DE4030031A1 - New substd. methoxyethyl-benzene derivs. - useful as components of liq. crystal media - Google Patents

Abstract

Benzene derivs. of formula (I) are claimed; R = H, or 1-15C alkyl or alkenyl, opt. substd. with one CN or CF3 gp. or at least one Hal, and opt. also contg. in-chain O, S, 1,3-cyclobutylene, CO, COO, OCO or OCOO gp(s). (with O atoms not directly connected to one another); A1, A2 = (a) trans-1,4-cyclohexylene, opt. with non-adjacent CH2 gp(s). replaced by O and/or S, opt. substd. with CN or F; (b) 1,4-phenylene, opt. with 1 or 2 CH replaced by N, opt. substd. with CN or F; or (c) 1,4-cyclohexenylene, 1,4-bicyclo(2.2.2)octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl or decahydro- or 1,2,3,4-tetrahydro-naphthalene-2,6-diyl; Z1 = -COO-, -OCO-, -CH2O-, -CH2CH2-, -CH=CH-, -CC- or single bond; L1, L2 = H or F; Y = F or Cl; Q = single bond, -CF2-, -OCF2- or -OCHF-; and m = 0, 1 or 2. USE/ADVANTAGE - (I) are useful as components of liq. crystal media (claimed); also claimed are LC media with at least 2 components, at least one of which is a cpd. (I), LC display elements contg. such LC media, and electro-optical display elements contg. such media as dielectric. Provides new stable LC or mesogenic cpds. (I) with comparatively low viscosity and relatively high dielectric anisotropy; LC media contg. (I) have a wide mesophase range, good optical and dielectric anisotropy and good low-temp. properties.

Description

The invention relates to novel benzene derivatives of the formula I,

wherein

R H, one unsubstituted, one simple by CN or CF₃ or at least one simple halogen substituted alkyl or alkenyl radical having 1 to 15 C atoms, wherein in these residues also one or more CH₂ groups each independently through each other

may be replaced so that O atoms are not directly linked to each other,
A¹ and A² each independently

• (a) trans-1,4-cyclohexylene radical, wherein also a or several non-adjacent CH₂ groups can be replaced by -O- and / or -S-,  
• (b) 1,4-phenylene radical, wherein also one or two CH groups can be replaced by N,
• (c) radical from the group 1,4-cyclohexenylene, 1,4-bicyclo (2,2,2) octylene, piperidine-1,4-diyl, Naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl,

where radicals (a) and (b) are substituted by CN or fluorine could be,

Z¹ is -CO-O-, -O-CO-, -CH₂O-, -OCH₂-, -CH₂CH₂-, -CH = CH-, -C≡C- or a single bond,
L 1 and L 2 are each independently H or F,
m 0, 1 or 2,
YF or Cl and
Q is a single bond, -CF₂-, -OCF₂- or -OCHF-

means.  

The invention further relates to the use of these Compounds as components of liquid-crystalline media and liquid crystal and electro-optical display elements, which contain the liquid-crystalline media according to the invention.

The compounds of the formula I can be used as components liquid crystalline media are used, in particular for displays based on the principle of the twisted cell, the Guest-host effect, the effect of deformation more upright Phases or the effect of dynamic dispersion.

The invention was based on the object new stable to find liquid-crystalline or mesogenic compounds which are suitable as components of liquid-crystalline media and especially at the same time a comparatively small Possess viscosity as well as a relatively high dielectric Anisotropy.

It has now been found that compounds of the formula I as Components of liquid-crystalline media excellently suitable are. In particular, they have comparatively low levels Viscosities. With their help can be stable liquid-crystalline media with a broad mesophase range and advantageous values for the optical and dielectric Obtained anisotropy. These media also have a lot good low temperature behavior.

Liquid crystals of the formula

r = 1 or 2

are already known from DE 32 09 178. From JP 62-1 03 057 are compounds of the formulas

and

known. Finally, JP 63-216858 discloses compounds of the formula

described. From DE-OS 30 42 391 and DE-OS 31 39 130  Compounds of the following formulas are known:

Various compounds with liquid crystalline properties, in which terminal a CF₃ group is bound, are already known (US-P 43 30 426, US-P 46 84 476; J.C. Liang and S. Kumar, Mol. Cryst. Liq. Cryst. , 1987; Vol. 142, pp. 77-84). However, these connections often have one strong smectogenic character and are practical for many Applications less suitable.

