Oxygen Transfer Reaction of 4-Dimethylaminoazoxybenzenes by Sulfuric Acid or UV Irradiation

When a mixture of 4-dimethylamino-ONN-azoxybenzene (1α) and 4-dimethylamino-NNO-azoxybenzene (1β) (α: β=2.1: 1.0) was treated with warm 70% sulfuric acid, 4-dimethylaminoazobenzene (3) and 4- (4-dimethylaminophenylazo) phenol (4) were obtained. It was also found that 1β had a probability of isomerization to 1α, but 1α did not isomerize to 1β under the reaction conditions. _??_ Under the same reaction conditions, 4-dimethylnitrorylazobenezene (2) gave 4 in higher yield than 3in contrast to the case of the reaction of the mixture of 1α and 1β. _??_ When a benzene solution of a mixture of 1α and 1β(α: β= 3.0: 1.0) was irradiated with UV light, 5-(dimethylamino) -2-phenylazophenol (6) was obtained as a rearrangment product, and the apparent fl/a ratio (1β/1α) did not changed in this reactions. It was found that the compound 6 isomeriz ed to 1α under UV irradiation in benzene. _??_ When a benzene solution of the mixture of 1α and 1β(α: β=3.0: 1.0) was irradiated in the presence of trichloroacetic acid, a higher yield of 6 was obtained compared with that in the absence of trichloroacetic acid.