DD261803A5 - CHIRAL-TREATED SMEKTIC LIQUID CRYSTALLINE PHASE - Google Patents

Abstract

According to the invention, the component used in the novel chiral tilted smectic liquid-crystalline phase is at least one optically active compound of the formula I R1A1Z1A2R2 (I) in which, for example: R1 and R2 are H, an optionally substituted alkyl group having 1-12 C atoms, F, CL, Br, CN and others al .; A is optionally in the 2-, 3-, 5- or 6-position by hydroxy, halogen, nitrile and / or an alkyl group or a fluorinated alkyl group each having 1-10 C atoms, optionally substituted 1,4-cyclohexylene or 1,4-cyclohexenylene group and the like al .; A2 optionally substituted 1,4-phenylene u. al .; Z1 COO, OCO, CH2CH2, OCH2, CH2O or a single bond.

Description

Z ¹ and Z ² R ³

Field of application of the invention

The invention relates to a chiral tilted smectic liquid-crystalline phase having at least two liquid-crystalline components.

The chiral tilted smectic liquid crystalline phase of the present invention is used as a dielectric in electro-optical display elements.

Characteristic of the known state of the art

Like similar compounds described in DE-OS 3515373, the compounds of the formula I can be used as components of chiral tilted smectic liquid-crystalline phases.

Chiral touted smectic liquid crystalline phases with ferroelectric properties can be prepared by adding base mixtures having one or more tinted smectic phases to a suitable chiral dopant (L A. Beresnev et al., Mol. Cryst. Liq. Cryst. 89, 327 [1982] HR Brand et al., J. Physique 44, [Iett], L-771 [1983]). Such phases can be used as dielectrics for fast switching displays based on the principle of SSFLC technology described by Clark and Lagerwall (NA Clark and ST Lagerwall, Appl. Phys. Lett., 36, 899 [1980], US Patent 4,367,924) based on the ferroelectric properties of the chiral tilted phase. In this phase, the elongated molecules are arranged in layers, the molecules having a tilt angle to the layer normal. As layer progresses

Layer, the tilt direction changes by a small angle with respect to an axis perpendicular to the layers, so that a helical structure is formed. In displays based on the principle of SSFLC technology, the smectic layers are arranged perpendicular to the plates of the cell. The helical arrangement of the templating directions of the molecules is suppressed by a very small spacing of the plates (about 1-2 pm). This forces the longitudinal axes of the molecules to align in a plane parallel to the plates of the cell, giving rise to two excellent tilt orientations. By applying a suitable alternating electric field, it is possible to switch back and forth between these two states in the liquid-crystalline phase having a spontaneous polarization. This switching process is much faster than conventional twisted-cell (TN-LCD's) based on nematic liquid crystals. A major disadvantage to many applications of currently available materials with chiral tilted smectic phases (such as Sc *) is that the dielectric anisotropy has values greater than zero or, if negative, only slightly nonzero values. Negative values of dielectric anisotropy are required if the required planar orientation is effected by superposition of the drive field with a small amplitude AC holding field (J. M. Geary, SID Meeting, Orlando / Florida, April / May 1985, Lecture 8.3).

Object of the invention

The aim of the invention is the provision of improved chiral tutted smectic liquid-crystalline phases, which do not have the disadvantages of known chiral tutted smectic liquid-crystalline phases.

Explanation of the essence of the invention

The invention has for its object to find new compounds that are suitable as components of such phases

According to the invention, at least one optically active compound of the formula I as components of chiral dyed smectic mixtures

R ¹ -A ¹ -Z ¹ -A ² -R ² I

applied, in which

Ri-A ^ Z ¹ R ¹ -AZ \ R ¹ -A ⁴ -Z ¹ or R ¹ -AA ⁴ -Z ¹ ,

R ¹ and R ^{2 are} each H, an alkyl group having 1-12 C atoms, wherein also one or two non-adjacent CH ₂ groups

may be replaced by O atoms and / or -CO groups and / or -CO-O groups and / or -CH = CH groups and / or -CH-halogen and / or -CHCN groups, F, Cl, Br, CN or R ³ -A ³ -Z ² ,

A in the 2-, 3-, 5- or 6-position by hydroxy, halogen, nitrile and / or an alkyl group or a fluorinated

Alkyl group each having 1-10 C atoms, wherein also one or two non-adjacent CH ₂ groups replaced by -0 -, - CO -, - O-CO -, - CO-O and / or -CH = CH- may be substituted 1,4-cyclohexylene or 1,4-cyclohexenylene group in which also one or two non-adjacent CH ₂ groups may be replaced by -O- and / or -S-substituted, which may also be substituted in 1 and or4-position by hydroxy, halogen, nitrile and / or an alkyl group or a fluorinated alkyl group each having 1-4 C atoms, wherein also one or two non-adjacent CH ₂ groups by -0 -, - CO -, - O -CO -, - C0-0 and / or -CH = CH-substituted, A ² , A ³ and A ^{4 are} each unsubstituted or by one or two F and / or Cl atoms and / or CH ₃ groups and / or CN groups substituted 1,4-phenylene, wherein also one or two CH groups may be replaced by N, 1,4-cyclohexylene, wherein also one or two non-adjacent CH ₂ groups by 0 Atoms and / or S atoms may be replaced, piperidi n-1,4-diyl, 1,4-bicyclo (2,2,2) -octylene, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl groups

Z ¹ and Z ^{2 are} each CO-0 -, - 0-C0 -, - CH ₂ CH ₂ -, OCH ₂ -, - CH ₂ O- or a single bond,

R ³ H, an alkyl group of 1-12, wherein also one or two non-adjacent CH ₂ groups by 0-atoms

and / or -CO-groups and / or -CO-O groups and / or -CH = CH groups, F, Cl, Br or CN.

It has now been found that the use of compounds of the formula I as components of chiral tutted smectic mixtures may substantially reduce the aforementioned disadvantages. The compounds of the formula I are thus eminently suitable as components of chiral dyed smectic liquid-crystalline phases. In particular, with their help chemically stable chiral tilted smectic liquid crystalline phases with favorable ferroelectric phase ranges, in particular with broad Sc * phase ranges, negative or positive dielectric anisotropy, low optical anisotropy, favorable pitch height and for such phases high values for the spontaneous polarization can be produced , P is the spontaneous polarization in nC / cm ² .

In addition, with the provision of the compounds of the formula I, the range of liquid-crystalline substances which are suitable for the production of ferroelectric mixtures from a variety of application-technical points of view is considerably widened considerably.

