The search for the active base operating in alkoxide promoted E2 reactions in low polar solvents: A kinetic analysis of the elusive problem

Abstract

Partial kinetic orders in base for 1-decene, cis-2-decene and trans-2-decene formation from the reaction of 2-decyl bromide with t-C4H9OK in tetrahydrofuran and in tert-butanol and with t-C4H9ONa in tert-butanol have been determined and their significance for assessment of active base has been probed. It has been ascertained that assessment of active base in alkoxide promoted E2 reactions is model-dependent. An unambiguous evidence has been provided by a kinetic analysis of the effect of base concentration on olefin-isomer distribution in the reaction. Two alternative kinetic models of this effect have been devised, the one assuming a competition of several active base species for a single substrate and the other a competition between an uncomplexed and alkoxide-complexed substrate for a single active base. Compatibility of both kinetic models with experimental data has been demonstrated.