Kinetics and mechanism of proton transfer between disubstituted benzoic acids and carbinol base of crystal violet in chlorobenzene

Abstract

An investigation on the detailed kinetics of proton transfer between a set of di- and monofluoro- and chloro(2,3-, 2,5-, 2,6-, 3,5-, 2-, and 3-) benzoic acids (HA) and Crystal Violet carbinol base in chlorobenzene favors a mechanism in terms of fast equilibrium between HA and D to form a H-bonded complex, D⋯HA, followed by rate-limiting proton transfer along the H-bond to form the colored ion pair DH+A- under the combined influence of monomer HA catalyst, nonreactive cyclic dimer (HA)2 inhibitor, and hyperacidic homoconjugated complex H(HA2) catalyst through a transition state with nearly 60% charge separation. © 2008 American Chemical Society.