DE3812191A1 - CHIRAL OR ACHIRREL RING LINKS - Google Patents

Abstract

Chiral or achiral cyclic compounds of formula R<1>-(A<1>-Z<1>)m-A<2>-Q<1>-C*R DEG CF3-X, wherein R<1> denotes alkyl or perfluoralkyl which can be interrupted by O- and/or -CO- and/or -CO-O- and/or -CH=CH- and/or -CH halogen- and/or -CHCN- and/or -O-CO-CH halogen- and/or -CO-O-CHCN-, F, Cl, Br, CN or -Q<1>-C*R DEG CF3-X; A<1> and A<2> denote unsubstituted 1,4-phenylene or 1,4-phenylene substituted with one or two F and/or CH3 and/or CN, wherein one or two CH groups can also be replaced by 1,4-cyclohexane, wherein one or two non-neighbouring CH2 groups can be replaced by O and/or S, 1-(4-) cyano-1,4-cyclohexylene, piperidin-1,4-diyl, 1,4-bicyclo(2,2,2)-octylen, 1,3,4-thiadiazol-2,5-diyl naphthalen-2,6-diyl, decahydronaphthalen-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl; Z<1> denotes -CO-O-, -O-CO-, -CH2CH2-, -OCH2-, -CH2O, -C=C-, or a single bond; X denotes H or CH3; C* denotes a carbon atom bonded to four different substituents; or m = 1, 2 or 3; Q<1> denotes -O-, -O-CO-, -CO-O- or a single bond, and in the case in which at least one of the rings A<1> and A<2> is replaced by 1,4-phenylene substituted by one or two F atoms or A<1> is unsubstituted 1,4-phenylene, wherein one CH group is replaced by N, also denotes -O-(CH2)n-, -O-CO-(CH2)n- or -CO-O-(CH2)n, where n = 1, 2, 3 or 4; R DEG is alkyl different from X, or, if Q is a single bond, alkoxy or alkanoyloxy. Said compounds can be used as chirally oriented smectic liquid crystal phases.

Description

The invention relates to chiral or achiral ring compounds of the formula (I)

R¹- (A¹-Z¹) _m -A 2 -Q¹-C * R ° CF₃-X (I)

wherein
R¹ is an alkyl or perfluoroalkyl group each having 1-12 C atoms, wherein one or two non-adjacent CH₂- or CF₂ groups by O atoms and / or -CO groups and / or -CO-O- Groups and / or -CH = CH groups and / or -CHHalogen and / or -CHCN groups and / or -O-CO-CHHalogen and / or -CO-O-CHCN groups may be replaced, H, F, Cl, Br, CN, or -Q¹-C * R ° CF₃-X, where Q¹, R ° and X have the meaning given,
A¹ and A² are each independently of one another unsubstituted or substituted by one or two F and / or CH₃ 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 one or two non-adjacent CH₂ groups may be replaced by O atoms and / or S atoms, 1- (4-) cyano-1,4-cyclohexylene, piperidine-1,4-diyl, 1 , 4-bicyclo (2,2,2) octylene, 1,3,4-thiadiazole-2,5-diyl, naphthalene-2,6-diyl-decahydronaphthalene-2,6-diyl or 1,2,3 , 4-tetrahydronaphthalene-2,6-diyl,
Each Z¹ is -CO-C-, -O-CO-, -CH₂CH₂-, -OCH₂-, -CH₂O-, -C≡C- or a single bond,
X is H or CH₃,
C * is a carbon atom linked to four different substituents,
m 1, 2 or 3
Q¹ is -O-, -O-CO-, -CO-O-, or a single bond, and
R ° is an alkyl group having 1 to 10 C atoms other than X, or, if Q is a single bond, also an alkoxy or alkanoyloxy group each having 1 to 10 C atoms
with the proviso that X is CH₃ when Q¹ is -O-CO-.

The compounds of the formula I can be used as similar in DE-OS 35 15 373 described compounds as components chiral tilted smectic liquid crystalline Phases are used.  

Chiral tilted smectic liquid crystalline phases with ferroelectric properties can be produced Be prepared by mixing basic mixtures with one or more tilted smectic phases with a suitable chiral dopant (L.A. Beresnev et al., Mol. Cryst. Liq. Cryst. 89, 327 (1982); H. R. Brand et al., J. Physique 44, (Lett.), L-771 (1983). Such Phases can act as dielectrics for fast switching Displays are used on the one of Clark and Lagerwall described principle of SSFLC technology (N.A. Clark and S. T. Lagerwall, Appl. Phys. Lett. 899 (1980); USP 43 67 924) based on the ferroelectric Properties of the chirally tilted phase based. In this phase are the elongated Molecules are arranged in layers, with the molecules have a tilt angle to the layer normal. At the Progression from layer to layer changes Tilt direction at a small angle with respect to a perpendicular to the layers standing axis, so that a Helix structure is formed. In displays that are on the Principle of SSFLC technology are smectic Layers perpendicular to the plates of the cell arranged. The helical arrangement of the Tiltrichtungen The molecules are separated by a very small distance Plates (about 1-2 μm) suppressed. This will be the Longitudinal axes of molecules forced to move in a plane parallel to the plates of the cell, thereby Two excellent tilt orientations arise. By Applying a suitable alternating electric field can in the liquid crystal having a spontaneous polarization Phase between these two states. and be switched. This switching process is much faster than conventional twisted Cells (TN-LCD's) based on nematic liquid crystals based.  

A big drawback to many applications currently available materials with chiral tilted smectic Phases (such as Sc *) are their relatively high optical anisotropy caused by relatively high viscosity values conditional not sufficiently short switching times, as well as that the dielectric anisotropy values greater than zero or, if negative, only slightly zero has different values. Negative values of the dielectric Anisotropy is required if the required planar orientation by overlay of the control field with an AC holding field with smaller Amplitude (J. M. Geary, SID Convention, Orlando / Florida, April / May 1985, lecture 8.3).

It has now been found that the use of compounds of formula I as components of chiral tilted smectic mixtures the mentioned disadvantages substantially can diminish. The compounds of the formula I are thus as components chiral tilted smectic liquid crystalline phases excellently suitable. In particular are chemically very stable with their help chiral tilted smectic liquid crystalline phases with favorable ferroelectric phase ranges, in particular with broad Sc * phase ranges, negative or also positive dielectric anisotropy, lower optical anisotropy, favorable pitch height, lower Viscosity and for such phases high values for the spontaneous polarization and very short switching times produced. P is the spontaneous polarization in nC / cm².

