CH678947A5 - Poly:cyclic cyclohexene cpds. with di:fluoro-phenylene ring - Google Patents

Abstract

New di-, tri- and tetra-cyclic cyclohexene derivs. contg. 2,3-difluoro- 1,4-phenylene ring(s) are of formula (I): R1-A1-Z1-A2-(Z2-A3)m-R2 (I) R1 and R2 = 1-15C alkyl or 3-15C alkenyl, opt. with one CN or at least one F or Cl substit., in which a CH2 gp. can be replaced by -O-, -CO-, -O-CO-, -CO-O- or -O-CO-O-; and one of R1 and R2 can also = CN; A1, A2 and A3 = 1,4-cyclohexenylene, trans-1,4-cyclohexylene, in which one or two non-adjacent CH2 gps. can be replaced by -O-, or 1,4-phenylene, opt. with one or two F substits., in which one or two CH gps. can be replaced by N, at least one of A1-3 being = 2,3-difluoro- 1,4-phenylene and at least one = 1,4-cyclohexenylene; Z1 and Z2 = -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH2CH2- or a single bond. (I) can be prepd. (not claimed) by standard methods, as described e.g., in Houben-Weyl, Methoden der Organischen Chemie, Georg-Thieme-Verlag, Stuttgart.

Description

       

  
 



  The invention relates to cyclohexene derivatives of the formula I
 
 R <1> -A <1> -Z <1> -A <2> - (Z <2> -A <3>) m-r <2> I
 
 wherein
 R <1> and R <2> in each case independently of one another unsubstituted alkyl with 1-15 C atoms or alkenyl with 3-15 C atoms which is simply substituted by cyan or at least simply by fluorine or chlorine, in which radicals a CH2 group is also represented by -O- , -CO-, -O-CO-, -CO-O- or -O-CO-O- can be replaced, one of the radicals R <1> and R <2> also CN,
 m 0, 1 or 2,
 A <1>, A <2> and A <3> each independently of the other 1,4-cyclohexenylene, trans-1,4-cyclohexylene, in which one or two non-adjacent CH2 groups can also be replaced by -O-, or unsubstituted or 1,4-substituted by fluorine Phenylene, in which one or two CH groups can also be replaced by N,
 Z <1> and Z <2> each independently of one another -CO-O-, -O-CO-, -CH2O-, -OCH2-,

   -CH2CH2- or a single bond,
 with the proviso that at least one of groups A <1>, A <2> and A <3> 2,3-difluoro-1,4-phenylene and at least one of the remaining groups A <1>, A <2> and A <3> 1,4-cyclohexenylene.



  For the sake of simplicity, Cyc in the following means a 1,4-cyclohexylene group, Dio a dioxane-2,5-diyl group, Dit a dithiane-2,5-diyl group, Pyd a pyridine-2,5-diyl group, Pyr a pyrimidine-2, 5-diyl group, Pyz a pyridazine-3,5-diyl group, Phe a 1,4-phenylene group, PheF a group of the formula
EMI2.1
 



  PheF2 is a group of the formula
EMI2.2
 



  and Che a group of the formula
EMI2.3
 



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



  It is known that dielectrically positive compounds with trans-1,4-cyclohexylene and 1,4-cyclohex-1-enylene groups have a low optical anisotropy with simultaneously reduced viscosity than those with 1,4-phenylene groups (for example DE OS 3 023 368). The advantage of the 1,4-cyclohexenylene group over the 1,4-cyclohexyl group is based on the fact that there is no cis / trans isomerism in these. A disadvantage is their high sensitivity to actinic radiation. In particular, cyclohexene derivatives, whose double bond is conjugated to other electron systems, undergo chemical changes due to the radiation of light.



  Compounds of formula I with negative anisotropy of the dielectric constant (DELTA epsilon = epsilon PARALLEL - epsilon ORTHOGONAL <0, where epsilon PARALLEL mean the dielectric constant along the longitudinal axis of the molecule and e ORTHOGONAL mean the dielectric constant perpendicular to it) are aligned in an electrical field with their longitudinal axes perpendicular to the direction of the field. This effect is known and is used to control the optical transparency in various liquid crystal displays, e.g. in liquid crystal cells of the light scattering type (dynamic scattering), of the so-called DAP type (deformation of aligned phases) or of the guest / host type (guest host interaction).