With regard to the most diverse fields of application of such However, compounds with a high Δε were desirable have further connections available on the specific applications precisely tailor-made properties respectively.

With the provision of compounds of the formula I is also quite generally the range of liquid crystalline Substances that differ in various application Aspects for the production of liquid crystalline Mixtures are suitable, considerably widened.  

The compounds of the formula I have a wide range of applications. Depending on the choice of substituents These compounds can be used as base materials serve, from which liquid-crystalline media for the most part Part are composed; but it can also connections of the formula I liquid-crystalline base materials be added to other classes of compounds, for example the dielectric and / or optical anisotropy and / or the elastic properties of such a dielectric to influence and / or the threshold voltage and / or to optimize its viscosity.

The compounds of the formula I are colorless in the pure state and form liquid crystalline mesophases in one for the Electro-optical use conveniently located temperature range. Chemically, thermally and against light, they are stable.

The invention thus relates to the compounds of Formula I and the use of these compounds as Components of liquid-crystalline media. Subject of the Invention are also liquid-crystalline media with a Content of at least one compound of the formula I and Liquid crystal display elements, in particular electro-optical Display elements containing such media.

For the sake of simplicity, A³ will mean one below Remainder of the formula

Cyc is a 1,4-cyclohexylene radical,  Che is a 1,4-cyclohexenylene radical, Dio is a 1,3-dioxane-2,5-diyl radical, With a 1,3-dithiane-2,5-diyl residue, Phe one 1,4-phenylene, Pyd is a pyridine-2,5-diyl, Pyr is a Pyrimidine-2,5-diyl and Bi is a bicyclo (2,2,2) octyl radical, where Cyc and / or Phe are unsubstituted or mono- or may be substituted twice by F or CN. L is Preferably F.Y is preferably F. Preferably one or in particular both radicals L¹ and L² F.

A₁ and A₂ are preferably selected from the group Cyc, Che, Phe, Pyr, Pyd and Dio, preferably only one of in the molecule residues A₁ and A₂ Che, Phe, Pyr, Pyd or Dio is.

The compounds of the formula I accordingly comprise Compounds with two rings of subformula Ia:

R-A²-CH₂OCH₂CH₂-A³-Q-Y (Ia)

Compounds with three rings of sub-formulas Ib and Ic:

R-A¹-Z¹-A²-CH₂OCH₂CH₂-A³-Q-Y (Ib)

R-A¹-A²-CH₂OCH₂CH₂-A³-Q-Y (Ic)

and compounds with four rings of the subformulae Id bis If:

R-A¹-A¹-A²-CH₂OCH₂CH₂-A³-Q-Y (Id)

R-A¹-A¹-Z¹-A²-CH₂OCH₂CH₂-A³-Q-Y (Ie)

R-A¹-Z¹-A¹-Z¹-A²-CH₂OCH₂CH₂-A³-Q-Y (If)

Among them, especially those of the sub-formulas Ia and Ic prefers.

In the compounds of the formulas above and below Y preferably denotes F.

R is preferably alkyl, furthermore alkoxy. A¹ and / or A² are preferably Phe, Cyc, Che, Pyr or Dio. Prefers contain the compounds of formula I no more than one the radicals Bi, Pyd, Pyr, Dio or Dit.

Preference is also given to compounds of the formula I and of all Partial formulas in which A¹ and / or A² once or twice by F or simply by CN substituted 1,4-phenylene means. In particular, these are 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene and 3,5-difluoro-1,4-phenylene as well 2-cyano-1,4-phenylene and 3-cyano-1,4-phenylene. In a A particularly preferred embodiment is A 2 3,5-difluoro-1,4-phenylene and m 1 or 2.

Z 1 is preferably a single bond, -CO-O-, -O-CO- and -CH₂CH₂-, secondarily preferably -CH₂O- and -OCH₂-.  

Preferred compounds of this type correspond to the partial formula I '

wherein R, A¹, A², m, L, Q and Y are those given in formula I. Have meaning. Also the preferred meanings for R, A¹, A², m, L, Q and Y correspond to those for the compounds of Formula I.

m is preferably 1 or 0, particularly preferably 0.

If R is an alkyl radical and / or an alkoxy radical, this may be straight-chain or branched. Preferably if it is straight-chain, has 2, 3, 4, 5, 6 or 7 carbon atoms and therefore preferably denotes ethyl, propyl, butyl, pentyl, Hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy or Heptoxy, furthermore methyl, octyl, nonyl, decyl, undecyl, Dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octoxy, Nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy or tetradecoxy.  

