3,4,5-三氟-2-甲基苯类液晶化合物的合成与性能

以3,4,5-三氟苯酚、3,5-二氟-4'-烷基联苯为原料,经酚羟基保护反应、丁基锂/碘甲烷上甲基反应、Williamson醚化反应等5步反应最终合成4-[二氟(3,4,5-三氟-2-甲基-苯氧基)甲基]-3,5-二氟-4'-烷基联苯类化合物。纯化后目标产物的气相色谱纯度≥99.5%,总收率约为47%,结构经~1HNMR及GC-MS确证。其中,合成2-(3,4,5-三氟-2-甲基-苯氧基)四氢吡喃适宜的物质的量比为n(2-(3,4,5-三氟苯氧基)四氢吡喃)∶n(丁基锂)=1∶1.2,3,4,5-三氟-2-甲基苯酚和4-溴二氟甲基-3,5-二氟-4'-烷基联苯醚化反应的最优化条件为在DMSO中反应4 h。将该化合物添加到液晶的基础配方中,能降低旋转粘度(γ1),提高液晶的响应速度,增加介电各向异性(Δε),降低阈值电压。

Synthesis and Properties of Liquid Crystal Compound Containing 3, 4, 5-Trifluoro-2-methyl-benzene

4-[Difluoro-(3,4,5-trifluoro-2-methyl-phenoxy)-methyl]-3,5-difluoro-4'-alkyl-biphenyl derivative was synthesized via phenolic hydroxyl protection,butyl lithium/methyl iodide methylation,and Williamson etherification reaction (five steps' reaction) by employing 3,4,5-trifluoro-phenol and 3,5-difluoro-4'-alkyl-biphenyl as starting materials.After purification processing,the total yield was 47％ with the purity was 99.5％ (GC),the structure was confirmed by 1HNMR and GC-MS.For the synthesis of 2-(3,4,5-trifluoro-2-methyl-phenoxy) tetrahydropyran,the optimum mole ratio of 2-(3,4,5-trifluorophenoxy) tetrahydropyran and butyl lithium was 1∶1.2.The optimum reaction time and solvent for etherification of 3,4,5-trifluoro-2-methyl-phenol with 4-(bromo-difluoro-methyl)-3,5-difluoro-4'-methyl-biphenyl were 4 h and DMSO,respectively.The addition of the compound into the basic formula of liquid crystal not only could reduce the rotational viscosity (y1),and the response time could be improved,as well as the dielectric anisotropy (△ε) could be improved,and threshold voltage could be reduced.