Abstract: Compounds of the formula ##STR1## wherein Z represents a single covalent bond or --CH.sub.2 CH.sub.2 --, R.sup.1 denotes 1E-alkenyl with 2-10 carbon atoms or 3E-alkenyl with 4-10 carbon atoms and R.sup.2 is alkyl with 1-10 carbon atoms, 2E-alkenyl with 3-10 carbon atoms or 3-alkenyl with 4-10 carbon atoms,as well as their use in liquid crystalline mixtures and for electro-optical purposes.

Abstract: Compounds of the formula ##STR1## wherein m represents is the number 0 or 1; A is a single covalent bond, --CH.sub.2 --CH.sub.2 --, --OCH.sub.2 --, --COO-- or --OOC--; rings B, C and D are 1,4-phenylene optionally substituted with cyano, halogen or lower alkyl; Y.sup.1 and Y.sup.2 are hydrogen or one of them also is cyano; and R.sup.1 and R.sup.2 each represents C.sub.1 -C.sub.18 -alkyl or C.sub.2 -C.sub.18 alkenyl, either of which is optionally halogen-substituted, in which one CH.sub.2 group or two non-adjacent CH.sub.2 groups is/are optionally replaced by oxygen; with the provisos that at least one of R.sup.1 and R.sup.2 has a chiral carbon atom or a C-C double bond or both when A is --COO-- and at least one of R.sup.1 and R.sup.2 has a C-C double bond when A is a single covalent bond, their preparation, liquid crystalline mixtures containing these compounds and their use for electro-optical purposes are described.

Abstract: There is described compounds of the formula ##STR1## wherein X stands for CH and Y stands for N or X stands for N and Y stands for CH; A.sup.1 and A.sup.2 signify single covalent bonds or one of the groups A.sup.1 and A.sub.2 also signifies trans-1,4-cyclohexylene, cis-4-cyano-trans-1,4-cyclohexylene or 1,4-phenylene optionally substituted with halogen or methyl; ring B represents trans-1,4-cyclohexylene, 1,4-phenylene optionally substituted with halogen or methyl or, when A.sup.2 signifies a single covalent bond, also cis-4-cyano-trans-1,4-cyclohexylene; R.sup.1 denotes an optionally halogen-substituted alkyl or alkenyl group in which optionally one CH.sub.2 group or two non-adjacent CH.sub.2 groups is/are replaced by --O--, --COO-- and/or --OOC--; R.sup.2 signifies an optionally halogen-substituted alkyl or alkenyl group in which optionally one CH.sub.2 group or two non-adjacent CH.sub.2 groups is/are replaced by --O--, --COO-- and/or --OOC-- or R.sup.

Abstract: Compounds of the formula ##STR1## wherein m represents is the number 0 or 1; A is a single covalent bond, --CH.sub.2 --CH.sub.2 --, --OCH.sub.2 --, --COO-- or --OOC--; rings B, C and D are 1,4-phenylene optionally substituted with cyano, halogen or lower alkyl; Y.sup.1 and Y.sup.2 are hydrogen or one of them also is cyano; and R.sup.1 and R.sup.2 each represents C.sub.1 -C.sub.18 -alkyl or C.sub.2 -C.sub.18 alkenyl, either of which is optionally halogen-substituted, in which one CH.sub.2 group or two non-adjacent CH.sub.2 groups is/are optionally replaced by oxygen; with the provisos that at least one of R.sup.1 and R.sup.2 has a chiral carbon atom or a C--C double bond or both when A is --COO-- and at least one of R.sup.1 and R.sup.2 has a C--C double bond when A is a single covalent bond, their preparation, liquid crystalline mixtures containing these compounds and their use for electro-optical purposes are described.

Abstract: Compounds of the formula ##STR1## wherein m stands for a whole number of 4-7 and n stands for 0 or a positive whole number; ring A represents trans-1,4-cyclohexylene or a 2,5-disubstituted pyrimidine ring; Z signifies a single covalent bond or, insofar as ring A represents trans-1,4-cyclohexylene, also the ethylene group --CH.sub.2 CH.sub.2 --; X denotes hydrogen or fluorine; and R represents the group --NCS or --CN,their manufacture, liquid crystalline mixtures which contain these compounds and the use of these compounds and mixtures for electro-optical purposes are described.