  When using a liquid crystal with positive dielectric anisotropy, its homogeneous orientation (which is achieved by treating the plate surface) is homeotropically aligned by applying a voltage, i.e. the cell is switched from "colored" to "colorless". In this way, colorless characters are displayed on a colored background. In contrast, when using a liquid crystal with negative dielectric anisotropy, its homeotropic orientation (by treating the plate surface) is aligned by applying a voltage parallel to the electrode surfaces, which enables the display of colored picture elements on a colorless background.



  The ECB effect (electrically controlled birefringence) or DAP effect (deformation of erected phases) was first described in 1971 (MF Schieckel and K. Fahrenschon, "Deformation of nematic liquid crystals with vertical orientation in electrical fields", Appl. Phys. Lett 19 [1971], 3912). Works by J.F. Kahn (Appl. Phys. Lett. 20 [1972], 1193) and G. Labrunie and J. Robert (J. Appl. Phys. 44 [1973], 4869).



  The work of J. Robert and F. Clerc (SID 80 Digest Techn. Papers [1980], 30), J. Duchene (Displays 7 [1986], 3) and H. Schad (SID 82 Digest Techn. Papers [1982] , 244) have shown that liquid crystalline phases must have high values for the ratio of the elastic constants K3 / K1, high values for the optical anisotropy DELTA n and values for the dielectric anisotropy DELTA epsilon values in order for to be able to use highly informative display elements based on the ECB effect.



  It is known that the ratio of the elastic constants K3 / K1 can be influenced favorably by introducing non-conjugated double bonds (e.g.) M. Schadt (Chimia 41, 347 [1987]).



  Electro-optical display elements based on the ECB effect have a homeotropic edge orientation, i.e. the liquid crystalline phase has a negative dielectric anisotropy.



  For the technical application of this effect in electro-optical display elements, LC phases are required, which have to meet a variety of requirements. The chemical resistance to moisture, air and physical influences such as heat, radiation in the infrared, visible and ultraviolet range and electrical DC and AC fields are particularly important here.



  Furthermore, technically usable LC phases require a liquid-crystalline mesophase in a suitable temperature range and a low viscosity.



  There is therefore still a great need for liquid-crystalline phases with favorable meso ranges, high values for K3 / K1, high optical anisotropy DELTA n, negative dielectric anisotropy DELTA epsilon and high long-term stability.



  Compounds of the formula I are also suitable as components of chirally tilted smectic phases.



   Chirally tilted smectic liquid crystalline phases with ferroelectric properties can be produced by adding a suitable chiral dopant to base mixtures with one or more tilted smectic phases (LA Veresnev et al., Mol. Cryst. Liq. Cryst. 89, 327 [ 1982]; HR Brand et al., J. Physique 44 [lett.], L-771 [1983]). Such phases can be used as dielectrics for fast-switching displays based on the principle of SSFLC technology described by Clark and Lagerwall (NA Clark and ST Lagerwall, Appl. Phys. Lett. 36, 899 [1980]; USP 4,367,924) based on the ferroelectric properties of the chirally tilted phase.



  A number of liquid-crystalline compounds with weakly negative dielectric anisotropy have already been synthesized. On the other hand, relatively few liquid crystal components with a large negative anisotropy of the dielectric constant are known. In addition, the latter generally have disadvantages, e.g. poor solubility in mixtures, high viscosity, high melting points and chemical instability. There is therefore a need for further compounds with negative dielectric anisotropy which make it possible to further improve the properties of mixtures for a wide variety of electro-optical applications.



  Liquid crystal components with negative dielectric anisotropy, which have two or three rings linked via carboxyl groups or covalent bond and one or more side groups, such as halogen, cyano or nitro groups, are known from DE 2 240 864, DE 2 613 293, DE 2 835 662, DE 2,836,086 and EP 023 728.



