The chemistry of ylids. XVI. The acidifying effects of 'onium groups

Abstract

An examination of the pKa's of a series of phenacyl 'onium salts has indicated that the acidifying effects of the 'onium groups increase in the order arsonium < phosphonium < sulfonium. The acidifying effects of the 'onium atom substituents increase in the order methyl < n-butyl < phenyl. These observations have been accounted for in terms of pπ–dπ overlap between the carbanion and the heteroatom of the 'onium group.