DE3606788A1 - Cyclohexane derivatives - Google Patents

Abstract

Cyclohexane derivatives of the formula I <IMAGE> in which R denotes an alkyl group having 1-12 C atoms in which one or two non-adjacent CH2 groups can also be replaced by O, -CO-O- or -OCO-, X denotes -CN, -COOR<1>, -OOCR<1>, -COR<1>, -OR<1> or R<1> and R<1> denotes an alkyl group having 1-12 C atoms, are suitable as components in liquid-crystalline phases.

Description

The invention relates to new cyclohexane derivatives of the formula I. wherein
R is an alkyl group with 1-12 C atoms, in which one or two non-adjacent CH ₂ groups can also be replaced by O, -CO-O- or -OCO-,
X -CN, -COOR ¹ , -OOCR ¹ , -COR ¹ , -OR ¹ or R ¹ and
R ^{1 is} an alkyl group with 1-12 C atoms.

The compounds of formula I can, like similar, e.g. B. from DE-OS 27 02 598 known compounds as components liquid crystalline dielectrics are used, especially for displays based on the principle of twisted Cell, the guest-host effect, the effect of Deformation of erected phases or the effect of based on dynamic scattering.

The invention was based, new stable task find liquid-crystalline or mesogenic compounds, the as components of liquid crystalline dielectrics are suitable.  

It has been found that the compounds of formula I as Components of liquid crystalline dielectrics excellent are suitable. In particular, they are stable with their help liquid crystalline phases with relatively low optical Anisotropy and producible with a high nematic character, which are reflected in electro-optical display elements the principle of the twisted cell and / or the guest Host effect through a particularly favorable angle dependency of contrast.

With the provision of the compounds of formula I is also generally the range of liquid crystalline Substances that are different application aspects for manufacturing nematic mixtures show considerably widespread.

The compounds of formula I have a wide range Scope of application. Depending on the selection of the Substituents can use these compounds as base materials serve from which liquid crystalline phases are composed for the most part, it can but also compounds of formula I liquid crystalline Base materials from other classes of compounds added for example the angle dependency of the contrast and / or the optical anisotropy of a to influence such phase. The connections of the Formula I are also suitable as intermediates for Manufacture of other substances that prove to be ingredients Let liquid crystalline dielectrics be used.

The compounds of formula I are in a pure state colorless and filter liquid crystalline mesophases in one conveniently located for electro-optical use Temperature range. Chemical, thermal and they are very stable against light.  

The invention thus relates to the compounds of the formula I and a process for their preparation, characterized in that for the preparation of carbonitriles of the formula I (X = CN) the corresponding carboxylic acids (X = COOH) or one of their reactive derivatives in the corresponding Acid amides are converted and dehydrated, or a corresponding acid chloride is reacted with sulfamide, or the corresponding carboxylic acid compounds or one of their reactive derivatives are reacted with a corresponding alcohol or one of its reactive derivatives to produce carboxylic acid esters of the formula I (X = -COOR ¹ ) , or that for the preparation of acyl compounds of the formula I (X = -COR ₁ ) the corresponding carboxylic acid compounds or one of their reactive derivatives are converted into the corresponding nitriles and these are reacted with a corresponding Grignard compound, or that for the preparation of the alkyl compounds (X = R ¹ ) the the corresponding carboxylic acid compounds or one of their reactive derivatives are converted into the corresponding keto compounds (X = -COR ¹ ) and reduced,
or treating a compound which otherwise corresponds to the formula I but contains one or more reducible groups and / or CC bonds instead of H atoms with a reducing agent,
or that the corresponding alcohols (R ¹ = H) or one of their reactive derivatives are etherified to prepare alkoxy compounds (X = OR ¹ ),
or that for the alkanoyloxy derivatives of the formula I (X = -COOR ¹ ) the corresponding alcohols (X = OH) or one of their reactive derivatives are reacted with a corresponding carboxylic acid or one of their reactive derivatives.

The invention furthermore relates to the use of the compounds of formula I as components of liquid crystalline Phases. The subject of the invention are also liquid-crystalline phases containing at least one compound of the formula I and liquid crystal display elements, especially electro-optical Display elements that contain such phases.

