The Effects of Surfactants on Cannizzaro Reaction of Benzaldehyde

Abstract

The Cannizzaro reaction in alkaline solution for benzaldehyde was studied in the presence of sodium dodecyl sulfate (SDS), dodecyltrimethylammonium chloride (DTAC), hexadecyl trimethylammonium chloride (CTAC), polyethylene glycol monooleyl ether (POMOE) and polyethylene glycol p-nonylphenyl ether (PONPE) at 40°, 50° and 60°C, respectively.
The kinetic and thermodynamic parameters of the reaction were evalu ated from the rate constant of the reaction for each surfactant.
In gelfiltration on a Cellulofine G CL-25 m column, micelles of surfactants at concentrations above the CMC behaved similarly to polymerizing systems. From the gelfiltration data, partition coefficients, molar concentration and concentration effects of solutes in micelle and bulk phases were calculated.
The results obtai n ed were as follows.1) Anionic micelle decreased the reaction rate, while cationics increased it.2) Linear relationships existed between E_a and ΔS_a and between k_obs and concentration of surfactants.3) Benzaldehyde and NaOH were strongly partitioned in micellar phase of the surfactants, especially in those of DTAC and CTAC.
POMOE and PONPE were uniquely partitioned with one of the reaction product (PhCOONa).4) From the kinetic data for bulk and micelle phases (kb and km), it was found that the reaction was accelerated principally due to electrostatic charge and concentration effect by the micelles, followed by lowering of the entropy of activation.