Abstract: The invention relates to liquid-crystalline nematic mixtures which are used in electro-optical components, as well as to methods for their preparation.The object of the invention is liquid-crystalline mixtures for electro-optical arrangements possessing high positive electrical anisotropy at a high clarification point, as well as methods for their preparation.According to the invention, liquid-crystalline nematic mixtures are used, wherein at least one component is a 1,4-disubstituted benzene derivative and the other compound is an ester of 4-[2,2-dicyano-ethenyl]-phenol of the general formula ##STR1## wherein R.sup.1 denotes added groups of various characters such as alkyl or alkoxy for example, X is aromatic, cycloaliphatic or a heterocyclic ring system such as phenyl or cyclohexyl for example; and Y is a connector such as carbonyloxy, azomethine, azoxy.These are prepared by reaction with reactive acid derivatives, particularly acid chlorides, or by a Knoevenagel-condensation by reacting respective 4-subst.

Abstract: A nematic liquid crystal mixture for modulation of the transmitted or incident light and for rendition of colored numerals, symbols and images in electro-optical devices, the said mixture comprising(a) a nematic liquid crystal adapted for reorientation in an electrical field due to its dielectric anisotropy and(b) a dichroic dyestuff adapted for simultaneous orientation changes together with the said nematic liquid crystal between a light absorption and a light transmission position based on the guest-host effect, the said dyestuff being an s-tetrazine derivative having an elongate molecular structure and having the formula ##STR1## wherein X is ##STR2## R.sup.1 and Y is R.sup.2 -- or ##STR3## R.sup.1 being H--, F--, Cl--, Br--, J--, O.sub.2 N--, NC--, HO--, H.sub.2 N--, C.sub.n H.sub.2n+1 NH--, C.sub.n H.sub.2n+1 (CH.sub.3)N--, C.sub.n H.sub.2n+1" --, C.sub.n H.sub.2n+1 O--, C.sub.n H.sub.2n+1 S--, C.sub.n H.sub.2n+1 COS--, C.sub.n H.sub.2n+1 COO--, C.sub.n H.sub.2n+1 OOC--, C.sub.n H.sub.2n+1 CO-- or C.sub.