3-hydroxyproline.3-Hydroxy-~proline has also been identified as a regular constituent of
collagen hydrolysates. The diastereoisomeric cis-3-hydroxyDL-proline was synthesized by oxidation of N-carbobenzyloxy-3-hydroxy-~~-proline
methyl ester with CrO3 in acetone,
reduction with sodium borohydride, hydrolysis of the ester,
catalytic decarbobenzyloxylation and separation of the
mixture (about 1:I) of diastereoisomeric 3 - h y d r o x y - ~ ~ prolines by chromatographic techniques. Both cis- as well as
appear to be building stones of the
peptide antibiotic telomycin [4]. The use of NaBT4 in the
reduction of suitable 3- and 4-ketoproline derivatives has
permitted the preparation of selectively tritiated 3- and 4hydroxyprolines which have been used as substrates for the
enzymes that effect the incorpxation of free into bound hydroxyproline in systems such as chicken embryos as well as
Streptomyees antibioticus. These studies, carried out in the
laboratory of S. Udenfriend also used selectively triated proline derivatives for the investigation of the mechanism of
hydroxylation of proline to free or bound hydroxyproline.
[Physiologisch-chemischesInstitut, Universitat GieDen
(Germany), July 19th, 19621
WB 617/52 IE]
A New Procedure for the Determination
of the Acidity of Very Strong Acids
F. Klages, K. Bott, and
P. Hegenberg, Munich (Germany)
In order to investigate the influence of hydrogen bridges on
the acidity of acids, the evaluation of acidity according to the
rate of decomposition of aliphatic diazo-compounds by acids
in ethylene chloride was examined. The diazo-compounds:
bis(phenylsulphony1)diazomethane (I), tetrachlorodiazocyclopentadiene (11), and tetraphenyldiazocyclopentadiene(III),
which display varying sensitivities towards acids, were used.
B. Witkop, Bethesda, Md. (U.S.A.)
For some time it has been known that hydrolysates of vertebrate and invertebrate collagens show a n unidentified peak
(Stein and Moore analyzer) in front of hydroxyproline and
adjacent to methionine sulfoxides. This peak has now been
identified as belonging to a new natural amino acid, viz. 3[lo] St. Goldschmidt et al., Liebigs Ann. Chem. 447, 197 (1926);
456, 152 (1927).
[I 11 W. Wislicenusand K.Russ,Ber.dtsch.chem.Ges.43,2713(1910).
[I21 S. R. Palit et al., Makromolekulare Chem. 36, 89 (1959);
38, 96 (1960); J. Polymer Sci. 50, 45 (1961).
Angew. Chem. internal. Edit.
1 Vol. I (1962) 1 No. I 1
With a sufficient excess of acid, the decomposition reaction is
always pseudo-monomolecular and allows the determination
[I] F. Irreverre, K. Morita, A. V. Robertson, and B. Witkop, Biochem. biophys. Research Commun., in press.
[2] A. V.RobertsonandB. Witkop,J.Amer. chem.Soc.84,1697(1962).
[3] N. Zzumiya, J. E. Francis, A. V. Robertson, and B. Witkop,
J. Amer. chem. SOC.84, 1702 (1962).
[4] F. Zrreverre, unpublished observations.
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hydrocarbonic, radical, ions, amines, aromatic
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