含CF_2O桥键四氢吡喃液晶化合物的合成与性能

以对二溴苯、5-烷基-四氢吡喃-2-酮和3,4,5-三氟-2-甲基苯酚为原料,经过丁基锂反应、脱羟基、Suzuki和Williamson等共5步反应最终合成2[4′[二氟(3,4,5-三氟2-甲基苯氧基)甲基]-3′,5′-二氟-[1,1′联苯]-4-基]-5-烷基四氢吡喃类液晶化合物。反应中考察了温度、溶剂、催化剂和原料比对反应收率的影响。其中脱羟基反应滴加温度-70℃~-80℃,原料羟基化合物:三乙基硅烷:三氟化硼乙醚的摩尔比为1∶1.5∶2.5;Suzuki反应选用四(三苯基磷)钯反应收率最高;3,4,5-三氟-2-甲基苯酚的Williamson醚化最优条件为在DMSO与水的混合溶剂中醚化6h。纯化后目标产物气相色谱纯度≥99.5%,总收率约为35.6%,结构经1 HNMR及GC-MS确证。该化合物添加到液晶的基础配方中,能增加介电各向异性(Δε),降低阈值电压。

Synthesis and properties of the tetrahydropyrane liquid crystal compound containing CF2O bridge

2[4'[difluoro(3,4,5trifluoro2methylphenoxy)methyl]-3',5'difluoro[1,1'biphenyl]-4yl]-5alkyltetrahydropyran derivatives was synthesized via butyl lithium, dehydroxylation, Suzuki and Williamson reaction (five steps'reaction) by employing 1,4-Dibromo-benzene, 5-alkyl-tetrahydro-pyran-2-one and 3,4,5-Trifluoro-2-methyl-phenol as starting materials. The effects of reaction temperature, solvent, catalyst and material ratio on the yield were investigated. The optimum reaction conditions for the Dehydroxylation reaction, the mole ratio of hydroxyl compounds, triethylsilane and boron trifluoride diethyl ether is 1:1.5:2.5 under the drop-temperature at -70~-80℃. For the Suzuki reaction, (beta-4)-platinum was the best catalysts. The optimum reaction condition for Williamson etherification of 3,4,5-Trifluoro-2-methyl-phenol were 6 h in DMSO-water mixed solvent. After purification processing, the total yield was 35.6% with the purity was 99.5% (GC), the structure was characterized by ¹H NMR and GC-MS.The addition of the compound into the basic formula of liquid crystal, could improve the dielectric anisotropy (△ε), and could reduce threshold voltage as well.