| 摘要 |
In the preparation of a 1,1-dihalogenoalkene of the formula <IMAGE> in which R1 is a hydrogen atom or an optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, aralkenyl or aryl radical, and R2 is an optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, aralkenyl or aryl radical, or R1 and R2 together form an optionally branched and/or optionally benzo-fused hydrocarbon chain, and X1 and X2 each independently is a halogen atom, wherein a carbonyl compound of the formula <IMAGE> is reacted with a trihalogenoacetate of the formula <IMAGE> in which X3 is a halogen atom, and M(+) is an alkali metal ion or one equivalent of an alkaline earth metal ion, in the presence of an approximately equimolar amount of a phosphorus-containing compound, the improvement which comprises employing as said phosphorus-containing compound a phosphorous acid trialkyl ester or a phosphorous acid triamide and effecting the reaction at a temperature between about 0 DEG and 200 DEG C. A preferred end product is <IMAGE> and the preferred phosphorus-containing compound is trimethyl phosphite, triethyl phosphite, tripropyl phosphite or phosphorous acid tris-dimethyl-amide.
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