Oxaalkyl is preferably straight-chain 2-oxapropyl (= Methoxymethyl), 2- (= ethoxymethyl) or 3-oxabutyl (= 2-methoxyethyl), 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-oxo-octyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.

If R is an alkyl radical in which a CH₂ group is replaced by -CH = CH-, so this can be straight or be branched. Preferably, it is straight-chain and has 2 up to 10 C atoms. He means especially vinyl, Prop-1 or prop-2-enyl, but-1, 2- or but-3-enyl, Pent-1-, 2-, 3- or pent-4-enyl, hex-1, 2-, 3-, 4- or Hex-5-enyl, hept-1, 2-, 3-, 4-, 5- or hept-6-enyl, Oct-1, 2-, 3-, 4-, 5-, 6- or oct-7-enyl, non-1-, 2-, 3-, 4-, 5-, 6-, 7- or non-8-enyl, Dec-1, 2-, 3-, 4-, 5-, 6-, 7-, 8- or dec-9-enyl.

If R is an alkyl radical in which a CH₂ group replaced by -O- and one by -CO-, these are preferably adjacent. Thus, these include an acyloxy group -CO-O- or an oxycarbonyl group -O-CO-. Preferably these are straight-chain and have 2 to 6 carbon atoms.

They therefore mean especially acetyloxy, propionyloxy, Butyryloxy, pentanoyloxy, hexanoyloxy, acetyloxymethyl, Propionyloxymethyl, butyryloxymethyl, pentanoyloxymethyl, 2-acetyloxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl,  3-acetyloxypropyl, 3-propionyloxypropyl, 4-acetyloxybutyl, Methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, Pentoxycarbonyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, Propoxycarbonylmethyl, butoxycarbonylmethyl, 2- (methoxycarbonyl) ethyl, 2- (ethoxycarbonyl) ethyl, 2- (propoxycarbonyl) ethyl, 3- (methoxycarbonyl) propyl, 3- (ethoxycarbonyl) propyl, 4- (methoxycarbonyl) -butyl.

If R is an alkyl radical in which a CH₂ group by unsubstituted or substituted -CH = CH- and a adjacent CH₂ group replaced by CO or CO-O or O-CO- is, it may be straight or branched. Preferably it is straight-chain and has 4 to 13 carbon atoms. He therefore means especially acryloxymethyl, 2-acryloyloxyethyl, 3-acryloyloxy-propyl, 4-acryloyloxybutyl, 5-acryloyloxypentyl, 6-acryloyloxyhexyl, 7-acryloyloxyheptyl, 8-acryloyloxyoctyl, 9-acryloyloxynonyl, 10-acryloyloxydecyl, methacryloyloxymethyl, 2-methacryloyloxyethyl, 3-methacryloyloxypropyl, 4-methacryloyloxybutyl, 5-methacryloyloxypentyl, 6-methacryloyloxyhexyl, 7-methacryloyloxyheptyl, 8-methacryloyloxyoctyl, 9-Methacryloyloxynonyl.

If R is a monosubstituted by CN or CF₃ Alkyl or alkenyl radical, then this radical is preferred straight-chain and the substitution by CN or CF₃ in the ω position.  

If R is at least one halogen substituted Alkyl or alkenyl radical, then this radical preferably straight-chain and halogen is preferably F or Cl. In the case of multiple substitution, halogen is preferably F. The resulting radicals also include perfluorinated radicals. For single substitution, the fluorine or chlorine substituent be in any position, but preferably in ω-position.

Compounds of the formula I which are required for polymerization reactions suitable wing groups R are suitable for the preparation of liquid-crystalline polymers.

Compounds of the formulas I with branched wing groups R occasionally because of better solubility in the Of conventional liquid-crystalline base materials of importance but especially as chiral dopants, if they are are optically active. Smectic compounds of this type are suitable themselves as components for ferroelectric materials.

Compounds of the formula I with S _A phases are suitable, for example, for thermally addressed displays.

Branched groups of this type usually do not contain more than one chain branch. Preferred branched radicals R is 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.  

