A KINETIC STUDY OF OXIDATION OF VARIOUS SUBSTITUTED N,alpha-DIPHENYLNITRONES BY N-CHLORO-3-METHYL-2,6-DIPHENYLPIPERIDIN-4-ONE

摘要

The kinetics of oxidation of various substituted N,alpha-diphenylnitrones by N-chloro-3-methyl-2,6-diphenylpiperidin-4-one(NCP)has been studied in aqueous acetonitrile in the presence of perchloric acid.The overall order of the reaction is found to be two and one with respect to oxidant and substrate,respectively.The rate increases with increasing the addition of H~+ion.The increase in rate with decreasing the percentage of water suggesting the presence of an ion-dipole interaction.All the kinetic results reveals that an electron-withdrawing group increases the rate and electron-donating group decreases the rate.The Hammett's plot of lg k_2 versus a is linear with the positive'rho'values increase with increase in temperature suggesting that it is an entropy-controlled reaction.The results are consistent with the proposed rate law.