Can. J. Chem. 59,839 (1981). The rates of rearrangement of N-bromo-4-chloroacetanilide to 2-bromo-4-chloroacetanilide catalyzed by trifluoroacetic acid and trifluoroacetic acid-d have been measured as a function of acid concentration in chlorobenzene at T = 323 K. Similar experiments have been carried out with N-bromoacetanilide and N-bromo-4-chloro-2,6-dideuterioacetanilide. A comprehensive analysis of the observed rates for each substrate as a function of acid concentration reveals that the rearrangements involve at least three mechanistic steps when trifluoroacetic acid is the catalyst. In contrast, the rate of rearrangement of N-bromoacetanilide catalyzed by trichloroacetic acid at T = 288 K appears to follow a limiting form of the same rate law. Earlier observations are assessed in the light of the proposed mechanism, and it is concluded that both present and past work can be satisfactorily rationalized in terms of an intramolecular migration of bromine.

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Palladium-catalyzed synthetic methodology has been developed for the synthesis of 2-aminobenzenesulfonic acids from benzothiazoles in good to excellent yields using chloramine-B in alkaline (pH 12) acetonitrile/water (1:1) at 80 C.

The 2‐aminobenzenesulfonic acids (II) are efficiently obtained from benzothiazoles (I) using chloramine‐B in the presence of a Pd‐catalyst under alkaline conditions.