If R represents an alkyl radical in which two or more CH₂ groups are replaced by -O- and / or -CO-O-, so can this be straight-chain or branched. Preferably, he is branched and has 3 to 12 carbon atoms. He means accordingly especially bis-carboxy-methyl, 2,2-bis-carboxy-ethyl, 3,3-bis-carboxy-propyl, 4,4-bis-carboxy-butyl, 5,5-bis-carboxypentyl, 6,6-bis-carboxy-hexyl, 7,7-bis-carboxy-heptyl, 8,8-bis-carboxy-octyl, 9,9-bis-carboxy-nonyl, 10,10-bis-carboxy-decyl, Bis (methoxycarbonyl) methyl, 2,2-bis (methoxycarbonyl) ethyl, 3,3-bis- (methoxycarbonyl) -propyl, 4,4-bis (methoxycarbonyl) -butyl, 5,5-bis- (methoxy-carbonyl) -pentyl, 6,6-bis (methoxycarbonyl) hexyl, 7,7-bis (methoxycarbonyl) heptyl, 8,8-bis (methoxycarbonyl) octyl, bis (ethoxycarbonyl) methyl, 2,2-bis- (ethoxycarbonyl) -ethyl, 3,3-bis (ethoxycarbonyl) propyl, 4,4-bis (ethoxycarbonyl) butyl, 5,5-bis- (ethoxycarbonyl) -hexyl.

Compounds of the formula I which are more than suitable for polycondensations suitable wing groups R are suitable for illustration liquid crystalline polycondensates.

Formula I includes both the racemates of these compounds as also the optical antipodes and their mixtures.

Among these compounds of the formula I and the sub-formulas those are preferred in which at least one the radicals contained therein one of the specified preferred Has meanings.  

In the compounds of formula I are those stereoisomers preferred in which the rings cyc and piperidine trans-1,4-disubstituted. Those of the above named formulas containing one or more groups Pyd, Pyr and / or Dio, each enclosing the two 2,5-positional isomers.

Some especially preferred smaller groups of Compounds are those of subformulae I1 and I2:

The 1,4-cyclohexenylene group preferably has the following structures:

The compounds of the formula I are known per se Methods presented in the literature (eg in the Standard works such as Houben-Weyl, Methods of the Organic Chemistry, Georg Thieme Verlag, Stuttgart Bd IX, p. 867 ff.) are described, under reaction conditions, the known and suitable for the reactions mentioned.

It is also known by itself, not closer make use of the variants mentioned.

Compounds of the invention may e.g. B. be prepared by a compound of formula II,

wherein R, A¹, A², Z¹ and m are as defined, metalated according to the following reaction scheme and then reacted with a suitable electrophile:

Scheme 1

From the resulting phenol are the target products with Q = OCF₂ or OCHF according to known methods, eg. B. by reaction with Chlorodifluoromethane or carbon tetrachloride / HF available.

Other synthetic methods will be apparent to those skilled in the art. For example, in the 5-position, appropriately substituted 1,3-difluorobenzene compounds or monofluorinated analogs (L 2 = H) can be converted into the 2-OCF 2 Y-1,3-difluoro compounds or monofluorinated analogs (L 2 = H) according to the above scheme, and the radical R- (A¹-Z¹) _m -A²-CH₂OCH₂CH₂ subsequently by reactions customary in liquid-crystal chemistry (for example esterification, etherification or couplings, for example, according to the article E. Poetsch, Kontakte (Darmstadt) 1988 (2) , P. 15).

Scheme 2

Other synthetic methods will be apparent to those skilled in the art. For example, in the 5-position, appropriately substituted 1,3-difluorobenzene compounds can be converted into the 2-Y-1,3-difluoro compounds according to the above scheme, and the radical R- (A¹-Z¹) _m -A²-Z² can then be converted by reactions customary in liquid-crystal chemistry (for example, esterification, etherification or couplings, for example, according to the article E. Poetsch, Contacts (Darmstadt) 1988 (2), p.

The compounds of the formula I, wherein L¹ = L² = F and Q-Y CF₃ means can be by metalation the unsubstituted 3,5-difluorophenyl compounds with n-BuLi, subsequent reaction with iodine and implementation of the Iodine compound with trifluoroacetic acid sodium salt according to produce the following scheme:

The compounds of the invention with L¹ = F and L² = H and Q-Y = CF₃ can be prepared by reacting 3-fluoro-4-iodobromobenzene with CF₃COONa in the Benzotrifluoridverbindung converted the corresponding Grignard compound with ethylene oxide reacted and the resulting primary alcohol etherified.  

In general, the compounds of formula I can be also according to Scheme 3, wherein the etherification to I

Scheme 3

according to methods known per se (Branko Juri, Tetrahedron 44, 6677 (1988)).  

