Solvent effects on the rate constants for reaction of trichloromethylperoxyl radicals with organic reductants

Absolute rate constants for the reactions of trichloromethylperoxyl radicals with chlorpromazine and trolox have been determined by pulse radiolysis in 16 different solvents. The rate constants were found to vary over two orders of magnitude (10⁷-10⁹ L mol^-1 s^-1) and to correlate with the Hildebrand solubility parameter (cohesive energy density) of the solvent better than with any other single solvent parameter. The correlation was satisfactory for ClPz and did not improve significantly by including additional parameters. For trolox, however, the correlation was relatively poor but was improved considerably by taking into account the basicity of the solvent. This effect is due to the transfer of a proton upon the oxidation of trolox.