Steric effects at acyclic and bridgehead carbons attached to carbonyls

The rates of alkaline hydrolysis of seven acyclic and bridgehead esters of p-nitrophenyl carboxylic acids have been kinetically found to vary inversely with the size of the substituent R group. Computer assisted molecular modeling techniques were used to suggest a steric and electrostatic rationale for the effect of R group size upon the rate of hydrolysis.