ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 3, pp. 503!505. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + P.Yu. Andreev, E.V. Potapenko, I.P. Pogorelova, S.N. Krasil’nikov, A.N. Band, 2008, published in Zhurnal Prikladnoi Khimii,
2008, Vol. 81, No. 3, pp. 518!520.
A New Procedure for Preparing 3,4-Dinitrobenzoic Acid
P. Yu. Andreev, E. V. Potapenko, I. P. Pogorelova, S. N. Krasil’nikov, and A. N. Band
Institute of Chemical Technologies, Dal’ East-Ukrainian National University, Rubezhnoe,
Lugansk oblast, Ukraine
Received September 26, 2007
Abstract-A new efficient procedure of synthesis of 3,4-dinitrotoluene from 3-nitro-4-aminotoluene was
developed. Oxidation of 3,4-dinitrotoluene with an ozone3oxygen mixture to 3,4-dinitrobenzoic acid in
the presence of cobalt(II) acetate was studied.
Along with other isomeric dinitrobenzoic acids,
3,4-dinitrobenzoic acid (DNBA) is widely used as
intermediate in synthesis of photosensitive materials
for electrophotography [1, 2], X-ray contrast agents
[3, 4], and modifying and vulcanizing agents for
polyurethane plastics .
In common practice, DNBA is synthesized by oxi-
dation of 3,4-dinitrotoluene (DNT) with Cr(VI) com-
pounds or potassium permanganate. Oxidation with
mineral oxidants proceeds under mild conditions;
however, it is characterized by low selectivity and
formation of large amounts of toxic wastes. Addition-
al and important problem in synthesis of DNBA is the
fact that the dinitrotoluenes are obtained as an isomer-
ic mixture from which the desired 3,4 isomer (DNT)
should be isolated.
With the aim to develop a new procedure of syn-
thesis of DNBA, we studied the synthesis of DNT
from 3-nitro-4-aminotoluene (NAT) and the liquid-
phase oxidation of DNT with ozone3oxygen mixture
in glacial acetic acid.
For the synthesis of DNT we developed a proce-
dure based on the known procedure of synthesis of
2-dinitrobenzene from 2-nitroaniline . This proce-
dure involves diazotization of NAT with subsequent
substitution of nitro group for diazo group. The yield
of DNT is 92%.
Considering drawbacks of mineral oxidants, oxida-
tion of DNT with ozone is of practical interest. At
30oC and atmospheric pressure, ozone reacts with
DNT by two competing pathways, at double bonds of
the aromatic ring and at the methyl group:
OH + O
76 ozonides, (3)
where Ar is C
Among the aromatic products, we identified 3,4-di-
nitrobenzaldehyde (DNBAld) and traces of 3,4-dini-
trobenzyl alcohol (DNBAlc) in the initial period of
the reaction and DNBA in deeper stages (Fig. 1).
The yield of products formed by oxidation of the
methyl group in DNT is 38%.
The selectivity of oxidation at the methyl group in-
creases on adding variable-valence metal salts [7, 8].
c 0 10
Fig. 1. Content of components of the reaction mixture as
a function of time in oxidation of DNT with ozone3oxygen
= 8.30 10
= 0.125, [O
M; T =30oC. (c) Concentration and (t) time;
the same for Fig. 2. (1) DNT, (2) DNBA, (3) DNBAld, and