With the provision of the compounds of the formula I is also quite generally the range of liquid crystalline Substances that are under different application-technical aspects for the production ferroelectric mixtures are significantly widened.  

The compounds of the formula I have a broad Scope of application. Depending on the selection of the Substituents may use these compounds as base materials serve, from which liquid crystalline phases for are composed predominantly; but it can also compounds of the formula I liquid-crystalline Added base materials from other classes of compounds be, for example, the dielectric and / or optical anisotropy and / or the spontaneous Polarization and / or the phase range and / or the Tilt angle and / or the pitch and / or the switching times to vary in such a phase. The connections of the Formula I are also suitable as intermediates for Production of other substances that are as ingredients let use liquid-crystalline phases.

The compounds of the formula I are in a pure state colorless and show favorable values of optical anisotropy on. Partially show the compounds of formula I. liquid-crystalline mesophases in one for the electro-optic use conveniently located temperature range, however, it can also be isotropic or monotropic liquid crystalline compounds of the formula I as components chiral tilted smectic phases advantageous be used. Chemical, thermal and against Light, they are very stable.

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

The invention also relates to chiral tilted smectic liquid crystalline phases containing at least one compound of formula I with at least one linked to four different substituents Carbon atom.  

The invention further such phases with a content of at least one compound of the formula I. and liquid crystal display elements, in particular electro-optical Display elements, such phases contain.

For the sake of simplicity, in the following, Ph means one 1,4-phenylene group, wherein also one or two CH groups may be replaced by N, Cy is a 1,4-cyclohexylene group, which also includes one or two non-adjacent ones CH₂ groups can be replaced by O atoms and Bi a bicyclo (2,2,2) octylene group.

Wherein the 1,4-phenylene group is represented by one or two F atoms and / or CH₃ and / or CN groups may be substituted.

Above and below, R¹, m , A¹, A², Q¹, X, R ° and Z¹ have the indicated meaning, unless expressly stated otherwise.

The compounds of the formula I accordingly comprise in particular compounds of sub-formula Ia (with two rings)

R¹-A¹-Z¹-A²-Q¹-C * R ° CF₃X (Ia)

and Ib (with three rings):

R¹- (A¹-Z¹) ₂-A²-Q¹-C * R ° CF₃X (Ib)

and Ic (with four rings):

R¹- (A¹-Z¹) ₃-A²-Q¹-C * R ° CF₃X (Ic)

Of these, those of formula Ia and Ib are particular prefers.  

The preferred compounds of formula Ia include those of sub-formulas Ia1 to Ia4:

R¹-Ph-Z¹-Ph-Q¹-C * R ° CF₃X (Ia1)

R¹-Ph-Z¹-Cy-Q¹-C * R ° CF₃X (Ia2)

R¹-Cy-Z¹-Ph-Q¹-C * R ° CF₃X (Ia3)

R¹-Cy-Z¹-Cy-Q¹-C * R ° CF₃X (Ia4)

These include those of sub-formulas Ia1 particularly preferred.

The preferred compounds of formula Ib include those of sub-formulas Ib1 to Ib9:

R¹-Ph-Z¹-Ph-Z¹-Ph-Q¹-C * R ° CF₃X (Ib1)

R¹-Ph-Z¹-Ph-Z¹-Cy-Q¹-C * R ° CF₃X (Ib2)

R¹-Cy-Z¹-Ph-Z¹-Cy-Q¹-C * R ° CF₃X (Ib3)

R¹-Ph-Z¹-Cy-Z¹-Ph-Q¹-C * R ° CF₃X (Ib4)

R¹-Ph-Z¹-Cy-Z¹-Cy-Q¹-C * R ° CF₃X (Ib5)

R¹-Cy-Z¹-Cy-Z¹-Ph-Q¹-C * R ° CF₃X (Ib6)

R¹-Cy-Z¹-Ph-Z¹-Cy-Q¹-C * R ° CF₃X (Ib7)

R¹-Cy-Z¹-Cy-Z¹-Cy-Q¹-C * R ° CF₃X (Ib8)

R¹-Cy-Z¹-Ph-Z¹-Ph-Q¹-C * R ° CF₃X (Ib9)

Particular preference is given to compounds of the formula I in which R ° is an alkyl group other than X, preferably 1 to 7 carbon atoms. Particularly preferred are hexyl, Pentyl, butyl, i-butyl, propyl, i -propyl, methyl and Ethyl, especially methyl. Q¹ is preferably -O-CO- (wherein the carbonyl carbon atom with the asymmetric carbon atom C *), -O-, -CO-O- (wherein this group via the oxygen atom with the asymmetric C-atom C * is linked) or an Ein specialized binding (-).  

In the preferred compounds of the preceding and following Formulas in which Q¹ represents a single bond is R ° an alkyl group different from X, preferably having 1 to 7 C atoms, an alkoxy or an alkanoyloxy group with preferably in each case 1 to 7 carbon atoms.

Particularly preferred alkyl groups are hexyl, pentyl, butyl, i-butyl, propyl, i-propyl, methyl and ethyl, in particular Methyl (X = H); particularly preferred alkoxy groups Hexoxy, pentoxy, i-butoxy, propoxy, i-propoxy, methoxy and ethoxy, especially methoxy; particularly preferred Alkanoyloxy groups are hexanoyloxy, pentanoyloxy, butyryloxy, Propionyloxy, acetyloxy and formyloxy, in particular Acetyloxy.

In the preferred compounds of the preceding and following Formulas may include the alkyl radicals, in which one is CH₂ group (alkoxy or oxaalkyl) replaced by an O atom may be straight or branched. Preferably they have 5, 6, 7, 8, 9 or 10 carbon atoms and Accordingly, preferably pentyl, hexyl, heptyl, octyl, Nonyl, decyl, pentoxy, hexoxy, heptoxy, octoxy, nonoxy or decoxy, and also ethyl, propyl, butyl, undecyl, Dodecyl, propoxy, ethoxy, butoxy, undecoxy, dodecoxy, 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.