For the sake of simplicity, "Cyc" in the following means one 1,4-cyclohexylene group.

In the compounds of formula I are those stereoisomers preferred, wherein all three 1,4-cyclohexylene groups are trans-substituted in the 1,4-position.

The compounds of formula I accordingly include preferred compounds of the sub-formulas Ia to Ig

R-Cyc-CH ₂ CH ₂ -Cyc-CH ₂ CH ₂ -Cyc-CN (Ia)
R-Cyc-CH ₂ CH ₂ -Cyc-CH ₂ CH ₂ -Cyc-R ¹ (Ib)
R-Cyc-CH ₂ CH ₂ -Cyc-CH ₂ CH ₂ -Cyc-COOR ¹ (Ic)
R-Cyc-CH ₂ CH ₂ -Cyc-CH ₂ CH ₂ -Cyc-CO-R ¹ (Id)
R-Cyc-CH ₂ CH ₂ -Cyc-CH ₂ CH ₂ -Cyc-OOCR ¹ (Ie)
R-Cyc-CH ₂ CH ₂ -Cyc-CH ₂ CH ₂ -Cyc-CH ₂ O alkyl (If)
R-Cyc-CH ₂ CH ₂ -Cyc-CH ₂ CH ₂ -Cyc-OR ¹ (Ig)

Compounds of the sub-formulas Ia-Ic are preferred and Ie, in particular Ia, Ib and Ie used. Especially Ib and Ic are preferred.  

In the compounds of the formulas above and below, the alkyl radicals R, in which one ("alkoxy" or "oxaalkyl") or two ("alkoxyalkoxy" or "dioxaalkyl") non-adjacent CH ₂ groups can be replaced by O atoms can be straight-chain or branched. They are preferably straight-chain, have 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms and are therefore preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, ethoxy, Propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, nonoxy, decoxy, 2-oxapropyl (= methoxymethyl), 2 - (= ethoxymethyl) or 3-oxabutyl (= 2-methoxymethyl), 2-, 3- or 4-oxapentyl , 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2 -, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl, furthermore methyl, undecyl , Dodecyl, methoxy, undecoxy, dodecoxy, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9- or 10-oxaundecyl, 2-, 3-, 4-, 5-, 6 -, 7-, 8-, 9-, 10- or 11-oxadodecyl, 1,3-dioxabutyl (= methoxymethoxy), 1,3-, 1,4- or 2,4-dioxapentyl, 1,3-, 1 , 4-, 1,5-, 2,4-, 2,5- or 3,5-dioxahexyl, 1,3-, 1,4-, 1,5-, 1,6-, 2,4-, 2,5-, 2,6-, 3,5-, 3,6- or 4,6-dioxaheptyl 1,3-, 1,4-, 1,5-, 1,6-, 1,7-, 2,4-, 2,5-, 2,6-, 2,7-, 3,5-, 3,6-, 3,7-, 4,6-, 4,7- or 5,7-dio xaoctyl, 1.3-, 1.4-, 1.5-, 1.6-, 1.7-, 1.8-, 2.4-, 2.5-, 2.6-, 2.7 -, 2.8-, 3.5-, 3.6-, 3.7-, 3.8-, 4.6-, 4.7-, 4.8-, 5.7- or 5.8 -Dioxanonyl, 1,3-, 1,4-, 1,5-, 1,6-, 1,7-, 1,8-, 1,9-, 2,4-, 2,5-, 2, 7-, 2.8-, 2.9-, 3.5-, 3.6-, 3.7-, 3.8-, 3.9-, 4.6-, 4.7-, 4, 8-, 4.9-, 5.7-, 5.8- or 5.9-dioxadecyl.

R is preferably alkyl or alkoxy, especially n-alkyl.  

Compounds of the formulas I and Ia to Ig with branched wing groups R or R ¹ can occasionally be important because of their better solubility in the customary liquid-crystalline base materials, but in particular as chiral dopants if they are optically active. Branched groups of this type usually contain no more than one chain branch. Preferred branched radicals R and R ¹ 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-oxa-3-methylbutyl, 3- Oxa-4-methylpentyl. Such compounds are suitable as components of ferroelectric liquid crystal phases.