  DE 3 023 368 describes compounds of the formula R <1> -Che1-Phe-R <2> claims, where Phe can also be substituted once or twice with nitrile and / or halogen. However, no individual compounds of the formula according to the invention are mentioned there. The person skilled in the art could therefore neither easily derive synthesis possibilities for the claimed compounds from the prior art nor recognize that the compounds according to the invention predominantly have conveniently located mesophase regions and are distinguished by a large negative anisotropy of the dielectric with a simultaneously low viscosity.



  There is also no reference to the possibility of using the compounds according to the invention in displays based on SSFLC technology, since the compounds claimed there have low smectic tendencies.



  The object of the invention was to demonstrate stable, liquid-crystalline or mesogenic compounds with a large negative anisotropy of the dielectric and at the same time a low viscosity.



  It has been found that the compounds of the formula I are particularly suitable as components of liquid-crystalline phases. In particular, they can be used to produce stable liquid-crystalline phases with a wide mesophase range and comparatively low viscosity.



  The compounds of the formula I are also suitable as components of chirally tilted smectic liquid-crystalline phases.



  With the provision of the compounds of the formula I, the range of liquid-crystalline substances which are suitable for the preparation of liquid-crystalline mixtures from various technical points of view is also very broadly widened.



  The compounds of formula I have a wide range of applications. Depending on the choice of the substituents, these compounds can serve as base materials from which liquid-crystalline phases 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, for example to improve the dielectric and / or optical anisotropy and / or the viscosity and / or the spontaneous polarization and / or the phase ranges and / or the tilt angle and / or the To vary the pitch of such a dielectric.



  The compounds of the formula I are also suitable as intermediates for the preparation of other substances which can be used as constituents of liquid-crystalline dielectrics.



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



  The invention thus relates to the compounds of the formula I, in particular the compounds of the formula II
 
 R <1> - (A DEG) n-Che-Z <1> - (A <1> -Z <2>) m-A <2> -R <2> II
 
 wherein
 R <1>, R <2>, Z <1>, Z <2>, A <1>, A <2> and m have the meaning given and
 A DEG trans-1,4-cyclohexylene,
 Che
EMI8.1
 
 n means 0 or 1,
 where the sum of m + n must not be three.



  The invention further relates to liquid-crystalline phases containing at least one compound of the formula I, and to liquid-crystal display elements which contain such phases. Such phases have particularly advantageous elastic constants and, because of their low DELTA epsilon / epsilon ORTHOGONAL values, are particularly suitable for TFT mixtures.



  The compounds of the formula I accordingly comprise compounds with two rings of the sub-formulas Ia and Ib:
 <tb> <TABLE> Columns = 2
 <tb> <SEP> R <1> -Che-PheF2-R <2> <SEP> Yes
 <tb> <SEP> R <1> Che-Z <1> -PheF2-R <2> <SEP> Ib
 <tb> </TABLE>



  Connections with three rings of the sub-formulas Ic to Il:
 <tb> <TABLE> Columns = 2
 <tb> <SEP> R <1> -Cyc-Che-PheF2-R <2> <SEP> Ic
 <tb> <SEP> R <1> -Cyc-CheZ <1> -PheF2-R <2> <SEP> Id
 <tb> <SEP> R <1> -Che-A <1> -PheF2-R <2> <SEP> Ie
 <tb> <SEP> R <1> -Che-PheF2-A <2> -R <2> <SEP> If
 <tb> <SEP> R <1> -Che-Z <1> -A <1> -PheF2-R <2> <SEP> Ig
 <tb> <SEP> R <1> -Che-Z <1> -PheF2-A <2> -R <2> <SEP> Ih
 <tb> <SEP> R <1> -Che-PheF2-Z <2> -A <2> -R <2> <SEP> II
 <tb> <SEP> R <1> -Che-A <1> -Z <2> -PheF2-R <2> <SEP> Ij
 <tb> <SEP> R <1> -Che-Z <1> -A <2> -PheF2-R <2> <SEP> Ik
 <tb> <SEP> R <1> -Che-Z <1> -PheF2-Z <2> -A <2> -R <2> <SEP> Il
 <tb> </TABLE>



