| abstract |
Process for the preparation of a dihalovinyl compounds of the general formula:n wherein R' represents an optionally-substituted cyclopropyl group or an optionally-substituted alkyl group, R 2 a methyl group or a hydrogen atom or R' and R 2 , together with the carbon atom to which they are attached jointly form a cycloalkyl group, and each Hal stands for a chlorine or bromine atom, characterised in that a trihalomethyl compound of the general formula:n wherein R', R 2 and Hal have the same meaning as in formula I and X represents a group -PQ 2 , -CO-OR or-SO 2 -R 4 wherein Q represents a halogen atom and R 3 and R 4 both represent an optionally-substituted alkyl group, is contacted with zinc and an alkanoic acid with up to 5 carbon atoms per molecule: The dihalovinyl compounds are intermediates in the manufacture of pyrethroid insecticides. |