DE4326393A1 - Trifluoroethoxypyri(mi)din derivatives and liquid-crystalline medium - Google Patents

Abstract

Trifluoroethoxypyri(mi)din derivatives of the formula I <IMAGE> in which R, -@-, X<1>, X<2>, Y<1>, Y<2>, Z<1>, Z<2> and m have the meanings given in Claim 1 are suitable as components of liquid-crystalline media.

Description

The present invention relates to trifluoroethoxypyri (mi) din Derivatives of the formula I,

wherein
R is an unsubstituted or substituted by CN, halogen or CF₃ alkyl or alkenyl radical having up to 15 carbon atoms, wherein in these radicals also one or more CH₂ groups each independently by -O-, -CO-, -CO -O-, -O-CO- or -O-CO-O- may be replaced so that O atoms are not directly linked to one another,

X¹, X²,
Y¹, Y²,
Z 1 and Z 2 are each independently N, CF or CH,
m 0, 1 or 2
mean,
provided that at least one of the groups present in the molecule is X¹, Y¹ or Z¹N.

The invention further relates to the use of this Ver compounds as components of liquid-crystalline media as well as Liquid crystal and electro-optical display elements, the contain liquid crystalline media according to the invention.

The compounds of the formula I can be liquid as components crystalline media are used, especially for Dis plays based on the principle of the twisted cell, the guest Host effect, the effect of deformation of upright phases or the effect of dynamic dispersion.

In EP 92-00270 the compounds of the formula I of of the general formula. Heteroaromatics will be there but not named.

The invention therefore an object of the invention, 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 high 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.

With the provision of compounds of the formula I is also quite generally the range of liquid crystalline Substances that vary in their application aspects of the production of liquid crystalline Mixtures are suitable, considerably widened.

The compounds of formula I preferably include the verbin of the formulas I1-I43,

R is preferably alkyl, furthermore alkoxy.  

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 tetra decoxy.

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 by -CH = CH- is replaced, this can be straight-chain or ver be branched. It is preferably straight-chain and has 2 to 10 C-atoms. He therefore 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 by -O- and one is replaced by -CO-, these are preferred adjacent. Thus, these contain 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, butoxy carbonyl, pentoxycarbonyl, methoxycarbonylmethyl, ethoxy carbonylmethyl, 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 neigh Bart CH₂ group is replaced by CO or CO-O or O-CO, so this can be straight-chain or branched. Preferably he is straight-chain and has 4 to 13 carbon atoms. He means accordingly especially acryloyloxymethyl, 2-acryloyloxyethyl, 3-acryloyl oxypropyl, 4-acryloyloxybutyl, 5-acryloyloxypentyl, 6-acry Loyloxyhexyl, 7-acryloyloxyheptyl, 8-acryloyloxyoctyl, 9-acryloyloxynonyl, 10-acryloyloxydecyl, methacryloyloxyme ethyl, 2-methacryloyloxyethyl, 3-methacryloyloxypropyl, 4-methacryloyloxybutyl, 5-methacryloyloxypentyl, 6-metha cryloyloxyhexyl, 7-methacryloyloxyheptyl, 8-methacryloyl oxyoctyl, 9-methacryloyloxynonyl.  

If R is an alkyl substituted by CN or CF₃, or alkenyl radical, this radical is preferably straight-chain and the substitution by CN or CF₃ in ω-Posi tion.

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-carboxy pentyl, 6,6-bis-carboxyhexyl, 7,7-bis-carboxyheptyl, 8,8- Bis-carboxy-octyl, 9,9-bis-carboxy-nonyl, 10,10-bis-carboxy decyl, bis (methoxycarbonyl) methyl, 2,2-bis (methoxycar ethyl), 3,3-bis- (methoxycarbonyl) -propyl, 4,4-bis- (methoxycarbonyl) -butyl, 5,5-bis (methoxycarbonyl) -pentyl, 6,6-Bis (methoxycarbonyl) hexyl, 7,7-bis (methoxycarbonyl) - heptyl, 8,8-bis (methoxycarbonyl) octyl, bis (ethoxycar ethyl), 2,2-bis- (ethoxycarbonyl) -ethyl, 3,3-bis- (ethoxycarbonyl) -propyl, 4,4-bis (ethoxycarbonyl) -butyl, 5,5-bis- (ethoxycarbonyl) -hexyl.

