Russian Journal of Organic Chemistry, Vol. 37, No. 5, 2001, pp. 673 676. Translated from Zhurnal Organicheskoi Khimii, Vol. 37, No. 5, 2001,
pp. 712 715.
Original Russian Text Copyright
2001 by Zhandarev, Kazin, Mironov.
Catalytic Liquid-Phase Reduction of Aromatic Nitro
Compounds Containing Highly Reactive Functional Groups
V. V. Zhandarev, V. N. Kazin, and G. S. Mironov
Demidov Yaroslavl State University, ul. Sovetskaya 14, Yaroslavl, 150000 Russia
Received July 10, 2000
Abstract Improved procedures have been proposed for fast and selective hydrogenation of aromatic nitro
compounds with the goal of obtaining practically important amines.
We have studied the effects of catalyst nature,
carboxylic and CH acids which are soluble in aqueous
solvent, temperature, reactant concentration, and solutions of salts and alkalies, and the second group
various additives on the hydrogenation of aromatic
nitro compounds containing highly reactive functional
groups and fragments, namely chlorine atom, cyano,
hydroxy, ether, ester, and carbonyl groups, amide and
sulfamide bonds, and pyrazolone ring. The goal of the
study was to find conditions ensuring high selectivity
of the process. The subjects for study were nitroarenes
which are used as starting compounds in the synthesis
of practically important aromatic amines: 2-(3-amino-
4-chlorobenzoyl)benzoic acid (I), 3-(3-aminobenz-
amido)-1-(2,4,6-trichlorophenyl)-4,5-dihydropyrazol-
5-one (II), 1-(2,4,6-trichlorophenyl)-3-(2-chloro-5-
aminoanilino)-4,5-dihydropyrazol-5-one (III), ethyl
(4-aminobenzoyl)cyanoacetate (IV), N-(3-amino-4-
chlorophenyl)-4-(2,4-di-tert-pentylphenoxy)butan-
amide (V), N-[4-(2,4-di-tert-pentylphenoxy)butyl]-4-
(4-aminophenoxy)-1-hydroxy-2-naphthalenecarbox-
amide (VI), N-[3,5-bis(methoxycarbonyl)phenyl]-3-
amino-4-chlorobenzenesulfonamide (VII), N-(3-
amino-4-chlorophenyl)-4,4-dimethyl-3-oxopentan-
amide (VIII), and N-(3-amino-4-chlorophenyl)-1-
hydroxy-2-naphthalenecarboxamide (IX). Amino com-
pounds I IX are intermediate products in the synthesis
of anthraquinone dyes (amino acid I) and materials for
color photography (II IX). They are usually prepared
by reduction of the corresponding nitro compounds
with iron, iron and tin salts in acid medium [1, 2], or
molecular hydrogen over Raney nickel in the liquid
phase [3]. However, this catalyst does not ensure high
selectivity in the reduction of halogen-containing nitro
compounds: As a rule, the process is accompanied by
hydrodehalogenation, so that addition of appropriate
inhibitors is necessary.
included compounds soluble in organic solvents.
We have examined the reduction of 2-(4-chloro-3-
nitrobenzoyl)benzoic acid in a 5% aqueous solution
of sodium hydroxide in the presence of Raney nickel,
0.8% Pd/Al2O3, and 0.5% Pt/Al2O3. The degree of
hydrodehalogenation was 46, 3, and 0.4%, respec-
tively, the conversion of the nitroarene being com-
plete. Therefore, the platinum catalyst was selected
for further studies. We have found that hydrogenation
in an aqueous solution of sodium carbonate is more
advantageos: The resulting amine is formed in a larger
yield and with higher purity, the rate of the process
increases, and the activity of the catalyst is retained
throughout 3 4 series against one series in aqueous
alkali. Increase in the concentration of sodium car-
bonate from 5 to 20% accelerates the hydrogenation
process, presumably due to enhanced adsorption of
the initial nitro compound from more basic medium.
As a result, we proposed an improved procedure for
synthesizing the target amino compound [4, 5], which
ensures high rate of the process and its selectivity
(Table 1).
In the reduction of 3-(3-nitrobenzamido)-1-(2,4,6-
trichlorophenyl)-4,5-dihydropyrazol-5-one and
1-(2,4,6-trichlorophenyl)-3-(2-chloro-5-nitroanilino)-
4,5-dihydropyrazol-5-one we tried as solvents aqueous
solutions of ammonia, sodium carbonate, and sodium
hydroxide with various concentrations. In the syn-
thesis of compound II the best results were obtained
using 0.5% Pt/Al2O3 as catalyst in aqueous sodium
carbonate. Raising the concentration of Na2CO3 from
10 to 20% increases the rate of hydrogenation by
a factor of 1.8 2.2. The hydrogenation of 1-(2,4,6-tri-
chlorophenyl)-3-(2-chloro-5-nitroanilino)-4,5-dihydro-
pyrazol-5-one in aqueous ammonia and aqueous
The nitro and amino compounds under study were
divided into two groups. The first of these includes
1070-4280/01/3705-0673$25.00 2001 MAIK Nauka/Interperiodica