Laser flash photolysis has been used to determine bimolecular rate constants for the reaction of triplet excited state benzophenone with naphthalene in a range of room temperature ionic liquids. Comparison of the activation energies for this reaction with the activation energies for viscous flow indicated that the reaction operates under diffusion control in all liquids and at all temperatures studied. Using these data, we have obtained values for the limiting bimolecular rate constants between neutral reactants in these novel solvents. The importance of reliable k_d values in mechanistic studies is illustrated by a photochemical Diels Alder reaction. We also report the experimental procedures necessary for the preparation of colourless "spectroscopic grade" ionic liquids.
展开▼
