A process for the preparation of dihalovinyl compounds of the formula ##STR1## wherein each Hal is fluorine, chlorine or bromine, R.sup.1 is an optionally substituted hydrocarbyl group, R.sup.2 is a methyl group or a hydrogen atom, or R.sup.1 and R.sup.2 together with the carbon atom to which they are attached form cycloalkylidene group, which process comprises treating a trihalo compound of the formula ##STR2## wherein Hal, R.sup.1 and R.sup.2 have the above meanings and R.sup.3 is a hydrogen atom or ##STR3## in which M is an alkali atom, with PHal.sub.3.
一种制备式为##STR1##的二卤
乙烯化合物的方法,其中每个Hal是
氟、
氯或
溴,R.sup.1是可选取取代基的烃基基团,R.sup.2是甲基基团或氢原子,或者R.sup.1和R.sup.2与它们所连接的碳原子形成环烷基亚基团,该方法包括用PHal.sub.3处理式为##STR2##的三卤化合物,其中Hal、R.sup.1和R.sup.2具有上述含义,R.sup.3是氢原子或##STR3##,其中M是碱
金属原子。