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

Research paper by K. Rajasekaran, A. Sarathi, S. Ramalakshmi

Indexed on: 05 Nov '08Published on: 05 Nov '08Published in: Journal of Chemical Sciences



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, kobs, correlate with the Hammett σp+-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, Ks, correlate with the Hammett σ-constants and Hansch hydrophobicity constants-π of the substituents.