The compounds of the formula I have a wide range of applications. Depending on the choice of substituents, these compounds may serve as base materials from which liquid crystalline phases are predominantly composed; However, it is also possible to add compounds of the formula I to liquid-crystalline base materials from other classes of compounds, for example to obtain the dielectric and / or optical anisotropy and / or the

to vary spontaneous polarization and / or the phase range and / or the tilt angle and / or the pitch of such a phase. The compounds of the formula I are furthermore suitable as intermediates for the preparation of other substances which can be used as constituents of liquid-crystalline phases.

The compounds of the formula I are colorless in the pure state and have low values of optical anisotropy.

Some of the compounds of the formula I show liquid-crystalline mesophases in a temperature range which is favorably located for the electro-optical use, but it is also possible to use isotropic or monotropic liquid-crystalline compounds of the formula IaI components of chiral complex-active phases. Chemically, thermally and against light, they are very stable.

The invention thus relates to the use of the compounds of the formula I as components of liquid-crystalline phases.

The invention also relates to chiral tilted smectic liquid crystal phases containing at least one optically active compound of the formula I having at least one asymmetric carbon atom.

The invention further relates to liquid crystal display elements, in particular electro-optical display elements containing such phases.

For the sake of simplicity, in the following, Ph denotes a 1,4-phenylene group, in which also one or two CH groups can be replaced by N, Cy denotes a 1,4-cyclohexylene group, in which also one or two non-adjacent CH ₂ groups are replaced by O-- Atoms can be replaced and Bi a bicyclo (2,2,2) octylene group.

Above and below, R ¹ , R ² , R ³ , A ¹ , A ² , A ³ , A ⁴ , A, Z ¹ and Z ^{2 have} the meaning given, unless expressly stated otherwise.

The compounds of the formula I accordingly comprise, in particular, compounds of the partial formulas Ia and Ib (with two rings)

Ri_A-A ² -R ² I a

R'-A-Z'-A ^ R ² I b

Ie to Ik (with three rings),

Ri_A ⁴ -AA ² R ² Ie

Ri_A-A ⁴ -A ² -R ² If

Ri-A ⁴ -AZ ¹ -A ² -R ² Ig

Ri-AA ^ Z'-A ^ R ² I h

R ¹ -AZ ¹ -A ² -A ³ -R ³ I i

R ³ -A ³ -Z ² -AZ ¹ -A ² -R ² Ij

R'-A-Z'-A ^ -A ^ R ³ Ik

Ip to laa (with four rings),

Ri_A ⁴ -AA ² -A ³ -R ³ I ρ

Ri_A-A ⁴ -A ² -A ³ -R ³ Iq

R ³ -A ³ -Z ² -A ⁴ -AA ² -R ² I r

rS-aS-A ^ AZ ^ -R ² Is

Ri- _A _ _A 4_ _A 2_ _Z 2_ _A 3_ _R 3 | _t

Ri_A-A ⁴ -Z ¹ -A ² -A ³ -R ³ I u

Ri_A ⁴ -AZ ¹ -A ² -A ³ -R ³ Iv

r'-A ⁴ -AZ ¹ -A ² -Z ² -A ³ -R ³ Iw

Ri-AA -'-Z ^ -Z ^ R ³ Ix

rS.aS-Z ^ -AZ ^ -R ² Iy

R ³ -A ³ -Z ² -AA ⁴ -Z ¹ -A ² -R ² Iz

R3_ _A 3_ _Z 2_ _A _ _Z 1_ _A 2_ _Z 2_ _A 3_ _R 3 | _ag

as well as lab to lak (five rings),

R3_ _A 3_ _Z 2_ _A 4_ _A _ _Z 1_ _A 2_ _Z 2_ _A 3_ _R 3 | _{from R} 3_ _A 3_ _Z 2_ _A _ _A 4_ _Z 1_ _A 2_ _Z 2_ _A 3_ _R 3, _ac R3_ _A 3_ _A 4_ _A _ _Z 1_ _A 2_ _Z 2_ _A 3_ _R 3 Lad R ³ -A ³ -Z ² -A ⁴ -AA ² -Z ² -A ³ -R ³ I ae R3_ _A 3_ _Z 2_ _A 4_ _A _ _Z 1_ _A 2_ _A 3_ _R 3 | _gf

R3_ 3_A _A-A ⁴ -A ² -Z ² -A ³ -R ³ I ag

R3_ _A 3_ _Z 2_ _A _ _A 4_ _A 2_ _A 3_ _R 3 | g _h R3_ _A 3_ _A 4_ _A _ _Z 1_ _A 2_ _A 3_ _R 3 | _{aj R} 3_ _A 3_ _A 4_ _A _ _A 2_ _A 3_ _R 3 laj

R3_ _A 3_ _A _ _A 4_ _A 2_ _A 3_ _R 3 | _ak

Of these, particular preference is given to those of the formulas Ia, Ib, Ie, If, Ig, Ih, Ii, Ip and Iq. The preferred compounds of the formula Ia include those of the subformulae I a 1 to I a 3:

R ¹ -A-Ph-R ² I a I

R ¹ -A-Cy-R ² I a

R ¹ -A-Bi-R ² Ia3

Of these, those of sub-formulas I a 1 and Ia 2 are particularly preferred.

The preferred compounds of the formula Ib include those of the partial formulas Ib1 to Ib3:

F ^ -A - ^ - Ph-R ² I b 1

R ^ A-Z'-Cy-R ² Ib2

R ^ A-Z'-Bi-R ² Ib3

Among them are those of the formulas I and I b 1 b2, especially those wherein Z ¹ is -CO-O-, 0-C0- or-CH ₂ -CH ₂ -bedeutet particularly preferred.

The preferred compounds of the formula Ie include those of the subformulae 1 e 1 and Ie 2:

R ^ Cy-A-Cy-R ² Ie 1

R'-Cy-A-Ph-R ² Ie ²

The preferred compounds of the formula If include those of the partial formulas If 1 to If 4:

R ¹ -A-Cy-Cy-R ² If 1

R ¹ -A-Ph-Ph-R ² If 2

R ^ A-Ph-Cy-R ² If 3

R ^ A-Cy-Ph-R ² If 4

Among them, those of the sub-formulas If 1 and If 4 are particularly preferred.

The preferred compounds of the formula Ig include those of the partial formulas Ig 1 to Ig 3:

R'-Cy-A-Z'-Cy-R ² I g 1

R ¹ -Cy-AZ ¹ -Ph-R ² I g 2

R'-Ph-A - ^ - Cy-R ² Ig3

These include those of the subformulae Ig 1, especially those wherein Z ¹ is -CO-O-, -0-CO-OdBr-CH ₂ CH ₂ - is particularly preferred.