  Connections with four rings of the sub-formulas Im to Iz6:
 <tb> <TABLE> Columns = 2
 <tb> <SEP> R <1> -Cyc-Che-PheF2-A <2> -R <2> <SEP> Im
 <tb> <SEP> R <1> -Cyc-Che-A <1> -PheF2-R <2> <SEP> In
 <tb> <SEP> R <1> -Cyc-Che-Z <1> -A <1> -PheF2-R <2> <SEP> Io
 <tb> <SEP> R <1> -Cyc-Che-Z <1> -PheF2-A <2> -R <2> <SEP> Ip
 <tb> <SEP> R <1> -Cyc-Che-PheF2-Z <2> -A <2> -R <2> <SEP> Iq
 <tb> <SEP> R <1> -Cyc-Che-A <1> -Z <2> -PheF2-R <2> <SEP> Ir
 <tb> <SEP> R <1> -Cyc-Che-Z <1> -A <1> -Z <2> -PheF2-R <2> <SEP> Is
 <tb> <SEP> R <1> -Cyc-Che-Z <1> -PheF2-Z <2> -A <2> -R <2> <SEP> It
 <tb> <SEP> R <1> -Che-PheF2-A <2> -A <2> -R <2> <SEP> Iu
 <tb> <SEP> R <1> -Che-A <1> -PheF2-A <2> -R <2> <SEP> Iv
 <tb> <SEP> R <1> -Che-A <1> -A <2> -PheF2-R <2> <SEP> Iw
 <tb> <SEP> R <1> -Che-Z <1> -A <1> -A <2> -PheF2-R <2> <SEP> Ix
 <tb> <SEP> R <1> -Che-Z <1> -A <1> -PheF2-A <2> -R <2> <SEP> Iy
 <tb> <SEP> R <1> -Che-Z <1> -PheF2-A <2> -A <2> -R <2> <SEP> Iz
 <tb> <SEP> R <1> -Che-PheF2-Z <2> -A <2> -A <2> -R <2> <SEP> Iz1
 <tb>

    <SEP> R <1> -Che-A <1> -Z <2> -PheF2-A <2> -R <2> <SEP> Iz2
 <tb> <SEP> R <1> -Che-A <1> -Z <2> -PheF2-R <2> <SEP> Iz3
 <tb> <SEP> R <1> -Che-A <1> -A <2> -Z <2> -PheF2-R <2> <SEP> Iz4
 <tb> <SEP> R <1> -Che-A <1> -PheF2-Z <2> -A <2> -R <2> <SEP> Iz5
 <tb> <SEP> R <1> -Che-PheF2-A <2> -Z <2> -A <2> -R <2> <SEP> Iz6
 <tb> </TABLE>



  In the above formulas Ia to Iz6, Che denotes a 1,4-cyclohexenylene group of the formula:
EMI10.1
 



  In the compounds in which the Che group is adjacent to a PheF2 group or the group A <1> Phe, PheF, Pyr, Pyd, Pyz means, Che is preferably Che1 or Che2, in particular Che1.



  In the above compounds of the formulas Ia to Iz6, Z <1> and Z <2> -CO-O-, -O-CO-,
 -CH2O-, OCH2- or -CH2CH2-, but preferably -CO-O-, -O-CO- or -CH2CH2-.



  In the compounds of the formulas Ia to Iz6, in which the Che group of a Z <1> group is adjacent and means Che3 is Z <1> preferably -O-CO-, -CH2O-, -OCH2- or -CH2CH2-, in particular
 -CH2CH2- or -CH2O-.



  In the compounds of the formulas above and below, R <1> and R <2> preferably alkyl, furthermore alkoxy. Furthermore, one of the radicals R <1> and R 2 also mean CN, in the formulas above and below the radical R preferably denotes <2> CN.



  A <1> and A <2> are Phe, Pyr, Pyd, Pyz, Cyc, Dio, Dit, PheF and PheF2, the compound of the formula I preferably contains no more than one of the residues PheF2, Pyr, Pyd, Pyz, Dio, Dit.



