Evidence for an open transition state in the transfer of a carbonyl acyl group between phenolate anions

Abstract

Rate constants for transesterification between 2,4-dinitrophenyl 4-methoxy-2,6-dimethylbenzoate and thirteen substituted phenolate anions obey a Brønsted equation with β_nuc 0.19; the bond making and breaking parameter for the completely symmetrical reaction of the ester with 2,4-dinitrophenolate anion indicates significant benzoylium ion character in the transition state of the concerted displacement reaction.