Proton-transfer mechanism in the decarboxylation of ammonium trichloroacetate in acetonitrile
Abstract
The rate constants, k, for the decomposition of ammonium trichloroacetate in acetonitrile were determined at 298 K BHCCl3COO [graphic omitted] CHCl3+ CO2+ B where B is an N-base. The first-order decarboxylation of trichloroacetic acid in the presence of N-bases is strongly dependent upon proton transfer in ([graphic omitted]) complexes.
Discussion of the rate constants, k, obtained shows 3 types of complexes in the proton-transfer mechanism, i.e. a symmetrically positioned proton, and without proton transfer for 2 cases: [graphic omitted]. The sigmoidal curve of rate constants, – log k, plotted against pKANa(BH+) describes the location of the proton in the hydrogen bridge. The behaviour of (CCl3COOHR)– complexes has many similarities to the molecular complexes, CCl3COOHB, discussed above. Implications of these results for carboxylate additives in overbased lubricating oils are discussed.