DE4414647B4 - Cyclohexane derivatives and liquid crystalline medium - Google Patents

Abstract

Cyclohexane derivatives of the formula I, where at least one of the radicals R 1 and R 2 is an alkenyl radical having 2 to 7 carbon atoms and the other radical R 1 or R 2 is an unsubstituted or monosubstituted by CN or CF 3 or at least one halogen-substituted alkyl or alkenyl radical with 1 to 10 carbon atoms, means.

Description

wobei
mindestens einer der Reste
R¹ und R² einen Alkenylrest mit 2 bis 7 C-Atomen bedeutet und der andere Rest R¹ oder R² einen unsubstituierten oder einen einfach durch CN oder CF₃ oder einen mindestens einfach durch Halogen substituierten Alkyl- oder Alkenylrest mit 1 bis 10 C-Atomen,
bedeutet.The invention relates to cyclohexane derivatives of the formula I,

in which
at least one of the radicals
R ¹ and R ^{2 is} an alkenyl radical having 2 to 7 carbon atoms and the other radical R ¹ or R ^{2 is} an unsubstituted or substituted by CN or CF ₃ or at least one halogen-substituted alkyl or alkenyl radical having 1 to 10 C. -atoms,
means.

The invention further relates to the use of these compounds as components of liquid-crystalline media.

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

The invention had the object of finding new stable liquid-crystalline or mesogenic compounds which are suitable as components of liquid-crystalline media and, in particular, at the same time have a comparatively low viscosity and a relatively high nematogeneity.

However, in view of the various uses of such compounds with low Δε, it was desirable to have available further compounds with high nematogeneity, which have precisely tailor-made properties for the respective applications. With the aid of the compounds according to the invention, it is possible to realize STN mixtures with surprisingly good steepness. In comparison to the corresponding dialkylated compounds, these substances have higher clearing points, better solubility, and a much lower tendency to form smectic phases.

Similar compounds are in the EP 0 256 097 B1 . DE 40 05 869 A1 . EP 0 365 962 A1 . EP 0 388 150 A1 and EP 0 471 287 A1 described. However, in contrast to the compounds according to the invention, these have an alkenyloxy radical instead of an alkenyl radical or are only encompassed by a generic formula.

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

With the provision of compounds of the formula I, the range of liquid-crystalline substances which are suitable for the production of liquid-crystalline mixtures from a variety of application-technical points of view is also broadly broader.

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

The compounds of the formula I are colorless in the pure state and form liquid-crystalline mesophases in a temperature range which is favorably located for the electro-optical use. Chemically, thermally and against light, they are stable.

The invention thus relates to the compounds of the formula I. The invention furthermore relates to liquid-crystalline media containing at least one compound of the formula I.

R³ bzw. R⁴ bedeutet in den Teilformeln I1 bis I4 vorzugsweise H oder Methyl.A very particularly preferred smaller group of compounds are those of the subformulae I1 and I4:
(R ³ , R ⁴ : H or C _1-5 -alkyl)

R ³ or R ⁴ in the part formulas I1 to I4 is preferably H or methyl.

If R ¹ or R ^{2 is} an alkyl radical, this may be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, 6 or 7 carbon atoms and therefore preferably denotes ethyl, propyl, butyl, pentyl, hexyl, heptyl, furthermore methyl, octyl, nonyl or decyl.

If R ¹ and / or R ^{2 is} an alkyl radical in which one CH ₂ group has been replaced by -CH = CH-, this may be straight-chain or branched. It is preferably straight-chain and has 2 to 10 C atoms. It 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 ¹ or R ² represents an easily by CN or CF ₃ alkyl or alkenyl radical, this radical is preferably straight-chain and the substitution by CN or CF ₃ in ω-position.

If R ¹ and / or R ^{2 is} an alkyl or alkenyl radical which is at least monosubstituted by halogen, this radical is 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 fluoro or chloro substituent may be in any position, but preferably in the ω position.

Compounds of the formula I having branched wing groups R ¹ and R ² may occasionally be of importance because of 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 are isopropyl, 2-butyl (= 1-methylpropyl), isobutyl (= 2-methylpropyl), 2-methylbutyl, isopentyl (= 3-methyl-butyl), 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-propylpentyl.

Compounds of the formula I which have wing groups R ¹ and R ² suitable for polycondensations are suitable for the preparation of liquid-crystalline polycondensates.

Formula I includes both the racemates of these compounds and the optical antipodes and mixtures thereof.

Preferred among these compounds of the formula I and the sub-formulas are those in which at least one of the radicals contained therein has one of the preferred meanings given.

