An improved process for the preparation of halomethyl cyclopropanes and particularly pure halomethyl cyclopropanes

In an improved process for the production of halogen methyl cyclopropanes of formula (I) in which Hal is chlorine or bromine and R to R are mutually independently hydrogen, optionally substituted C1-C10 alkyl or optionally substituted C6-C10 aryl, the corresponding hydroxymethyl propanes are mixed with chlorine or bromine and an organic phosphorus compound, and chlorine or bromine is reacted in an excess of at least 5 mol % (in relation to te hydroxymethyl cyclopropane). It is thus possible to obtain highly pure products containing little 1-halogen-3-butene.