Acid hydrolysis of 3-aryl-5-trinitromethyl-1,2,4-oxadiazoles

Full text of DOI:10.1023/A:1013116612723

Russian Journal of Organic Chemistry, Vol. 37, No. 9, 2001, pp. 1353 1354. Translated from Zhurnal Organicheskoi Khimii, Vol. 37, No. 9, 2001,
p. 1418.
Original Russian Text Copyright
2001 by Tyrkov.
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Acid Hydrolysis of 3-Aryl-5-trinitromethyl-1,2,4-oxadiazoles
A. G. Tyrkov
Astrakhan State Pedagogical University, ul. Tatishcheva 20a, Astrakhan, 414056 Russia
e-mail: astpedun@astranet.ru
Received June 7, 2000
3,5-Diphenyl-1,2,4-oxadiazole is known to be
stable under conditions of acid hydrolysis [1]. The
reaction of 5-trinitromethyl-3-phenyl-1,2,4-oxadiazole
(I) with dilute (1:1) hydrochloric acid resulted in
formation of benzamide oxime (V) via decomposition
of the oxadiazole ring. Attempted selective hydrolysis
of trinitromethyl group in I under mild conditions
(acetic acid) afforded 5-hydroxy-3-phenyl-1,2,4-oxa-
diazole (III) (Scheme 1).
of compound I or II, 50 ml of acetic acid, and 10 ml
of water was refluxed for 1 h. The solution was
evaporated, and the residue was subjected to column
chromatography (10 250-mm column) on activated
silica gel (Silicagel 100/400 m) using diethyl ether
as eluent. We isolated 0.5 g (63%) of 5-hydroxy-3-
phenyl-1,2,4-oxadiazole (III), mp 203 C [3], or 0.6 g
(68%) of 5-hydroxy-3-(4-tolyl)-1,2,4-oxadiazole (IV),
mp 220 C [4].
The acid hydrolysis of 3-(4-tolyl)-5-trinitromethyl-
1,2,4-oxadiazole (II) takes a similar pathway. It is
reasonable to presume that 5-hydroxy derivatives III
and IV are formed as intermediates when the acid
hydrolysis of I and II is performed under more severe
conditions. In fact, heating of 5-hydroxy-3-phenyl-
1,2,4-oxadiazole (III) in boiling dilute hydrochloric
acid gave benzamide oxime (V). It is quite probable
that the reaction involves elimination of the trinitro-
methyl group from oxadiazoles I and II to give com-
pounds III and IV; the latter are then converted into
benzamide oximes V and IV.
Hydrolysis of 3-aryl-5-trinitromethyl-1,2,4-oxa-
diazoles I and II in hydrochloric acid. A mixture of
3 mmol of compound I or II, 30 ml of concentrated
hydrochloric acid, and 10 ml of water was refluxed for
3 h. The solution was evaporated, and the residue was
purified by column chromatography (see above) with
benzene as eluent. We isolated 0.2 g (53%) of benz-
amide oxime (V), mp 78 80 C [5], or 0.3 g (61%) of
4-methylbenzamide oxime (VI), mp 147 C [6].
Hydrolysis of 3-aryl-5-hydroxy-1,2,4-oxadiazoles
III and IV in hydrochloric acid. A mixture of
3 mmol of compound III or IV, 15 ml of concentrated
hydrochloric acid, and 5 ml of water was refluxed for
2.5 h. The solution was evaporated, and the residue
Compounds I and II were synthesized by the
procedure described in [2].
Hydrolysis of 3-aryl-5-trinitromethyl-1,2,4-oxa- was purified by column chromatography (see above)
diazoles I and II in acetic acid. A mixture of 5 mmol with benzene as eluent. We isolated 0.15 g (35%) of
Scheme 1.
I, III, V, R = H; II, IV, VI, R = 4-CH3.
1070-4280/01/3709-1353$25.00 2001 MAIK Nauka/Interperiodica

1354
TYRKOV
compound V, mp 78 80 C, or 0.1 g (30%) of VI,
mp 146 147 C.
3. Adams, P., Kaiser, D.W., and Peters, G.A., J. Org.
Chem., 1953, vol. 18, pp. 934 941.
Compounds III VI showed no depression of the
4. Eloy, F., Fortsch. Chem. Forsch., 1965, vol. 4, no. 4,
melting point on mixing with authentic samples.
pp. 807 876.
5. Spravochnik khimika (Chemist’s Handbook), Nikol’-
skii, B.P., Ed., Leningrad: Goskhimizdat, 1963, vol. 2,
p. 474.
REFERENCES
1. Tiemann, F. and Kruger, P., Ber., 1884, vol. 17,
no. 12, pp. 1685 1698.
6. Busev, A.I., Sintez novykh organicheskikh reagentov
dlya neorganicheskogo analiza (Synthesis of New
Organic Reagents for Inorganic Analysis), Moscow:
Mosk. Gos. Univ., 1972, p. 211.
2. Ladyzhnikova, T.D., Altukhov, K.V., and Solov’-
ev, N.A., Zh. Org. Khim., 1986, vol. 22, no. 12,
pp. 2618 2619.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 9 2001