New bridged 5-(trans-4-(trans-4-alkenyl-cyclohexyl)-cyclohexyl)-2-substituted-1-fluoro- or 1,3-difluoro-benzene compounds are used for liquid crystal medium for electro-optical purposes, preferably electro-optical displays

摘要

Bridged 5-(trans-4-(trans-4-alkenyl-cyclohexyl)-cyclohexyl)-2-substituted-1-fl uoro- and -1,3-difluoro-benzene compounds (I), in which the rings are separated by (i) an ethylene or n-butylene chain and (ii) a carboxyl, ether, difluoroethylene or difluoromethylene-oxy group or a single bond, are new. New bridged 5-(trans-4-(trans-4-alkenyl-cyclohexyl)-cyclohexyl)-2-substituted-1-fl uoro- and -1,3-difluoro-benzene compounds are of formula (I) and have rings separated by (i) an ethylene or n-butylene chain and (ii) a carboxyl, ether, difluoroethylene or difluoromethylene-oxy group or a single bond. A, A' = (CH2CH2)n in one case and Z in the other; R = 2-15C alkenyl, optionally mono-substituted by cyano (CN) or trifluoromethyl (CF3) or at least mono-substituted by halogen, in which 1 or more methylene (CH2) groups may be replaced by oxygen (O), sulfur (S), 1,3-cyclobutylene, carbonyl (CO), carboxy (CO-O- or O-CO) or carbonato (O-CO-O) without adjacent O atoms; Y = fluorine (F), chlorine (Cl), pentafluorosulfanyl (SF5), isothiocyanato (NCS) or halogenated 1-5C alk(en)yl or alk(en)oxy; L = hydrogen (H) or F; Z = -COO-, -CH2CH2-, -CH2O-, -OCH2-, -C2F4, -CF2O-, -OCF2- or a single bond; n = 1 or 2 Independent claims are also included for: (a) Liquid crystal (LC) media, based on a mixture of polar compounds with positive dielectric anisotropy, which contain compound(s) (I); (b) Electro-optical LC displays containing this medium.