Intramolecular displacement of alkoxide ions by the ionised carboxy-group: hydrolysis of alkyl hydrogen dialkylmaleates

Abstract

The pH-independent hydrolysis reactions of the title ester acids and their anions, and the acid catalysed hydrolysis of the ester acids, are all subject to highly efficient intramolecular nucleophilic catalysis. The carboxylate group of the ester anions can displace leaving groups as poor as isopropoxide, 10¹³ times more basic, in an unassisted reaction which shows the highest sensitivity to leaving group ever measured for ester hydrolysis. Intramolecular catalysis by the carboxy-group is more efficient for esters derived from alcohols with pK_a > 13·6, and is itself subject to external general base catalysis.