On the mechanism of the Angeli-Rimini reaction
Department of Organic Chemistry, Faculty of Chemistry, National Autonomous University of Mexico, Mexico City (CDMX), Mexico.
Research Article
International Journal of Chemical and Pharmaceutical Research Updates, 2025, 05(02), 001-004.
Article DOI: 10.53430/ijcpru.2025.5.2.0032
Publication history:
Received 18 October 2025; revised on 26 November 2025; accepted on 28 November 2025
Abstract:
An Organic Chemistry Theoretical Study has been carried out in order to elucidate which of the two reaction sequencies for the Angeli-Rimini test is correct. After the critical study, the conclusion is that the Gattermann sequence is right, and the Hassner proposal, wrong, including the mechanism in Wikipedia for it. A complete mechanism is provided for the Gattermann series of reactions, commenting step by step both the reaction and the mechanism. The reagent is benzenesulphohydroxamic acid that forms the hydroxamate in alkaline medium. Then occurs a concerted mechanism causing nitroxyl elimination and formation of sodium benzenesulphinate. The anion of nitroxyl adds to the aldehyde and the resulting alkoxide is neutralized by water. The hydroxy nitroso intermediate isomerises to hydroxy oxime and this produces the final hydroxamic acid by rearrangement.
Keywords:
Angeli-Rimini reaction; Benzenesulphohydroxamic acid; Gattermann sequence; Isomerization; Nitroxyl; Reaction mechanism
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