Kinetics and mechanism of hydrolysis of insecticidal O-(methylcarbamoyl)oximes

The hydrolysis of various insecticidal benzaldoxime and acetophenoxime carbamates was investigated for hydroxide ion concentrations ranging from 0.01 to 5.0 N at 25 "C. The reactions were found to be first order with respect to both hydroxide ion and the ester. The data suggest the involvement of an ElcB elimination mechanism with formation of an isocyanate intermediate. The Hammett p values were different from those usually reported for such a reaction scheme since the imine bond weakens the substituent effects.