The Boyland-Sims oxidation is the reaction between peroxydisulfate ions and aromatic amines to form the arylamine ortho sulfate. The intermediate is an arylhydroxylamine-O-sulfonate, which then rearranges to the arylamine <i>o</i>-sulfate. The long-standing mechanism of a nucleophilic attack by the amine on peroxide oxygen has been questioned by Marjanović <i>et al</i>. who have proposed a nitrenium ion intermediate as the reactive species rather than the uncharged amine. The nitrenium ion proposal was based on relatively low-level calculations. It has been challenged by a variety of experimental observations. We present here new computations at a high-level of density functional theory (B3LYP/6-311++G**) to model both arylhydroxylamine-O-sulfonate and nitrenium ion pathways. In this study, the energetics of reaction intermediates in both mechanisms are computed for two aromatic amines, aniline and 2,4-dinitroaniline. Our initial results suggest that the Boyland-Sims oxidation reactions proceed via the arylhydroxylamine-O-sulfonate intermediate as predicted earlier, which makes doubtful the importance of a nitrenium ion in this process.

Computational insights on the structure of transition states and intermediates of the Boyland-Sims oxidation reaction

ACS Spring Meeting 2021

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