Micellar catalysis in the retro-Knoevenagel reaction of ethyl-α-cyanocinnamates

Abstract

Kinetics of base catalysed hydrolytic cleavage of ethyl α-cyanocinnamate (ECC) and several para-substituted ECC have been investigated spectrophotometrically in the presence of anionic surfactant sodium laurylsulphate (NaLS). The rate of cleavage of ECC was retarded by NaLS. The pseudo-first order rate constants, k obs, correlate with the Hammett σ p + -constants. The σ + value (0·86) in aqueous medium is less than σ + value (1·11) in 0·02 M NaLS. Kinetic data were analysed by Menger-Portnoy and Piszkiwicz model. The substrate-micelle binding constants, K s , correlate with the Hammett σ-constants and Hansch hydrophobicity constants-π of the substituents.