| 摘要 |
Compounds of the formula I R1-A1-Z1-A2-R2 I wherein R1 and R2 are each H, an alkyl, alkoxy, alkanoyl, alkanoyloxy or alkoxycarbonyl group with in each case 1-10 C atoms, F, Cl, Br, CN or R3-A3-Z2-, A1 is -A-, -A4-A-or -A-A4-, A is a 1,3-dioxane-2,5-diyl or a 1,3-dithiane-2,5-diyl group, A2, A3 are each a 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, and A4 1,3-dithiane-2,5-diyl, piperidine-1,4-diyl or 1,4-bicyclo(2,2,2)octylene group, or a 1,4-phenylene, pyrimidine-2,5-diyl or pyridazine-3,6-diyl group which is unsubstituted or substituted by one or two F and/or Cl atoms and/or CH3 groups and/or CN groups, Z1 and Z2 are each -CO-O-, -O-CO-, -CH2CH2-, -OCH2-, -CH2O or a single bond and R3 is H, an alkyl, alkoxy, alkanoyl, alkanoyloxy or alkoxycarbonyl group with in each case 1-10 C atoms, F, Cl, Br or CN, with the proviso that (a) at least one group A2, A3 and/or A4 contains lateral substituents, (b) 1,3-dioxane-2,5-diyl and 1,3-dithiane-2,5-diyl groups are not substituted by alkoxy, alkanoyl, alkanoyloxy, alkoxycarbonyl, F, Cl, Br, CN or R3-A3-Z2 in the 2-position and piperidine-1,4-diyl groups are not substituted by these radicals in the 1-position, (c) Z1 is not -CH2CH2-if A1 is -A-and (d) Z1 is not -CO-O-if A1 is -A-A4-and -A2-R2 is 3-chloro-4-cyanophenyl and (e) all lateral substituents on pyrimidine-2,5-diyl and pyridazine-3,6-diyl groups are attached to C-atoms, can be used as components of liquid crystal phases.
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