A New Application of High-Viscosity Kinetics. An Attempt to Identify a Site of Solvent Reorganizations around a Reactant

Thermal fading of a colored species photochemically generated from so-called chromenes was kinetically studied in highly viscous media. The reaction was retarded by an increase in viscosity at viscosities higher than 10 2 Pas. We propose to use substituent dependence of this retarding effect as a tool to identify the main site of solvent reorganizations around the reactant molecule in the activation step.