Abstract
The kinetic regularities and mechanisms of oxidation reactions of 2- and 3-aminotoluene and its acylation derivatives by the gases that contain ozone in the glacial acetic acid have been studied. It has been established that ozone attacks mainly the lone pair of electrons of the nitrogen atom with formation, mainly, of polymers of azo compounds. The products oxidation on methyl group are not formed in these conditions. The direction of the ozone’s attack can be altered and directed on the methyl group, as well as by an aromatic ring, by acylation of the amino group. The total yield of the products of oxidation of the methyl group of 2- and 3-acetamidotoluene is 5,1 and 12,4 % respectively. The process of liquid-phase catalytic oxidation of 2- and 3-acetamidotoluene by the ozone in the presence of transition metal salts and their mixtures with potassium bromide to the corresponding acetamidobenzoic acids has been investigated as well. At the presence of acetate Co (II) the output of 2- and 3-acetamidobenzoic acid 25,0 and 31,2% respectively. We found out that the use of our catalytic system (ozone – acetamidotoluene - Co (III) – glacial acetic acid - potassium bromide) significantly increases the reaction rate and the selectivity of substrate oxidation of methyl groups. The main product of oxidation of 2- and 3-acetamidotoluene becomes 2- and 3-acetamidobenzoic acid (55,0 and 71,2 % respectively). Replacing ozone-air mixture with the ozone-oxygen mixture leads to higher yield of 2-acetamidobenzoic acid 70,0 % and 3- acetamidobenzoic acid 86,0 %.
Highlights
In the acetic acid the toluene react with ozone mostly for double bonds of the aromatic ring to form ozonides
2-aminobenzoic acid (2-ABA) is produced from phthalimide [6], 3-aminobenzoic acid (3-ABA) is produced by reconstitution from 3-nitrobenzoic acid [7], which in its turn is the product of oxidation of 3-nitrotoluene by mineral-oxidants and molecular oxygen
In order to obtain the necessary information for producing selective syntheses of aminobenzoic acids, we further studied kinetic characteristics and mechanism of reaction of ozone with acetaminotoluenes in the presence of salts of transition metals (STM) that were found to be electron donors during ozonation [11]
Summary
In the acetic acid the toluene react with ozone mostly for double bonds of the aromatic ring to form ozonides. Investigation of the influence of electron donor and acceptor substituents on the oxidation of the methylbenzenes and their derivatives by ozone in acetic acid were carried out in [2, 3]. It is shown that in the presence of electron donor (-CH3, -OH) substituents direction of attack by ozone of the methyl group is virtually absent, but the presence of electron acceptor (-NO2) substituents increases selectivity of the methyl group to 36 % [3]. The data of the oxidation of animotoluenes by ozone in the acetic acid in the literature are mostly absent. The study of the reaction of ozone with 2- and 3-aminotoluene in acetic acid to further clarify the nature of the substituent influence on the selectivity and composition of the oxidation products of methylbenzenes are actual
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