AMINOLYSIS OF O-(2,4-DINITROPHENYL)-P,P'-DISUBSTITUTED BENZOPHENONE OXIMES IN BENZENE - EVIDENCE FOR HIRST MECHANISM

The reactions of O-(2,4-dinitrophenyl)-substituted p,p'-dimethoxybenzo phenone oxime, p,p'-fluorobenzophenone oxime and p,p'-dichlorobenzophe none oxime with pyrrolidine and piperidine in benzene were found to be third order in amine, with no uncatalytic route. The overall rate is a combined effect of rates of two routes, one of which increases and t he other decreases with rise in temperature. The relative contribution of the two routes to overall rate varies with temperature, nucleofugi city of the substrate, nucleophilicity and concentration of amine, As a result, the effect of temperature on the overall rate for some react ions is positive and for others negative. This unusual temperature eff ect on the overall rate supports Hirst's mechanism.