A¹ and A² are preferably Cy or Ph. In the compounds In the formulas above and below, Ph is preferably a 1,4-phenylene (Phe), a one or two times by F, CN and / or CH₃ substituted 1,4-phenylene group  (PheX) a pyrimidine-2,5-diyl- (pyr), a pyridine-2,5- diyl- (Pyn), a pyrazine-3,6-diyl or a pyridazine 2,5-diyl group, particularly preferably Phe, PheX, Pyr or Pyn. Preferably, the compounds of the invention contain not more than a 1,4-phenylene group, wherein one or two CH groups are replaced by N. Cy is preferably a 1,4-cyclohexylene group. Especially preferred however, are compounds of the formula I in which one of the Groups A¹ and A² are substituted in the 1- or 4-position by CN 1,4-cyclohexylene group and the nitrile group is in axial position, d. H. the group A¹ or A² has the following configuration:

Particular preference is given to compounds of the formula I and the preceding sub-formulas, which is a grouping -Ph-Ph- included. -Ph-Ph- is preferably -Phe-Phe-, Phe-Pyr or Phe-Pyn. Particularly preferred are the groups

such as furthermore unsubstituted or one or more times through Fluorine-substituted 4,4'-biphenylyl.

Particular preference is given to compounds of the formula I. and the following sub-formulas which describe a 2,3-difluoro- Contain 1,4-phenylene group.

The groups Z¹ are each independently preferably a single bond, secondarily preferred -O-CO-, -CO-O-, -C≡C- or -CH₂CH₂ groups. In particular Preference is given to compounds of the formulas I or the sub-formulas Ib1 to Ib9 wherein a group Z¹-CH₂CH₂- and the other means -O-CO- or -CO-O-.  

X in the compounds of the preceding and following Formulas, preferably CH₃.

The preferred meaning of Q¹ is -O-, -O-CO-, -CO-O- and a single bond.

In the compounds of formula I, in which Q¹ is a single bond means, and X is a hydrogen atom, means the group adjacent to the asymmetric C atom C * A² preferably Cy.

Compounds of the preceding and following formulas branched Wing groups R¹ may be important. Branched groups of this kind usually contain no more than two chain branches. R1 is preferred a straight-chain group or a branched one Group with no more than one chain branch.

Preferred branched radicals are isopropyl, 2-butyl (= 1-methylpropyl), isobutyl (= 2-methylpropyl), tert-butyl, 2-methylbutyl, isopentyl (= 3-methylbutyl), 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 2-ethylhexyl, 5-methylhexyl, 2-propylpentyl, 6-methylheptyl, 7-Methyloctyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexoxy, 1-methylhexoxy, 1-methylheptoxy, 2-oxa 3-methylbutyl, 3-oxa-4-methylpentyl.

The radical R¹ can also be an optically active organic Be residual with an asymmetric carbon atom. Preferably is then the asymmetric carbon atom with two differently substituted C atoms, one H atom and a substituent selected from the group  Halogen (especially F, Cl or Br), alkyl or alkoxy each with 1 to 5 carbon atoms and CN linked. The optical active organic radical preferably has the formula

wherein

X 'is -CO-O-, -O-CO-, -O-CO-O-, -CO-, -O-, -S-, -CH = CH-, -CH = CH-COO- or a single bond .
Q 'alkylene having 1 to 5 carbon atoms, in which also a non-X' CH₂ group by -O-, -CO-, -O-CO-, -CO-O- or -CH = CH- be replaced can, or a single bond,
Y 'is CN, halogen, methyl or methoxy, and
R⁵ is an alkyl group other than Y having 1 to 15 carbon atoms, wherein also one or two non-adjacent CH₂ groups by -O-, -CO-, -O-CO-, -CO-O- and / or -CH = CH- can be replaced,
means.
X 'is preferably -CO-O-, -O-CO-, -CH = CH-COO- (trans) or a single bond. Particularly preferred are -CO-O - / - O-CO- or a single bond.
Q 'is preferably -CH₂-, -CH₂CH₂-, -CH₂CH₂CH₂- or a single bond, particularly preferably a single bond.
Y 'is preferably CH₃, -CN, F or Cl, particularly preferably CN or F.
R⁵ is preferably straight-chain or branched alkyl having 1 to 10, in particular having 1 to 7, carbon atoms.

Among the compounds of the formula I and Ia to Ic are those in which at least one of them is preferred radicals contained one of the preferred meanings given Has.

In the compounds of the formula I and in the preceding and following sub-formulas, - (A 1 -Z 1) _m -A 2 - is preferably a group of the following formulas 1 to 39 or their mirror image:

Groups of the formulas 1, 5, 7, 9, 10, 11, 12, 13, 14, 22 and 39 especially those of the formulas 5 and 7, are particularly preferred.

Some more preferred smaller groups of compounds of the formula I are those of the subformulae B, C, D, E, F, G, H, I and J:

R¹- (A¹) _m -A²-OOC-C * (CH₃) (CF₃) -R ° B R¹- (A¹) _m -A²-OC * (CH₃) (CF₃) -R ° C R¹- (A¹) _m -A²-C * (CH₃) (CF₃) -OCO-R ° D R¹- (A¹) _m -A²-C * (CH₃) (CF₃) -OR ° e R¹- (A¹) _m -A²-C * (CH₃) (CF₃) -R ° F R¹- (A¹) _m -A²-C * H- (CF₃) -O-CO-R ° G R¹- (A¹) _m -A²-C * H- (CF₃) -OR ° H R¹- (A¹) _m -A²-CO-OC * H- (CF₃) -R ° I R¹- (A¹) _m -A²-OC * H- (CF₃) -R ° J

wherein R¹, R °, A¹ and A² have the meaning given in formula I. m is preferably 1 or 2. - (A¹) _m -A²- is preferably

or a reflection of this Formulas. R¹ is preferably straight-chain alkyl or Alkoxy with 5 to 12 C atoms. R ° is preferably straight-chain or branched alkyl having 1 to 5 C atoms.

Those of the above formulas, which is a or more groups Dio, Dit, Pip and / or Pyr, enclose the two possible 2.5- (Dio, Dit, Pyr) or 1,4-position isomers (Pip).

The compounds of the formula I are known per se Methods prepared as in the literature (eg in the standard works such as Houben-Weyl, Methoden of Organic Chemistry, Georg-Thieme-Verlag, Stuttgart) are described, under reaction conditions, known and suitable for the reactions mentioned are. You can also of known, here unspecified variants make use.

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

Thus, the compounds of formula I or to the Production of suitable precursors can be made by a compound otherwise conforming to formula I but in place of H atoms one or more contains reducible groups and / or C-C bonds, reduced.  

