Quantitative Structure-Activity Assessment of the Regioisomers of Methyl Indole using Hydrodynamic Voltammetry

The quantitative structure-activity assessment of the three regioisomers of methyl indole using hydrodynamic voltammetry through chlorination kinetics was undertaken to elucidate the regiospecific effect of the methyl moiety. The reagent used was N-chlorosuccinimide. The reactions were found to be very rapid and followed second order kinetics. The rapidity of the reactions necessitated the use the special technique employed herein. The variation in the reaction rates with temperature was studied. The specific reaction rate, energy of activation, entropy change and the pre-exponential factor for each of the three reactions were evaluated. The specific reaction rates at 306 K for 1-methyl indole, 2-methyl indole and 3-methyl indole were found to be 68.8 M-1s-1, 460 M-1s-1 and 50 M-1s-1 respectively. These kinetic and related thermodynamic data obtained for the three regioisomers of methyl indole were found to be concomitant with the ease of the reaction dynamics considering the regiospecificity of the methyl moiety on indole.