The preferred compounds of the formula Ih include those of the partial formulas Ih1 to Ih 4:

R ^ A-Cy - ^ - Cy-R ² Ih1

R ^ A-Ph - ^ - Ph-R ² I h 2

R'-A-Ph-Z'-Cy-R ² Ih3

R ¹ -A-Cy-Z ¹ -Ph-R ² Ih4

These include those of the subformulae I h 1,1 h 2 and I h 3, in particular those in which Z ¹ denotes -CO-O-, -O-C0- or -CH ₂ CH ₂ -, in particular -CO-O-, particularly preferred.

The preferred compounds of the formula Ii include those of the subformulae Ii 1 and Ii 4:

R'-A-Z'-Cy-Cy-R ³ I i 1

R ¹ -AZ ¹ -Ph-Cy-R ² Ii2

R'-A-Z'-Cy-Ph-R ² Ii3

R'-AZ ^ Ph-Ph-R ² I i 4

Of these, particular preference is given to those in which Z ^{1 is} -O-CO-COO-O-OdBr-CH ₂ CH ₂ -. The preferred compounds of the formula Ip include those of the subformulae I ρ 1 and Ip 2:

R ¹ -Cy-A-Ph-Ph-R ³ I ρ 1

R ^ Cy-A-Ph-Cy-R ³ I ρ 2

The preferred compounds of the formulas Iq include those of the partial formulas Iq 1 and Iq 2:

R ¹ -A-Ph-Ph-Cy-R ³ Ig 1 *

R 1 A-Ph-Cy-Cy-R ³ I q 2

In the compounds of the formulas above and below, R ¹ , R ² and R ^{3 are} preferably alkyl, furthermore alkoxy or another oxaalkyl group.

Preference is furthermore given to compounds of the formulas above and below in which one of the radicals R ¹ , R ² or R ^{3 is} -CO-alkyl, -CO-O-alkyl-OCO-alkyl or -OCOO-alkyl and the other is alkyl or alkoxy ,

In the preferred compounds of the formulas above and below, the alkyl radicals in which also a CH ₂ group (alkoxy or oxaalkyl) may be replaced by an O atom may be straight-chain or branched. Preferably, they are straight-chain, have 5,6,7,8,9 or 10 C-atoms and therefore preferably pentyl, hexyl, heptyl, octyl, nonyl, decyl, pentoxy, hexoxy, heptoxy, octoxy, nonoxy or decoxy, furthermore also Ethyl, propyl, butyl, undecyl, dodecyl, propoxy, ethoxy, butoxy, undecoxy, dodecocy, 2-oxapropyl (= 2-methoxymethyl), 2 - (= ethoxymethyl) or 3-oxabutyl (= 2-methoxypentyl), 2-, 3 or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl.

A ² , A ³ and A ⁴ are preferably Cy or Ph. In the compounds of the formulas above and below, Ph is preferably a 1,4-phenylene or a pyrimidine-2,5-diyl group, more preferably 1,4-phenylene , Cy is preferably a 1,4-cyclohexylene group.

Z ¹ and Z ² are preferably single bonds, more preferably -O-C0 -, -CO-O or -CH ₂ CH ₂ groups.

A is preferably a 2-, 3-, 5- or 6-position by hydroxy, halogen, nitrile and / or alkyl group having preferably 1-5 C atoms, wherein also one or two non-adjacent CH ₂ groups preferably by -O - and / or -CO- may be substituted, substituted 1 ACyclohexylengruppe, which may also be substituted in the 1- and / or 4-position by halogen, nitrile and / or an alkyl group having 1-4 C-atoms, in particular by nitrile can. A is preferably a group selected from the formulas (A) to (C),

(A) (B) (C)

W W W

wherein WOH, halogen, nitrile, alkyl, alkoxy, oxaalkyl, alkanoyl, alkanoyloxy or alkoxycarbonyl each having 1 to 10 carbon atoms.

Preference is furthermore given to compounds of the formulas (A) - (C) in which W is preferably alkyl, alkoxy, halogen or nitrile.

W is particularly preferably CH ₃ .

A also includes the mirror images of formulas (A) to (C).

R ¹ -A is furthermore preferably a group of the formulas (D) - (F)

R ⁴ R ⁴ R ⁴

wherein R ^{4 is} preferably n-alkyl, n-alkoxy, n-alkoxycarbonyl, (each preferably having 1 to 10, in particular having 1 to 7, carbon atoms) or CN. R ¹ here means H.

Particularly preferred are (D) and (F), wherein R ^{4 is} preferably CH ₃ .

Preferred meaning of W is F, Cl, CN, -CH ₃ and -CH ₂ CH ₃ . Particularly preferred are the groups (A) and (B). Particularly preferred for Z ¹ ISt-CO-O ₇ -O-CO-OdBr-CH ₂ CH ₂ -, in particular the -CH ₂ CH ₂ group.

Compounds of the above and below formulas having branched wing groups R ¹ , R ² and R ³ , respectively, may occasionally be of importance for better solubility in the usual liquid crystalline base materials. Branched groups of this type usually contain no more than one chain branch.

Preferred branched radicals are isopropyl, 2-butyl (= 1-methylpropyl), isobutyl (= 2-methylpropyl), 2-methylbutyl, isopentyl (= 3-methylbutyl), 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2 Propylpentyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexoxy, 1-methylhexoxy, 1-methylheptoxy, 2-0xa-3-methylbutyl, 3-oxa-4- methylpentyl.

Among the compounds of the formula I and Ia to Iq, preference is given to those in which at least one of the radicals contained therein has one of the preferred meanings given.

In the compounds of the abovementioned formulas, preference is given to those stereoisomers in which the substituents R ¹ -, R ¹ -A ⁴ -, R ² -A ² -Z ¹ - or R ² -A ² -Z ¹ -A ⁴ - are in the 1- and4-position of the ring Atrans-constantly and occupy the equatorial position, while the optional additional substituent on A in an 1 or 4-position assumes an axial position. These are usually more stable; In many cases, the cis compounds (or mixtures) can be treated by treatment with a base, e.g. B. with K-tert-butylate in an inert solvent ₍ such as dimethyl sulfoxide, convert into the trans compounds.

Oersubstituentewinden Groups of formulas (A) to (C) can take equatorial or axial positions. Those of the abovementioned formulas which contain one or more groups Dio, Dit, Pip and / or Pyr each include the two possible 2,5- (Dio, Dit, Pyr) or 1,4-position isomers (Pip).

The compounds of the formula I are prepared by methods known per se, as described in the literature (eg in the standard works such as Houben-Weyl, Methods of Organic Chemistry, Georg Thieme Verlag, Stuttgart), under Reaction conditions which are known and suitable for the said reactions. One can also make use of known per se, not mentioned here variants.

If desired, the starting materials can also be formed in situ, such that they are not isolated from the reaction mixture, but immediately reacted further to give the compounds of the formula I.

