A COMPUTATIONAL STUDY OF THE WALLACH REARRANGEMENT

Treatment of azoxybenzene and its derivatives with acids is known to r esult in the Wallach rearrangement, which leads to 2- or 4-hydroxyazob enzenes. Starting in the 1960s, experimental findings have lead to the proposal of several mechanisms for this rearrangement. In this work, molecular orbital theory employing the semiempirical AM1 method is use d to locate and discuss the energetics of the intermediates and the tr ansition states for this rearrangement. Based on the results of AM1 ca lculations in vacuum and in solution, the most plausible mechanistic p athways are proposed and discussed.