Kinetics and mechanism of halogenation of aniline, p-toluidine and o-toluidine using N-chloro-p-toluene sulphonamide (CAT) under buffer conditions in ethanol – water mixtures.

Kinetics of halogenation of aniline, p-toluidine and o-toluidine have been investigated by using N- chloro-p-toluene sulphonamide(CAT) under buffer conditions in ethanol - water mixtures. The kinetic orders are first order in chlorinating agent with all substrates. Dependence on substrate is fractional with aniline and p-toluidine but first order with o-toluidine. Increase in ethanol content decreases the rate in all the cases. Amis treatment has been applied and the molecular radii have been found to be reasonable with all substrates. Continuous pH profile has been investigated and the species at pH 1 and 6.85 is RNHCl whereas between 2.5 and 3.5 it is RNCl2 and the species at 4.5 is HOCl. The order of reactivity is p-toluidine > o-toluidine > aniline. Solvent parameters suggested by Grunwald - Winstein (Y), Dimroth (ET) and Kosower (Z) have been applied and it is observed that all the treatments are useful in explaining the solvent behaviour.