As reducible groups are preferably -CH = CH groups into consideration, further z. B. free or esterified Hydroxy groups, aromatically bonded halogen atoms or Carbonyl groups. Preferred starting materials for the reduction correspond to the formula I, but can instead of -CH₂CH₂ group is a -CH = CH group and / or an Make a -CH₂ group a -CO-group and / or Place an H atom one free or one functional modified (eg in the form of its p-toluene sulphonate) OH group included.

The reduction can z. B. be carried out by catalytic Hydrogenation at temperatures between about 0 ° and about 200 ° and pressures between about 1 and 200 bar in one inert solvents, e.g. As 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 like cyclohexane. Suitable catalysts appropriate precious metals such as Pt or Pd, in the form of Oxides (eg., PtO₂, PdO), on a support (eg., Pd on Carbon, calcium carbonate or strontium carbonate) or in can be used finely divided form.

Ketones can also be prepared by the methods of Clemmensen (with Zinc, amalgamated zinc or tin and hydrochloric acid, appropriate in aqueous-alcoholic solution or in heterogeneous Phase with water / toluene at temperatures between about 80 and 120 °) or Wolff-Kishner (with hydrazine, expedient in the presence of alkali such as KOH or NaOH in one high boiling solvents at temperatures between about 100 and 200 °) to the corresponding compounds of the formula I, contain the alkyl groups and / or -CH₂CH₂ bridges, be reduced.  

Furthermore, reductions with complex hydrides are possible. For example, arylsulfonyloxy groups with LiAlH₄ be removed reductively, in particular p-toluene sulfonyloxymethyl groups are reduced to methyl groups, Suitably in an inert solvent such as diethyl ether or THF at temperatures between about 0 and 100 °. Double bonds can (even in the presence of CN groups!) With NaBH₄ or tributyltin hydride in methanol be hydrogenated; so arise z. B. from 1-Cyancyclo hexene derivatives, the corresponding Cyclohexanderivate.

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

As reactive derivatives of said carboxylic acids In particular, the acid halides are suitable, especially the chlorides and bromides, further the anhydrides, e.g. B. also mixed anhydrides, azides or esters, in particular Alkyl esters with 1-4 C atoms in the alkyl group.

As reactive derivatives of said alcohols or Phenols come in particular the corresponding metal alcoholates or phenolates, preferably an alkali metal like Na or K, into consideration.

The esterification is beneficial in the presence of a inert solvent performed. Well suited especially 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 hexame thyltriamid, hydrocarbons such as benzene, toluene or Xylene, halogenated hydrocarbons such as carbon tetrachloride or tetrachlorethylene and sulfoxides such as dimethylsulfoxide or sulfolane. Water immiscible solvents can simultaneously be beneficial to the azeotropic Distilling off the esterification formed Water can be used. Occasionally, too Excess of an organic base, eg. Pyridine, quinoline or triethylamine as a solvent for the esterification be applied. The esterification can also be in the absence a solvent, e.g. B. by simply heating of the components in the presence of sodium acetate become. The reaction temperature is usually between -50 ° and + 250 °, preferably between -20 ° and + 80 °. At these temperatures are the esterification reactions usually after 15 minutes to 48 hours completed.

Specifically, the reaction conditions for the esterification depend largely by the nature of the starting materials used from. So is a free carboxylic acid with a free alcohol or phenol usually present a strong acid, for example a mineral acid such as hydrochloric acid or sulfuric acid, reacted. A preferred Reaction is the reaction of an acid anhydride or in particular an acid chloride with a Alcohol, preferably in a basic environment, wherein especially alkali metal hydroxides such as sodium or potassium hydroxide, alkali metal carbonates or bicarbonates such as sodium carbonate, potassium carbonate or potassium hydrogen carbonate, 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 added to the sodium or potassium alcoholate or phenolate, z. B. by treatment with ethanolic sodium or potassium hydroxide, this isolated and 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 added, appropriate at temperatures between about -25 ° and + 20 °.

Dioxane derivatives or dithiane derivatives of the formula I are expediently by reaction of a corresponding aldehyde (or one of its reactive derivatives) with a corresponding 1,3-diol or a corresponding 1,3-dithiol (or one of their reactive derivatives) prepared, preferably in the presence of an inert Solvent such as benzene or toluene and / or a Catalyst, eg. As a strong acid such as sulfuric acid, Benzene or p-toluenesulfonic acid, at temperatures between 20 ° and about 150 °, preferably between 80 ° and 120 °. As reactive derivatives of the starting materials are primarily acetals.

The aldehydes mentioned and 1,3-diols or 1,3-dithiols and their reactive derivatives are known in part, All can be done without difficulty according to standard procedures of organic chemistry from the literature Connections are made. For example, the Aldehydes 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 reaction of corresponding dihalides available with NaSH.

Ethers of the formula I are corresponding by etherification Hydroxy compounds, preferably corresponding phenols, obtainable, wherein the hydroxy compound expediently first in a corresponding metal derivative, for. B. by Treat with NaH, NaNH₂, NaOH, KOH, Na₂CO₃ or K₂CO₃ in the corresponding alkali metal alcoholate or alkali metal phenolate is transferred. This can then with the appropriate Alkyl halide, sulfonate or dialkyl sulfate be implemented, 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 ° and 100 °.

The optically active ethers of formula I (wherein Q¹ = O) is obtained from the optically active carboxylic acids of formula

R¹- (A¹-Z¹) _m -A²-OC * R ° (CO₂H) -X

through implementation with sulfur tetrafluoride according to US Patent 41 87 381.

These optically active carboxylic acids can be prepared from the corresponding benzyl esters by hydrogenolytic cleavage. These benzyl esters are obtained by reacting the alcohols or phenols of the formula R 1 - (A 1 -Z 1) _m -A 2 -OH with the optically active 2-hydroxy carboxylic acid benzyl esters by the method of O. Mitsunobu, Synthesis 1981, 1.

For the preparation of nitriles of the formula I or for the preparation suitable precursors can also be appropriate Chloro or bromo compounds of the formula I or suitable precursors are reacted with a cyanide, suitable with a metal cyanide such as NaCN, KCN or Cu₂ (CN) ₂, z. In the presence of pyridine in an inert Solvents such as DMF or N-methylpyrrolidone Temperatures between 20 ° and 200 °.

The optically active compounds of the formula I are obtained through the use of appropriate optically active output materials and / or by separation of the optical antipodes by chromatography according to known methods.

