Abstract: The invention relates to a liquid-crystalline medium based on a mixture of polar compounds of positive dielectric anisotropy, characterized in that it contains one or more compounds of the general formula I ##STR1## in which L is H or F, X is F, Cl, CF.sub.3, OCF.sub.3 or OCHF.sub.2, and R is alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 7 carbon atoms.

Abstract: Supertwist liquid-crystal displays having excellent characteristic line steepness are obtained if the nematic liquid-crystal mixture satisfies the following conditions:a nematic phase range of at least 60.degree. C.,a viscosity of 30 mPa.s or less,.DELTA..epsilon./.epsilon..perp.<1.5, where .DELTA..epsilon. denotes the dielectric anisotropy and .epsilon..perp. denotes the dielectric constant in the direction of the short axis of the liquid-crystal molecules, and.DELTA..epsilon. is greater than or equal to +5,and is based on the following components:a) compounds having a high .epsilon..perp. and a clearly positive dielectric constant, selected from the group comprising the formulae 1-8: ##STR1## and/or compounds of the formula A and/or B ##STR2## and, if appropriate, compounds selected from the group comprising the formulae 9 to 11 ##STR3## and b) relatively non-polar compounds having a large .epsilon..perp.

Abstract: Compounds of the formula IR.sup.1 --A.sup.1 --A.sup.2 --R.sup.2 IwhereinR.sup.1 and R.sup.2 are each alkyl with 1-15 C atoms, and wherein one or two non-adjacent CH.sub.2 groups can also be replaced by --O--, --S--, --CO--, --O--CO--, --CO--O--, --CO--S--, --S--CO--, --CHHalogen--, --CHCN-- and/or --CH.dbd.CH--,A.sup.1 is 1,4-phenylene, trans-1,4-cyclohexylene or a single bond andA.sup.2 is ##STR1## in which Z is --O--CO--, --CO--O--, --S--CO--, --CO--S--, CH.sub.2 O--, --OCH.sub.2 -- or --CH.sub.2 CH.sub.2 --, with the proviso that, if A.sup.1 is a single bond, A.sup.2 is ##STR2## are suitable as components of chirally tilted smectic liquid crystal phases.

Abstract: The invention relates to a liquid-crystalline mixture containing one or more compounds of the general formula ##STR1## in which R.sup.1 is straight-chain alkyl having 2 to 12 carbon atoms in which, in addition, one CH.sub.2 group may be replaced by --O-- or --CH.dbd.CH--, the ring A is 1,4-phenylene or trans-1,4-cyclohexylene, and r is 0 or 1, and one or more highly dielectrically positive compounds selected from the group comprising the compounds of the general formulae II, III and IV in a weight ratio between the compounds of the formula I and the compounds of the formulae II, III and IV of from 1:10 to 10:1: ##STR2## in which R.sup.2 has one of the meanings indicated for R.sup.1, and X and Y are each, independently of one another, CH or N, ##STR3## in which R.sup.2 has one of the meanings indicated for R.sup.1, and X' and Y' are CH.sub.2 or O, ##STR4## in which R.sup.2 has one of the meanings indicated for R.sup.1, r is as defined above, the rings A.sup.1 and A.sup.

Abstract: The invention relates to a process for the reaction of fluorinated or chlorinated aromatics with electrophiles at the ortho position relative to the fluorine or chlorine atom, characterized in that a strong base is added to a mixture of the fluorinated or chlorinated aromatic and the electrophile.

Abstract: Novel 2,5-disubstituted heterocyclic compounds of the formula I ##STR1## in which n is 1 to 10,Het is ##STR2## Ring A is trans-1,4-cyclohexylene or, in the case where Het= ##STR3## X=--OCF.sub.3 or --OCHF.sub.2 and/or Y=Z=F, is alternatively 1,4-phenylene,X is CN, F, Cl, --CF.sub.3, --OCF.sub.3 or --OCHF.sub.2, andY and Z are each, independently of one another, H or F, can be used as components of liquid-crystalline media.

Abstract: Chiral 1,2-difluorobenzene derivatives are suitable as components of chiral tilted smectic liquid-crystalline phases.

