Mechanism of the interaction of formaldehyde, o-diketone, and 1,2-dinitro benzene
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, 07(02), 045-048.
Article DOI: 10.53022/oarjcp.2025.7.2.0020
Publication history:
Received on 03 November 2025; revised on 16 December 2025; accepted on 19 December 2025
Abstract:
The mechanisms in the reaction sequence of the interaction of formaldehyde, o-diketone, and 1,2-dinitrobenzene in alkaline medium, have been provided. The different points of view regarding the mechanism of the Cannizzaro reaction have been discussed.
A cross Cannizaro reaction between formaldehyde and o-diketone occurs. The resulting α-ketol is the key intermediate since the entering hydride ion is now an acidic hydrogen which reacts with the anion of the zwitter ion in a nitro group. Then is reaction with a hydride ion yielding a nitroso group after dehydration. A further reduction to o-nitro-phenylhydroxylamine and rearrangement to a dibasic o-quinone di-imine salt gives the violet salt observed in the test. That is, the hydroxylamine is oxidised to the salt of iso-nitroso group, and the nitro group is reduced to nitronate.
Keywords:
o-Diketone; Formaldehyde; α-Ketol; o-Nitro-phenylhydroxylamine; o-Quinone-di-imine derivative; Halochromism
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