Effect of solvent on the reactivity of the benzophenone free radical anion

Abstract

The rates of reaction of potassium benzophenone with organic halides have been measured in a range of solvents. As the solvating power of the medium increases the rate constant increases and this runs parallel to a progressive shift to the red of the visible absorption peak of the benzophenone free radical anion. The results of kinetic and spectroscopic work with the benzophenone free radical anion have been summarized; they demonstrate the existence of a simple generalization, viz., any perturbation of the benzophenone anion which leads to a red shift of the visible peak is always accompanied by an increase in the rate constant of the organic halid reaction, and these changes appear always to run parallel to a decrease in the electrostatic field on the anion.