KINETICS AND MECHANISM OF PTC C-ALKYLATION IN THE PRESENCE OF SOLID METAL FLUORIDES, CATALYZED BY CROWN ETHERS AND ONIUM SALTS

We have studied the kinetics of C-alkylation of 2-methylacetate ester (HA) by prenyl chloride (RY) in the presence of solid metal fluoride (MF), catalyzed by crown ether (CE) or onium salt (QX). We have shown that in crown ether systems the kinetics is first order with respect to all four components while in QX systems the kinetics is of variable order with respect to RY, and we observe extremal dependences of the alkylation rate on the amount of MF, QX, or HA. In contrast to the crown ether, the onium salt does not solubilize the source of F anion, but rather coordinates the reagents on the surface of the solid metal fluoride. The inhibiting effects of the reagents in the presence of QX are due to the selective adsorption of the reagents on the surface of the solid phase and competition between HA and QX for the F anion. We have established that the process is retarded by traces of water in both systems, and that there is a synergistic effect when crown ether and QX are used jointly as the catalyst.