New halogen-substd. 1,2-di:phenyl-ethane cpds. and use - in liq. crystal medium for LCD and electro-optical display with low viscosity

摘要

Halogen-substd. 1,2-diphenylethane cpds. of formula (I) are new. In (I) R = 1-12C alkyl, in which one or 2 non-adjacent CH2 gps. may be replaced by -O- and/or -HC=CH-; L0-3 each = H or F; X = F, Cl or CF3 or, if L1 and/or L2 = F, X may also = H, OCF3 or OCHF2. (I) can be prepd. (not claimed) by standard methods, e.g. as described in Houben-Weyl, Methoden der Organischen Chemie, Georg-Thieme-Verlag, Stuttgart. USE/ADVANTAGE - (I) are useful in liq. crystalline (LC) media, esp. for use in LCDs and electrooptical displays. (I) are stable LC or mesogenic cpds. and give LC media with favourable dielectric anisotropy and low viscosity. (I) are not excessively smectogenic and have a wide m nematic mesophase range, good low temp. properties and high specific resistance. In an example, 1-(p-(Ethoxy)-phenyl)-2-(3,4- difluorophenyl)-ethene (II), m.pt. 109 deg.C, was prepd. by heating a mixt. of 1-bromo-3,4-difluorobenzene, p-ethoxystyrene, Pd acetate, tri-o-tolylphosphine, acetonitrile and NEt3 under reflux. (II) as hydrogenated and worked up, giving 1-(p-(ethoxy)-phenyl)-2-(3,4 difluorophenyl)-ethane, m.pt. 31 deg.C,viscosity 13 mPa.s (20 (20 deg.C).r