Esters of formula I, wherein Q¹ is -O-CO- and the Carbonyl carbon atom directly with the asymmetric C-atom C * is linked, can easily from the corresponding optically active 2-trifluoromethyl-2-methyl carboxylic acids (X = CH₃) by esterification with mesogenic Alcohols or phenols, eg. B. the formula

R¹- (A¹-Z¹) _m -A²-OH

or be prepared with alcohols of the formula R ° -OH. The esterification can according to one of the above Methods are performed. Preferably, one operates however, the DCC indicated in the examples Method.

The optically active 2-trifluoromethylcarboxylic obtained one from the optically active dialkylated Malonsäurehalbestern according to US Patent 41 87 381 by reaction with Sulfur tetrafluoride and subsequent saponification of Ester.  

Also by reaction of the optically active dialkylated 2-cyanocarboxylic acids (prepared according to DE-OS 36 38 026) with sulfur tetrafluoride, reduction of the cyano group with z. As diisobutylaluminum hydride and subsequent oxidation Optically active 2-trifluoromethylcarboxylic acids are obtained.

The optically active or dialkylated Malonsäurehalbester can z. By F. Bjorkling et al., Tetrahedron Letters by enzymatic cleavage of the corresponding malonic acid diester z. B. be prepared with pork liver esterase.

Furthermore, it is possible the racemic Malonhalbester by racemate resolution by means of optically active bases separate. Preferred bases here are ephedrine, quinine, Threobase and dehydroabiethylamine called. A preferred Embodiment of this racemate resolution is, after that Separation of the desired diastereomer, the remaining through an intramolecular transesterification in to transfer the racement and this again a racemate resolution to undergo. (see DE-OS 35 41 450).

Esters of the formula I wherein Q¹ -CO-O- or R ° represents an alkanoyloxy group, can be readily prepared from the corresponding optically active 1-trifluoromethylalkan-1-ols by esterification with mesogenic carboxylic acids z. Example of the formula R¹- (A¹-Z¹) _m -A²-CO₂H or be prepared with carboxylic acids of the formula R ° -CO₂H. The esterification can be carried out by one of the aforementioned methods. However, preference is given to using the DCC method specified in the examples.

The optically active 1-trifluoromethylalkan-1-ols can by reduction of the corresponding trifluoromethylalkyl ketones with optically active reducing agents or enzymatically be obtained with dehydrogenases.

They can also be resolved by racemate resolution from the racemic 1-trifluoroalkan-1-ols as in Optical Resolution Procedures for Chemical Compounds, Vol. 3, Manhattan College, Riverdale, New York 10471.

Furthermore, optically active 1-trifluoroalkan-1-ols by enzymatic cleavage of the racemic 2-acetyloxy 1,1,1-trifuoralkanes with lipases according to J.T. Lin, T. Yamazaki, T. Kitazume J. Org. Chem., 52, 3211-3217 (1987) become.

The trifluoromethyl ketones required as starting materials can z. For example, E.T. McBee, O.R. Pierce, D.O. Meyer, J. Am. Chem. Soc., 77, 917 (1955) by reaction of Lithiumorganylene or Grignard reagents with trifluoroacetic acid or their derivatives.

The racemic 1-trifluoromethylalkan-1-ols may, for. B. Kitazume et al., J. of Fluorine Chemistry, 24, 419 (1984) also by reaction of lithium organyls be obtained with trifluoroacetaldehyde.

Examples of suitable mesogenic acids are as follows listed:

The phases according to the invention contain at least one, preferably at least two compounds of the formula I. Particularly preferred are inventive chiral tilted smectic liquid crystalline phases whose achiral base mixture in addition to compounds of the formula I.  at least one other component with negative or absolute small positive dielectric anisotropy contains. The chirality is preferably partial or completely on chiral compounds of the Formula I. These phases preferably contain one or two chiral compounds of the formula I. However, they may also achiral compounds of formula I (for example in the form of a racemate), wherein then the chirality of the phase by other optically active compounds is caused. If chiral Compounds of formula I are used, are suitable in addition to the pure optical antipodes also mixtures with an enantiomeric excess. The others mentioned above Component (s) of the achiral base mixture can be 1 to 50%, preferably 10 to 25%, make the base mixture. As further components with amount smaller positive or negative dielectric anisotropy are suitable Compounds of the subformulae (Va) to Vq):

R⁴ and R⁵ are each preferably straight-chain or branched alkyl, alkoxy, alkanoyloxy or alkoxycarbonyl having in each case 3 to 12 C atoms. X "is O or S, preferably O. n is 0 or 1.

Particularly preferred are the compounds of the sub-formulas (Va), (Vb), (Vd) and (Vf), wherein R⁴ and R⁵ are each straight-chain Alkyl or alkoxy each having 5 to 10 carbon atoms means.

The compounds of sub-formulas (Vc), (Vh) and (Vi) are suitable themselves as additives to melting point depression and usually the base mixes with not more than 5%, preferably 1 to 3% added. R⁴ and R⁵ mean in the compounds of sub-formulas (Vc), (Vh) and (Vi) preferably straight-chain alkyl of 2 to 7, preferably 3 to 5, C atoms. Another to lower the melting point suitable in the phases according to the invention Link class is that of the formula

wherein R⁴ and R⁵ for (Vc), (Vh) and (Vi) specified preferred Have meaning.

As other components with negative dielectric Anisotropy are also compounds containing the structural element M, N or O.

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

R 'and R "are each preferably straight-chain Alkyl or alkoxy groups each having 2 to 10 carbon atoms. 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 Groups Q¹ and Q² also a single bond.

Q³ and Q⁴ are each 1,4-phenylene, 4,4'-biphenylyl or trans-1,4-cyclohexylene. One of the groups Q³ and Q⁴ may also be 1,4-phenylene, wherein at least one CH group is replaced by N. R "'is an optical one active residue with an asymmetric carbon atom the structure

R "'preferably has the formula

with the preferred meanings mentioned above.

Particularly preferred components with negative dielectric Anisotropy are those described in WO 86-00529 Compounds with the structural element M or N. Particularly preferred are those of formula VId  

wherein alkyl is a straight-chain or branched alkyl group preferably having 3 to 10 C atoms and R 'is the above has meaning given. Further preferred are compounds corresponding to the formula VId, wherein one or both the rings linking single bonds through a group selected from -CH₂CH₂-, -O-CO- or -CO-O- are replaced. Particularly preferred compounds of the formula VIc are those of formula VIc ':

wherein A is 1,4-phenylene or trans-1,4-cyclohexylene, Z ° is CH or N and n is 0 or 1.

The compounds of the formula I are also suitable as components nematic liquid crystalline phases, e.g. B. for Avoiding reverse twist.