  R <1> and R In the formulas above and below, <2> preferably have 1-13 C atoms, in particular 3-12 C atoms. Compounds of the formulas I in which R <1> and R 1 to 7 carbon atoms, preferably 3 to 6 carbon atoms, are particularly suitable for liquid-crystalline phases for display elements based on the ECB effect. Compounds of formula I, however, in which R <1> and R <2> 7-15 carbon atoms, preferably 8-12 carbon atoms, are suitable for liquid-crystalline phases with ferroelectric properties. In R <1> and R <2> one or two CH2 groups can also be replaced. Preferably only one CH2 group is replaced by -O-, -CO-, -O-CO-, -CO-O- or OCO-O, in particular by -O- or CO-O.



  If R <2> means a cyano group, then its neighboring group is A <3> or A <2> preferably Phe, PheF, PheF2 or Pyr, especially PheF2.



  If R <1> and R <2> Alkyl radicals in which one ("alkoxy" or "oxaalkyl") or two ("alkoxylakoxy" or "dioxaalkyl") non-adjacent CH2 groups can be replaced by O atoms, they can be straight-chain or be branched. They are preferably straight-chain, have 2, 3, 4, 5, 6 or 7 carbon atoms and are therefore preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy, and also methyl , Octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octoxy, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy or tetradecoxy.



  Oxaalkyl preferably means 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-oxaoctyl, 2-, 3-, 4-, 5-, 6 -, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl, 1,3-dioxabutyl (= methoxymethoxy), 1,3-, 1 , 4-, 2,4-Dioxa pentyl, 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.



  If R <1> and R <2> mean an alkenyl radical, this can be straight-chain or branched. It is preferably straight-chain and has 2 to 10 carbon atoms. Accordingly, it 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> and R <2> mean an alkyl radical in which a CH2 group is replaced by -O-CO- or -CO-O-, this can be straight-chain or branched. It is preferably straight-chain and has 2 to 6 carbon atoms. Accordingly, it means especially acetyloxy, propionyloxy, butyryloxy, pentanoyloxy, hexanoyloxy, acetyloxymethyl, propionyloxymethyl, butyryloxymethyl, pentanoyloxymethyl, 2-acetyloxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl, 3-acetyloxypropyl, methoxycarbonyl, methoxycarbonyl 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.



  Compounds of formula I with branched wing groups R <1> and / or R <2> 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. Smectic compounds of this type are suitable as components for ferroelectric materials.



  Branched groups of this type usually contain no more than one chain branch. Preferred branched radicals R <1> and / or R <2> 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, 4-methylhexyl, 2-nonyl, 2-decyl, 2-dodecyl, 6-methyloctoxy, 6-methyloctanoyloxy, 5-methylheptyloxycarbonyl, 2-methylbutyryloxy, 3-methylvaleryloxy, 4-methylhexanoyloxy, 2-chloropropionyloxy, 2-chloro 3-methylbutyryloxy, 2-chloro-4-methylvaleryloxy, 2-chloro-3-methylvaleryloxy, 2-methyl-3-oxapentyl, 2-methyl-3-oxahexyl.



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



  Preferred compounds of the formulas I and Ia to Iz6 are those in which at least one of the radicals contained therein has one of the preferred meanings indicated.



   Of the binuclear compounds of sub-formulas Ia and Ib, those of sub-formulas I1 to I6 are preferred:
 <tb> <TABLE> Columns = 2
 <tb> <SEP> R <1> -Che1-PheF2-R <2> <SEP> I1
 <tb> <SEP> R <1> -Che2-PheF2-R <2> <SEP> I2
 <tb> <SEP> R <1> -Che3-PheF2-R <2> <SEP> I3
 <tb> <SEP> R <1> -Che1-Z <1> -PheF2-R <2> <SEP> I4
 <tb> <SEP> R <1> -Che2-Z <1> -PheF2-R <2> <SEP> I5
 <tb> <SEP> R <1> -Che3-Z <1> -PheF2-R <2> <SEP> I6
 <tb> </TABLE>