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) or by the DCC method (DCC = dicyclohexylcarbodiimide) to be obtained.

The corresponding carboxylic acids and alcohols or phenols are known or can be analogous to known methods getting produced.

The synthesis of some particularly preferred compounds is specified in the following:

Scheme 4

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) or by the DCC method (DCC = dicyclohexylcarbodiimide) to be obtained.

The corresponding carboxylic acids and alcohols or phenols are known or can be analogous to known methods getting produced.

In a further process for the preparation of the compounds of formula I is reacted with an aryl halide with an olefin in the presence of a tertiary amine and a palladium catalyst (see R.F. Heck, Acc. Chem. Res. 12 (1979) 146). Suitable aryl halides are, for example, chlorides, Bromides and iodides, especially bromides and iodides. The for the success of the coupling reaction required tertiary Amines, such as As triethylamine, are also suitable as Solvent. As palladium catalysts are, for example its salts, in particular Pd (II) acetate, with organic Phosphorus (III) compounds such. B. triarylphosphines suitable. One can do this in the presence or absence of one inert solvent at temperatures between about 0 ° and 150 °, preferably between 20 ° and 100 °, work; when Solvents come z. As nitriles such as acetonitriles or Hydrocarbons such as benzene or toluene into consideration. The aryl halides and olefins used as starting materials are widely available commercially or can be known from the literature Processes are prepared, for example by halogenation of corresponding parent compounds or by elimination reactions with corresponding alcohols or halides.  

In this way, for example stilbene derivatives can be produced. The style levels can still be made by reacting a 4-substituted benzaldehyde with a corresponding phosphorylide according to Wittig. But you can also produce formula I tolans by substituting for Olefins monosubstituted acetylene used (Synthesis 627 (1980) or Tetrahedron Lett. 27, 1171 (1986)).

Furthermore, for the coupling of aromatics aryl halides be reacted with aryl tin compounds. To be favoured these reactions with the addition of a catalyst such. B. a palladium (O) complex in inert solvents such as Hydrocarbons at high temperatures, eg. B in boiling Xylene, carried out under protective gas.

Couplings of alkynyl compounds with aryl halides may be prepared analogously to A.O. King, E. Negishi, F.J. Villani and A. Silveira in J. Org. Chem. 43, 358 (1978) Procedures are performed.

Tolanes of the formula I can also over the Fritsch Buttenberg Wiechell rearrangement (Ann., 279, 319, 1984) are rearranged in the 1,1-diaryl-2-haloethylene become diarylacetylenes in the presence of strong bases.

Tolans of formula I can also be prepared by Brominate the corresponding stilbene and then subjected to dehydrohalogenation. One can at known, not mentioned here variants of this Apply implementation.  

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 treatment 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 implemented are, suitably in an inert solvent such. B. Acetone, 1,2-dimethoxyethane, DMF or dimethyl sulfoxide or also with an excess of aqueous or aqueous-alcoholic NaOH or KOH at temperatures between about 20 ° and 100 °.

The starting materials are either known or can be used in Be prepared analogously to known compounds.

The liquid-crystalline media according to the invention contain preferably in addition to one or more inventive Compounds as further constituents 2 to 40, in particular 4 to 30 components. Very particularly preferably included these media in addition to one or more inventive Compounds 7 to 25 components. These other ingredients are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, in particular Substances from the classes of the azoxybenzenes, Benzylidenaniline, Biphenyls, terphenyls, phenyl or cyclohexyl benzoates, Cyclohexane-carboxylic acid phenyl or cyclohexyl esters, Phenyl or cyclohexyl esters of cyclohexylbenzoic acid, Phenyl or cyclohexyl esters of cyclohexylcyclohexanecarboxylic acid, Cyclohexyl-phenylester of benzoic acid,  cyclohexanecarboxylic acid or cyclohexylcyclohexanecarboxylic acid, Phenylcyclohexanes, cyclohexylbiphenyls, phenylcyclohexylcyclohexanes, Cyclohexylcyclohexanes, cyclohexylcyclohexylcyclohexenes, 1,4-bis-cyclohexylbenzenes, 4,4'-biscyclohexylbiphenyls, Phenyl- or cyclohexylpyrimidines, phenyl- or cyclohexylpyridines, phenyl- or cyclohexyl-dioxanes, Phenyl or cyclohexyl-1,3-dithiane, 1,2-diphenylethane, 1,2-dicyclohexylethane, 1-phenyl-2-cyclohexylethane, 1-cyclohexyl-2- (4-phenyl-cyclohexyl) -ethanes, 1-cyclohexyl-2-biphenylylethanes, 1-phenyl-2-cyclohexyl-phenylethanes, optionally halogenated stilbenes, benzylphenyl ether, Tolans and substituted cinnamic acids. The 1,4-phenylene groups in these compounds may also be fluorinated.

