Nucleophilic Reactivities of Ketene Acetals

Abstract

Abstract The kinetics of the reactions of ketene acetals with benzhydrylium ions have been followed photometrically. The reactions proceed with rate‐determining C−C bond formation that is considerably faster than expected for outer‐sphere electron transfer processes. Structure−reactivity relationships are discussed. The excellent correlations between the observed second‐order rate constants (log k 2 ) and the previously reported electrophilicity parameters ( E ) of benzhydrylium ions suggest that several of the compounds investigated in this work can be used as reference nucleophiles for the development of electrophilicity scales. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)