A process for the preparation of 2-(2',2',2',-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the formula ##STR1## in which one of the radicals R.sub.1 and R.sub.2 is methyl and the other is hydrogen or methyl, or R.sub.1 and R.sub.2 together are an alkylene group having 2 to 4 carbon atoms, and X and Y are each chlorine or bromine, comprising reacting a 2,4,4,4-tetrahalogenobutyric acid chloride in the presence of an organic base with an ethylene compound which is disubstituted in 1-position by the radicals R.sub.1 and R.sub.2, as defined above, to form a 2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one and then rearranging the latter, in the presence of a catalyst, into a 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one of the above formula; said 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones being valuable intermediates for the preparation of 2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid and its insecticidally active esters; as well as the 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the above formula and the intermediates utilized for their preparation.
一种制备式为##STR1##的2-(2',2',2'-三卤乙基)-4-卤代
环丁酮的方法,其中R.sub.1和R.sub.2中的一个是甲基,另一个是氢或甲基,或者R.sub.1和R.sub.2共同是具有2至4个碳原子的烷基基团,X和Y分别是
氯或
溴,包括在有机碱的存在下,将2,4,4,4-四卤
丁酸氯化物与在1-位置被上述定义的基团R.sub.1和R.sub.2二取代的
乙烯化合物反应,形成2-(2',2',2'-三卤乙基)-2-卤代
环丁酮,然后在催化剂的存在下将后者重排成上述式子的2-(2',2',2'-三卤乙基)-4-卤代
环丁酮;所述的2-(2',2',2'-三卤乙基)-4-卤代
环丁酮是制备2-(2',2'-二卤
乙烯基)-
环丙烷羧酸及其杀虫活性
酯类的有价值的中间体;以及上述式子中的2-(2',2',2'-三卤乙基)-4-卤代
环丁酮和用于其制备的中间体。