Photochemistry of 2,2'-dinitrodiphenylmethanes: Irradiations in neutral, acidic and alkaline media

Abstract

Photolysis of 2,2'-dinitrodiphenylmethane (1) in isopropyl alcohol affords dibenzo[c,f][l,2]diazepin-11-one 5-oxide (7) as the major product. Dibenzo[c,f][l,2]diazepin-11-one 5,6-dioxide (6), acridone (8) and 2,2'-dinitrobenzophenone (9) are also formed in the reaction. Irradiation of (1) in ethanolic sulphuric acid on the other hand yields 3-(2'-nitropheny1)-2,l-benzisoxazole (11) as the major product; small amounts of (7), (8) and (9) are also isolated. Photoconversion of (1) in triethylamine and alcoholic triethylamine proceeds very slowly and compounds (7), (8) and (9) only are isolated from the photolysed solution. Some aspects of the mechanism are discussed.