Among the compounds of formula I and Ia to Ig preferred are those in which at least one of the residues contained therein one of the preferred Has meanings.

The compounds of formula I can be known per se Methods are produced as they are in the Literature (e.g. in standard works such as Houben Weyl, Methods of Organic Chemistry, Georg-Thieme- Verlag, Stuttgart) are described under Reaction conditions for the reactions mentioned are known and suitable. You can also start from well-known variants not mentioned here Make use.  

If desired, the starting materials can also be in are formed in such a way that they can be extracted from the The reaction mixture is not isolated, but continues immediately converted to the compounds of formula I. As raw materials the known p- [trans- 4- (trans-4-R-cyclohexylethyl) cyclohexylethyl] benzonitrile, or those obtainable therefrom by saponification Carboxylic acids. In addition to the corresponding free carboxylic acids their reactive derivatives are also suitable. As reactive derivatives of the carboxylic acids mentioned acid halides are particularly suitable, especially the chlorides and bromides, also the anhydrides, Azides or esters, especially alkyl esters with 1-4 carbon atoms in the alkyl group.

As reactive derivatives of the alcohols mentioned come especially the corresponding metal alcoholates into consideration, wherein M is an equivalent of a metal, preferably an alkali metal such as Na or K.

To produce the nitriles of the formula I (X = CN), corresponding acid amides in which a CONH ₂ group is used instead of the CN groups can be dehydrated. The amides are e.g. B. from the corresponding acid halides by reaction with ammonia. The corresponding acid halides can in turn be known from the corresponding carboxylic acids, for. B. with thionyl chloride. Suitable dehydrating agents for dehydrating the amides are, for example, inorganic acid chlorides such as SOCl ₂ PCl ₃ , PCl ₅ , POCl ₃ , SO ₂ Cl ₂ , COCl ₂ , and also P ₂ O ₅ , AlCl ₃ (e.g. as a double compound with NaCl) , aromatic sulfonic acids and sulfonic acid halides. You can work in the presence or absence of an inert solvent at temperatures between about 0 ° and 150 °; come as a solvent, for. B. bases such as pyridine or triethylamine, aromatic hydrocarbons such as benzene, toluene or xylene or amides such as DMF into consideration.

The nitriles of the formula I can also be prepared corresponding acid halides, preferably the chlorides, react with sulfamide, suitably in an inert solvent like tetramethyl sulfone at temperatures between about 80 ° and 150 °, preferably at 120 °. To Normal work-up can isolate the nitriles directly.

To prepare the esters of formula I (X = -OOCR ¹ ), an appropriate alcohol or one of its reactive derivatives is preferably reacted with a corresponding carboxylic acid or one of its reactive derivatives.

To prepare the esters of formula I (X = -COOR ¹ ), a corresponding carboxylic acid or one of its reactive derivatives is preferably reacted with a corresponding alcohol or one of its reactive derivatives.

Suitable reactive derivatives of the alcohols mentioned are in particular the corresponding metal alcoholates of the formula R ¹ OM, in which M is an equivalent of a metal, preferably an alkali metal such as Na or K.

As reactive derivatives of the carboxylic acids mentioned the acid halides are particularly suitable the chlorides and bromides, also the anhydrides, azides or esters, in particular alkyl esters with 1-4 C atoms in the alkyl group.

The esterification is advantageous in the presence of a inert solvents performed. Are well suited in particular 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. Solvents immiscible with water can also be used for azeotropic distillation of the water formed during the esterification will. Occasionally, an excess of one organic base, e.g. B. pyridine, quinoline or triethylamine applied as a solvent for the esterification will. The esterification can also take place in the absence of one Solvent, e.g. B. by simply heating the components in the presence of sodium acetate will. The reaction temperature is usually between -50 ° and + 250 °, preferably between -20 ° and + 80 °. At the esterification reactions are in these temperatures usually ended after 15 minutes to 48 hours.

