The Ortho-Para Ratio and the Intermediate in the Persulfate Oxidation of Aromatic Amines (the Boyland-Sims Oxidation)

Article abstract of DOI:10.1021/jo00034a016

The previous belief that the persulfate oxidation of aromatic amines gives the o-sulfate exclusively is untrue; substantial quantities of the para isomer are produced.Kinetic studies on 2,4- and 2,6-disubstituted aromatic amines show that the rate of reaction with persulfate is nearly the same for both isomers.The probable intermediate in this reaction is the arylhydroxylamine-O-sulfonate.This was demonstrated by showing that the reaction between N,N-dimethylaniline N-oxide and the sulfur trioxide-pyridine complex gives material which rearranges to a mixture of N,N-dimethyl aniline o- and p-sulfates in the same ratio as is given by the persulfate oxidation of N,N-dimethylaniline.The ortho-para ratio is unaffected by dilution.This leads to the conclusion that the degreee of intramolecularity of the rearrangement is the same for the formation of both the ortho and para isomers.