These liquid crystalline phases according to the invention exist from 2 to 25, preferably 3 to 15 components, including at least one compound of the formula I. other ingredients 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-bis-cyclohexylbenzenes, 4,4'-biscyclohexylbiphenyls,  Phenyl or cyclohexylpyrimidines, phenyl or cyclo hexylpyridazines and their N-oxides, phenyl or cyclo hexyldioxanes, phenyl or cyclohexyl-1,3-dithiane, 1,2-diphenylethanes, 1,2-dicyclohexylethanes, 1-phenyl-2- cyclohexylethanes, optionally halogenated stilbenes, Benzyl phenyl ethers, tolans and substituted cinnamic acids.

The most important as constituents of such liquid-crystalline Leave phases in question characterized by the formula (I '),

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

wherein L and E are each a carbo- or heterocyclic ring system from the 1,4-disubstituted benzene and Cyclohexane rings, 4,4'-disubstituted biphenyl, Phenylcyclohexane and cyclohexylcyclohexane systems, 2,5-disubstituted pyrimidine and 1,3-dioxane rings, 2,6-disubstituted naphthalene, di- and tetrahydronaphthalene, Quinazoline and tetrahydroquinazoline formed Group, G

-CH = CH- -N (O) = N- -CH = CY- -CH = N (O) - -C≡C- -CH₂-CH₂- -CO-O- -CH₂-O- -CO-S- -CH₂-S- -CH = N- -COO-Phe-COO-

or a CC 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 also CN, NC, NO₂, CF₃, F, Cl or Br.

For most of these compounds R 'and R "are from each other different, with one of these residues usually an alkyl or alkoxy group. But others too Variants of the proposed substituents are in use. Many such substances or mixtures thereof are commercially available. All these substances are available according to methods known from the literature.

The phases according to the invention contain about 0.1 to 99, preferably 10 to 95%, of one or more compounds of the formula I. Further preferred are inventive liquid crystalline phases containing 0.1-40, preferably 0.5-30% of one or more compounds the formula I.

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

By suitable additives, the liquid-crystalline Phases according to the invention are modified so that they in all previously known types of liquid crystal display elements can be used.

Such additives are known in the art and in the Literature described in detail. For example, you can Conducting salts, preferably ethyldimethyldodecylammonium 4-hexyloxybenzoate, tetrabutylammonium tetraphenylboranate  or complex salts of crown ethers (see, for example, I. Haller et al., Mol. Cryst. Liq. Cryst. Volume 24, pages 249-258 (1973)) to improve conductivity, pleochroic Dyes for producing colored guest host Systems or substances for changing the dielectric Anisotropy, viscosity and / or orientation be added to the nematic phases.

Such substances are z. B. in DE-OS 22 09 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430, 28 53 728 and 29 02 177 described.

The following examples are intended to illustrate the invention, without limiting it. Mp = melting point, bp = clearing point. Above and below mean percentages Weight percent; All temperatures are in degrees Celsius specified. "Usual processing" means: one gives Water, extracted with methylene chloride, The organic phase is dried, evaporated and purified the product by crystallization and / or chromato graphy.

It also means:
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

To a mixture of 0.1 mol of optically active 2-methyl-2 trifluoromethyloctanoic acid (prepared from the optically active 2-methoxy-2-hexylmalonsäuremonomethylester with Sulfur tetrafluoride and subsequent saponification with Potassium hydroxide in ethanol), 0.1 mol of 4-hexyloxy-4'-hydroxy biphenyl, 150 ml of dichloromethane and 1 mmol of 4-N, N-dimethyl Aminopyridine is added to a mixture of 0.1 mol of dicyclo hexylcarbodiimide and 50 ml of dichloromethane. After 24 hours Stir at room temperature, remove the solid Ingredients and usual workup are obtained optically active 4- (2-methyl-2-trifluoromethyloctanoyloxy) -4'-hexyl oxybiphenyl.

The following optically active compounds are prepared analogously posed:

4- (2-methyl-2-trifluoromethylpropionyloxy) -4'-hexyloxybi phenyl
4- (2-Methyl-2-trifluoromethyl-butylyloxy) -4'-hexyloxybi-phenyl
4- (2-methyl-2-trifluoromethylpentanoyloxy) -4'-hexyloxybi phenyl
4- (2-methyl-2-trifluoromethylhexanoyloxy) -4'-hexyloxybi phenyl
4- (2-Methyl-2-trifluoromethylheptanoyloxy) -4'-hexyloxybi phenyl
4- (2-Methyl-2-trifluoromethyl-nonanoyloxy) -4'-hexyloxybi phenyl
4- (2-Methyl-2-trifluoromethyl-propionyloxy) -4'-octyloxybi-phenyl
4- (2-methyl-2-trifluoromethyl-butyryloxy) -4'-octyloxybi-phenyl
4- (2-methyl-2-trifluoromethylpentanoyloxy) -4'-octyloxybi phenyl
4- (2-methyl-2-trifluoromethylhexanoyloxy) -4'-octyloxybi phenyl
4- (2-Methyl-2-trifluoromethylheptanoyloxy) -4'-octyloxybi phenyl
4- (2-methyl-2-trifluoromethyloctanoyloxy) -4'-octyloxybi phenyl
4- (2-Methyl-2-trifluoromethyl-nonanoyloxy) -4'-octyloxybi phenyl

Analogously, 4- (trans-alkylcyclohexyl) phenols are obtained optically active 4- (2-methyl-2-trifluoromethylalkanoyloxy) - 1- (trans-4-alkylcyclohexyl) benzenes:

4- (2-Methyl-2-trifluoromethyl-nonanoyloxy) -1- (trans-4-pentylcyclohexyl) benzene
4- (2-Methyl-2-trifluoromethylpropionyloxy) -1- (trans-4-pentylcyclohexyl) benzene
4- (2-Methyl-2-trifluoromethyl-butyryloxy) -1- (trans-4-pentylcyclohexyl) -benzene
4- (2-Methyl-2-trifluoromethylpentanoyloxy) -1- (trans-4-pentylcyclohexyl) benzene
4- (2-Methyl-2-trifluoromethylheptanoyloxy) -1- (trans-4-pentylcyclohexyl) benzene
4- (2-Methyl-2-trifluoromethyloctanoyloxy) -1- (trans-4-pentylcyclohexyl) benzene

