Mechanism of the 10-methylacridinium ion-sensitized photooxidation of N,N-dibenzylhydroxylamine and its derivatives in acetonitrile

Abstract

The 10-methylacridinium ion (MA⁺)-sensitized photooxidation of substituted N,N-dibenzylhydroxylamines (1) in acetonitrile occurred mainly by a superoxide ion mechanism to give N-benzylidenebenzylamine N-oxides (2) and hydrogen peroxide quantitatively. Analysis of substituent effects on the limiting quantum yield for formation of 2 showed that back electron transfer (ET) from the 10-methylacridinyl radical (MA˙) to the radical cation 1⁺˙ proceeds in the Marcus ‘normal region’. In addition, this back ET was found to take place in preference to one-electron reduction of O₂ by MA˙.