Mechanism of the oxidation of phenylmercaptoacetates by potassium hexacyanoferrate(III): structural and substituent effects
- 1 January 1990
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 7,p. 1061-1066
- https://doi.org/10.1039/p29900001061
Abstract
Mechanistic investigations of the oxidation of phenylmercaptoacetates by potassium hexacyano-ferrate(III) in aqueous sodium hydroxide reveal that the oxidation follows first-order kinetics in each of the oxidant, substrate and OH– at constant ionic strength. While added radical scavenger, acryl-amide, enhances the rate, potassium hexacyanoferrate(II) retards it. Studies with different substrates indicate that the substrate must possess an acidic proton. It has also been realised that d-orbitals of sulphur are important in stabilizing the intermediate by dπ–pπ bonding. Rate studies with substituted phenylmercaptoacetates give an excellent Hammett correlation with a positive reaction constant (ρ 1.31). On the basis of kinetic evidence, a mechanism which involves an initial reversible proton abstraction followed by another reversible electron transfer step has been postulated.Keywords
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