Abstract: 2,5-substituted 1,3,4-thiadiazoles of the general formula ##STR1##The aforementioned compounds are used in amounts of 0.1 to 80 mole percent in mixtures for electrooptical arrangements for the modulation of transmitted and reflected light, as well as for the colored or black-and-white display of numerals, symbols and moving or still pictures. The compounds endow the liquid-crystalline mixtures with an extended phase field of the smectic C phase, negative dielectric anisotropy and the property of forming optically active C phases upon admixture with optically active compounds.

Abstract: Liquid crystal substituted 1,3-dioxanes and mixtures containing the same.The invention relates to liquid crystal substituted 1,3-dioxanes and substances containing the same, for electro-optical arrays for the modulation of incident or transmitted light as well as for the reproduction of figures, symbols and images.The object of the invention is nematic liquid-crystal substances with favorable properties with respect to melting and clear points, stability toward thermal stress, effect of light, chemicals and electric fields as well as loss of color and processes for their production.The object is accomplished by the creation of new nematic liquid-crystal substances.According to the invention, liquid crystal 2,5-disubstituted derivatives of 1,3-dioxane of the general formula ##STR1## are proposed, wherein ##STR2## The new substances may be used in mixtures containing at least one of the substances according to the invention.

Abstract: The invention relates to nematic liquid crystals in electro-optical components for the modulation of light as well as for the representation of numerals, signs and images and to a method for producing the same.It is the object of the invention to create nematic liquid crystals which are well suited for electro-optical devices, preferably for two-frequency operation.It has been found that pure or mixed 2-n-alkyl-1, 4-bis-[4-acyloxy]-benzenes of the general formula ##STR1## wherein R.sup.3 =n-C.sub.m H.sub.2m+1, with m=3 to 14, are well suited for utilization in electro-optical components.It was found that 2-n-alkyl-1,4-bis-[acyloxy]-benzene which is well suited for electro-optical components, and especially for two-frequency operations, can be produced by the conversion of a correspondingly substituted benzoic acid or cyclohexane carboxylic acid or a reaction-capable derivative thereof with the corresponding 2-n-alkylhydroquinone--also in the form of its phenylate--at a temperature ranging from 0.degree. C.

Abstract: The invention relates to liquid crystal nematic substances for electro-optical devices for the modulation of light, for the reproduction of numerals, signs and images as well as an orienting medium for spectroscopy and gas chromatography.It was found that compounds containing two or three rings, connected by carboxyl groups are new liquid crystal nematic substances of the general formula ##STR1## where R.sup.1 =C.sub.n H.sub.2n+1, CN; R.sup.2 =C.sub.m H.sub.2m+1, CN;R.sup.3 =H, CH.sub.3, C.sub.2 H.sub.5 Cl, Br; x=0 or 1; m,n=numbers from 1 to 10 are suitable for electro-optical arrangements for the modulation of transmitted or reflected light as well as for the reproduction of numeral signals and images, and further, as an orienting medium for spectroscopy and gas chromotography.Other liquid crystal substances or non-liquid crystalline substances, particularly dyes, may be added to the substances according to the invention.

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: Liquid crystal substituted 1,3 dioxanes and mixtures containing the same.The invention relates to liquid crystalline substituted 1,3 dioxanes and substances containing the same, for electrooptical arrays for the modulation of incident or transmitted light as well as for the reproduction of figures, symbols and images.The objects of the invention are nematic crystal liquid substances with favorable properties with respect to melting and clear points; stability toward thermal stress, effect of light, chemicals and electric fields as well as loss of color; and processes for their production.The task is solved by the creation of new nematic liquid-crystal substances.As per invention, liquid crysalline 2,5-disubstituted derivatives of 1,3-dioxane of the general formula: ##STR1## are proposed, wherein: ##STR2## The new substances are used in mixtures containing at least one of the substances according to the invention.

Abstract: The invention concerns crystalline liquid substituted 1,3-dioxanes and compositions containing the same for use in electro-optical components, characterized by at least one compound of the general formula: ##STR1## R.sup.3 =C.sub.n H.sub.2n+1 ; C.sub.n H.sub.2n+1 O, Cl, Br, CN, NO.sub.2, and where R.sup.4 =C.sub.n H.sub.2n+1 and n=1 to 10.

Abstract: The invention describes nematic compositions for electrooptical devices for modulation of the transmitted or incident light and for the rendition of numbers, symbols and images as orientation in the spectroscopy and gas chromatography.

Abstract: As the liquid crystal substance in electro-optical devices or as the stationary phase in gas chromatography is employed a compound of the formula ##STR1## in which R.sub.1 and R.sub.2 each is C.sub.n H.sub.2n+1 --, C.sub.n H.sub.2n+1 O--, C.sub.n H.sub.2n+1 COO-- or C.sub.n H.sub.2n+1 OCOO--, n being an integer of from 1 to 10, and R.sub.3 is Cl--, Br--, CH.sub.3 --, C.sub.2 H.sub.5 --, CH.sub.3 CO-- or CH.sub.3 OOC--.