11 a (i) hv,(ii) hu, benzene, 2-naphthol. photolysis of compounds 1 and 2 in ethanol was not affected by 0.01 M 2-naphthol, whereas an important change results in the reactions in benzene. Thus, the formation of the o-hydroxy derivative 8 from 1 is suppressed, giving place to 1-[(4-methoxyphenyl) azo]-2-hydroxynaphthalene (9), whereas product 7 formed from 2 remains predominant, the corresponding trapping product 10 being formed only in ...