Thus, the compounds of the formula I can be prepared by reducing a compound which otherwise corresponds to the formula I but contains one or more reducible groups and / or C-C bonds instead of Η-atoms.

Suitable reducible groups are preferably -CH = CH groups, furthermore, for example, free or esterified hydroxy groups, aromatically bonded halogen atoms or carbonyl groups. Preferred starting materials for the reduction correspond to the formula I, but instead of a -CH ₂ CH ₂ group, they may be a -CH = CH group and / or a -CO ₂ group instead of a -CH ₂ group and / or instead of a -CH ₂ group Η atoms contain a free or a functional (eg in the form of their p-toluenesulfonate) modified OH group.

The reduction can z. Example, by catalytic hydrogenation at temperatures between about O ⁰ C and about 200 ⁰ C and pressures between about 1 and 200 bar in an inert solvent, for. An alcohol such as methanol, ethanol or isopropanol, an ether such as tetrahydrofuran (THF) or dioxane, an ester such as ethyl acetate, a carboxylic acid such as acetic acid or a hydrocarbon such as cyclohexane. Suitable catalysts are suitably noble metals such as Pt or Pd, which can be used in the form of oxides (eg PtO ₂ , PdO), on a support (eg Pd on carbon, calcium carbonate or strontium carbonate) or in finely divided form ,

Ketones can also be prepared by the methods of Clemmensen (with zinc, amalgamated zinc or tin and hydrochloric acid, suitably in aqueous-alcoholic solution or in heterogeneous phase with water / toluene at temperatures between about 80 and 120 ° C) or Wolff-Kishner (with hydrazine, suitably in the presence of alkali such as KOH or NaOH in a high boiling solvent such as diethylene glycol oderTriethylenglykol at temperatures between about 100 and 200 ⁰ C) to the corresponding compounds of formula I, the alkyl and / or-CH ₂ CH ₂ bridges are reduced , Furthermore, reductions with complex hydrides are possible. For example, arylsulfonyloxy with LiAIH ₄ may be removed reductively, especially p-Toluolsulfonyloxymethylgruppenzu methyl groups are reduced, advantageously in an inert solvent such as diethyl ether or THF at temperatures between etwaO and 100 ⁰ C. double bonds (also in the presence of CN groups!) With NaBH ₄ or tributyltin hydride in methanol are hydrogenated; For example, from 1-Cyancyclohexenderivaten arise the corresponding cyclohexane derivatives.

Esters of formula I can also be obtained by esterification of corresponding carboxylic acids (or their reactive derivatives) with alcohols or phenols (or their reactive derivatives).

Particularly suitable as reactive derivatives of said carboxylic acids are the acid halides, especially the chlorides and bromides, and also the anhydrides, eg. As well as mixed anhydrides, azides or esters, especially alkyl esters with 1-4 carbon atoms in the alkyl group.

Suitable reactive derivatives of said alcohols or phenols are, in particular, the corresponding metal alcoholates or phenolates, preferably an alkali metal such as Na or K.

The esterification is advantageously carried out in the presence of an inert solvent. Especially suitable are ethers such as diethyl ether, di-n-butyl ether, THF, dioxane or anisole, ketones such as acetone, butanone or cyclohexanone, amides such as DMF or phosphoric acid hexamethyltriamide, hydrocarbons such as benzene, toluene or xylene, halogenated hydrocarbons such as carbon tetrachloride or tetrachlorethylene and sulfoxides such as dimethyl sulfoxide or sulfolane. Water-immiscible solvents can also be advantageously used to azeotropically distill off the water formed in the esterification. Occasionally, an excess of an organic base, for example pyridine, quinoline or triethylamine can be used as a solvent for the esterification. The esterification can also be carried out in the absence of a solvent, for example by simply heating the components in the presence of sodium acetate. The reaction temperature is usually between -50 ° C and +250 ⁰ C, preferably between -20 ⁰ C and +80 ⁰ C. At these temperatures, the esterification reactions are generally complete after 15 minutes to 48 hours.

In particular, the reaction conditions for the esterification depend largely on the nature of the starting materials used. Thus, a free carboxylic acid is reacted with a free alcohol or phenol usually in the presence of a strong acid, for example a mineral acid such as hydrochloric acid or sulfuric acid. A preferred reaction method is the reaction of an acid anhydride or, in particular, an acid chloride with an alcohol, preferably in a basic medium, using as bases in particular alkali metal hydroxides such as sodium or potassium hydroxide, alkali metal carbonates or bicarbonates such as sodium carbonate, potassium carbonate or potassium bicarbonate, alkali metal acetates such as sodium or potassium acetate, Alkaline earth metal hydroxides such as calcium hydroxide or organic bases such as triethylamine, pyridine, lutidine, collidine or quinoline are of importance. Another preferred embodiment of the esterification is that the alcohol or phenol is first converted into the sodium or potassium alcoholate or phenolate, z. B. by treatment with ethanolic sodium or potassium hydroxide solution, this isolated and suspended together with sodium bicarbonate or potassium carbonate with stirring in acetone or diethyl ether and this suspension with a solution of the acid chloride or anhydride in diethyl ether, acetone or DMF, advantageously at temperatures between about 25 ° Cund + 2O ⁰ C. Dioxane derivatives or dithiane derivatives of the formula I are useful by reaction of a corresponding aldehyde (or one of its reactive derivatives) with a corresponding V, 3-diol or a corresponding 1,3-dithiol (or one of their reactive derivatives), preferably in the presence of an inert solvent such as benzene or toluene and / or a catalyst, e.g. As a strong acid such as sulfuric acid, benzene or p-toluenesulfonic acid, at temperatures between 20 ⁰ C and about 150 ⁰ C, preferably between 8O ⁰ C and 12O ⁰ C. Suitable reactive derivatives of the starting materials are primarily acetals.

The mentioned aldehydes and 1,3-diols or 1,3-dithiols and their reactive derivatives are known in some cases, all of which can be prepared without difficulty by standard methods of organic chemistry from compounds known from the literature. For example, the aldehydes are obtainable by oxidation of corresponding alcohols or by reduction of corresponding carboxylic acids or their derivatives, the diols by reduction of corresponding diesters and the dithiols by reacting corresponding dihalides with NaSH.

For the preparation of nitriles of the formula I, corresponding acid amides, for. For example, those in which instead of the radical X is a CONH ₂ group are dehydrated. The amides are z. B. from corresponding esters or acid halides by reaction with ammonia available. Dehydrating agents are, for example, inorganic acid chlorides such as SOCI _2, PCI _3, PCI _6, POCl _3, SO ₂ Cl _2, COCl _2, P ₂ S _5, AICI ₃ (z. B. as a double compounds are further P ₂ O ₅ with NaCl), aromatic sulfonic acids and sulfonic acid halides. It can operate in the presence or absence of an inert solvent at temperatures between about 0 ⁰ C and 150 ° C; suitable solvents are, for example, bases such as pyridine or triethylamine, aromatic hydrocarbons such as benzene, toluene or xylene or amides such as DMF.