Abstract: The invention relates to novel phenylcyclohexanes of the formula I ##STR1## in which Q is CH--Hal or C--Hal.sub.2 where Hal is F or Cl,n is 1 to 5,r is 0 to 6,A is a single bond, ##STR2## X is F, Cl, --CF.sub.3, --OCF.sub.3 or --OCHF.sub.2, and Y and Z are each, independently of one another, H or F.

Abstract: The invention relates to novel benzene derivatives of the formula I ##STR1## in which n is 0, 1, 2, 3, 4, 5, 6 or 7,Q is --O--, --CH.dbd.CH-- or a single bond,r is 0, 1, 2, 3, 4 or 5,s is 0, 1 or 2,X is F, Cl, OCHF.sub.2 or CF.sub.3,L is H or F, andA is ##STR2## Z, Z-Ar, Ar-Z, Z-Cyc in which Z is a single bond, --(CH.sub.2).sub.2 -- or --(CH.sub.2).sub.4 --, Ar is 1,4-phenylene or biphenyl-4,4'-diyl and Cyc is trans-1,4-cyclohexylene.

Abstract: Disclosed are trifluoromethylcyclohexane derivatives of the formula I ##STR1## whereinR is an alkyl or alkenyl radical having up to 18 C atoms which is unsubstituted or substituted by CN or by at least one halogen, and in which one or more non-adjacent CH.sub.2 groups may be replaced by a radical selected from the group comprising --O--, --S--, --CO--, --O--CO--, --CO--O-- and --C.tbd.C--,A.sup.1 and A.sup.2 are each, independently of one another,a) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N,b) a 1,4-cyclohexylene radical, in which one or two non-adjacent CH.sub.2 groups may be replaced by --O-- or --S--,c) a 1,4-cyclohexenylene, piperidine-1,4-diyl, 1,4-bicyclo[2,2,2]-octylene or naphthalene-2,6-diyl radical,it being possible for the radicals a) and b) to be monosubstituted or polysubstituted by halogen atoms or cyano and/or methyl groups, ##STR2## Z.sup.1 and Z.sup.2 are each, independently of one another, --CO--O--, --O--CH--, --CH.sub.2 CH.sub.2 --, --CH(CN)--CH.sub.

Abstract: The invention relates to fluorophenylpyridines of the formula I: ##STR1## where R.sup.1 and R.sup.2 are substituted and unsubstituted monovalent organic radicals.

Abstract: The invention relates to 5-oxy-2-phenylpyridines of the formula I ##STR1## in which m and n, independently of one another, are each from 1 to 18,Q.sup.1 is --O--, trans-1,4-cyclohexylene, 1,4-phenylene or a single bond, andQ.sup.2 is --CO--, ##STR2## or a single bond, with the provisos that in the case where Q.sup.1 =Q.sup.2 =a single bond, the sum of m+n.gtoreq.11, and in the case where Q.sup.2 =CO, the radical C.sub.n H.sub.2n+1 is straight-chain, and to ferroelectric liquid-crystalline media containing these compounds.

Abstract: The invention relates to a liquid crystalline medium having at least two components, where at least one component is a haloacetylene derivatives of the formula IR.sup.1 --A.sup.1 --Z.sup.1 --(A.sup.2 --Z.sup.2).sub.m --A.sup.3 --C.tbd.C--X IwhereinR.sup.1 is an alkyl or alkenyl radical having up to 15 carbon atoms which is unsubstituted or monosubstituted by CN, halogen or CF.sub.3, or such a radical wherein one or more CH.sub.2 groups is replaced, in each case independently of one another, by --S--, --O--, ##STR1## --CO--, --CO--O--, --O--CO-- or --O--CO--O-- in such a manner that sulfur and/or oxygen atoms are not linked directly to one another,A.sup.1, A.sup.2 and A.sup.3, in each case independently of one another, are(a) a trans-1,4-cyclohexylene radical or --S-- one or more non-adjacent CH.sub.