  Of the trinuclear compounds of the formulas Ic to II, those of the sub-formulas I8 to I49 are preferred:
 <tb> <TABLE> Columns = 2
 <tb> <SEP> R <1> -Cyc-Che1-PheF2-R <2> <SEP> I7
 <tb> <SEP> R <1> -Cyc-Che2-PheF2-R <2> <SEP> I8
 <tb> <SEP> R <1> -Cyc-Che3-PheF2-R <2> <SEP> I9
 <tb> <SEP> R <1> -Che1-Phe-PheF2-R <2> <SEP> I10
 <tb> <SEP> R <1> -Che2-Phe-PheF2-R <2> <SEP> I11
 <tb> <SEP> R <1> -Che1-Cyc-PheF2-R <2> <SEP> I12
 <tb> <SEP> R <1> -Cyc-Che1-Z <1> -PheF2-R <2> <SEP> I13
 <tb> <SEP> R <1> -Cyc-Che2-Z <1> -PheF2-R <2> <SEP> I14
 <tb> <SEP> R <1> -Cyc-Che3-Z <1> -PheF2-R <2> <SEP> I15
 <tb> <SEP> R <1> -Che1-PheF2-Phe-R <2> <SEP> I16
 <tb> <SEP> R <1> -Che2-PheF2-Phe-R <2> <SEP> I17
 <tb> <SEP> R <1> -Che3-PheF2-Phe-R <2> <SEP> I18
 <tb> <SEP> R <1> -Che3-PheF2-Cyc-R <2> <SEP> I19
 <tb> <SEP> R <1> -Che2-PheF2-Cyc-R <2> <SEP> I20
 <tb> <SEP> R <1> -Che1-PheF2-Phe-R <2> <SEP> I21
 <tb> <SEP> R <1> -Che3-PheF2-Che1-R <2> <SEP> I22
 <tb> <SEP> R <1> -Che1-Z <1> -PheF2-Phe-R <2>

    <SEP> I23
 <tb> <SEP> R <1> -Che2-Z <1> -PheF2-Phe-R <2> <SEP> I24
 <tb> <SEP> R <1> -Che3-Z <1> -PheF2-Phe-R <2> <SEP> I25
 <tb> <SEP> R <1> -Che3-Z <1> -PheF2-Cyc-R <2> <SEP> I26
 <tb> <SEP> R <1> -Che2-Z <1> -PheF2-Cyc-R <2> <SEP> I27
 <tb> <SEP> R <1> -Che1-Z <1> -PheF2-Cyc-R <2> <SEP> I28
 <tb> <SEP> R <1> -Che1-Z <1> -Phe-PheF2-R <2> <SEP> I29
 <tb> <SEP> R <1> -Che2-Z <1> -Phe-PheF2-R <2> <SEP> I30
 <tb> <SEP> R <1> -Che3-Z <1> -Phe-PheF2-R <2> <SEP> I31
 <tb> <SEP> R <1> -Che3-Z <1> -Cyc-PheF2-R <2> <SEP> I32
 <tb> <SEP> R <1> -Che2-Z <1> -Cyc-PheF2-R <2> <SEP> I33
 <tb> <SEP> R <1> -Che1-Z <1> -Cyc-PheF2-R <2> <SEP> I34
 <tb> <SEP> R <1> -Che1-PheF2-Z <1> -Phe-R <2> <SEP> I35
 <tb> <SEP> R <1> -Che2-PheF2-Z <1> -Phe-R <2> <SEP> I36
 <tb> <SEP> R <1> -Che3-PheF2-Z <1> -Phe-R <2> <SEP> I37
 <tb> <SEP> R <1> -Che3-PheF2-Z <1> -Cyc-R <2> <SEP> I38
 <tb> <SEP> R <1> -Che2-PheF2-Z <1> -Cyc-R <2> <SEP> I39
 <tb> <SEP> R <1> -Che1-PheF2-Z <1> -Cyc-R <2> <SEP> I40
 <tb>

    <SEP> R <1> -Che1-Phe-Z <1> -PheF2-R <2> <SEP> I41
 <tb> <SEP> R <1> -Che3-Cyc-Z <1> -PheF2-R <2> <SEP> I42
 <tb> <SEP> R <1> -Che1-Z <1> -PheF2-Z <2> -Phe-R <2> <SEP> I43
 <tb> <SEP> R <1> -Che2-Z <1> -PheF2-Z <2> -Phe-R <2> <SEP> I44
 <tb> <SEP> R <1> -Che3-Z <1> -PheF2-Z <2> -Phe-R <2> <SEP> I45
 <tb> <SEP> R <1> -Che1-Z <1> -PheF2-Z <1> -Che3-R <2> <SEP> I46
 <tb> <SEP> R <1> -Che2-Z <1> -PheF2-Z <1> -Che2-R <2> <SEP> I47
 <tb> <SEP> R <1> -Che1-Z <1> -PheF2-Z <1> -Cyc-R <2> <SEP> I48
 <tb> <SEP> R <1> -Che2-Z <1> -PheF2-Z <1> -Cyc-R <2> <SEP> I49
 <tb> <SEP> R <1> -Che3-Z <1> -PheF2-Z <1> -Cyc-R <2> <SEP> I50
 <tb> </TABLE>



