液晶单体4-(反-4-正丙基环己基)-氟苯的合成

Synthesis of 4-(trans-4-n-propylcyclohexyl)-fluorobenzene for monomer of liquid crystal

以新蒸馏过的环己烯和丙酰氯为原料,与三氯化铝和氟苯一起采用“一锅法”制备4-(4-丙酰基环己基)-氟苯。首先将环己烯与丙酰胺的混合物在搅拌下于-10℃逐滴加入到三氯化铝的氟苯悬浮液中,而后将该反应混合物在40℃下搅拌反应2h即可得4-(4-丙酰基环己基)-氟苯。环己烯、丙酰氯、三氯化铝、氟苯投料摩尔比为1∶1∶1.5∶2。第二步反应是用黄鸣龙法将4-(4-丙酰基环己基)-氟苯还原为4-(反-4-正丙基环己基)-氟苯。最后经减压蒸馏和数次重结晶得到纯度大于99.5%的产品4-(反-4-正丙基环己基)-氟苯。

A new method of synthesis of 4- （ trans-4-n-propylcyclohexyl）-fluorobenzene was described. Two steps that the production of 4-（4-propionylcyclohexyl） -fluorobenzene and its reduction were involved in this method. The first step, a mixture of cyclohexene and propionyl chloride was added dropwise to a suspension of aluminum chloride in fluorobenzene with stirring and cooling to - 10 ℃. The mol ratio of cyclohexene, propionyl chloride, aluminumchloride and fluorobenzene was 1 ： 1 ： 1.5 ： 2. The reaction mixture was stirred subsequently at 40 ℃ for 2 h and the 4- （4-propionylcyclohexyl） -fluorobenzene was gotten.The second step, the 4-（4-propionylcyclohexyl）fluorobenzene was reduced to 4-（ trans-4-n-propylcyclohexyl ） -fluorobenzene by HuangMinglong reduction, which was distilled under reduced pressure （0.67--1.33 kPa） and recrystallized several times from ethanol. The pure compound was gotten and the purity was higher than 99.5%.