In the compounds of formula I, those stereoisomers are preferred in which the rings are trans-1,4-disubstituted cyclohexane rings.

The compounds of the formula I are prepared by methods known per se, as described in the literature (eg in the standard works such as Houben-Weyl, Methods of Organic Chemistry, Georg-Thieme). Verlag, Stuttgart), under reaction conditions which are known and suitable for the reactions mentioned.

One can also make use of known per se, not mentioned here variants.

The compounds of the invention may, for. B. be prepared as follows:
(R ³ , R ⁴ : H or alkyl) Scheme 1

The liquid-crystalline media according to the invention preferably contain, in addition to one or more compounds according to the invention, as further constituents 2 to 40, in particular 4 to 30 components. With very particular preference these media contain, in addition to one or more compounds according to the invention, 7 to 25 components. These further constituents are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, in particular substances from the classes of azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, phenyl or cyclohexyl benzoates, cyclohexanecarboxylic acid phenyl or cyclohexyl esters, phenyl or cyclohexyl esters Cyclohexylbenzoic acid, phenyl or cyclohexyl esters of cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl esters of benzoic acid, of cyclohexanecarboxylic acid or of cyclohexylcyclohexanecarboxylic acid, phenylcyclohexanes, cyclohexylbiphenyls, phenylcyclohexylcyclohexanes, cyclohexylcyclohexanes, cyclohexylcyclohexylcyclohexenes, 1,4-biscyclohexylbenzenes, 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-cycloh exyl-2-biphenylylethanes, 1-phenyl-2-cyclohexyl-phenylethanes, optionally halogenated stilbenes, benzylphenyl ethers, tolans and substituted cinnamic acids. The 1,4-phenylene groups in these compounds can also be fluorinated.

The most important compounds which may be used as further constituents of media according to the invention can be characterized by the formulas 1, 2, 3, 4 and 5: R'-LE-R '' 1 R'-L-COO-E-R "2 R'-L-OOC-E-R "3 R'-L-CH ₂ CH ₂ -E-R "4 R'-LC≡C-R "5

In formulas 1, 2, 3, 4 and 5, L and E, which may be the same or different, each independently represents a bivalent radical selected 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 is unsubstituted or substituted by fluorine 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-diaxan-2,5-diyl.

Preferably, one of L and E is Cyc, Phe or Pyr. E is preferably Cyc, Phe or Phe-Cyc. Preferably, the media according to the invention comprise 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 simultaneously 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 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 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. In the following, this smaller subgroup will be called Group A and the compounds will be referred to as Partial Formulas 1a, 2a, 3a, 4a and 5a. In most of these compounds R 'and R "are different from each other, 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) _l 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, -CF ₃ , -OCHF ₂ or -OCF ₃ .

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

In another smaller subgroup of the compounds of formulas 1, 2, 3, 4 and 5, R "is -CN; this subgroup is referred to below as group C and the compounds of this subgroup are described respectively with sub-formulas 1c, 2c, 3c, 4c and 5c. In the compounds of sub-formulas 1c, 2c, 3c, 4c and 5c, R 'has the meaning given for the compounds of sub-formulas 1a-5a and is preferably alkyl, alkoxy or alkenyl.

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

In addition to compounds of the formula I according to the invention, the media according to the invention preferably comprise one or more compounds which are selected from the group A and / or group B and / or group C. The mass fractions of the compounds from these groups on the media according to the invention 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% wherein the sum of the mass fractions of the compounds of the groups A and / or B and / or C contained in the respective inventive media is preferably 5 to 90% and in particular 10 to 90%.

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

The preparation of the media according to the invention is carried out in a conventional manner. In general, the components are dissolved in each other, useful at elevated temperature. By means of suitable additives, the liquid-crystalline phases according to the invention can be modified so that they can be used in all hitherto known types of liquid-crystal display elements. Such additives are known to the person skilled in the art and are described in detail in the literature (H. Kelker / R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980). For example, pleochroic dyes can be added to produce colored guest-host systems or to modify the dielectric anisotropy, viscosity and / or orientation of the nematic phases.