If R is at least one halogen substituted Alkyl or alkenyl radical, then this radical is preferred Were straight-chain and halogen is preferably F or Cl. at Multiple substitution is halogen preferably F. The resul ting residues also include perfluorinated residues. at Simple substitution can be the fluorine or chlorine substituent in be any position, but preferably in the ω position.  

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 kind eig as components for ferroelectric materials.

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-methyl butyl), 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-propylpentyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethyl hexoxy, 1-methylhexoxy, 1-methylheptoxy.

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

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

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

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

In the compounds of formula I those are stereoisomes preferred in which the cyclohexane ring trans-1,4-disub is substituted.

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), and Although under reaction conditions, for the aforementioned Umset tongues are known and suitable.

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

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

The compounds of the invention can be as follows Produce reaction schemes easily.

Scheme 1

Scheme 2

Scheme 3

Scheme 4

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. This further inventory Parts are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, esp substances from the classes of azoxybenzenes, benzylidene anilines, biphenyls, terphenyls, phenyl- or cyclohexylbenes zoates, cyclohexane-carboxylic acid phenyl or cyclohexyl esters, Phenyl or cyclohexyl esters of cyclohexylbenzoic acid, Phenyl or cyclohexyl esters of Cyclohexylcyclohexancar bonsäure, Cyclohexyl-phenylester of benzoic acid, the cyclo hexanecarboxylic acid or cyclohexylcyclohexanecarboxylic acid, Phenylcyclohexanes, cyclohexylbiphenyls, phenylcyclohexyl  cyclohexanes, cyclohexylcyclohexanes, cyclohexylcyclohexyl cyclohexenes, 1,4-biscyclohexylbenzenes, 4,4'-biscyclohexyl biphenyls, 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-cyclo hexyl 2- (4-phenyl-cyclohexyl) -ethanes, 1-cyclohexyl-2-biphe nylylethanes, 1-phenyl-2-cyclohexyl-phenylethanes, given if halogenated stilbenes, benzylphenyl ethers, 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, where Phe unsubstitu substituted or fluorine-substituted 1,4-phenylene, Cyc  trans-1,4-cyclohexylene or 1,4-cyclohexylene, Pyr pyrimi din-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.

Preferably, one of L and E is Cyc, Phe or Pyr. e is preferably Cyc, Phe or Phe-Cyc. Preferably ent 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 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 of Ver compounds of formulas 1, 2, 3, 4 and 5 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 treated with the subformulae 1a, 2a, 3a, 4a and 5a designated. For most of these compounds, R 'and R '' different from each other, with one of these radicals 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 is} Cl₁, 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 sub-formulas 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 has R 'indicated in the compounds of the sub-formulas 1a-5a 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 Verbindun of this subgroup are correspondingly subformulated 1c, 2c, 3c, 4c and 5c. In the compounds of Partial formulas 1c, 2c, 3c, 4c and 5c has R 'in the verbin of the sub-formulas 1a-5a given meaning and is 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 according to literature known methods or in analogy available.

Preferred media can in addition to the invention Verbin of formula I only from compounds of group B best hen. Further preferred are media that in addition to the verbin of formula I, compounds of group B and 0-20% Contain compounds of group A and / or C.  

The media of the invention contain in addition fiction 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 of 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%, in particular 10 to 65%
Group C: 0 to 80%, preferably 5 to 80%, in particular 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 erfindungs proper connections. Further preferred are media, ent holding more than 40%, in particular 45 to 90% of inventions compounds according to 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, pleochroiti dyestuffs for producing colored guest-host systems or substances for changing the dielectric anisotropy pie, the viscosity and / or the orientation of the nematic Phases are added.

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

The following examples are intended to illustrate the invention, without to limit them. Above and below mean percentanga ben weight percent. All temperatures are in degrees Celsius specified. Mp means melting point, bp = 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 visco sity (mm² / sec) was determined at 20 ° C.

"Usual work-up" means: one gives if necessary Add water, extracted with dichloromethane, diethyl ether or Toluene, separates, the organic phase is dried, evaporated and purifies the product by distillation under reduced pressure Pressure or crystallization and / or chromatography. The following Abbreviations are used:

DMEU 1,3-dimethyl-2-imidazole dinone
KOT potassium tertiary butoxide
THF tetrahydrofuran
pTsOH p-toluenesulfonic acid

example 1

0.385 moles of sodium hydride (80% in paraffin) are dissolved in 20 ml Suspended THF and dropwise at room temperature with 0.385 mol of trifluoroethanol in 35 ml of THF. After 0.5 h 0.350 mol of 2-chloro-5-bromopyrimidine are dissolved in 175 ml of THF dropped to the reaction mixture. It is stirred for 0.5 h, mixed with water and methyl tert-butyl ether and works as usual.

