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Detection of the Phenylsufur Radical.

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These results supply information on the fine structure of the
cyanines and contribute to the theoretical interpretation of
these dyes. Our investigations are therefore continued on a
broad basis.
Received, February 15th, 1963
NM R-Spectrometer.
Preparation of 1-Hydroxypropane-2-sulfonicAcid
By Dr. Heinz Schmitz, Dr. H. Grosspietsch,
Dr. H. Kaltenhiiuser, and Dr. H.Wendt
Farbwerke Hoechst AG. vormals Meister Lucius & Bruning,
FrankfurtIMain-Hiichst (Germaiiy)
I-Hydroxypropane-2-sulfonicacid is said to have been
prepared by Raschig and Prahl [l] bq treating chloropropylene glycol acetate with K2SO3 (synthesis I) and by Manecke [2]by hydrolysis of an anhydride of the acid made by
treating sulfuryl chloride with n-propanol and dehydrochlorinating the propyl chlorosulfonate obtained (synthesis
11). As rearrangements may possibly occui in these syntheses,
we have prepared 1-hydroxypropane-2-sulfonicacid by
reduction of cr-sulphonylpropionic acid with LiAIFI4 in
dioxan (synthesis 111).
I
LiAIH4
d H3C-CH-CHZOH
dioxan
I
SOsH
SO3H
The infrared spectrum of the barium salt of this acid was
different from those of the barium hydroxypropanesulfonates
made by syntheses I and 11, which corresponded. The
hydroxypropancsulfonic acid made by the othei authors
must therefore be either 2-hydroxypropane-1-sulfonicacid
or 1 -hydroxypropane-3-sulfonic
acid. The latter is obtainable
by hydrolysis of 1,3-propanesultone; the infrared spectrum
of its barium salt differs from the spectra of the barium salts
obtained by syntheses I, 11, and 111. 2-Hydroxypropane-lsulfonic acid was made by reduction of acetonesulfonic acid
(synthesis IV); its barium salt had the same infrared spectrum
as that of the barium salts from syntheses J and 11.
I t can also be shown by comparison of the melting points of
the phenylhydrazonium salts and of the N-methylaminopropanesulfonic acids (obtained by reaction with methylamine) that the hydroxypropanesulfonic acids described both
by Raschig and Piahl and by Manecke are in fact 2-hydioxypropane- 1 -sulfonic acid.
Method of
synthesis
1
Phenylhydrazoniurn salt
rn.p.[ “C];
m.p.
By Dozent Dr. Ulrich Schmidt and
Dip1.-Chem. Asmus Muller
[Z 454/292 IE]
[ l ] G. Scheibe, H . J . Friedrich, and G. Hohlneicher,Angew. Chem.
73, 383 (1961).
[2] The investigations were carried out with a Varian A 60 Mode
H2C-CH-COOH
Detection of the Phenylsulfur Radical [11
N-Methylaminopropanesulfonic acid
m.p. [ T I ; mixed m.p. I “Cl
Chemisches Laboratorium
der Universitit FreiburgIBreisgau (Germany)
P
Ionic radicals of doubly-bonded sulfur (R--S-R) were
detected by us in oxidized solutions in sulfuric acid of di-pmethoxyphenyl sulfide, p-di(arylthio)benzenes, and tetraphenylthiophenes [l]. Free radicals of singly-bonded sulfur
(R-So) have been sought repeatedly, but were not found
hitherto [2]. However, the existence of the phenylsulfur
radical (Ph --SO)has now been demonstrated by us.
On irradiating diphenyl sulfide vapor with short-wave ultraviolet light at 1 mm. Hg pressure and high carrier-gas (N2)
speeds, phenylsulfur radicals were detected as thiophenol by
dehydrogenation of injected cumene 10 cni from the irradiated
zone.
Irradiation of diphenyl sulfide vapor without carrier-gas at
0.1 mm Hg pressure resulted in the formation of a red
coating of Ph -S. a few cm away on a finger cooled with
liquid nitrogen. This was stable for some hours in vcicuo at
-2OO”C, but disappeared within a few minutes at -100°C.
Thiophenol was formed by disproportionation or dehydrogenation of diphenyldisulfide.
Measurement of the electron spin resonance spectrum at
-200 “C showed a strong signal with a typically anisotropic
g factor. The g tensor is almost axisymmetrical with limiting
values g I = 2.006 and gi 1 = 2.012 as far as can be determined
from the powder spectra. This indicates that the unpaired
electron is associated mainly with the sulfur, since such a
large degree of g anisotropy can only be explained by an
electron which is strongly localized.
Received, February 25th, 1963
[Z 453/281 IE]
[ l ] Communication No. 2 on Organosulfur Radicals; Communication No. 1 : Angew. Chem. 72, 708 (1960).
[2] For literature references, see Communication No. 3, Liebigs
Ann. Chem., in the press.
Proton-Resonance Investigations of
“4 (or 5)-Substituted Imidazoles”
By Prof. Dr. H. A. Staab and Dr. A. Mannschreck
Organisch-chemisches Jnstitut
der Universitat Heidelberg (Germany)
Tautomeric forms A and B of 4 (or 5)substituted imidazoles
cannot be isolated [I]. It has also not been possible to determine whether these compounds exist as either structure A or
structure B.
193.5
-
111
IV
I1 f IV
A
194
135
135
Willems [3] also designated a substance he obtained from 2bromopropanol and N a ~ S 0 3 as 1-hydroxypropane-2-sulfonic acid, as it proved to be identical with the acid described
by Manecke. It appears from our work that Willems too
obtained 2-hydroxypropane-1-sulfonicacid.
Received, February 21st, 1963
[Z 451/280 IE]
[ I ] F. Raschig and W. Prahl, Ber. dtsch. chem. Ges. 61, 185
(1928).
[2] G. Manecke, Chem. Ber. 85, 160 (1952).
[3] J. Willerns, Bull. SOC.chim. Belg. 64, 409 (1955).
216
13
193.5
Concepts, such as the hypothesis of a special “mesohydric
tautomerism” [2], or the postulate [3] based on spectroscopic
results that, in both the crystalline state and non-polar solvents, imidazoles exist as ion-pairs made up of imidazole
anions and imidazole cations led to the assumption that it is
impossible to differentiate between 4-and 5-substituted imidazoles [3,4]. Our proton-resonance experiments show that
such postulates do noi apply to the 4(or 5)-substituted
imidazoles investigated in the present work. They demonstrate that these compounds exist predominantly in one
definite form, for which distinction can be made between 4and 5-substitution on the basis of the respective spin-spin
coupling constants.
Angew. Chem. internat. Edit. / Vol. 2 (1963) No. 4
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