With 4-alkyl-2 ', 3'-difluoro-4'-hydroxybiphenyl (prepared from 4'-alkyl-2,3-difluorobiphenyl by ortho-Lithiierung with n-butyllithium, reacting with boric acid trimethyl ester and subsequent cleavage with H₂O₂ in acetic acid) is obtained analogously optically active 4- (2-methyl-2-trifluoromethylalkanoyloxy) - 2,3-difluoro-4'-alkylbiphenyls:

4- (Methyl-2-trifluoromethyl-propionyloxy) -2,3-difluoro-4'-propyl-biphenyl
4- (Methyl-2-trifluoromethylbutryloxy) -2,3-difluoro-4'-propylbiphenyl
4- (Methyl-2-trifluoromethylpentanoyloxy) -2,3-difluoro-4'-propylbiphenyl
4- (Methyl-2-trifluoromethylhexanoyloxy) -2,3-difluoro-4'-propylbiphenyl
4- (Methyl-2-trifluoromethylheptanoyloxy) -2,3-difluoro-4'-propylbiphenyl
4- (Methyl-2-trifluoromethyloctanoyloxy) -2,3-difluoro-4'-propylbiphenyl
4- (Methyl-2-trifluoromethyl-nonanoyloxy) -2,3-difluoro-4'-propylbiphenyl

With 4- (5-alkylpyrimidin-2-yl) phenols is obtained analogously optically active 4- (2-methyl-2-trifluoromethylalkanoyloxy) - 1- (5-alkylpyrimidine-2-yl) benzenes:

4- (2-Methyl-2-trifluoromethyl-propionyloxy) -1- (5-pentyl-pyrimidin-2-yl) -benzene
4- (2-Methyl-2-trifluoromethyl-butylyloxy) -1- (5-pentyl-pyrimidin-2-yl) -benzene
4- (2-Methyl-2-trifluoromethylpentanoyloxy) -1- (5-pentyl-pyrimidin-2-yl) -benzene
4- (2-Methyl-2-trifluoromethylhexanoyloxy) -1- (5-pentyl-pyrimidin-2-yl) -benzene
4- (2-Methyl-2-trifluoromethylheptanoyloxy) -1- (5-pentyl-pyrimidin-2-yl) -benzene
4- (2-Methyl-2-trifluoromethyloctanoyloxy) -1- (5-pentyl-pyrimidin-2-yl) -benzene
4- (2-Methyl-2-trifluoromethyl-nonanoyloxy) -1- (5-pentyl-pyrimidin-2-yl) -benzene

example 2

To a mixture of 0.1 mol of 4-octyloxybiphenyl-4'-yl carboxylic acid, 0.1 mol of optically active 1-trifluoromethyl ethanol (prepared according to J.W. Crawford J. Chem. Soc. 1965, 4280), 1 mmol of 4-N, N-dimethylaminopyridine and 150 ml Dichloromethane is added to a mixture of 0.1 mol of dicyclo hexylcarbodiimide and 50 ml of dichloromethane. After 10 hours Stir at room temperature, filtering off the solid components and usual workup is obtained optically active 4-octyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoro methylethyl) ester.

Analogously, the following optically active compounds Herge provides:

4-Octyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethylpropyl) ester
4-octyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethylbutyl) ester
4-Octyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethylpentyl) ester
4-octyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethyl hexyl) ester
4-Octyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethyl heptyl) ester
4-Octyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethyl octyl) ester
4-Hexyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethylpropyl) ester
4-Hexyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethylbutyl) ester
4-Hexyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethylpentyl) ester
4-Hexyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethyl hexyl) ester
4-Hexyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethyl heptyl) ester
4-Hexyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethyl octyl) ester
4-Ethyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethylpropyl) ester
4-Ethyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethylbutyl) ester
4-Ethyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethylpentyl) ester
4-Ethyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethyl hexyl) ester
4-Ethyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethyl heptyl) ester
4-Ethyloxybiphenyl-4'-ylcarboxylic acid (1-trifluoromethyl octyl) ester

Analogously, 4-alkyl-2 ', 3'-difluorobiphenyl 4'-ylcarboxylic acids (prepared from 4-alkyl-2 ', 3'-difluoro biphenylene by ortho-lithiation with n-butyllithium and Carboxylation with carbon dioxide) optically active 4-alkyl-2 ', 3'- difluoro-4'-ylcarbonsäure- (1-trifluoromethylalkyl) - ester:

4-Pentyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethyl) ethyl ester
4-Pentyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethylpropyl) ester
4-Pentyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethylbutyl) ester
4-Pentyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethylpentyl) ester
4-Pentyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethylhexyl) ester
4-Pentyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethylheptyl) ester
4-Pentyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethyloctyl) ester
4-Octyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethyl) ethyl ester
4-octyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethylpropyl) ester
4-octyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethylbutyl) ester
4-Octyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethylpentyl) ester
4-Octyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethylhexyl) ester
4-octyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethylheptyl) ester
4-Octyl-2 ', 3'-difluorobiphenyl-4'-ylcarboxylic acid (1-trifluoromethyloctyl) ester

With 4- (trans-4-alkylcyclohexyl) benzoic acids one contains analogously optically active 4- (trans-4-alkylcyclohexyl) benzoic acid acid (1-trifluoromethylalkyl) ester:

4- (trans-4-pentylcyclohexyl) benzoic acid (1-trifluoromethyl ethyl) ester
4- (trans-4-pentylcyclohexyl) benzoic acid (1-trifluoromethylpropyl) ester
4- (trans-4-pentylcyclohexyl) benzoic acid (1-trifluoromethylbutyl) ester
4- (trans-4-pentylcyclohexyl) benzoic acid (1-trifluoromethylpentyl) ester
4- (trans-4-pentylcyclohexyl) benzoic acid (1-trifluoromethyl hexyl) ester
4- (trans-4-pentylcyclohexyl) benzoic acid (1-trifluoromethyl heptyl) ester
4- (trans-4-pentylcyclohexyl) benzoic acid (1-trifluoromethyl octyl) ester

example 3

0.1 mol of 4- (2- (trans-4-heptylcyclohexyl) ethyl) phenyl 4-hydroxybenzoic acid ester (prepared by hydrogenolytic Cleavage of the corresponding benzyl ether, the by esterification of 4-benzyloxybenzoic acid with 4- (2- (trans-heptylcyclohexyl) ethyl) phenol with dicylocarbodiimide is obtained) is analogously to Example 1 with 0.1 ml  esterified optically active 2-methyl-2-trifluoromethyloctanoic acid. Obtained after usual workup optically active 1- (2- (trans-4-nonylcyclohexyl) ethyl) -4- (4- (2- methyl-2-trifluormethyloctanoyloxy) benzoyloxy) benzene.

