activation parameters and relation of activation entropy with solvent polarity in thermal rearrangement of 7,7-dichloro-[a,c]- dibenzo-[4,1,0]-bicycloheptane

thermal rearrangement of 7,7-dichloro-[a,c]-dibenzo-[4,1,0]-bicycloheptane (1) to 5,6-dichloro-5hdibenzo-[a,c]-cycloheptene (2) was studied in the solid phase and in solvents with different polarities. thefirst-order constants at various temperatures for the rearrangement process were evaluated from theabsorption time data. the activation parameters for this rearrangement were obtained from the temperaturedependent of the rate constants. variation of solvent polarity has no influence on ea, but a markeddifference in δs# is observed. abinitio investigation of the thermal ring-opening support the experimentaldata. solvating of r+, x- ions in transition state could explain the trend.