Tabelle B:

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: Code for R ¹ , R ² , L ¹ and L ² R ¹ R ² L ¹ L ² nm C _n H _{2n + 1} C _m H _{2m + 1} H H n Om C _n H _{2n + 1} OC _m H _{2m + 1} H H nO.m OC _n H _{2n + 1} C _m H _{2m + 1} H H n C _n H _{2n + 1} CN H H nN.F C _n H _{2n + 1} CN H F nF C _n H _{2n + 1} F H H nOF OC _n H _{2n + 1} F H H n Cl C _n H _{2n + 1} Cl H H nF.F C _n H _{2n + 1} F H F nF.FF C _n H _{2n + 1} F F F nCF ₃ C _n H _{2n + 1} CF ₃ H H nOCF ₃ C _n H _{2n + 1} OCF ₃ H H nOCF ₂ C _n H _{2n + 1} OCHF ₃ H H nS C _n H _{2n + 1} NCS H H RVSN C _r H _{2r + 1} -CH = CH-C _s H _2s - CN H H rESn C _r H _{2r + 1} -OC _s H _2s - CN H H nAm C _n H _{2n + 1} COOC _m H _{2m + 1} H H nOCCF ₂ .FF C _n H _{2n + 1} OCH ₂ CF ₂ H F F Table A:

Table B:

The following examples are intended to illustrate the invention without limiting it. Above and below, percentages are by weight. All temperatures are in degrees Celsius. Mp means melting point, bp = clearing point. Furthermore, K = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The data between these symbols represent the transition temperatures. Δn means optical anisotropy (589 nm, 20 ° C) and the viscosity (mm ² / sec) was determined at 20 ° C.

"Conventional work-up" means: water is optionally added, extracted with dichloromethane, diethyl ether, methyl tert-butyl ether or toluene, separated, the organic phase is dried, evaporated and the product is purified by distillation under reduced pressure or crystallization and / or chromatography.

DMF

N,N-Dimethylformamid

DMEU

1,3-Dimethyl-2-imidazolidinon

KOT

Kalium-tertiär-butanolat

THF

Tetrahydrofuran

pTsOH

p-Toluolsulfonsäure

Beispiel 1

Schritt 1.1

The following abbreviations are used:

DMF

N, N-dimethylformamide

DMEU

1,3-dimethyl-2-imidazolidinone

KOT

Potassium tert-butoxide

THF

tetrahydrofuran

pTsOH

p-toluenesulfonic acid

example 1

Step 1.1

0.206 mol of lithium aluminum hydride are suspended in 130 ml of THF and treated dropwise with a solution of 0.206 mol of I dissolved in 620 ml of THF. The mixture is refluxed for 2.5 h, allowed to cool to 5-10 ° C and cautiously mixed with 8 ml of H ₂ O and 70 ml of THF. After addition of 90 ml of a sat. Sodium carbonate solution is mixed with water and methyl tert-butyl ether and worked up as usual. Step 1.2

0.17 mol of pyridinium chlorochromate and 28 g of Celite are suspended in 220 ml of 1,2-dichloropropane and treated while stirring with 0.17 mol II dissolved in 1.2 l of 1,2-dichloropropane. It is stirred overnight, the precipitate is filtered off with suction and the filtrate is worked up as usual. Step 1.3

0.204 mmol III and 0.244 mol Ethyltriphenylphosphoniumbromid are dissolved in 25 ml of THF and presented at 0 ° C in a nitrogen atmosphere and treated dropwise with 2.4 g of potassium tert.butylat dissolved in 20 ml of THF at -70 ° C added. The mixture is allowed to warm with stirring to room temperature, treated with water and brine, acidified with 2 N hydrochloric acid and worked up as usual. Step 1.4

In a nitrogen atmosphere 23.3 mmol IV are dissolved in 30 ml of toluene and boiled with 6.2 mmol of benzenesulfinic acid sodium salt and 8.5 ml of 1 N hydrochloric acid at reflux. Then it is worked up as usual. The product is eluted with dichloromethane over a silica gel column. K 80 S _B 248 N 259 I; Δε = 1.75

hergestellt: R¹ R⁴ C₂H₅ CH₃ C₂H₅ C₂H₅ C₂H₅ n-C₃H₇ n-C₃H₇ CH₃ n-C₃H₇ C₂H₅ n-C₃H₇ n-C₃H₇ n-C₅H₁₁ CH₃ n-C₅H₁₁ C₂H₅ n-C₅H₁₁ n-C₃H₇ n-C₅H₁₁ CH₃ n-C₅H₁₁ C₂H₅ n-C₅H₁₁ n-C₃H₇ CH₃-CH=CH- CH₃ CH₃-CH=CH- C₂H₅ CH₃-CH=CH- n-C₃H₇ Beispiel 2

