Esters of 4-[2,2-dicyano-ethenyl]-phenols

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.-benzoic acid-[4-formyl-phenyl esters] or 4-alkyl-cyclohexanecarboxylic acid-[4-formyl-phenyl esters] with malonic acid dinitrile.

Dependencies are inferred from the claim text.