Abstract
When each benzene solution of azoxybenzene, 2,2′-dimethylazoxybenzene, 4,4′-dimethylazoxybenzene, 2,2′-dichloroazoxybenzene and 4,4′-dichloroazoxybenzene was irradiated with UV light in the presence of acetic acid. The corresponding 2-hydroxyazobenzene was obtained in higher yield than in the absence of the acid. Rearrangement products 2-hydroxy-4-methylazobenzene(8) and 2-hydroxy-4′-methylazobenzene(9) were also obtained in higher yield under the UV irradiation of 4-methyl-ONN-azoxybenzene(7α) (α : β = 3.5 : 1.0) in the presence of acetic acid. Under the same reaction conditions, two rearrangement products 8 and 9 were also obtained from 4-methyl-NNO-azoxybenzene(7β) (α : β = 0.0 : 1.0). The β,α-isomerization from 7β to 7α did not take place at all in this reaction. This was different from the photochemical reaction of 7β (α : β = 0.0 : 1.0) in the presence of trichloroacetic acid. The product yields of 8 and 9 seem to be dependent on the concentration of acetic acid.
