As a part of series of investigation of the Wallach rearrangement, the reactions of various azoxybenzene derivatives with chlorosulfuric and polyphosphoric acid were studied and compared with the Wallach rearrangement using sulfuric acid. The following results were obtained. (1) The reactivity of azoxybenzene derivatives toward these acids is dependent on their acidity function ; chlorosulfuric>sulfuric>polyphosphoric acid. (2) The reaction of azoxybenzene derivatives with chlorosulfuric acid generally gives hydroxyazobenzenes in higher ortho-para ratios than that in the case of the Wallach rearrangement using sulfuric acid. Azoxybenzene derivatives having electron-releasing group tend to give the corresponding azobenzenes in high yield. (3) With polyphosphoric acid, the reactivity of azoxybenzenes depended on the acidity function reported by Downing et al., and higher ortho-para ratios and lower yield of azo compounds were generally recognized in comparison with the Wallach rearrangement using sulfuric acid.