The most important as further constituents according to the invention Media eligible connections can be through the Formulas 1, 2, 3, 4 and 5 characterize:

R'-L-E-R '' (1)

R'-L-COO-E-R '' (2)

R'-L-OOC-E-R '' (3)

R'-L-CH₂CH₂-E-R '' (4)

R'-L-C≡C-E-R "(5)

In formulas 1, 2, 3, 4 and 5, L and E are the same or may be different, each independently a bivalent radical from the group consisting of -Phe-, -Cyc-, -Phe-Phe-, -Phe-Cyc, -Cyc-Cyc, -Pyr-, -Dio, -G-Phe- and -G-Cyc- and their mirror images formed group, wherein Phe unsubstituted or fluorine-substituted 1,4-phenylene, Cyc trans-1,4-cyclohexylene or 1,4-cyclohexylene, Pyr  Pyrimidine-2,5-diyl or pyridine-2,5-diyl, Bio 1,3-dioxane-2,5-diyl and G 2- (trans-1,4-cyclohexyl) -ethyl, pyrimidine-2,5-diyl, Pyridine-2,5-diyl or 1,3-dioxane-2,5-diyl mean.

Preferably one of the radicals L and E is Cyc, Phe or Pyr. e is preferably Cyc, Phe or Phe-Cyc. Preferably included the media of the invention one or more components selected from the compounds of the formulas 1, 2, 3, 4 and 5, wherein L and E are selected from the group Cyc, Phe and Pyr and at the same time one or more components selected from the compounds of the formulas 1, 2, 3, 4 and 5, wherein one of the radicals L and E is selected from the Group Cyc, Phe and Pyr and the other radical is selected from the group -Phe-Phe, -Phe-Cyc, -Cyc-Cyc, -G-Phe- and -G-Cyc-, and optionally one or more components selected from the compounds of the formulas 1, 2, 3, 4 and 5, wherein the radicals L and E are selected from the group -Phe-Cyc, -Cyc-Cyc, -G-Phe and -G-Cyc-.

R 'and R' 'in a smaller subgroup mean the Compounds of formulas 1, 2, 3, 4 and 5 are each independently alkyl, alkenyl, alkoxy, alkoxyalkyl, alkenyloxy or alkanoyloxy of up to 8 carbon atoms. Hereinafter this smaller subgroup is called group A and the Compounds are described with the sub-formulas 1a, 2a, 3a, 4a and Designated 5a. For most of these compounds, R ' and R "are different from each other, wherein one of these radicals is usually alkyl, alkenyl, alkoxy or alkoxyalkyl.  

In a smaller subgroup of compounds of formulas 1, 2, 3, 4 and 5, other than group B, R '' is -F, -Cl, -NCS or - (O) _i CH ₃ - _{(k + 1)} F _k Cl ₁ , where i is 0 or 1 and k + 1 is 1, 2 or 3; the compounds in which R "has this meaning are designated by the subformulae 1b, 2b, 3b, 4b and 5b. Particular preference is given to those compounds of the subformulae 1b, 2b, 3b, 4b and 5b in which R "has the meaning -F, -Cl, -NCS, -CF₃, -OCHF₂ or -OCF₃.

In the compounds of sub-formulas 1b, 2b, 3b, 4b and 5b R 'has the compounds of the sub-formulas 1a-5a given meaning and is preferably alkyl, alkenyl, Alkoxy or alkoxyalkyl.

In another smaller subgroup of compounds of Formulas 1, 2, 3, 4 and 5 are R "-CN; this subgroup is hereinafter referred to as group C and the compounds this subgroup will be correspondingly subformulated 1c, 2c, 3c, 4c and 5c. In the compounds of Partial formulas 1c, 2c, 3c, 4c and 5c have R 'in the compounds of sub-formulas 1a-5a and meaning preferably alkyl, alkoxy or alkenyl.