Abstract: Supertwist liquid crystal display elements with excellent steepness of the characteristic are obtained, if the nematic liquid crystal mixture satisfies the following conditions:a nematic phase range of at least 60.degree. C.,a viscosity of 30 mPa.s or lower, and.DELTA..epsilon./.epsilon..perp.<2.0, where .DELTA..epsilon. is the dielectric anisotropy and .epsilon..perp. is the dielectric constant in the direction of the short axis of the liquid crystal molecules.

Abstract: The invention relates to a liquid-crystal matrix display having integrated nonlinear components and containing a liquid-crystal mixture having particularly high specific resistance.

Abstract: The invention relates to a liquid-crystalline medium for electrooptical display elements based on the ECB effect, containing two components A and B which themselves comprise one or more individual compounds, component A having clearly negative dielectric anistropy and giving the liquid-crystalline phase a dielectric anistrophy of .ltoreq.-0.3, and component B having pronounced nematogeneity and a viscosity of not more than 30 mPa.s at 20.degree. C.

Abstract: Pyrimidines of the formula I ##STR1## in which R is an alkyl group of 1-15 C atoms in which in addition one or two nonadjacent CH.sub.2 groups can be replaced by --O--, --CO--, --O--CO--, --CO--O--, --CHY-- and/or --CH.dbd.CH--, or is H, F, Cl or CN,X is --O--CH.sub.2 --R.sup.1, --S--R.sup.2, --NCS or --COO--A--R.sup.3,Y is halogen, CN or OH,R.sup.1 is an alkyl group of 1-15 C atoms, in which one or more nonadjacent CH.sub.2 groups are replaced by --O--, --CO--, --O--CO--, --CHY-- and/or by --CH.dbd.CH--,R.sup.2 is an alkyl group of 1-15 C atoms, in which in addition one or two nonadjacent CH.sub.2 groups can be replaced by --O--, --CO--, --O--CO--, --CO--O--, --CHY-- and/or --CH.dbd.CH--,A is a trans-1,4-cyclohexylene groups which is unsubstituted or monosubstituted or disubstituted by F and/or Cl atoms and/or CH.sub.3 groups and/or CN groups, or is a single bond, andR.sup.3 is an alkyl group of 1-15 C atoms, in which in addition one or two nonadjacent and, if A is a single bond, nonterminal CH.sub.

Abstract: The invention relates to novel tetracyclic benzene derivatives of the formula I ##STR1## in which n is 1 to 7, A is trans-1,4-cyclohexylene, 1,4-phenylene, 3-fluoro-1,4-phenylene or 3,5-difluoro-1,4-phenylene, X is F, Cl, CF.sub.3, --OCF.sub.3 or --OCHF.sub.2, and L, Y and Z are each, independently of one another, H or F.

Abstract: The invention relates to a matrix liquid crystal display containing integrated non-linear elements and a liquid crystal mixture which has a particularly high resistivity.

Abstract: Biphenylylethanes of the formula I,R.sup.1 --CH.sub.2 --X--(CH.sub.2 CH.sub.2).sub.m --Ph--Ph--CH.sub.2 CH.sub.2 --Ph--Y--CH.sub.2 --R.sup.2 Iin whichR.sup.1 and R.sup.2 are each, independently of one another, alkyl, alkenyl or oxaalkyl having up to 12 C atoms, and one of the radicals R.sup.1 and R.sup.2 is alternatively H,m is 0 or 1,X and Y are each, independently of one another, O, S, CO--O, O--CO, O--CO--O or a single bond, the radical X is alternatively 1,4-phenylene or trans-1,4-cyclohexylene, and the radical Y is alternatively trans-1,4-cyclohexylene, andis 1,4-phenylene, and one or two of the radicals Ph is alternatively 2- or 3-fluoro-1,4-phenylene,with the proviso that, in the case (a) where X=1,4-phenylene and m=1, one or two of the radicals Ph are 2- or 3-fluoro-1,4-phenylene, and (b) in the case where X=trans-1,4-cyclohexylene, m=0 and one or two of the radicals Ph are 2- or 3-fluoro-1,4-phenylene, are suitable as components of liquid-crystalline phases.