For the preparation of the above nitriles of the formula I can also corresponding acid halides, preferably the chlorides, with sulfamide, preferably in an inert solvent such as tetramethylene sulfone, at temperatures between about 80 ° C and 150 °, preferably at 120 ⁰ C. After the usual Work-up can be directly isolate the nitriles. Ethers of the formula I are obtainable by etherification of corresponding hydroxy compounds, preferably corresponding phenols, wherein the hydroxy compound is first expediently converted into a corresponding metal derivative, eg. B. by treatment with NaH, NaNH ₂ , NaOH, KOH, Na ₂ CO ₃ or K ₂ CO _{3 is converted} into the corresponding alkali metal or alkali metal phenolate. This can then be reacted with the appropriate alkyl halide, sulfonate or dialkyl sulfate, suitably in an inert solvent such as acetone, 1,2-dimethoxyethane, DMF or dimethyl sulfoxide or an excess of aqueous or aqueous-alcoholic NaOH or KOH at temperatures between about 20 ⁰ C and 100 ° C. Cyclohexanonderivate of formula I are further acid-catalyzed rearrangements of the corresponding epoxides by 'literature known methods, eg. B. by treatment with BF ₃ etherate accessible. The epoxides are obtainable by epoxidation of the corresponding cyclohexane derivatives by standard methods.

For the preparation of nitriles of the formula I, corresponding chlorine or bromine compounds of the formula I can be reacted with a cyanide, expediently with a metal cyanide such as NaCN, KCN or Cu ₂ (CN) ₂ , z. B. in the presence of pyridine in an inert solvent such as DMF or N-methylpyrrolidone at temperatures between 20 ⁰ C and 200 ⁰ C. The optically active compounds of formula I is obtained by the use of appropriate optically active starting materials and / or by separation of the optical Antipodes by chromatography according to known methods.

The phases according to the invention preferably contain at least three, in particular at least five compounds of the formula. Particular preference is given to chiral tilted smectic liquid-crystalline phases according to the invention, the achiral bismuth mixture containing, in addition to compounds of the formula I, at least one other component with a negative or small positive dielectric anisotropy. These further component (s) of the chiral base mixture may constitute 1 to 50%, preferably 10 to 25%, of the base mixture. Compounds of the subformulae Va to Vp are suitable as further components with an amount of small positive or negative dielectric anisotropy:

(F) n

20 R-H # -C0X "- <O> -R

R - <H * C0X "- <H» R

Va

Vb Vc

R ⁴ - / θ \ - / o - - COX "- 25 R ⁴ - / o - - COX" - / θ \ - / θ \ -

Vd Ve Vf

R ⁴ - / H V-COX- / O \ - / 0 \ -R ~

R - <H®-COO- <H

Vg Vh Vi

(F) n

R-

^l - / o> - <^ o \ -cox "- / o \ -r ⁵ vk

(F) n

R ⁴ - / o) - / o \ -X "CO- / o-R ⁵ Vl

I ⁵ Vm

(F) n

T.5

Vn

R ⁴ - / o> - / o \ -COX "-

-X ¹¹ CO-ZhV-

From

R ⁵ vp

R ⁴ and R ⁵ are each preferably straight-chain alkyl, alkoxy, alkanoyloxy or alkoxycarbonyl having in each case 3 to 12 C atoms.

X "is 0 and S, preferably O. η is O or 1.

Particularly preferred are the compounds of sub-formulas Va, Vb, Vd and Vf, wherein R ⁴ and R ⁵ each represent straight-chain alkyl or alkoxy each having 5 to 10 C atoms.

The compounds of sub-formulas Vc, Vh and Vi are useful as melting point depressant additives and are normally added to the base mixtures at not more than 5%, preferably 1 to 3%. R ⁴ and R ⁵ in the compounds of the sub-formulas Vc, V h and Vi are preferably straight-chain alkyl having 2 to 7, preferably 3 to 5, C atoms. Another class of compounds which is suitable for lowering the melting point in the phases according to the invention is that of

Formula _ ....: -

J ^ t ^^^^ t

O> -OOC-R ⁵

wherein R ⁴ and R ^{5 have} the preferred meaning given for Vc, Vh and Vi.

As further components with negative dielectric anisotropy are further compounds containing the

Structure element M, N or O.

CN CN Cl

\ JT -CH ₂ -CH- -CH-

M N

Preferred compounds of this type corresponding to the formulas VIb and VIc:

² I VIb CN R'-Q ³ -Q ⁴ -R ''' VIc

R 'and R "are each preferably straight-chain alkyl or alkoxy groups each having 2 to 1OC atoms, and Q ¹ and Q ^{2 are} each 1,4-phenylene, trans-1,4-cyclohexylene, 4,4'-biphenylyl , 4- (trans-4-cyclohexyl) -phenyl, trans / trans-4,4'-bicyclohexyl or one of the groups Q ¹ and Q ² also a single bond.

Q ³ and Q ^{4 are} each 1,4-phenylene, 4,4'-biphenylyl or trans-1,4-cyclohexylene. One of the groups Q ³ and Q ⁴ may also denote 1,4-phenylenes in which at least one CH group has been replaced by N. R '"is an optically active residue with a

Cl CN

I. I

asymmetric carbon of structure " ¹ CH - or - CH -. Particularly preferred compounds of formula VIc are those of formula VIc ':

¹ "many"

where A is 1,4-phenylene or trans-1,4-cyclohexylene and η is O or 1.

The compounds of formula I are also useful as components of nematic liquid-crystalline phases, e.g. to avoid reverse twist.

These liquid-crystalline phases according to the invention consist of 2 to 25, preferably 3 to 15 components, including at least one compound of the formula I. The other constituents are preferably selected from the nematic or nematogenic substances, in particular the known substances, from the classes of azoxybenzenes, benzylideneanilines, Biphenyls, terphenyls, phenyl or cyclohexyl benzoates, cyclohexane-carboxylic acid phenyl or cyclohexyl esters, phenylcyclohexanes, cyclohexylbiphenyls, cyclohexylcyclohexanes, cyclohexylnaphthalenes, 1,4-biscyclohexylbenzenes, 4,4'-biscyclohexylbiphenyls, phenyl- or cyclohexylpyrimidines, phenyl- or cyclohexylpyridazines as well as their N-oxides, phenyl- or cyclohexyldioxanes, phenyl- or cyclohexyl-1,3-dithiane, 1,2-diphenylethane, 1,2-dicyclohexylethane, 1-phenyl-2-cyclohexylethane, optionally halogenated stilbenes, benzylphenyl ethers, tolans and substituted cinnamic acids.