In particular, the reaction conditions depend on the Esterification largely depends on the nature of the used Starting materials. So is a free carboxylic acid a free alcohol usually in the presence of a strong acid, for example a mineral acid such as Hydrochloric acid or sulfuric acid. A preferred one The reaction is the reaction of an acid anhydride  or in particular an acid chloride with an alcohol, preferably in a basic environment, whereby as bases in particular alkali metal carbonates or bicarbonates like sodium carbonate, sodium hydrogen 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, lutidene, collidine or Quinoline are important. Another preferred Embodiment of the esterification is that one the alcohol first in the sodium or potassium alcoholate transferred, e.g. B. by treatment with ethanolic Soda or potash lye, this isolated and together with Sodium bicarbonate or potassium carbonate with stirring suspended in acetone or diethyl ether and this suspension with a solution of the acid chloride or anhydride mixed in diethyl ether, acetone or DMF, appropriate at temperatures between approximately -25 ° and + 20 °.

To produce the acyl compounds of the formula I (X = -CO-R ¹ ) from the corresponding carboxylic acids, the corresponding nitrile is first prepared as described. The latter is preferably reacted with a Grignard compound of the general formula R ¹ MHal, in which M is metal, preferably magnesium and Hal is halogen, preferably bromide, and is then hydrolyzed. The Grignard compound is prepared in a known manner with magnesium and the corresponding alkyl halide R ¹ Hal, preferably R ¹ Br, in an ether, preferably diethyl ether or tetrahydrofuran, under conditions customary for such reactions.

To prepare the alkyl compounds of the formula I (X = R ¹ ) are preferably in corresponding ketones (X = -CO-R ¹ ) by the methods of Clemmensen (with zinc, amalgamated zinc or tin and hydrochloric acid, advantageously in aqueous alcoholic Solution or in heterogeneous phase with water / toluene at temperatures between about 80 ° and 120 °) or Wolff-Kishner (with hydrazine, expediently in the presence of alkali such as KOH or NaOH in a high-boiling solvent such as diethylene glycol or triethylene glycol at temperatures between about 100 ° and 200 °) reduced to the corresponding compounds of formula I.

The compounds of formula I can also be prepared by using compounds that are otherwise of the formula I correspond, but instead of H atoms one or several reducible groups and / or C-C bonds included, reduced.

As reducible groups are preferably carbonyl groups, in particular keto groups, further z. B. free or esterified hydroxy groups. Preferred starting materials for the reduction have the formula I, but can instead of a cyclohexane ring or a cyclohexane ring cyclohexanone and / or in place of a -CH ₂ CH ₂ group, a -CO-group and / or in place of a -CH ₂ group is a -CO group and / or instead of an H atom contain a free or a functional (e.g. in the form of its p-toluenesulfonate) modified OH group.

The reduction can e.g. B. done by catalytic hydrogenation at temperatures between about 0 ° and about 200 ° and pressures between about 1 and 200 bar in an inert solvent, for. B. an alcohol such as methanol, ethanol or isopropanol, an ester 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 (e.g. PtO ₂ , PdO), on a support (e.g. Pd on carbon, calcium carbonate or strontium carbonate) or in finely divided form .

For the preparation of the ethers of the formula I is preferred a corresponding alcohol or one of its reactive Derivatives with a corresponding alkyl halide, implemented sulfonate or dialkyl sulfate, conveniently 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 °.

Advantageously, the hydroxy compound is previously in a corresponding metal derivative, for. B. by treatment with NaH, NaNH ₂ , NaOH, KOH, Na ₂ CO ₃ or K ₂ CO ₃ in the corresponding alkali metal alcoholate.