Analogously, the following compounds of the formula

produced: R ¹ R ⁴ C ₂ H ₅ CH ₃ C ₂ H ₅ C ₂ H ₅ C ₂ H ₅ nC ₃ H ₇ nC ₃ H ₇ CH ₃ nC ₃ H ₇ C ₂ H ₅ nC ₃ H ₇ nC ₃ H ₇ nc ₅ H ₁₁ CH ₃ nc ₅ H ₁₁ C ₂ H ₅ nc ₅ H ₁₁ nC ₃ H ₇ nc ₅ H ₁₁ CH ₃ nc ₅ H ₁₁ C ₂ H ₅ nc ₅ H ₁₁ nC ₃ H ₇ CH ₃ -CH = CH- CH ₃ CH ₃ -CH = CH- C ₂ H ₅ CH ₃ -CH = CH- nC ₃ H ₇ Example 2

0.0204 mol of III and 0.0204 mol of methyltriphenylphosphonium bromide are dissolved in 25 ml of THF in a nitrogen atmosphere and cooled to 0-5 ° C. After addition of 2.4 g of potassium tert-butoxide dissolved in 20 ml at -5 ° C is allowed to warm to room temperature and stirred for 2 h at room temperature. Then it is worked up as usual. K 37 S _B 225 N 235.1 I Δn = + 0.089; Δε = 1.75

The isomerization is carried out analogously to step 1.4.

hergestellt. Mischungsbeispiele Beispiel A PCH-3 22,0% Klärpunkt [°C]: +86 PCH-4 11,0% Δn [589 nm, 20°C]: +0,1067 PCH-5 9,0% STN 240° PCH-301 17,0% d·Δn [μm]: 0,85 CCP-2OCF₃ 6,0% V_(10,0,20) [V]: 2,22 CCP-3OCF₃ 6,0% V₉₀/V₁₀: 1,044 CCP-4OCF₃ 6,0% CCP-5OCF₃ 6,0% CBC-33F 4,0% CBC-53F 3,0% CCC-3-V 10,0% Beispiel B PCH-3 21,8% Klärpunkt [°C]: +79 ME2N.F 2,6% ME3N.F 3,0% K6 8,0% PCH-301 4,0% CCH-34 10,8% CCH-35 7,2% CCC-3V 12,0% CP-1V-N 3,0% CC-3-2V 9,0% CCP-1-V 9,0% CCP-1-V1 8,4% CCP-3OCF₃ 1,2% Beispiel C PCH-3 25,0% Klärpunkt [°C]: +82 CP-1V-N 5,0% ME2N.F 3,0% ME3N.F 3,0% K6 5,0% PCH-301 2,0% CCH-34 3,0% CCH-35 4,0% CC-3-2V 15,0% CCP-1-V 15,0% CCP-1-V1 4,0% CCC-3-V 10,0% Beispiel D PCH-3 25,0% Klärpunkt [°C]: +81 CP-1V-N 5,0% ME2N.F 2,0% ME3N.F 3,0% ME4N.F 4,0% PCH-301 2,0% CCH-34 9,0% CCH-35 4,0% PTP-102 2,0% CC-3-2V 15,0% CCP-1-V 15,0% CCP-1-V1 4,0% CCC-3-V 10,0% Beispiel E PCH-3 19,0% Klärpunkt [°C]: +83 PCH-4 9,0% ME2N.F 2,0% ME3N.F 2,0% K6 6,0% PCH-301 12,0% CCH-34 16,0% CCP-1-V 14,0% CCP-1-V1 10,0% CCC-3-V 10,0% Beispiel F PCH-3 24,0% Klärpunkt [°C]: +81 PCH-4 18,0% Δn [589 nm, 20°C]: +0,1103 PCH-301 11,0% STN 240° PCH-302 5,0% d·Δn [μm]: 0,85 BCH-301 8,0% V_(10,0,20) [V]: 2,30 BCH-302 8,0% V₉₀/V₁₀: 1,042 CCH-34 16,0% CCC-3-V 10,0% Beispiel G PCH-3 21,0% Klärpunkt [°C]: +84 PCH-4 9,0% Δn [589 nm, 20°C]: +0,1070 PCH-5 9,0% STN 240° PCH-301 16,0% d·Δn [μm]: 0,85 CCP-2OCF₃ 5,0% V_(10,0,20) [V]: 2,28 CCP-3OCF₃ 5,0% V₉₀/V₁₀ 1,04 CCP-4OCF₃ 5,0% CCP-5OCF₃ 5,0% PTP-201 2,0% CCC-1-V 130% CCC-3-V 10,0% Beispiel H PCH-3 23,0% Klärpunkt [°C]: +85 PCH-4 16,0% Δn [589 nm, 20°C]: +0,1405 PCH-302 22,0% STN 240° K6 3,0% d·Δn [μm]: 0,85 CCP-3OCF₃ 4,0% V_(10,0,20) [V]: 2,23 CPTP-301 4,0% V₉₀/V₁₀ 1,045 CPTP-302 3,0% PTP-201 5,0% BCH-301 5,0% BCH-302 5,0% CCC-3-V 10,0% Analog will be the following connections