The most important compounds which can be considered as constituents of such liquid-crystalline phases can be characterized by the formula I '

R'-L-G-E-R "I '

wherein L and E are each a carbo- or heterocyclic ring system of the 1,4-disubstituted benzene and cyclohexane rings, 4,4'-disubstituted biphenyl, phenylcyclohexane and cyclohexylcyclohexane systems, 2,5-disubstituted pyrimidine and T, 3 Dioxane rings, 2,6-disubstituted naphthalene, di- and tetrahydronaphthalene, quinazoline and tetrahydroquinazoline,

G -CH = CH- -N (O) = N-

-CH = CY- -CH = N (O) -

-U ⁼⁼ \ -r - - \ s Π 2 - ^ * Π 2-

-CO-O- CH ₂ -O-

-CO-S- -CH ₂ -S-

-CH = N- -COO-Phe-COO-

or a C-C single bond, Y is halogen, preferably chlorine, or-CN, and

R 'and R "is alkyl, alkoxy, alkanoyloxy, alkoxycarbonyl or alkoxycarbonyloxy having up to 18, preferably up to 8 carbon atoms, or one of these radicals is also CN, NC, NO ₂ , CF ₃ , F, Cl or Br.

In most of these compounds, R 'and R "are different from each other, one of these radicals usually being an alkyl or alkoxy group, but other variants of the substituents provided are also common Many of these substances or mixtures thereof are commercially available The phases according to the invention contain from about 0.1 to 99, preferably from 10 to 95,% of one or more compounds of the formula ## STR8 ## Further preferred are liquid-crystalline phases according to the invention containing from 0.1 to 40, preferably 0.5 to 5%. 30% of one or more compounds of the formula I.

The preparation of the phases according to the invention takes place in itself per se. In general, the components are dissolved in each other, useful at elevated temperature.

By means of suitable additives, the liquid-crystalline phases according to the invention can be modified in such a way that they can be used in all hitherto known types of liquid-crystal display elements.

Such additives are known in the art and described in detail in the literature. For example, conductive salts, preferably ethyldimethyldodecylammonium 4-hexyloxybenzoate, tetrabutylammonium tetraphenylboranate or complex salts of crown ethers (cf., for example, Haller, J et al., Mol. Cryst. Liq. Cryst., Volume 24, pages 249-258 [cf. 1973]) to improve the conductivity, pleoch roitische dyes for the preparation of colored guest host systems or substances for changing the dielectric anisotropy, the viscosity and / or the orientation of the nematic phases are added. Such substances are e.g. in DE-OS 2209127, 2240864, 2321 632, 2338281, 2450088, 2637430, 2853728 and 2902177.

-IU- ΔΌ I ÖIKS

embodiments

The following examples are intended to illustrate the invention without limiting it. Mp = melting point, bp = clearing point. Above and below, percentages are by weight; All temperatures are in degrees Celsius. "Working up" means adding water, extracting with methylene chloride, separating, drying the organic phase, evaporating and purifying the product by crystallisation and / or chromatography.

K: crystalline solid state, S: smectic phase (the index indicates the phase type), N: nematic state, Ch: cholesteric phase, I: isotropic phase. The number between two symbols indicates the transformation temperature in degrees Celsius.

Example 1:

a) To a solution of 36 g (+ (- S-methylcyclohexanone in 630 ml of THF is added 105 g 2,4,6-

Triisopropylbenzenesulfonic acid hydrazide and stirred for 2 hours at room temperature. Then 450 ml of methanol and 65 g of KCN are added and heated to reflux for 2 hours. After customary workup and subsequent fractional distillation to obtain a mixture of diastereomeric 3-Methylcyclohexancarbonitrile.

b) To a solution of 17 g of S-methylcyclohexanecarbonitrile in 140 ml of THF is added at -78 ⁰ C, a lithium diisopropylamide solution (prepared from 14OmITHF, 16g diisopropylamine and 100ml of 1.6 molar butyllithium solution in hexane), after 2 hours 25g diethyl carbonate and stir for another hour. After warming to room temperature and pouring to 300 ml of ice water, it is neutralized with dil. Hydrochloric acid. After customary work-up and distillation to obtain a mixture of diastereomeric 3-methyl-i-cyano-cyclohexanecarboxylic acid ethyl ester.

This ester is saponified by heating with ethanolic potassium hydroxide. After neutralization, extraction with methyl tert-butyl ether and distilling off the solvent, the mixture of diastereomeric 1-cyano-3-methylcyclohexancarbonsäuren.

c) To a mixture of 16 g of i-cyano-3-methyl-cyclohexanecarboxylic acid, 25 g of 4'-hexyl-biphenylol-4,1,2g 4-diethylaminopyridine and 200 ml of methylene chloride is added at room temperature, a solution of 23 g of dicyclohexylcarbodiimide in 50 ml CH ₂ Cl ₂ and stirred for 2 hours. After customary work-up and separation by column chromatography (silica gel / toluene), the pure product obtained by recrystallization is 4'-hexylbiphenyl-4-yl-1-cyano-3-methylcyclohexanecarboxylate, m.p. 51 ° C, [α] g ° = +2.2 "C.

Analog are produced:

