Mechanism of the hydrolysis of α-(p-nitrophenyl)cinnamonitrile derivatives

The rate constant hydrolysis of alpha-(p-nitrophenyl)cinnamonitrile(NCPN) and its derivatives have been determined at various pH, and the rate equation which can be applied over a wide pH range is obtained. On the basis of the rate equation, hydrolysis product, general base, and substituent effects, a plausible mechanism of hydrolysis has been proposed: At pH < 4.0, the hydrolysis was initiated by the addition of water to beta-carbon of the carbon-carbon double bond. At pH > 8.5, the addition of hydroxide ion to the double bond was rate controlling. In the range of pH 4.0-8.5, these two reactions occurred competitively.