苯二酚酯类液晶的合成和性能研究——Ⅱ.高负性液晶反-4′-烷基环己烷羧酸-2,3-二氰基-4-正丙氧基苯酚酯的新合成法及其性能

Studies on the Synthesis and Properties of Ester Liquid Crystals of Hydroquinone Ⅱ. A Novel Synthesis of Liquid Crystals with High Negative Dielectric Anisotropy of 4-n-Propoxyl-2, 3-Dicyanophenyl Trans-4'-Alkylcyclohexanecar-boxylate and their B

以苯和对苯醌为初始原料,经多步反应合成了下列结构的化合物改变了中间体4-正丙氧基-2,3-二氰基苯酚(Ⅱ)的合成方法,以2,3-二氰基对苯二酚为原料,通过PTC-Williamson反应合成了新的化合物4-烯丙氧基-2,3-二氰基苯酚(Ⅲ)(产率66%)。对Ⅲ进行选择性催化氢化,得到Ⅱ(产率95%以上)。两步总产率62%以上,较一般的Williamson合成法产率高20%以上。测定了Ⅰ的相变温度和介电各向异性等,结果表明,这是一类适于配制室温负性液晶材料的单体液晶。

A new synthetic pathway of compounds(Ⅰ) is described, which structure is n—C_3H_7O—(?) (Ⅰ) where R=n-hexyl or n-heptyl. Both two compounds are prepared successfully from raw materials of benzene and p-benzoquinone in multisteps with high yield. The synthetic method of 4-n-propoxyl-2, 3-dicyanophenol (Ⅱ) is changed. By PTC-Williamson reaction, a novel compound of 4-allyloxyl-2, 3-dicyanophenol (Ⅲ) is synthesized from allyl chloride and 2, 3-dicyano-1, 4-benzenediol, the yield of Ⅲ is 66%. In the presence of Pd-C catalyst, Ⅱ is synthesized by selective hydrogenation from Ⅲ, the yield of Ⅱ is over 95%. The total yield of the two steps is above 62%. The phase transition temperatures and dielectric anisotropy of Ⅰ have been determined.