A variable mechanism for the nucleophilic vinylic substitutions in a series of gem-dihalogenated alkenes by a bidentate sulfur nucleophile: an experimental and AM1 theoretical study

Abstract

The nucleophilic substitutions of a series of gem-dihalogenated alkenes 3, 5, 7, 8, and 9 (RS) 2 C=CX 2 (X=Cl, F) with 1,2-benzenedithiolate b have been studied. Depending on the structures of the R groups (alkyl, saturated and unsaturated cycloalkyls, aromatic ring), the course of the reactions and the structures of the yielded products are modified. In the frame of the addition-elimination-type mechanism for these nucleophilic substitutions, the energy contents of the anionic intermediates, resulting from the additions of the nucleophile b to the unsaturated centers, is calculated at the AM1 method level. For the compounds 5, 7, 8, and 9, the calculated energies nicely corroborate the experimental results