Kinetics of retroaldol reaction of <i>para </i> substiltuted, <i>β</i>-nitrostyrenes and , <i>β</i> -methyl-, <i>β</i>-nitrostyrenes

Abstract

The kinetics of retroaldol reaction, of <i>β</i>-nitrostyrene and <i>β</i>-methyl- <i>β</i>-nitrostyrene and their <i>para-</i> substituted derivatives have been studied spectrophotometrically 1:1 methanol-water (v/v) in the presence of sodium hydroxide. The order is unity in [<i>β</i> -nitrostyrene] and fractional in [OH^-]. In the reaction of <i>β</i>-meyhyl-<i>β</i> nitro styrene the order in [substrate] and [OH^-] is unity each. On the basis of the kinetic data, a stepwise reftion mechanism has been proposed which involves nucleo-philic attack of OH^- on the α-carbon and subsequent cleavage of C<i>_α </i> - C<i>_β</i> bond. The rate of <i>β</i> methyl-<i>β</i> nitrostyrene is less than that of <i>β</i> nitrostyrene. Eletron withdrawing substituents accelerate the reaction and electron-releasing substituents retard it. Satisfactory Hammett correlations have been observed in both reaction series.