Effects of α-substitution on the rate of chloromercuriolactonization of phenyl esters of γδ-unsaturated acids

Abstract

Second-order rate constants for the reaction of several phenyl esters of α-alkyl-and/or α-aryl-substituted allylacetic acids with mercury(II) chloride have been determined in 50% aqueous ethanol. It was found that α-substitution increases the rate of reaction. The rate constants can be correlated with the dual substituent parameter expressions (i) and (ii). In the systems studied the steric coefficient is much larger log k₂= log k₂^o+ρ*σ*+δE_s(i) log k₂= log k₂^o+ρ*σ*+ψν(ii) than the polar one, suggesting that the effect of the substituents on the rate of the reaction is essentially steric in nature, with a small additional contribution from the polar effect.