Abstract: Optically active pyrimidines of the formula ##STR1## wherein Z is --(CH.sub.2).sub.n -- or --(CH.sub.2).sub.n --O-- wherein n is an integer of 1 to 4 and each of the symbols X is a nitrogen atom and each of the symbols Y is --CH-- or each of the symbols Y is a nitrogen atom and each of the symbols X is --CH--,useful for electro-optical purposes, as well as liquid crystalline mixtures for electro-optical purposes containing compounds of the formula Ia and/or Ib, are described.The compounds of formulas Ia and Ib are useful for electro-optical purposes, for example, in electro-optical apparatuses.

Abstract: Liquid crystal mixtures having positive anisotropy of the dielectric constants comprising a nematogenic material having a clearing point above 60.degree. C., one or more compounds of the formula ##STR1## wherein R.sub.1 and R.sub.2 are hydrogen or straight-chain alkyl, provided that at least one of R.sub.1 and R.sub.2 is other than hydrogen and that R.sub.1 and R.sub.2 together contain no more than 9 carbon atoms,and, if desired, one or more additional doping agents, are described.

Abstract: Liquid crystal mixtures having positive anisotropy of the dielectric constants which comprise a nematogenic mixture with a clearing point above 60.degree. C. which is doped with an organic solvent or solvent mixture with a specific resistance of at least 10.sup.7 Ohm.cm. as well as a dipole moment along the longitudinal axis of the molecule of less than 3.5 Debye, or with a compound of the formula ##STR1## wherein R.sub.14 and R.sub.15 are straight-chain alkyl containing a total of not more than 14 carbon atoms or R.sub.14 is straight-chain alkyl and R.sub.15 is straight-chain alkoxy containing a total of not more than 8 carbon atoms,or a compound of the formula ##STR2## wherein R.sub.16 and R.sub.17 are straight-chain alkyl containing a total of not more than 6 carbon atoms,or a compound of the formula ##STR3## wherein R.sub.16 and R.sub.17 are straight-chain alkyl containing a total of not more than 6 carbon atoms,or mixtures thereof, are described.

Abstract: Phenyl-pyrimidines of the formula ##STR1## wherein R.sub.1 and R.sub.2 are as hereinafter set forth, are described. The end products are useful as liquid crystals.

Abstract: Compounds of the formula ##STR1## wherein when X is nitrogen, Y and Z are --CH--; or when Y is nitrogen, X and Z are --CH--; or when Z is nitrogen, X and Y are --CH--; and one of R.sub.1 and R.sub.2 is cyano and the other is straight-chain alkyl of 1 to 7 carbon atoms, straight-chain alkoxy of 1 to 7 carbon atoms or straight-chain alkanoyloxy of 2 to 7 carbon atoms,Prepared by a variety of methods, are described. The compounds of the invention are useful as components of nematic mixtures.

Abstract: Liquid crystalline alkylcinnamic acid p'-cyanophenyl esters, useful, for example, for electro-optical purposes, are described.

Abstract: Liquid crystal substances or compounds of the formula ##STR1## wherein R is as hereinafter set forth, as well as compositions and electro-optical apparatuses containing them are described.

Abstract: Liquid crystal substances or compounds of the formula ##STR1## wherein X is ##STR2## and R is straight-chain alkyl, straight-chain alkoxy, straight-chain alkanoyloxy or p-alkyloxycarbonyloxy,As well as compositions and electro-optical apparatuses containing them, are described.

Abstract: Liquid crystal substances or compounds of the formula ##STR1## wherein R is as hereinafter set forth, AS WELL AS COMPOSITIONS AND ELECTRO-OPTICAL APPARATUSES CONTAINING THEM ARE DESCRIBED.

Abstract: Liquid crystalline compounds of the formula ##STR1## wherein R is as hereinafter set forth, WHICH ARE USEFUL AS DIELECTRICS IN ELECTRO-OPTICAL DEVICES, ARE DESCRIBED.

Abstract: Liquid crystal substances or compounds of the formula ##STR1## wherein X is ##STR2## and R is straight-chain alkyl, straight-chain alkoxy, straight-chain alkanoyloxy or p-alkyloxycarbonyloxy,As well as compositions and electro-optical apparatuses containing them, are described.

Abstract: Phenyl-pyrimidines of the formula ##STR1## wherein R.sub.1 and R.sub.2 are as hereinafter set forth, are described. The end products are useful as liquid crystals.

Abstract: Liquid crystalline mixtures comprising at least three compounds of the formula ##SPC1##Wherein R is n-butyl, n-pentyl, n-hexyl, n-heptyl or n-octyl, which may additionally contain other nematic or non-nematic substances, are described. The liquid crystalline mixtures are useful, for example, as dielectrics for electro-optical purposes.

Abstract: Liquid crystal substances or compounds of the formula ##SPC1##Wherein R is as hereinafter set forth,As well as compositions and electro-optical apparatuses containing them are described.

Abstract: Liquid crystal substances or compounds of the formula ##SPC1##Wherein R is as hereinafter set forth, as well as compositions and electro-optical apparatuses containing them are described.

Abstract: Liquid crystalline compounds of the formula ##SPC1##Wherein R is as hereinafter set forth, which are useful as dielectrics in electro-optical devices, are described.