  Of the tetranuclear compounds of the formulas Im to Iz6, those of the partial formulas I51 to I62 are preferred:
 <tb> <TABLE> Columns = 2
 <tb> <SEP> R <1> -Cyc-Che1-PheF2-Phe-R <2> <SEP> I51
 <tb> <SEP> R <1> -Cyc-Che3-PheF2-Phe-R <2> <SEP> I52
 <tb> <SEP> R <1> -Cyc-Che3-PheF2-Cyc-R <2> <SEP> I53
 <tb> <SEP> R <1> -Cyc-Che1-PheF2-Cyc-R <2> <SEP> I54
 <tb> <SEP> R <1> -Che1-PheF2-Phe-Phe-R <2> <SEP> I55
 <tb> <SEP> R <1> -Che3-PheF2-Phe-Phe-R <2> <SEP> I56
 <tb> <SEP> R <1> -Che3-PheF2-Che1-Phe-R <2> <SEP> I57
 <tb> <SEP> R <1> -Che3-PheF2-Cyc-Phe-R <2> <SEP> I58
 <tb> <SEP> R <1> -Che3-PheF2-Cyc-Cyc-R <2> <SEP> I59
 <tb> <SEP> R <1> -Che1-PheF2-Cyc-Cyc-R <2> <SEP> I60
 <tb> <SEP> R <1> -Che1-PheF2-Cyc-Phe-R <2> <SEP> I61
 <tb> <SEP> R <1> -Che1-PheF2-Che1-Phe-R <2> <SEP> I62
 <tb> </TABLE>



  Those of the formulas Ia to Iz6 and I1 to I62 mentioned above which contain one or more groups dio, dit, pyr, pyz and / or pyr each enclose the two possible 2,5-position isomers.



  In the above compounds, the groups Z <1> and Z <2> each independently of one another -CO-O-, -O-CO-, -CH2O-, -OCH2- or -CH2CH2-, preferably -CO-O-, -O-CO- or
  -CH2CH2-.



  The compounds of formula I are prepared by methods known per se, as described in the literature (for example in the standard works such as Houben-Weyl, Methods of Organic Chemistry, Georg-Thieme-Verlag, Stuttgart), under reaction conditions that are known and suitable for the above-mentioned implementations. Use can also be made of variants which are known per se and are not mentioned here in detail.



  If desired, the starting materials can also be formed in situ in such a way that they are not isolated from the reaction mixture, but instead are immediately converted further into the compounds of the formula I.



  Compounds of the formula I can be obtained starting from 1,2-difluorobenzene.



  This is metallized according to a known method (e.g. A.M. Roe et al., J. Chem. Soc. Chem. Comm., 22, 582 [1965]) and reacted with the corresponding electrophile. With the 1-substituted 2,3-diflurobenzene obtained in this way, this reaction sequence can be carried out a second time and the 1,4-disubstituted 2,3-difluorobenzene derivatives of the formula I are obtained. 1,2-difluorobenzene or

   1-Substituted 2,3-difluorobenzene is in an inert solvent such as diethyl ether, tetrahydrofuran, dimethoxyethane, tert-butyl methyl ether or dioxane, hydrocarbons such as hexane, heptane, cyclohexane, benzene or toluene or mixtures of these solvents, optionally with the addition of a complexing agent such as tetramethylethylenediamine or hexamethylphosphoric acid with phenyllithium, lithium tetramethylpiperidine, n-, sec- or tert-butyllithium at temperatures from -100 ° C. to +50 ° C., preferably -78 ° C. to 0 ° C.



