Abstract: The compounds of the general formula (I) ##STR1## are particularly highly suitable as components of smectic, liquid-crystal mixtures, the symbols having the following meaning: R.sup.1 and R.sup.2 denote identical or different, straight-chain or branched alkyl or alkenyl groups which can contain asymmetric carbon atoms, containing 2 to 16 carbon atoms, in which one or more non-adjacent --CH.sub.2 -- groups can be replaced by --O-- and/or --S--, --A and --B each denote group ##STR2## in which the radicals R.sup.1, R.sup.2, in each case, are situated at the phenylene part of --A, --B and m and n denote 0 or 1, but m+n is always zero or 1.

Abstract: Liquid-crystal 5-phenylpyrmidine derivatives having S.sub.c or S.sup.*.sub.c phases and a process for preparing them. The new liquid-crystal 5-phenylpyrimidine derivatives have an S.sub.c or S.sup.*.sub.c phase and are described by the general formula (I) ##STR1## in which the symbols have the following meaning: R.sup.1 and R.sup.2 denote identical or different, straight-chain or branched alkyl or alkenyl groups having from k to 16 carbon atoms, with or without an asymmetric carbon atom, in which one or more non-adjacent --CH.sub.2 -- groups can be replaced by --O-- and /or --S----A and --B each denote ##STR2## in which the radicals R.sup.1, R.sup.2, in each case, are situated at the phenylene part of --A, --B andm and n denote 0 or 1, but m and n do not simultaneously denote 1, with the following provisos:(a) if m=n=0, k is 8, and in R.sup.2 the --CH.sub.2 -- group adjacent to the phenyl nucleus is replaced by --O--;(b) if m=1 and n=0, k is 2, and(c) if m=0 and n=1, k is 2 and in R.sup.2 the --CH.sub.

Abstract: Liquid-crystalline phenylpyrimidinyl cyclohexanecarboxylates having a smectic phase, a process for their preparation, and their use in liquid-crystal mixtures The phenylpyrimidinyl trans-cyclohexanecarboxylates of the general formula ##STR1## form a smectic C phase besides a relatively broad nematic phase when R.sup.1 denotes an alkyl radical having 10 to 16 carbon atoms, in particular 11 to 16 carbon atoms, or an alkoxy radical having 8 to 14 carbon atoms, and R.sup.2 denotes an alkyl radical having 2 to 9 carbon atoms. They are therefore particularly suitable as components of liquid-crystalline mixtures having a smectic C phase since they induce a relatively broad nematic phase or extend a narrow nematic phase which is present and extend the temperature range of the smectic C phase to low temperatures, but in particular to high temperatures.

Abstract: The novel compounds are aryl-2,3-epoxyalkyl ethers or thioethers or the corresponding thiirane compounds having a mesogenic aromatic component and a chiral component having a three-membered heterocyclic ring, wherein, in the general formula (1), ##STR1## the symbols have the following meaning: R.sup.1 =straight-chain or branched (C.sub.1 -C.sub.12) alkyl, where one or two non-neighboring CH.sub.2 groups may be replaced by O or S atoms.A=diazine-2,5-diyl or diazine-3,6-diyl,X and Y=O and/or S, andR.sup.2, R.sup.3 and R.sup.4, independently of one another=H, straight-chain (C.sub.1 -C.sub.10) alkyl or branched (C.sub.3 -C.sub.10) alkyl, where R.sup.2, R.sup.3 and R.sup.4 are not simultaneously H.The compounds are preferably employed in tilted smectic liquid-crystal phases which they convert into ferroelectric liquid-crystal phases; they have high values for spontaneous polarization or they induce high values for spontaneous polarization.