Process for the preparation of dihalovinyl compounds.

摘要

Dihalovinyl compounds, many of which are useful in the preparation of pyrethroid insecticide, and having the general formula: <CHEM> wherein R<1> represents an optionally-substituted cyclopropyl or an optionally-substituted alkyl group, R<2> a methyl group or a hydrogen atom or R<1> and R<2>, together with the carbon atom to which they are attached jointly form a cycloalkylidene group, and each Hal stands for a chlorine or bromine atom, are prepared by a process wherein a dihalophosphite of the general formula: <CHEM> wherein R<1>, R<2> and Hal have the same meaning as in formula I and Q represents a halogen atom, and is contacted with zinc in the absence of an alkanoic acid with fewer than 5 carbon atoms per molecule.