The dielectrics according to the invention consist of 2 to 25, preferably 3 to 15 components, including at least a compound of formula I. The other ingredients are preferably selected from the nematic or nematogenic substances, especially the known substances, from the classes of azoxybenzenes, benzylidene anilines, Biphenyls, terphenyls, phenyl- or cyclohexylbenzoates, Cyclohexane-carbon-acid-phenyl- or -cyclohexyl- esters, phenylcyclohexanes, cyclohexylbiphenyls, Cyclohexylcyclohexanes, cyclohexylnaphthalenes, 1,4-bis cyclohexylbenzenes, 4,4'-bis-cyclohexylbiphenyl, phenyl or cyclohexylpyrimidines, phenyl- or cyclohexylpyrimidines, Phenyl or cyclohexyl dioxanes, phenyl or  Cyclohexyldioxane, 1,2-bis-cyclohexylethane, 1-cyclohexyl 2-phenylethane, 1,2-bis-phenylethane, optionally halogenated stilbenes, benzylphenyl ether, tolanes and substituted cinnamic acids.

The most important as components of such liquid crystalline Dielectric compounds in question can be characterized by Formula II.

R′-L-G-E-R ″ II

wherein L and E each a carbo- or heterocyclic ring system from the unsubstituted or substituted by one or two F and / or Cl atoms and / or CH ₃ groups and / or CN groups and 1,4-phenylene and trans -1,4- cyclohexyl 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 tetrahydroquinoline educated group,

-CH = CH - N (O) = N- -CH = CY - CH = N (O) - -C≡C - CH ₂ CH ₂ - -CO-O - CH ₂ -O- -CO -S - CH ₂ -S- -CH = N - COO-Phe-COO-

or a CC single bond, Y halogen, preferably chlorine, or -CN, and R ′ and R ″ alkyl, alkoxyalkanoyloxy or alkoxycarbonyloxy having up to 18, preferably up to 8 carbon atoms, or one of these radicals also CN, NC, NO ₂ , CF ₃ , F, Cl or Br mean.

Most of these compounds have R 'and R ″ apart  different, with one of these residues mostly is an alkyl or alkoxy group. But others too Variants of the proposed substituents are common. Many such substances or mixtures thereof are commercially available. All of these substances are can be produced by methods known from the literature.

The dielectrics according to the invention generally contain at least 30, preferably 50-99, especially 60-98 Weight percent of the compounds of formula I and II. Of this, at least 5 percent by weight is preferably omitted usually 10-40 percent by weight on one or more Compounds of formula I. However, the invention also includes such liquid crystalline dielectrics, only less so, for example, for doping purposes as 5 weight percent, for example 0.1 to 3 weight percent one or more compounds of the formula I. up to 60 percent by weight of the dielectrics according to the invention turn off. Preferably contain the liquid crystalline Dielectrics according to the invention 10 to 30 percent by weight of one or more compounds of formula I.

The dielectrics according to the invention are produced in the usual way. Usually will the components dissolved in one another, expediently at elevated Temperature. With suitable additives liquid crystalline dielectrics according to the invention be modified so that they are known in all types of liquid crystal display elements can be used.  

Such additives are known to the expert and in the Literature described in detail. For example, you can Conductive salts, preferably ethyl-dimethyl-dodecyl-ammonium 4-hexyloxybenzoate, tetrabutylammonium tetraphenylboranate or complex salts of crown ethers (cf. e.g. I. Haller et al., Mol. Cryst. Liq. Cryst. Volume 24, pages 249-258 (1973)) to improve conductivity, dichroic Dyes for the production 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 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. Above and below mean Percentages percent by weight; all temperatures are given in degrees Celsius. "Normal refurbishment" means: water is added, extracted with methyl chloride, separates, the organic phase dries evaporates and purifies the product by crystallization and / or chromatography.

example 1

A mixture of 400 g of trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) - cyclohexylethyl] cyclohexane carboxylic acid (obtainable by alkaline saponification of p- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] - benzonitrile (EP-OS 01 29 177) with KOH in diethylene glycol at 150 ° C, esterification of the acid obtained by boiling in ethanol in the presence of concentrated sulfuric acid, Catalytic hydrogenation of the ester on a Rh catalyst at 3 bar and saponification of the hydrogenated ester) and 100 g of n-pentanol is in toluene in the presence of catalytic Amounts of p-toluenesulfonic acid in a water separator cooked and processed as usual. You get trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) - cyclohexylethyl] cyclohexane carboxylic acid pentyl ester.

