ChemInform Abstract: The Quest for Carbanion-Promoted Dissociative Pathways in the Hydrolysis of Aryl Phosphinates

Results of a kinetic study on the alkaline hydrolysis of the aryl (methylsulfonyl)methylphenylphosphinates 3a–i show that a dissociative mechanism is not operating in this reaction. Activation entropy data (ΔS‡=–-59.5 J mol–1K–1 for the 4-nitrophenyl ester) and good Hammett σ relationship (ρ= 1.45 ± 0.07) strongly suggest that an associative bimolecular mechanism occurs, in which negligible negative charge is generated on the leaving group in the rate-determining step.