25 mmol of 4-bromo-2- (2,2,2-trifluoroethoxy) -pyrimidine be with 30 mmol of p- (trans-4-pentylcyclohexyl) benzeneboronic acid, 65 ml Toluene, 30 ml ethanol, 40 ml 2 molar sodium carbonate solution and 0.1 g of tetrakis (triphenylphosphine) palladium (0) and refluxed overnight. After adding Petroleum ether (40-80 °) is worked up as usual. The Crude product is passed through a silica gel frit with n-hexane / methyl tert. butyl ether (5: 1). K 121 N 147.9 I, Δn = +0.141; Δε = 15.87  

The following compounds are prepared analogously:

Example 2

0.10 mol I are dissolved in 270 ml THF and treated with 0.09 mol II and 36 ml buffer solution (pH = 8) and to about 55 ° C. heated. After addition of 0.9 g of tetrakis (triphenylphosphine) - Palladium (0) is heated to boiling. 100 ml of 4% di-Na triumtetraborate 10 hydrate solution are added in portions to Given reaction mixture, so that the pH in the range of 6.4-7.4 lies. The mixture is allowed to cool overnight and mixed with water, n-hexane and methyl tert-butyl ether. The organic phase is separated and washed with water and saturated ter saline solution and finally dried. The Solvent is removed on the Rotavapor and the residue is purified by chromatography. K 95 N (84.3) I; Δn = +0.122, Δε = 22.5.

Analogously, the following compounds of the formula

manufactured:

R L CH₃ H CH₃ F C₂H₅ H C₂H₅ F n-C₃H₇ H n-C₃H₇ F n-C₄H₉ H n-C₄H₉ F n-C₅H₁₁ H n-C₆H₁₃ H n-C₆H₁₃ F

Example 3

0.13 mol of I are mixed with 0.15 mol of boronic acid II, 350 ml of toluene, 140 ml of ethanol, 180 ml of 2 molar sodium tetracarbonate solution and 3.7 g of tetrakis (triphenylphosphine) palladium (0) analog Example 1b) implemented.

0.065 mol of III are dissolved in 70 ml of THF and under nitrogen at -70 ° C first with 0.098 mol of lithium diisopropylamide (50%) and then treated with 0.098 mol trimethyl borate and stirred for 2 h. Thereafter, at -5 ° C with 16 ml of glacial acetic acid and Hydrolyzed 21 ml of water, with the reaction mixture heated to about 25 ° C. At 35-40 ° C add to the suspension carefully added dropwise 0.195 mol H₂O₂. One leaves on room temp Allow to cool and stir overnight. Subsequently, like worked up usual.

In a nitrogen atmosphere 33 mmol of 2,6-di-fluorophenol derivative from Example 3b) in 40 ml abs. DMEU dissolved and reacted with 33 mmol of sodium hydride. After addition of 36 mmol 2,2,2-Trifluorethylmethylsulfonat is heated to 140 ° C and stirred for 5 h. The reaction mixture is allowed to stand at room temperature overnight and then worked up as usual. K 110 S _A 194 I; Δn = +0.141, Δε = 22.88.

Analogously, the following compounds of the formula

manufactured:

Example 4

To 0.22 mol of 1,3-difluoro-5-pentylbenzene in 250 ml abs. THF at -78 ° C under nitrogen 0.25 moles of n-BuLi (15%) dropwise. It is stirred for 2 h at this temperature, dripping then 0.25 ml of trimethyl borate to the solution and leaves warm to room temperature. Last, the solution with 10% HCl and worked up as usual.

0.22 mol of the crude product, 550 ml of THF, 75 ml of buffer solution (pH = 8), 430 ml of 4% disodium tetraborate decahydrate solution and 0.18 mol of 2-chloro-5-bromopyrimidine are overnight Reflux cooked. After usual workup is the Solvent evaporates under reduced pressure. That so product obtained is continued without further purification processed.