The following are produced analogously:
methyl trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane carboxylate
trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane carboxylic acid ethyl ester
prop-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane carboxylate
butyl trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane carboxylate
trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane carboxylic acid hexyl ester

Example 2

A mixture of 41.5 g of the amide of trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexanecarboxylic acid (Example 1), which by converting the acid into the acid chloride and subsequent reaction with aqueous NH ₃ solution is available, 25 g of thionyl chloride and 200 ml of methylene chloride are refluxed with stirring for 12 h. After the volatile constituents have been removed in vacuo, the residue is worked up in the customary manner. Trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane carbonitrile is obtained.

The following are produced analogously:
trans-4- [trans-4- (trans-4-ethylcyclohexylethyl) cyclo hexane carbonitrile
trans-4- [trans-4- (trans-4-butylcyclohexylethyl) cyclo hexane carbonitrile
trans-4- [trans-4- (trans-4-pentylcyclohexylethyl) cyclo hexane carbonitrile
trans-4- [trans-4- (trans-4-hexylcyclohexylethyl) cyclo hexane carbonitrile
trans-4- [trans-4- (trans-4-heptylcyclohexylethyl) cyclo hexane carbonitrile

Example 3

39.7 g of the nitrile prepared according to Example 2 are in a mixture of ether and benzene according to P. Canonne et al., Tetrahedron Letters 21, 155 (1980) at 17.7 g Propyl magnesium bromide implemented. After hydrolysis with aqueous hydrochloric acid gives 1-butyryl-trans-4- [trans- 4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] - cyclohexane.

The following are produced analogously:
1-acetyl-trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane
1-propionyl-trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane
1-valeryl-trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane
1-Hexanoyl-trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane
1-heptanoyl-trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane

Example 4

38.6 g of toluenesulfonylhydrazone of the ketone from Example 3 in 1050 ml of glacial acetic acid are mixed in portions with 23.8 g of NaBH ₄ and stirred overnight. The solvent is then removed in vacuo, the residue is hydrolyzed and worked up in the usual way. 1-Butyl-trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane is obtained.

The following are produced analogously:
1-ethyl-trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane
1-propyl-trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane
1-butyl-trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane
1-Hexyl-trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane
1-heptyl-trans-4- [trans-4- (trans-4-n-propylcyclohexylethyl) cyclohexylethyl] cyclohexane

The following are examples of liquid crystalline according to the invention Phases:

Example A

A liquid crystal phase consisting of

6% 2-p-cyanophenyl-5-propyl-1,3-dioxane, 6% 2-p-cyanophenyl-5-butyl-1,3-dioxane, 10% p-trans-4-propylcyclohexyl-benzonitrile, 6% trans, trans-4′-ethoxycyclohexyl-4-propylcyclohexane, 18% trans, trans-4'-methoxycyclohexyl-4-pentylcyclohexane, 12% trans, trans-4′-ethoxycyclohexyl-4-pentylcyclohexane, 12% trans, trans-4'-butyryloxycyclohexyl-4-propylcyclohexane, 3% trans, trans-4-propylcyclohexylcyclohexane-4'-carbon acid trans-4-propylcyclohexyl ester, 3% trans, trans-4-propylcyclohexylcyclohexane-4'-carboxylic acid trans-4-pentylcyclohexyl ester, 3% trans, trans-4-butylcyclohexylcyclohexane-4'-carboxylic acid trans-4-propylcyclohexyl ester, 3% trans, trans-4-butylcyclohexylcyclohexane-4'-carboxylic acid trans-4-pentylcyclohexyl ester, 3% 1-propyl-trans-4- [trans-4- (trans-4-propylcyclohexylethyl) - cyclohexylethyl] cyclohexane, 4% 1-pentyl-trans-4- [trans-4- (trans-4-propylcyclohexylethyl) - cyclohexylethyl] cyclohexane, 3% 4,4'-bis (trans-4-propylcyclohexyl) -2-fluorobiphenyl, 4% 4,4'-bis (trans-4-pentylcyclohexyl) -2-fluorobiphenyl, and 4% 4- (trans-4-pentylcyclohexyl) -4 ′ - (trans-4-propylcyclohexyl) - 2-fluorobiphenyl

has no smectic / nematic phase transition down to -40 °, a viscosity of 19 · 10 ^-3 (780 · 10 ^-3 ) Pa · s at 20 ° (-30 °), an optical anisotropy of 0.084 and a threshold voltage of 2.7 Volt. This phase is characterized by positive dielectric anisotropy, a high clearing point and a broad nematic range.