4'-Ethylbiphenyl-4-yl-1-cyano-3-methylcyclohexanecarboxylate 4'-Propylbiphenyl-4-yl-1-cyano-3-methylcyclohexanecarboxylate 4'-butylbiphenyl-4-yl-1-cyano-3-methylcyclohexanecarboxylate 4 ' -Phenylbiphenyl-4-yl-1-cyano-3-methylcyclohexanecarboxylate 4'-Heptylbiphenyl-4-yl-1-cyano-3-methylcyclohexanecarboxylate 4'-Ethoxy-biphenyl-4-yl-1-cyano-3-methylcyclohexanecarboxylate 4'-propoxybiphenyl 4-yl-1-cyano-3-methylcyclohexanecarboxylate 4'-butoxybiphenyl-4-yl-1-cyano-3-methylcyclohexanecarboxylate 4'-pentoxybiphenyl-4-yl-1-cyano-3-methylcyclohexanecarboxylate ^ '- hexoxybiphenyl ^ - yl-i-cyano-S-methylcyclohexanecarboxylate 4'-Heptoxybiphenyl-4-yl-1-cyano-3-methylcyclohexanecarboxylate 4'-ethylbiphenyl-4-yl-1-cyano-3-ethylcyclohexanecarboxylate 4'-propylbiphenyl-4-yl 1-cyano-3-ethylcyclohexanecarboxylate 4'-butylbiphenyl-4-yl-1-cyano-3-ethylcyclohexanecarboxylate 4'-pentylbiphenyl-4-yl-1-cyano-3-ethylcyclohexanecarboxylate 4'-hexylbiphenyl-4-yl-1 cyan-3-ethylcyclohexanecarboxylate 4'-Heptylbiphenyl-4-yl-1-cyano-3-ethylcyclohexanecarboxylate 4'-Eth oxybiphenyl-4-yl-1-cyano-3-ethylcyclohexanecarboxylate 4'-propoxybiphenyl-4-yl-1-cyano-3-ethylcyclohexanecarboxylate 4'-butoxybiphenyl-4-yl-1-cyano-3-ethylcyclohexanecarboxylate 4'-pentoxybiphenyl 4-yl-1-cyano-3-ethylcyclohexanecarboxylate 4'-Hexoxybiphenyl-4-yl-1-cyano-3-ethylcyclohexanecarboxylate 4'-Heptoxybiphenyl-4-yl-1-cyano-3-ethylcyclohexanecarboxylate 4'-ethylbiphenyl-4- yl-1-cyano-3-chlorocyclohexanecarboxylate 4'-propylbiphenyl-4-yl-1-cyano-3-chlorocyclohexanecarboxylate 4'-butylbiphenyl-4-yl-1-cyano-3-chlorocyclohexanecarboxylate 4'-pentylbiphenyl-4-yl 1-cyano-3-chlorocyclohexanecarboxylate 4'-hexylbiphenyl-4-yl-1-cyano-3-chlorocyclohexanecarboxylate 4'-Heptylbiphenyl-4-yl-1-cyano-3-chlorocyclohexanecarboxylate 4'-ethoxybiphenyl-4-yl-1 cyano-3-chlorocyclohexanecarboxylate 4'-Propoxy-biphenyl-4-yl-1-cyano-3-chloro-cyclohexanecarboxylate 4'-butoxy-biphenyl-4-yl-1-cyano-3-chloro-cyclohexanecarboxylate 4'-pentoxy-biphenyl-4-yl-1-cyano 3-Chlorocyclohexanecarboxylate 4'-Hexoxy-biphenyl-4-yl-1-cyano-3-chlorocyclohexanecarboxylate 4'-heptoxybiphenyl l-4-yl-1-cyano-3-chlorcyclohexancarboxylat.

Example 2:

To a mixture of 3.1 g of S-methylcyclohexanecarbonitrile and 30 ml of THF at -78 ° C is added a solution of lithium diisopropylamide (prepared from 3.3 g of diisopropylamine, 30 ml of THF and 19 ml of 1.6 molar butyllithium solution in hexane) and then a solution of 9.7 g of 1-bromo-2- (4'-pentylbiphenyl-4-yl) ethane in 30 ml of THF. The work-up is carried out analogously to Example 1 to give id-cyano-S-methylcyclohexyO ^ - ^ '- pentylbiphenyl ^ -yDethan, mp. 73 ° C, [α] § ⁰ = +1.1 ° C.

Analog are produced:

i-li-cyano-S-methylcyclohexyl-K'-ethyl-biphenyl-1-y-ethane 1- (1-cyano-3-methylcyclohexyl) -2- (4'-propyl-biphenyl-4-yl) -ethane 1- (1) Cyano-3-methylcyclohexyl) -2- (4'-butyl-biphenyl-4-yl) ethane 1- (1-cyano-3-methylcyclohexyl) -2- (4'-hexyl-biphenyl-4-yl) -ethane 1- (1 Cyano-3-methylcyclohexyl) -2- (4'-heptylbiphenyl-4-yl) ethane 1- (1-cyano-3-methylcyclohexyl) -2- (4'-ethoxybiphenyl-4-yl) ethane 1- ( 1-cyano-3-methylcyclohexyl) -2- (4'-propoxybiphenyl-4-yl) ethane 1- (1-cyano-3-methylcyclohexyl) -2- (4'-butoxybiphenyl-4-yl) ethane 1- ( 1-cyano-3-methylcyclohexyl) -2- (4'-pentoxybiphenyl-4-yl) ethane 1- (1-cyano-3-methylcyclohexyl) -2- (4'-hexoxy-biphenyl-4-yl) -ethane 1- ( 1-cyano-3-methylcyclohexyl) -2- (4'-heptoxybiphenyl-4-yl) ethane 1- (1-cyano-3-ethylcyclohexyl) -2- (4'-ethylbiphenyl-4-yl) ethane 1- ( 1-cyano-3-ethylcyclohexyl) -2- (4'-propylbiphenyl-4-yl) ethane 1- (1-cyano-3-ethylcyclohexyl) -2- (4'-butylbiphenyl-4-yl) ethane 1- ( 1-cyano-3-ethylcyclohexyl) -2- (4'-pentylbiphenyl-4-yl) ethane 1- (1-cyano-3-ethylcyclohexyl) -2- (4'-hexylbiphenyl-4-yl) ethane T- ( 1-cyano-3-ethyl cyclohexyl) -2- (4'-heptylbiphenyl-4-yl) ethane 1- (1-cyano-3-ethylcyclohexyl) -2- (4'-ethoxy-biphenyl-4-yl) -ethane 1- (1-cyano-3-yl) ethylcyclohexyl) -2- (4'-propoxybiphenyl-4-yl) ethane 1- {1-cyano-3-ethylcyclohexyl) -2- (4'-butoxybiphenyl-4-yl) ethane 1- (1-cyano-3-yl) ethylcyclohexyl) -2- (4'-pentoxybiphenyl-4-yl) ethane 1- (1-cyano-3-ethylcyclohexyl) -2- (4'-hexoxy-biphenyl-4-yl) ethane 1- (1-cyano-3-yl) ethylcyciohexyl) -2- (4'-heptoxybiphenyl-4-yl) ethane.

Example 3:

Analogously to Example 3, 1- (1-cyano-3-methylcyclohexyl) -2- [4- (4-pentylcyclohexyl) phenyl-1-yl] -ethane, mp. 92 ⁰ C, by reacting 1-bromo-2 - [4- (4-pentylcyclohexyl) phenyl-1-yl] -ethane with S-IV-ethylcyclohexanecarbonitrile.

Analog are produced:

1M l -cyan-3-methylcyclohexyl) -2- [4- (4-ethylcyclohexyl) phenyl-1-yl] ethane 1 - (1-cyano-3-methylcyclohexyl) -2- [4- (4-propylcyclohexyl) phenyl 1-yl] ethane T- (1-cyano-3-methylcyclohexyl) -2- [4- (4-butylcyclohexyl) phenyl-1-yl] ethane 1- (1-cyano-3-methylcyclohexyl) -2- [ 4- (4-hexylcyclohexyl) phenyl-1-yl] ethane 1- (1-cyano-3-methylcyclohexyl) -2- [4- (4-heptylcyclohexyl) phenyl-1-yl] ethane.

