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End Group Estimation in Polymer Compounds Using Dyes.

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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)
e
V (Biph)C=CH-N-CH=C(Biph)
-
VI (Biph)C=CH-N=CH-&Biph)
I
orange-yellow. m.p. 320 OC [lf]
red
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
copolymerisation.
[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
trans-3-hydroxy-~-proline,
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
trans-3-hydroxy-L-proline
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.
603
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