Example B

A liquid crystal phase consisting of

16% p-trans-4-propylcyclohexylbenzonitrile, 9% p-trans-4-butylcyclohexylbenzonitrile, 12% trans, trans-4'-propoxycyclohexyl-4-propylcyclohexane, 12% trans, trans-4′-methoxycyclohexyl-4-pentylcyclohexane, 12% trans, trans-4′-ethoxycyclohexyl-4-pentylcyclohexane, 9% trans, trans-4'-propylcyclohexyl-4-butyryloxycyclo hexane, 12% 1-pentyl-trans-4- [trans-4- (trans-4-propylcyclo hexylethyl) cyclohexylethyl] cyclohexane, 3% 4,4'-bis (trans-4-propylcyclohexyl) -2-fluorobi phenyl, 3% 4,4'-bis (trans-4-pentylcyclohexyl) -2-fluorobi phenyl, 5% 4- (trans-4-pentylcyclohexyl) -4 ′ - (trans-4-propyl cyclohexyl) -2-fluorobiphenyl, 3% 4,4'-bis (trans-4-propylcyclohexyl) biphenyl and 4% 4- (trans-4-pentylcyclohexyl) -4 ′ - (trans-4-propyl cyclohexyl) biphenyl

has an optical anisotropy of 0.084 and a threshold voltage of 2.5 volts.

Claims (6)

1. Cyclohexane derivatives of the formula I. wherein
R is an alkyl group with 1-12 C atoms, in which one or two non-adjacent CH ₂ groups can also be replaced by O, -CO-O- or -OCO-,
X -CN, -COOR ¹ , -OOCR ¹ , -COR ¹ , -OR ¹ or R ¹ and
R ^{1 is} an alkyl group with 1-12 C atoms. 2. A process for the preparation of cyclohexane derivatives of the formula I according to claim 1, characterized in that for the preparation of carbonitriles of the formula I (X = CN) the corresponding carboxylic acids (X = COOH) or one of their reactive derivatives is converted into the corresponding acid amides and these are dehydrated, or a corresponding acid chloride is reacted with sulfamide, or the corresponding carboxylic acid compounds or one of their reactive derivatives are reacted with a corresponding alcohol or one of its reactive derivatives to prepare carboxylic acid esters of the formula I (X = -COOR ¹ ),
or that the corresponding carboxylic acid compounds or one of their reactive derivatives are converted into the corresponding nitriles for the preparation of acyl compounds of the formula I (X = -COR ₁ ) and these are reacted with a corresponding Grignard compound,
or that the corresponding carboxylic acid compounds or one of their reactive derivatives are converted into the corresponding keto compounds (X = COR ¹ ) and reduced in order to prepare the alkyl compounds (X = R ¹ ),
or treating a compound which otherwise corresponds to the formula I but contains one or more reducible groups and / or CC bonds instead of H atoms with a reducing agent,
or that the corresponding alcohols (R ¹ = H) or one of their reactive derivatives are etherified to prepare alkoxy compounds (X = OR ¹ ),
or that the corresponding alcohols (X = OH) or one of their reactive derivatives are reacted with a corresponding carboxylic acid or one of their reactive derivatives to produce alkanoyloxy derivatives of the formula I (X = -OOCR ¹ ). 3. Use of the compounds of formula I according to claim 1 as components of liquid crystalline phases.   4. Liquid crystalline phases with at least two liquid crystalline phases Components, characterized in that at least one component connects the Formula I according to claim 1. 5. Liquid crystal display element, characterized in that it contains a phase according to claim 4. 6. Electro-optical display element, characterized in that there is a phase after as a dielectric Claim 4 contains.