The following optically active compounds are prepared analogously posed:

1- (2-trans-4-ethylcyclohexyl) -ethyl) -4- (4- (2-methyl-2-trifluoromethyloctanoyloxy) -benzoyloxy) -benzene.
1- (2-trans-4-propylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethyloctanoyloxy) -benzoyloxy) benzene.
1- (2-trans-4-butylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethyloctanoyloxy) -benzoyloxy) benzene.
1- (2-trans-4-pentylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethyloctanoyloxy) benzoyloxy) benzene.
1- (2-trans-4-hexylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethyloctanoyloxy) -benzoyloxy) benzene.
1- (2-trans-4-heptylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethyloctanoyloxy) -benzoyloxy) benzene.
1- (2-trans-4-octylcyclohexyl) -ethyl) -4- (4- (2-methyl-2-trifluoromethyloctanoyloxy) -benzoyloxy) -benzene.

1- (2-trans-4-ethylcyclohexyl) -ethyl) -4- (4- (2-methyl-2-trifluoromethyl-butylyloxy) -benzoyloxy) -benzene.
1- (2-trans-4-propylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethyl-butylyloxy) -benzoyloxy) -benzene.
1- (2-trans-4-butylcyclohexyl) -ethyl) -4- (4- (2-methyl-2-trifluoromethyl-butylyloxy) -benzoyloxy) -benzene.
1- (2-trans-4-pentylcyclohexyl) -ethyl) -4- (4- (2-methyl-2-trifluoromethyl-butylyloxy) -benzoyloxy) -benzene.
1- (2-trans-4-hexylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethyl-butylyloxy) -benzoyloxy) -benzene.
1- (2-trans-4-heptylcyclohexyl) -ethyl) -4- (4- (2-methyl-2-trifluoromethyl-butylyloxy) -benzoyloxy) -benzene.
1- (2-trans-4-octylcyclohexyl) -ethyl) -4- (4- (2-methyl-2-trifluoromethyl-butylyloxy) -benzoyloxy) -benzene.

1- (2-trans-4-ethylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethylhexanoyloxy) -benzoyloxy) benzene.
1- (2-trans-4-propylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethylhexanoyloxy) -benzoyloxy) benzene.
1- (2-trans-4-butylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethylhexanoyloxy) benzoyloxy) benzene.
1- (2-trans-4-pentylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethylhexanoyloxy) -benzoyloxy) benzene.
1- (2-trans-4-hexylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethylhexanoyloxy) -benzoyloxy) benzene.
1- (2-trans-4-heptylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethylhexanoyloxy) -benzoyloxy) benzene.
1- (2-trans-4-octylcyclohexyl) ethyl) -4- (4- (2-methyl-2-trifluoromethylhexanoyloxy) -benzoyloxy) benzene.

A mixture Example

A liquid crystalline mixture consisting of the following components:

4% 2-p-hexyloxyphenyl-5-heptylpyrimidine
5% 2-p-heptyloxyphenyl-5-heptylpyrimidine
5% 2-p-Octyloxyphenyl-5-heptylpyrimidine
5% 2-p-Nonyloxyphenyl-5-heptylpyrimidine
7% 2-p-hexyloxyphenyl-5-nonylpyrimidine
5% 2-p-heptyloxyphenyl-5-nonylpyrimidine
4% 2-p-Octyloxyphenyl-5-nonylpyrimidine
25% 2-p-Nonyloxyphenyl-5-nonylpyrimidine
10% 4-Octylthio-4 '- (4-heptylbenzoyloxy) biphenyl
8% 4-Octylthio-4 '- (4-nonylbenzoyloxy) biphenyl
10% 4-Octylthio-4 '- (4-octyloxybenzoyloxy) biphenyl

12% of 4- (2-methyl-2-trifluoromethyl-nonanoyloxy) -4'-hexyl-oxybiphenyl has a broad S _c range and high spontaneous polarization.

Claims (5)

1. Chiral or achiral ring compounds of the formula I R¹- (A¹-Z¹) _m -A 2 -Q¹-C * R ° CF₃-X (I) wherein
R¹ is an alkyl or perfluoroalkyl group each having 1-12 C atoms, wherein one or two non-adjacent CH₂- or CF₂ groups by O atoms and / or -CO groups and / or -CO-O- Groups and / or -CH = CH groups and / or -CHHalogen and / or -CHCN groups and / or -O-CO-CHHalogen and / or -CO-O-CHCN groups may be replaced, H, F, Cl, Br, CN, or -Q¹-C * R ° CF₃-X, where Q¹, R ° and X have the meaning given,
A¹ and A² are each independently of one another unsubstituted or substituted by one or two F and / or CH₃ 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 one or two non-adjacent CH₂ groups may be replaced by O atoms and / or S atoms, 1- (4-) cyano-1,4-cyclohexylene, piperidine-1,4-diyl, 1 , 4-bicyclo (2,2,2) octylene, 1,3,4-thiadiazole-2,5-diyl, naphthalene-2,6-diyl-decahydronaphthalene-2,6-diyl or 1,2,3 , 4-tetrahydronaphthalene-2,6-diyl,
Each Z¹ is -CO-O-, -O-CO-, -CH₂CH₂-, -OCH₂-, -CH₂O-, -C≡C- or a single bond,
X is H or CH₃,
C * is a carbon atom linked to four different substituents,
m 1, 2 or 3
Q¹ is -O-, -O-CO-, -CO-O- or a single bond, and
R ° is an alkyl group having 1 to 10 C atoms other than X, or, if Q¹ is a single bond, also an alkoxy or alkanoyloxy group having 1 to 10 carbon atoms each
with the proviso that X is CH₃ when Q¹ is -O-CO-. 2. Ring compounds according to claim 1, characterized in that that Q¹ is -CO-O- or -O-.   3. liquid crystalline phase with at least two liquid crystalline Components, characterized that at least one component is a compound of Formula I is. 4. Liquid crystal display element, characterized in that it is a liquid-crystalline phase according to claim 3 contains. 5. Electro-optical display element according to claim 2, characterized characterized in that it is a dielectric as a liquid crystalline phase according to claim 3 contains.