THE INFLUENCE OF SELECTIVE SOLVATION ON THE KINETICS OF REACTION BETWEEN MALACHITE GREEN AND HYDROXIDE ION

The kinetics of the reaction between malachite green and hidroxide ion was studied in several binary mixtures of water with alcohols (methanol, ethanol, 1-propanol, ethylene glycol and glycerol) and aprotic solvents (DMSO). In all solvents, the selective (preferential) solvation is present. A method for estimating the dielectric constant in the solvation shell and the constant of preferential solvation was proposed. The results indicate that the composition of solvent in the solvation shell depends on the nature of nonaqueous component; in solvents containing ethanol, 1-propanol and glycerol, the water is preponderant in the solvation shell, while in solvents containing methanol, ethylene glyol and DMSO, the nonaqueous component is in greater proportion than in bulk solution.