Photoreduction of 4-cyano-1-nitrobenzene in propan-2-ol

Abstract

The photoreduction of 4-cyano-1-nitrobenzene (CNB) in propan-2-ol (IP) proceeds via hydrogen abstraction by triplet nitro-compound from the solvent. The components of the resulting radical pair retransfer the hydrogen giving nuclear polarized reactants, diffuse apart, or undergo a second hydrogen transfer step which yields acetone and 4-cyanophenylhydroxylamine. This last material apparently leads to the nitroso-derivative, which yields 4-NCC₆H₄NHO in a second photochemical step. This radical with either 4-NCC₆H₄NO₂H or further 4-NCC₆H₄-NHO forms re-encounter pairs, and these lead to the arylhydroxylamine and to regeneration of the nitro- and nitroso-compounds.