produced. Mixing Examples Example A PCH-3 22.0% Clearing point [° C]: +86 PCH-4 11.0% Δn [589 nm, 20 ° C]: +0.1067 PCH-5 9.0% STN 240 ° PCH-301 17.0% d · Δn [μm]: 0.85 CCP-2OCF ₃ 6.0% V _(10,0,20) [V]: 2.22 CCP-3OCF ₃ 6.0% V ₉₀ / V ₁₀ : 1,044 CCP-4OCF ₃ 6.0% CCP-5OCF ₃ 6.0% CBC-33F 4.0% CBC-53F 3.0% CCC-3-V 10.0% Example B PCH-3 21.8% Clearing point [° C]: +79 ME2N.F 2.6% ME3N.F 3.0% K6 8.0% PCH-301 4.0% CCH-34 10.8% CCH-35 7.2% CCC 3V 12.0% CP-1V-N 3.0% CC-3-2V 9.0% CCP-V-1 9.0% CCP-1 V1 8.4% CCP-3OCF ₃ 1.2% Example C PCH-3 25.0% Clearing point [° C]: +82 CP-1V-N 5.0% ME2N.F 3.0% ME3N.F 3.0% K6 5.0% PCH-301 2.0% CCH-34 3.0% CCH-35 4.0% CC-3-2V 15.0% CCP-V-1 15.0% CCP-1 V1 4.0% CCC-3-V 10.0% Example D PCH-3 25.0% Clearing point [° C]: +81 CP-1V-N 5.0% ME2N.F 2.0% ME3N.F 3.0% ME4N.F 4.0% PCH-301 2.0% CCH-34 9.0% CCH-35 4.0% PTP 102 2.0% CC-3-2V 15.0% CCP-V-1 15.0% CCP-1 V1 4.0% CCC-3-V 10.0% Example E PCH-3 19.0% Clearing point [° C]: +83 PCH-4 9.0% ME2N.F 2.0% ME3N.F 2.0% K6 6.0% PCH-301 12.0% CCH-34 16.0% CCP-V-1 14.0% CCP-1 V1 10.0% CCC-3-V 10.0% Example F PCH-3 24.0% Clearing point [° C]: +81 PCH-4 18.0% Δn [589 nm, 20 ° C]: +0.1103 PCH-301 11.0% STN 240 ° PCH-302 5.0% d · Δn [μm]: 0.85 BCH-301 8.0% V _(10,0,20) [V]: 2.30 BCH-302 8.0% V ₉₀ / V ₁₀ : 1,042 CCH-34 16.0% CCC-3-V 10.0% Example G PCH-3 21.0% Clearing point [° C]: +84 PCH-4 9.0% Δn [589 nm, 20 ° C]: +0.1070 PCH-5 9.0% STN 240 ° PCH-301 16.0% d · Δn [μm]: 0.85 CCP-2OCF ₃ 5.0% V _(10,0,20) [V]: 2.28 CCP-3OCF ₃ 5.0% V ₉₀ / V ₁₀ 1.04 CCP-4OCF ₃ 5.0% CCP-5OCF ₃ 5.0% PTP 201 2.0% CCC-1-V 130% CCC-3-V 10.0% Example H PCH-3 23.0% Clearing point [° C]: +85 PCH-4 16.0% Δn [589 nm, 20 ° C]: +0.1405 PCH-302 22.0% STN 240 ° K6 3.0% d · Δn [μm]: 0.85 CCP-3OCF ₃ 4.0% V _(10,0,20) [V]: 2.23 CPTP-301 4.0% V ₉₀ / V ₁₀ 1,045 CPTP-302 3.0% PTP 201 5.0% BCH-301 5.0% BCH-302 5.0% CCC-3-V 10.0%

Claims (4)

Cyclohexane derivatives of the formula I,

where at least one of the radicals R ¹ and R ^{2 is} an alkenyl radical having 2 to 7 C atoms and the other radical R ¹ or R ^{2 is} an unsubstituted or an alkyl or alkenyl radical which is monosubstituted by CN or CF ₃ or at least monosubstituted by halogen with 1 to 10 carbon atoms, means. Compounds according to claim 1 of formula I1,

wherein R ^{3 is} H or an alkyl radical having 1 to 5 carbon atoms. Compounds according to claim 1 of the formula I4

wherein R ³ and R ^{4 are} each independently H or an alkyl radical having 1 to 5 carbon atoms. Liquid-crystalline medium having at least two liquid-crystalline components, characterized in that it contains at least one compound of the formula I.