Photochemical decomposition of 4-arylazo- and 4-arylazoxy-N,N-dialkylaniline N-oxides

Abstract

The 4-aryl-N,N-dialkylaniline N-oxides (1a–c) decompose on u.v. irradiation in aprotic solvents, undergoing deoxygenation as well as intramolecular hydrogen abstraction, to give amides and dealkylated products. The latter process is more important for the diethyl derivative (1b)(photo-Cope elimination). Visible irradiation is ineffective. The 4-arylazoxy-N,N-dialkylaniline N-oxides (2a–d) undergo photochemical deoxygenation from the amino group (major process) as well as from the azo group. The mechanism of these photoprocesses is discussed in general and in relation to the possible involvement of these N-oxide derivatives in photofading of the related azo dyes.