Surfactant effect on kinetic of reaction of some sulphonamides with p-dimethylaminobenzaldehyde: Surfactant-modified determination of sulphonamides in aqueous solution

摘要

Kinetics of condensation reactions of six sulpha drugs (I-VI) with p-dimethylaminobenzaldehyde (DAB) in a weakly acidic EthOH/H2O solution have been studied spectrophotometrically. The reaction was found to be first order with respect to DAB and zero order with respect to sulphonamide. The rate constants, activation energies, and other related thermodynamic functions have been determined. The effect of the presence of anionic surfactant sodium dodecyl sulphate (SDS) on the kinetics of this reaction in aqueous solution has been investigated. The observed rate constants increase with increasing the amount of SDS except for those of sodium sulphacetamide (VI). The surfactant molecules enhance the reaction rates (14-113 times) in concentrations less than critical micellar concentration (cmc).