Analogously to Example 1b), 77 mmol of the chlorine compound from Example 4a) are dissolved in 200 ml of toluene, 92 ml of ethanol and 123 ml of 2 molar sodium carbonate solution with 92 mmol of 3,5-di-fluorobenzoic acid in the presence of 2.4 g of tetrakis (triphenylphosphine). Palladium (0) reacted. The crude product is converted to the usual work-up analogous to Example 3b) and 3c) in the 2,2,2-trifluoroethoxy derivative. K 107 S _A (96) 1; Δn = +0.140, Δε = 19.43

The following compounds of the formula

are prepared analogously:

Example 5

76 mmol of 5-pentyl-2-chloropyrimidine are reacted with 87 mmol of 3,5-di fluorobenzeneboronic acid, 200 ml of toluene, 90 ml of ethanol, 120 ml 2 molar sodium carbonate solution and 2.4 g tetrakis (tri phenylphosphine) palladium (0) and overnight Reflux cooked. Then it is worked up as usual. The crude product is passed through a silica gel frit with toluene filtered.

Analogously to Example 3b) and 3c), the crude product is added to the 2,2,2- Trifluoroethoxyderivat transferred. K 66 I; Δn = + 0.106, Δε = 18,49

The compounds of the formula

are prepared analogously:

Example 6

To 28 mmol of 2- (3,5-difluorobenzene) -5-pentylpyrimidine from Bei Example 5a) in 110 ml of THF at -40 ° C 34 mmol lithium diisopropylamide added dropwise. It is stirred for 0.5 h at -40 ° C, heated to 0 ° C and hydrolyzed with water.

The crude product is weiterverarbei without further workup tet.

The 3,5-Difluoriodbenzolderivat (35 mmol) is analogous to example 1b) with 40 mmol of 3,5-Difluorbenzolboronsäure in 91 ml of toluene, 42 ml of ethanol, 56 ml 2molarer sodium carbonate solution with 1.1 g of tetrakis (triphenylphosphine) palladium (0) implemented. The crude product is converted into the 2,2,2-trifluoroethoxy derivative analogously to Example 3b) and 3c). K 90 S _A 91 I; Δn = +0.185; Δε = 30.35

Analogously, the following compounds of the formula

manufactured:

Example 7

0.385 moles of sodium hydride (80% in paraffin) are dissolved in 20 ml Suspended THF and dropwise at room temperature with 0.385 mol of trifluoroethanol in 35 ml of THF. After 0.5 h 0.350 mol of 2-chloro-5-bromopyridine are dissolved in 175 ml of THF dropped to the reaction mixture. It is stirred for 0.5 h, mixed with water and methyl tert-butyl ether and works as usual.

25 mmol of 4-bromo-2- (2,2,2-trifluoroethoxy) -pyridine with 30 mmol of p- (trans-4-pentylcyclohexyl) benzoic acid, 65 ml of toluene, 30 ml of ethanol, 40 ml 2molarer sodium carbonate solution and 0 , 1 g of tetrakis (triphenylphosphine) palladium (0) and boiled overnight under reflux. After addition of petroleum ether (40-80 °) is worked up as usual. The crude product is filtered through a silica gel frit with n-hexane / methyl tert-butyl ether (5: 1). K 87 S _B 111 S _A 112 N 126.2 I

Analogously, the following compounds of the formula are obtained

Examples mix

Example A PCH-5F | 9.0% PCH-6F 7.2% PCH-7F 5.4% CCP 2OCF₃ 7.2% CCP 3OCF₃ 10.8% CCP 4OCF₃ 8.1% CCP 5OCF₃ 8.1% BCH 3F.F 10.8% BCH 5F.F 9.0% ECCP 3OCF₃ 4.5% ECCP 5OCF₃ 4.5% CBC-33F 1.8% CBC-53F 1.8% CBC-55F 1.8% PYP 5OCCF₃.F.F 10.0% clearing point: 78 ° C Δn [589 nm, 20 ° C]: +0.0978 Δε [1 KHz, 20 ° C]: 6.60

Example B PCH-5F | 9.5% PCH-6F 7.6% PCH-7F 5.7% CCP 2OCF₃ 7.6% CCP 3OCF₃ 11.4% CCP 4OCF₃ 8.5% CCP 5OCF₃ 8.5% BCH 3F.F 11.4% BCH 5F.F 9.5% ECCP 3OCF₃ 4.8% ECCP 5OCF₃ 4.8% CBC-33F 1.9% CBC-53F 1.9% CBC-55F 1.9% PYPP-5OCCF₃.F.F 5.0% clearing point: 94 ° C Δn [589 nm, 20 ° C]: +0.0992 Δε [1 KHz, 20 ° C]: 6.12

