Electrogeneration of cyanomethyl anion from phenylsulphonylacetonitrile and cyanomethyltrimesitylphosphonium iodide and the relative acidities of XCH2CN (X = Ph3P+, Ph3As+, Mes3P+, or PhSO2)versus acetic acid in acetonitrile

Abstract

Contrary to a previous report, PhSO₂CH₂CN has been shown to exhibit a one-electron reduction (two-electron reductive cleavage followed by deprotonation of PhSO₂CH₂CN by ^–CH₂CN). Mes₃PH₂CN I^– behaves similarly. The relative acidities of XCH₂CN (X = Ph₃P⁺, Ph₃As⁺, Mes₃P⁺, or PhSO₂)versus acetic acid in acetonitrile has been studied both voltammetrically and spectrophotometrically. Ph₃PH₂CN is a stronger acid than CH₃CO₂H; Ph₃AsCH₂CN, Mes₃PH₂CN, and PhSO₂CH₂CN are weaker acids than CH₃CO₂H. PhSO₂CH₂CN and Mes₃-PCH₂CN I^– have been used in an electroanalytical method for studying the addition of ^–CH₂CN to various electrophiles.