Example A:

A liquid crystalline phase consisting of 24% of 4- (5-heptylpyrimidin-2-yl) phenyl (p-pentylbenzyl) ether 24% of 4- (5-heptylpyrimidin-2-yl) phenyl (p-heptylbenzyl) ether 18% trans-4-heptylcyclohexanecarboxylic acid (p-octoxyphenyl ester) ^ / otrans ^ -heptylcyclohexanecarboxylic acid-fp-nonoxyphenyl ester) TO ^ trans ^ -pentylcyclohexanecarboxylic acid fp-hexoxyphenylester) 9% 1-hydroxy-1- [r-1-cyano- Cis-4- (trans-4-pentylcyclohexyl) cyclohexyl] -3-methylcyclohexane has K 0 ⁰ C Sc * 45 ° C Sa 54 ^o C Ch 61.5 ⁰ C I.

Example B:

A liquid-crystalline phase consisting of

3% 2-p-hexyloxyphenyl-5-heptylpyrimidine,

3% 2-p-heptyloxyphenyl-5-heptylpyrimidine,

3% 2-p-octyloxyphenyl-5-heptylpyrimidine,

3% 2-p-Nonyloxyphenyl-5-heptylpyrimidine,

7% 2-p-hexyloxyphenyl-5-nonylpyrimidine,

27% 2-p-Nonyloxyphenyl-5-nonylpyrimidine,

26% of r-1-cyano-1-butyl-cis-4- (4'-octyloxy-biphenyl-4-yl) -cyclohexane,

13% of r-1-cyano-1-hexyl-cis-4- (4'-heptyl-biphenyl-4-yl) -cyclohexane,

5% r-1-cyano-cis-1- (4-pentylcyclohexyl) -trans-4- (4-pentylcyclohexyl) cyclohexane and

10% 4'-hexylbiphenyl-4-yl-1-cyano-3-methylcyclohexanecarboxylate

K -9 ⁰ C Sg 61 ⁰ C Sa 69 ⁰ C Ch 81 ° CI and a spontaneous polarization P ₃ = 7 nC / cm ² .

Example C:

A liquid crystalline phase consisting of 10% r-1-cyano-1-pentyl-cis-4- (4'-butyl-biphenyl-4-yl) -cyclohexane, 43% r-1-cyano-1-pentyl-cis-4 (4'-octylbiphenyl-4-yl) cyclohexane, 42% r-1-cyano-1-butyl-cis-4- (4'-octyloxybiphenyl-4-yl) cyclohexane and

5% 1-Hydroxy-1- [r-1-cyano-cis-4- (trans-4-pentylcyclohexyl) cyclohexyl] -3-methylcyclohexane has K 30 ⁰ C sg 65 ⁰ CS _A 90 ° C Ch 125 I and P _s = 1 nC / cm ² .

Example D:

A liquid crystalline phase consisting of 2% 2-p-hexyloxyphenyl-5-heptylpyrimidine, 7% 2-p-hexyloxyphenyl-5-nonylpyrimidine, 2% 2-p-heptyloxyphenyl-5-heptylpyrimidine, 2% 2-p-octyloxyphenyl-5 -heptylpyrimidine, 25% 2-p-Nonyloxyphenyl-5-nonylpyrimidine,

2% 2-p-Nonyloxyphenyl-5-heptylpyrimidine, 30% r-1-cyano-1-octyl-cis-4- (4'-octyloxybiphenyl-4-yl) cyclohexane, 5% r-1-cyano-1 heptyl-cis-4- (4'-hexylbiphenyl-4-yl) cyclohexane, 14% optically active r-1-cyano-1- (2-methylbutyl) -cis-4- (4'-heptyloxybiphenyl-4-yl) cyclohexane and

11% optically active 1- (1-cyano-3-methylcyclohexyl) -2- (4'-pentylbiphenyl-4-yl) -ethane shows K <-30 ⁰ C SJ 65 S _A 71 Ch 87 I and a spontaneous polarization P _s = +32.7 nC / cm ² .

Claims (1)

claims: 1. chiral tutted smectic liquid-crystalline phase having at least two liquid-crystalline components, characterized in that it comprises at least one optically active compound of the formula I. R ¹ -A ¹ -Z ¹ -A ² -R ² . R ¹ -A ¹ -Z ¹ R'-AZ ¹ , R ¹ -A ⁴ -AZ ¹ or R ¹ -AA ⁴ -Z ¹ R ¹ and R ^{2 are} each H, an alkyl group having 1-12 C atoms, wherein also one or two are not adjacent CH ₂ groups replaced by O atoms and / or CO groups and / or -CO-O groups and / or -CH = CH groups and / or -CH-halogen and / or -CHCN groups F, Cl, Br, CN or R ³ -A ³ -Z ² , A in the 2-, 3-, 5- or 6-position by hydroxy, halogen, nitrile and / or a Alkyl group or a fluorinated alkyl group each having 1-10 C atoms, wherein also one or two non-adjacent CH ₂ groups by -O -, - CO -, - O-CO-, -CO-O and / or -CH = CH-substituted, substituted 1,4-cyclohexylene or 1,4-cyclohexylene group, wherein also one or _two non-adjacent CH ₂ groups may be replaced by -O- and / or-S-, which may also be substituted in the 1 and / or 4 position by hydroxyl, halogen, nitrile and / or an alkyl group or a fluorinated alkyl group each having 1-4 C atoms, in which also one or _two non-adjacent CH ₂ groups is represented by -O-, -CO-, May each be unsubstituted or substituted by one or two F and / or Cl atoms and / or CHs groups and / or CN groups 1,4-phenylene, in which also one or two CH groups may be replaced by N, 1,4-cyclohexylene, wherein also one or _two non-adjacent CH ₂ groups may be replaced by O atoms and / or S atoms, Piper idin-1,4-diyl, 1,4-bicyclo (2,2,2) octylene, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl groups . j _ewe j | _s _C0-0 -, - 0-C0 -, - CH ₂ CH ₂ -, OCH ₂ -, - CH ₂ O- or a single bond, H, an alkyl group of 1-12, wherein also one or _two non-adjacent CH ₂ - Groups may be replaced by 0-atoms and / or -CO-groups and / or -CO-0-groups and / or -CH = CH groups, F, Cl, Br or CN means contains.
2. Use of the compounds of the formula I according to claim 1, characterized in that they are used as a liquid-crystalline phase. A ² , A ³ and A ⁴