In addition to the preferred compounds of groups A, B and C. are also other compounds of formulas 1, 2, 3, 4 and 5 with other variants of the proposed substituents common. All these substances are known from the literature Methods or by analogy.  

The media according to the invention contain, in addition to the invention Compounds of the formula I preferably one or several compounds which are selected from the Group A and / or Group B and / or Group C. The mass fractions the compounds from these groups on the inventive Media are preferred

Group A:
0 to 90%, preferably 20 to 90%, in particular 30 to 90%

Group B:
0 to 80%, preferably 10 to 80%, especially 10 to 65%

Group C:
0 to 80%, preferably 5 to 80%, especially 5 to 50%

where the sum of the mass fractions in the respective Compounds of the invention contained in the Groups A and / or B and / or C preferably 5% -90% and especially 10% to 90%.

The media according to the invention preferably contain 1 to 40%, in particular preferably 5 to 30% of inventive Links. Further preferred are media, containing more than 40%, in particular 45 to 90% Compounds of the invention. The media preferably contain three, four or five compounds of the invention.  

The preparation of the media according to the invention takes place in usual way. In general, the components are dissolved in each other, useful at elevated temperature. By Suitable additives can after the liquid crystalline phases of the invention are modified so that they are in all hitherto have become known types of liquid crystal display elements can be used. Such additives are those skilled in the art known and described in detail in the literature (H.Kalkker / R.Hatz, Handbook of Liquid Crystals, Verlag Chemistry, Weinheim, 1980). For example, pleochroic 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.

The following examples are intended to illustrate the invention, without to limit them. Above and below mean potency Weight. All temperatures are in degrees Celsius specified. Mp means melting point Kp = clearing point. Further K = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The information between these symbols represent the transition temperatures Δn means optical anisotropy (589 nm, 20 ° C) and the viscosity (mm² / sec) was determined at 20 ° C.  

In the present application and in the following examples, the structures of the liquid crystal compounds are indicated by acronyms, wherein the transformation into chemical formulas according to following Tables A and B takes place. All radicals C _n H _{2n + 1} and C _m H _{2m + 1} are straight-chain alkyl radicals with n or m C atoms. The coding according to Table B is self-evident. In Table A, only the acronym for the main body is given. In the individual case, a code for the substituents R 1, R 2, L 1 and L 2 follows separately from the acronym for the main body with a dash:

Table A

Table B

"Usual work-up" means: one gives if necessary Add water, extracted with methylene chloride, diethyl ether or toluene, separates, the organic phase dries, evaporated and the product is purified by distillation reduced pressure or crystallization and / or chromatography. The following abbreviations are used:

DAST diethylaminosulfur DCC dicyclohexylcarbodiimide DDQ dichlorodicyanobenzoquinone DIBALH diisobutylaluminum KOT Potassium tert-butoxide THF tetrahydrofuran pTSOH p-toluenesulfonic acid TMEDA tetramethylethylenediamine

example 1

A solution of 0.1 ml of 1-trans-4- (trans-4-n-propylcyclo hexyl) -cyclohexyl-4- (3,5-difluorophenyl) -2-oxabutane (prepared according to Scheme 1) and 0.1 M TMEDA in 300 ml THF is at about -65 ° with 0.1 M n-BuLi (1.5 M in hexane) dropwise added. The mixture is stirred for 30 minutes at this temperature and added dropwise at -60 to -70 ° C 0.1 m B (OCH₃) ₃. Man stirs 1/2 hour after. Then dripping 0.3 m H₂O₂ (30%), the temperature should not exceed + 40 ° C. To extractive workup gives the phenol, which be purified by crystallization or distillation can.  

From this phenol obtained OCHF₂ derivative by introduction of CHClF₂ in the THF solution of the phenolate. After extractive Work-up and customary purification are obtained 1- [trans-4- (trans-4-n-propylcyclohexyl) -cyclohexyl] -4- (4- difluoromethoxy-3,5-difluorophenyl) -2-oxabutane.

Example 2 to 5

Similarly, one obtains from the corresponding precursors of Formula II the following compounds according to the invention: (L¹ = F):

Example 6

In an autoclave, which is cooled to 0 °, it is filled 2 mol anhydrous hydrofluoric acid. Then you give out a mixture 0.18 mol of tetrachloromethane and 0.06 mol of 1- [trans-4- (trans- 4-n-propylhexyl) -cyclohexyl] -4- (4-hydroxy-3,5-difluorophenyl) -2-oxabu-tan (Example 1) too. The mixture is approx. Stirred at 150 ° C for 8 hours, cooled, poured onto ice-water and washed with ether. The two phases will be  stirred for about 30 minutes, separated and the ether solution with 5% KOH washed to alkaline reaction. After drying, Filtration, distilling off and purification are obtained 1- [trans-4- (trans-4-n-propylcyclohexyl) -cyclohexyl] -4- (4- trifluoromethoxy-3,5-difluorophenyl) -2-oxabutane.

