Abstract: The kinetics of cleavage of six arylcyclopropanes by mercuric acetate in acetic acid have been examined. The reaction is over-all second order, first order in each reactant. Activation parameters have been determined from the rates of the reactions at 25, 50, and 75”. Electron-releasing substituents facilitate the reaction. A correlation of the second-order rate constants and cr-has been obtained for the substituents p-MeO, p-Me, rn-Me, H, p-C1, ...