Hydroxide-promoted redox reactions in water of α-phenyl-4-nitrobenzenemethanol, α-(p-nitrophenyl)-4-pyridinemethanol, and α-(p-Nitrophenyl)-4-pyridinemethanol N-oxide steric inhibition of resonance

Article abstract of DOI:10.1002/jhet.5570330206

α-Phenyl-4-nitrobenzenemethanol (3) reacted with 1 M sodium hydroxide to yield 4,4′-dibenzoylazoybenzene (5) (51%), 4-hydroxy-4′-benzoylazobenzene (6) and benzoic acid (12% each), and smaller amounts of 4-aminobenzophenone and 4-nitrobenzophenone. Both α-phenyl-2-nitrobenzenemethanol (9) and 3,5-dimethyl-4-nitrobenzenemethanol (10a) did not react with 1 M sodium hydroxide, presumably due to steric hindrance. α-(p-Nitrophenyl)-4-pyridinemethanol (14) and its N-oxide 11 with 1 M sodium hydroxide yielded 4,4′-diaroylazoxybenzenes 15a and 12a, respectively, 4,4′-diaroylazobenzenes 15b and 12b, respectively, as well as 4-hydroxy-4′-aroylazobenzenes 16 and 13, respectively. The relative reaction rates were 11 > 14 > 3. Studies with 11 showed that the nitro group is involved in the redox reaction in preference to the N-oxide group.