Kinetics of the reaction of para-substituted nitrosobenzenes with methoxide ion in methanol
Abstract
The kinetics of the reaction of RC6H4NO with MeO– to yield RC6H4NN(O)C6H4R (R = H, p-NMe2, p-OMe, or p-Cl), or RC6H4NO2 in the presence of oxygen (R = H, p-OMe, or p-Cl) were studied as a function of temperature and MeO– concentration. ρ Values (3·9 and 4·0 at 25 °C, for azoxy formation and oxidation respectively) are consistent with the presence of a negative charge in the transition state, the rate-determining steps being the formation of RC6H4NOH· from RC6H4NO and MeO– for azoxy formation and the reduction of RC6H4NO2– by MeOH for oxidation. Activation parameters are discussed in the light of the proposed mechanism.