Novel compounds of the formula I ##STR1## in which each of Y.sup.1 and Y.sup.2 independently represents a fluorine, chlorine or bromine atom and each of R.sup.1 and R.sup.2 independently represents a hydrogen atom or an alkyl group having up to 10 carbon atoms, or R.sup.1 and R.sup.2 together represent an alkylene group having from 2 to 5 carbon atoms, may be converted by the action of base into the corresponding dihalovinylcyclopropane carboxylic acids.
化合物的新型式I的化合物为:##STR1## 在其中,Y.sup.1和Y.sup.2各自独立地表示
氟、
氯或
溴原子,R.sup.1和R.sup.2各自独立地表示氢原子或具有高达10个碳原子的烷基,或R.sup.1和R.sup.2一起表示具有2到5个碳原子的烷基,可以通过碱的作用转化为相应的二卤代
乙烯基环丙烷羧酸。