Kinetics of Oxidation of Aniline, N-Methylaniline, N,N'-Dimethylaniline by Chromic Acid

Abstract

Kinetics of oxidation of aniline by chromic acid has been studied in 10 % aqueous acetic acid and N-methylaniline, while the kinetics of oxidation of N,N'-dimethylaniline have been studied by chromic acid in 1 % aqueous acetic acid. The order with respect to oxidant for aniline, N-methylaniline, N,N'-dimethylaniline is one, zero, zero, respectively. The order with respect to substrate is one in each case. The rates constant were found to depend upon the concentration of HCl and H₂SO₄. The primary salt effect on the rate of oxidation is negligible. The reaction rate increases with the decrease of the dielectric constant of the medium in each case. An addition of Cu²⁺ and Ag⁺ ions have marked accelerating effect on all the three reactions, while in case of Mn²⁺ ions the rate is found to decrease in case of aniline and N,N'-dimethylaniline, but increase in case of N-methyl aniline. Thermodynamic parameters were evaluated and mechanisms for the reactions have been proposed. The isokinetic temperature has also been evaluated.