Example C PCH-5F | 9.0% PCH-6F 7.2% PCH-7F 5.4% CCP 2OCF₃ 7.2% CCP 3OCF₃ 10.8% CCP 4OCF₃ 8.1% CCP 5OCF₃ 8.1% BCH 3F.F 10.8% BCH 5F.F 9.0% ECCP 3OCF₃ 4.5% ECCP 5OCF₃ 4.5% CBC-33F 1.8% CBC-53F 1.8% CBC-55F 1.8% CUPY-5OCCF₃.F.F 10.0% clearing point: 90 ° C Δn [589 nm, 20 ° C]: +0.0995 Δε [1 KHz, 20 ° C]: 6.96

Example D PCH-5F | 9.0% PCH-6F 7.2% PCH-7F 5.4% CCP 2OCF₃ 7.2% CCP 3OCF₃ 10.8% CCP 4OCF₃ 8.1% CCP 5OCF₃ 8.1% BCH 3F.F 10.8% BCH 5F.F 9.0% ECCP 3OCF₃ 4.5% ECCP 5OCF₃ 4.5% CBC-33F 1.8% CBC-53F 1.8% CBC-55F 1.8% PYUP-5OCCF₃.F.F 10.0% clearing point: 90 ° C Δn [589 nm, 20 ° C]: +0.1058 Δε [1 KHz, 20 ° C]: 7.75

Example E PCH-5F | 9.5% PCH-6F 7.6% PCH-7F 5.7% CCP 2OCF₃ 7.6% CCP 3OCF₃ 11.4% CCP 4OCF₃ 8.5% CCP 5OCF₃ 8.5% BCH 3F.F 11.4% BCH 5F.F 9.5% ECCP 3OCF₃ 4.8% ECCP 5OCF₃ 4.8% CBC-33F 1.9% CBC-53F 1.9% CBC-55F 1.9% CPPY-5OCCF₃.F.F 5.0% clearing point: 96 ° C Δn [589 nm, 20 ° C]: +0.0992 Δε [1 KHz, 20 ° C]: 5.77

Example F PCH-5F | 9.0% PCH-6F 7.2% PCH-7F 5.4% CCP 2OCF₃ 7.2% CCP 3OCF₃ 10.8% CCP 4OCF₃ 8.1% CCP 5OCF₃ 8.1% BCH 3F.F 10.8% BCH 5F.F 9.0% ECCP 3OCF₃ 4.5% ECCP 5OCF₃ 4.5% CBC-33F 1.8% CBC-53F 1.8% CBC-55F 1.8% UPYP-5OCCF₃.F.F 10.0% clearing point: 91 ° C Δn [589 nm, 20 ° C]: +0.1013 Δε [1 KHz, 20 ° C]: 6.66.

Claims (12)

1. trifluoroethoxypyri (mi) din derivatives of the formula I, wherein
R is an unsubstituted or monosubstituted by CN, halogen or CF₃ alkyl or alkenyl radical having up to 15 C-Ato men, wherein in these radicals also one or more CH₂ groups each independently of each other by -O-, -CO-, -CO-O-, -O-CO- or -O-CO-O- may be replaced so that O atoms are not directly linked to one another, X¹, X²,
Y¹, Y²,
Z 1 and Z 2 are each independently N, CF or CH,
m 0, 1 or 2
mean,
with the proviso that at least one of the groups X¹, Y¹ or Z¹ in the molecule is N. 2. trifluoroethoxypyri (mi) din derivatives of the formula I in which m = 1. 3. trifluoroethoxypyrimidine derivatives of the formula wherein L¹ and L² are each independently H or F and R has the meaning given in claim 1. 4. trifluoroethoxypyrimidine derivatives of the formula wherein L¹ and L² are each independently H or F and R has the meaning given in claim 1. 5. trifluoroethoxypyrimidine derivatives of the formula wherein L¹ and L² are each independently H or F and R has the meaning given in claim 1. 6. trifluoroethoxypyrimidine derivatives of the formula wherein L¹ and L² are each independently H or F and R has the meaning given in claim 1. 7. trifluoroethoxypyrimidine derivatives of the formula wherein L¹ and L² are each independently H or F and R has the meaning given in claim 1. 8. Compounds of the formula wherein
Y 2 N, CF or CH
means. 9. Use of compounds of the formula I as components liquid-crystalline media. 10. Liquid-crystalline medium at least two liquid crystalline components, characterized in that it contains at least one compound of formula I. 11. Liquid crystal display element, characterized in that it is a liquid-crystalline medium according to claim 10 contains. 12. Electro-optical display element, characterized that it is a liquid-crystalline medium as a dielectric according to claim 10 contains.