On the mechanism of Siebold’s test for morphine
Department of Organic Chemistry, Faculty of Chemistry, National Autonomous University of Mexico, Mexico City (CDMX), Mexico.
Research Article
Publication history:
Received on 13 January 2024; revised on 23 February 2024; accepted on 26 February 2024
Abstract:
In this communication the reaction course of Siebold’s test for morphine is provided. The test is based on the interaction of the alkaloid in sulphuric acid with potassium perchlorate. Perchloric acid is the intermediate that gives rise the reactive species, ClO3+. A mixed perchlorate is formed by interaction with the phenolic group at C-3 in morphine. Protonation of this ester induces nucleophilic reaction at C-2 (Umpolung). A new perchlorate results with concomitant ketone formation at C-3 and elimination of chloric acid (first redox reaction). Enolization restores ring aromatization, and protonation of the perchlorate at C-2 produces a concerted push-pull mechanism, via three electron-shifts, that gives rise separation of chloric acid and formation of an ortho-quinone (second redox reaction).
Keywords:
o-Benzoquinone component; Organic-inorganic ester; Perchloric acid; Potassium perchlorate; Reactive intermediates; Redox reactions
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