由三氟异丙烯基溴化镁制备羧酸

以三氟丙烯和溴为原料加成制得1,2-二溴三氟丙烷，脱溴化氢得到2-溴三氟丙烯，再在一定条件下合成2-溴三氟丙烯的格氏试剂（三氟异丙烯基溴化镁），与CO2反应最终生成1-溴-2-三氟甲基丙酸。 用碳酸钠溶液萃取的方法得到0.8 g产品，纯度为99.6%，收率为3.6%。 对产物进行了MS、IR、1H NMR和13C NMR等表征，并分析了主要副产物1,2-二氟丙二烯和2,3-二三氟甲基-1,3-丁二烯及其与未反应的2-溴三氟丙烯间的2+2]或2+4]环加成反应产物。 确定以2-溴三氟丙烯为原料经格氏反应制羧酸较好的反应条件为：以THF为溶剂，1,2-二溴乙烷作引发剂，制备格氏试剂温度为30 ℃，CO2与格氏试剂反应温度为0 ℃。

Preparation of Carboxylic Acid from 3,3,3-Trifluoropropenylmagnesium Bromide

Propinic acid containing trifluoromethyl group was synthesized from 2-bromo-3,3,3-trifluoropropene,which was obtained via two steps:addition of 3,3,3-trifluoropropene and bromine followed by an elimination reaction.Then the reaction of magnesium,2-bromotrifluoropropene,different initiators and carbon dioxide in tetrahydrofuran produced 1-bromo-2-trifluoromethylpropionic,0.8 g of the product was obtained by extrated with 10% sodium carbonate solution.The purity of the product was 99.6% and the yield was 3.6%.Its structure was characterized by MS,IR,1H NMR and 13C NMR.The main by-products were 1,1-difluoropropadiene,2,3-bis(trifluoromethyl)-1,3-butadiene and their and cycloaddition products.The suitable synthesis conditions of the reactions were determined as follows:THF was used as reaction solvent,dibromoethane as the initiator,reaction temperature for preparing the Grignard reagent was 30 ℃,the Grignard reaction temperature was 0 ℃.