SOLVENT EFFECTS ON THE REACTIVITY OF SOLVATED ELECTRONS WITH ORGANIC SOLUTES IN METHANOL WATER AND ETHANOL WATER MIXED-SOLVENTS

The present work extends the study of solvent effects (J. Phys. Chem. 1988, 92, 1506 and 5142) to the binary solvents methanol/water and ethanol/water. The composition dependences of energies and entropies of activation for inefficient reactions (es- + toluene or phenol) are quite different from those for efficient reactions (es- + nitrobenzene or acetone). In ethanol/water, the inefficient reaction of es- with toluene makes an interesting change from being mainly entropy driven in pure water solvent (ΔS2‡ = -51 J/(mol·K) and E2 = 18 kJ/mol) to being mainly enthalpy driven in pure ethanol (E2 = 30 kJ/mol and ΔS2‡ = -11 J/(mol·K)). Correlations of es- reactivity with solvent viscosity and dielectric permittivity are discussed. © 1990 American Chemical Society.