The chemistry of the interaction of brucine with mercurous nitrate
Organic Chemistry Department, Faculty of Chemistry, National Autonomous University of Mexico, Mexico City (CDMX), Mexico.
Research Article
Open Access Research Journal of Chemistry and Pharmacy, 2026, 08(02), 053-056.
Article DOI: 10.53022/oarjcp.2026.8.2.0018
Publication history:
Received on 06 May 2026; revised on 22 June 2026; accepted on 24 June 2026
Abstract:
The interaction of brucine with mercurous nitrate gives a carmine colour (Flückiger test for brucine). In this communication the chemistry and mechanism of this assay are provided for the first time. Since strychnine is inert with the reagent, it can be deduced that the methoxy groups in 2,3-dimethoxy-strychnine (brucine) are the reaction site. A methoxy group can be demethylated in special conditions. This is in accordance with the experimental fact that is needed to heat at the water bath in order to obtain a positive result. The positive charge in mercurous nitrate, vicinal to another positive charge, is the driving force and captures an electron from a methoxyl, leaving a radical ion. Separation of a methyl radical originates electron coupling at the oxygen atom. The residual positive charge at this atom produces a synchronous mechanism, forming an ortho-benzoquinone and displacement of a methyl-carbonium ion.
In the inorganic intermediate, the captured electron produces metal-metal breaking and elemental mercury is formed, with two electrons in the 6s subshell.
Keywords:
Brucine; Driving force; Electron coupling; Flückiger test; Mercurous nitrate; Strychnine
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