Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 10, pp. 1586−1589.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © A.G. Galstyan, I.A. Zema, A.S. Bushuev, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 10, pp. 1653−1657.
AND INDUSTRIAL ORGANIC CHEMISTRY
Oxidation of 4-Aminotoluene by Ozone–Air Mixture
in the Presence of a Stop-Reagent
A. G. Galstyan, I. A. Zema, and A. S. Bushuev
Institute of Chemical Technologies, Dal’ East-Ukrainian National University, Rubezhnoe, Lugansk oblast, Ukraine
Received March 30, 2012
Abstract—A study of the liquid-phase oxidation of 4-aminotoluene by ozone to 4-amino benzaldehyde in the
presence of a manganese/bromide catalyst demonstrated that introduction of potassium bromide into the oxidiz-
ing system makes it possible to obtain 4-aminobenzaldehyde in the form of 4-(acetylamino)benzylidene diacetate
(84.5%) as the main product. A reaction scheme accounting for the results obtained was suggested.
4-Aminobenzaldehyde (4-AB) is widely used
in manufacture of pharmaceutical preparations and
organic dyes [1–4]. It is for the most part industrially
produced by reduction of 4-nitrotoluene with sulﬁ des in
an alkaline medium . Among disadvantages of this
method are the low yield of the product and formation
of large amounts of a toxic wastewater.
This study is devoted to analysis of the oxidation
process of 4-aminotoluene (4-AT) by an air–ozone
mixture in order to develop a low-waste method for
production of 4-AB in high yield.
It has been shown previously  that AT-4 reacts with
ozone as 4-acetylaminotoluene (4-AAT) in a solution of
acetic anhydride in the presence of sulfuric acid. This
fact is accounted for by the high rate of acylation by
acetic anhydride, which ends under the experimental
conditions while a mixture for ozonation is prepared.
Ozone attacks 4-AAT predominantly at the aromatic
ring [reaction (2)], and the selectivity of oxidation at the
methyl group [reaction (1)] does not exceed 26%:
→ Ozonolysis products. (2)
It was shown in  that the selectivity of oxidation
at the ethyl group increases to 84.5% in the presence
of a catalyst, manganese(II) acetate. The main oxidation
products are 4-(acetylamino)benzyl acetate (4-AABA,
65%) and 4-(acetylamino)benzylidene diacetate
(4-AABDA, 19.5%). It is impossible to oxidize 4-AT to
predominantly obtain 4-AB (in the acylated form) under
Proceeding with these studies, we examined the
possibility of making deeper the oxidation of 4-AAT
by its ozonation in the presence of a mixed manganese/
bromide catalyst, because it is known [8, 9] that the
catalytic activity of variable-valence metal ions grows
in a mixture with alkali metal bromides.
Our study demonstrated (Table 1) that addition of
potassium bromide to the oxidizing system at 30°C
does improve the selectivity and depth of oxidation at
the methyl group of 4-AAT with predominant formation
of 4-AABDA. The content of 4-AABDA in the
reaction products increases with the potassium bromide
concentration and reaches the maximum value at [KBr]
= 0.08 M (Table 1). At a [ArCH
] : [Mn(OAc)
[KBr] ratio of 5 : 1 : 1, the reaction yields, at an overall
selectivity in the system of 94.8%, 84.5% 4-AABDA,
10.3% 4-AABA, and trace amounts of 4-(acetylamino)
benzyl bromide (4-AABB).
Based on our experimental results and published data