On the interaction of Narcotine with ammonium vanadate, Johannson’s test
Department of Organic Chemistry, Faculty of Chemistry, National Autonomous University of Mexico, Mexico City (CDMX), Mexico.
Research Article
Open Access Research Journal of Chemistry and Pharmacy, 2025, 06(01), 001-003.
Article DOI: 10.53022/oarjcp.2025.6.1.0011
Publication history:
Received on 30 November 2024; revised on 08 January 2025; accepted on 10 January 2025
Abstract:
In this communication the reaction route of the interaction of narcotine with ammonium vanadate in sulphuric acid is provided (Johannson test). Besides the theoretical interest of know what is happening in the test tube at molecular level, the blood-red colour developed in this assay is a good approach to narcotine which can be confirmed by a positive result with another colour test. The chemistry is as follows: The active species is protonated meta-vanadic acid, formed in situ. Nucleophilic attack of an oxygen atom of the methylenedioxy group present in narcotine to the positive species, eliminates a water molecule and an oxonium ion is formed. This is neutralised by ring opening via concerted reaction of a water molecule and the δ+ methylene group. An organometallic vanadate and a hemiacetal result. Finally, acidolysis of the ester gives rise to a degradation. Vanadous acid and formaldehyde are eliminated and in the organic part an ortho-benzoquinone is formed. The production of the last three compounds involves six electron shifts in a concerted reaction mechanism.
Keywords:
Acidolysis; Halochromism; Organometallic Intermediate; Oxidation; Reactive Intermediates
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