MECHANISM OF OXIDATION OF SCHIFF BASES TO OXAZIRANES BY PEROXY ACIDS IN VARIOUS SOLVENTS

Hammett ρ values for peroxybenzoic acid oxidation of two series of Schiff bases, para-substituted N-benzal-t-butylamines and N-p-nitrobenzal-substituted benzylamines, were found to be -1.75 and -0.98, respectively. The ρ value for substituted peroxybenzoic acids as oxidizing agent was +0.78 and for substituted benzoic acids as catalyst was +0.22. The small solvent kinetic isotope effect, activation parameters in one case, along with the ρ values, suggested a concerted mechanism pictured as a nucleophilic displacement of the C=N bond of the Schiff base on the peroxy oxygen. © 1969, American Chemical Society. All rights reserved.