Example 7

A solution of 0.1M 1- [trans-4- (trans-4-n-propylcyclo hexyl) cyclohexyl] -4- (3,5-difluorophenyl) -2-oxabutane (prepared according to Scheme 3) and 0.1 M TMEDA in 300 ml THF is at about -65 ° with 0.1 M n-BuLi (1.5 M in hexane) dropwise added. It is stirred for 30 min. At this temperature and then slowly adds 0.2 M N-chlorosuccinimide in 70 ml of THF. After completion of the addition is allowed to warm to -20 ° and hydrolyzed with H₂O. By adding diethyl ether is the Product completely dissolved. After extractive Work-up and purification by chromatography and crystallization to obtain 1- [trans-4- (trans-4-n-propylcyclo hexyl) -cyclohexyl] -4- (4-chloro-3,5-difluorophenyl) -2-oxabutane.  

Example 8

A mixture of 0.025 m CuJ, 0.0125 m CF₃COONa and 0.0125 m 1- [trans-4- (trans-4-n-propylcyclohexyl) -cyclohexyl] -4- (4- iodo-3,5-difluorophenyl) -2-oxabutane [available according to Scheme 4] is dissolved in 100 ml of N-methylpyrrolidone with stirring Heated to 150 °. After an hour you work as usual extractive and obtained after chromatographic purification 1- [trans-4- (trans-4-n-propylcyclohexyl) -cyclo hexyl] -4- (4-trifluoromethyl-3,5-difluorophenyl) -2-oxabutane.

Example 9

I and II are analogous to the etherification process of Branko Juri (Tetrahedron 44, 6677 (1988)) to III. For this purpose, 21.9 g of I (0.1 mol), 17.6 g of II (0.1 mol), 0.5 ml Water, 1.82 g of cetyltrimethylammonium bromide (0.005 mol), 8 g NaOH (0.2 mol) and 25 ml of tetrahydrofuran at 70 ° C bath temperature vigorously stirred overnight. After cooling, it will open a lot of water poured (1 l), extracted with toluene, the Toluene extract evaporated after drying. chromatography  on silica gel with a toluene / hexane mixture gives 18 g III, in the Kugelrohr at 160 ° C air bath temperature (0.1 mm) is distilled. (II can be made from 3,4,5-trifluorobenzene magnesium bromide and ethylene oxide obtained). Leave analog the following bromides react.

Claims (6)

1. benzene derivatives of the formula I, whereinR is H, an unsubstituted, an alkyl or alkenyl radical having 1 to 15 carbon atoms, which is monosubstituted by CN or CF₃ or at least monosubstituted by halogen, wherein in these radicals also one or more CH₂ groups are each independently of one another may be replaced so that O atoms are not directly linked to each other,
A¹ and A² each independently

• (a) trans-1,4-cyclohexylene radical, in which also one or more non-adjacent CH₂ groups may be replaced by -O- and / or -S-,
• (b) 1,4-phenylene radical, wherein also one or two CH groups may be replaced by N.
• (c) radical from the group consisting of 1,4-cyclohexenylene, 1,4-bicyclo (2,2,2) octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6- diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl.

where radicals (a) and (b) may be substituted by CN or fluorine,
Z¹ is -CO-O-, -O-CO-, -CH₂O-, -OCH₂-, -CH₂CH₂-, -CH = CH-, -C≡C- or a single bond,
L 1 and L 2 are each independently H or F,
m 0, 1 or 2.
YF or Cl and
Q represents a single bond, -CF₂-, -OCF₂- or -OCHF-. 2. Use of compounds of the formula I as components liquid-crystalline media. 3. Liquid-crystalline medium with at least two liquid-crystalline Components, characterized in that it contains at least one compound of the formula I. 4. Liquid crystal display element, characterized in that it is a liquid-crystalline medium according to claim 3 contains. 5. Electro-optical display element, characterized that it is a liquid crystalline as a dielectric Medium according to claim 3 contains.