New di:substd. di:fluoro-benzene cpds. for use in dielectric medium - esp. for LCD or electro=optical display with low viscosity and high dielectric anisotropy

摘要

New 1,4-di-substd.-2,6-difluorobenzene cpds. (I) are of the formula (I) where R = 1-15C (halo)alkyl, in which CH2 gp(s) may be replaced by -O-, -S- (i), (ii), -CO-, -CO-O-, -O-CO-, or -O-CO-O-, such that O atoms are not linked directly; A1-2 independently = (a) trans,1-4-cyclohexylene, in which one or more non-adjaceent CH2 gps. may be replaced by -O- and/or -S-; (b) 1,4-phenylene, in which one or two CH gps. may be replaced by N; (c) 1,4-cyclohexenylene, 1,4-bicyclo(2,2,2)-octylene, pierpidine-1,4-diyl, naphth-2,6-diyl, decahydronaphth-2,6-diyl or 1,2,3,4-tetrahydronaphth-2,6-diyl, in which the (a) and (b) gps. may be substd. by CH or 1 or 2 F atoms; Z 1-2 independently = -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH2CH2-, -CH=CH0, -CC- or a single bond; m and n independently = 0, 1, 2, or 3; (m + n) = 1, 2 or 3; Y1 = H or F; Y2 = H, F or Cl; if Y1 = F, then Z1 and/or Z2 = -CO-O-, -O-CO-, -CH2-O-, -OCH2-, -CH2CH2- or -CH=CH- and/or A1 and/or A2 = 2-fluoro- or 2,6-difluoro-1,4-phenylene and/or n = 1 or 2. USE/ADVANTAGE - (I) are claimed for use in a liquid crystal (LC) medium contg. at least 2 LC components; and the medium is claimed for use in LCDs or dielectric in electrooptical displays. (I) are stable LC or mesogenic cpds. with relatively low viscosity and are useful in LC media with relatively low viscosity and/or high nematogenicity, relatively high clear point and relatively high dielectric anisotropy they give stable media with a wide mesophase range, favourable optical and dielectric anisotropy and excellent UV and temp. stability. (I) with an appropriate R substit. can be used e.g. in the prodn. of LC polymers and polycondensates, as chiral dopants, esp. for ferroelectric materials, for thermally addressed displays.