  The lithium-2,3-difluorophenyl compounds are reacted at -100 ° C. to 0 ° C., preferably at -50 ° C., with the corresponding electrophiles. Suitable electrophiles are aldehydes, ketones, nitriles, epoxies, carboxylic acid derivatives such as esters, anhydrides or halides, halogen formate or carbon dioxide. Particularly suitable electrophiles are cyclohexanone derivatives, in particular 1,4-cyclohexanedione monoketals.



  The potassium 2,3-difluorophenyl compounds are suitable for reaction with aliphatic halogen compounds. These are tert by transmetallation of the lithium compounds with potassium. Obtained butylate at -80 ° to -120 ° C.



   The lithium 2,3-difluorophenyl compounds are transmetallated for reaction with compounds which have several electrophilic reaction centers (e.g. an aldehyde group in addition to an ester group). The titanium 2,3-difluorophenyl compounds are particularly suitable for this.



  Compounds of the formula I which contain a Che1 or Che3 group are prepared by reacting corresponding 4-substituted cyclohexanones with suitable nucleophiles and the resulting tert. Dehydrated alcohols. Suitable nucleophiles are organometallic compounds such as Grignard reagents, potassium, lithium or titanium organyls, or cyanides such as potassium or sodium cyanide or trimethylsilyl cyanide.



  Compounds of the formula I which contain a Che2 group are based on known cyclohex-2-encarboxylic acids (Z <1> = -CO-O-) (e.g. V.S. Bezborodov, et al. Zh. Org. Khim., 1 150 [1987]) or the corresponding butadienes.



  The compounds of the formula I can be prepared by reducing a compound which otherwise corresponds to the formula I but contains one or more reducible groups and / or C-C bonds instead of H atoms.



  Suitable reducible groups are preferably carbonyl groups, in particular keto groups, furthermore e.g. free or esterified hydroxyl groups or aromatically bound halogen atoms. Preferred starting materials for the reduction correspond to the formula I, but can be a cyclohexene ring or cyclohexanone ring instead of a cyclohexane ring and / or a -CH = CH group instead of a -CH2CH2 group and / or a -CO instead of a -CH2 group -Group and / or instead of an H atom contain a free or a functionally modified (eg in the form of its p-toluenesulfonate) OH group.



  The reduction can e.g. are carried out by catalytic hydrogenation at temperatures between about 0 ° and about 200 ° and pressures between about 1 and 200 bar in an inert solvent, e.g. an alcohol such as methanol, ethanol or isopropanol, an ether such as tetrahydrofuran (THF) or dioxane, an ester such as ethyl acetate, a carboxylic acid such as acetic acid or a hydrocarbon 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. PtO2, PdO), on a support (e.g. Pd on carbon, calcium carbonate or strontium carbonate) or in finely divided form.



  Ketones can also by the Clemmensen method (with zinc, amalgamated zinc or tin and hydrochloric acid, expediently in aqueous-alcoholic solution or in a heterogeneous phase with water / toluene at temperatures between about 80 and 120 °) to give the corresponding compounds of the formula I, containing alkyl groups and / or -CH2CH2 bridges can be reduced.



  Reductions with complex hydrides are also possible. For example, arylsulfonyloxy groups can be removed reductively with LiAlH4, in particular p-toluenesulfonyloxymethyl groups can be reduced to methyl groups, expediently in an inert solvent such as diethyl ether or THF at temperatures between about 0 and 100 °. Double bonds can be hydrogenated with NaBH4 or tributyltin hydride in methanol.



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



  Suitable reactive derivatives of the carboxylic acids mentioned are in particular the acid halides, especially the chlorides and bromides, and also the anhydrides, e.g. also mixed anhydrides, azides or esters, especially alkyl esters with 1-4 C atoms in the alkyl group.



  Suitable reactive derivatives of the alcohols or phenols mentioned are in particular the corresponding metal alcoholates or phenolates, preferably an alkali metal such as Na or K.



  The esterification is advantageously carried out in the presence of an inert solvent. Particularly suitable are 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. Water-immiscible solvents can at the same time advantageously be used for azeotropically distilling off the water formed during the esterification. Occasionally, an excess of an organic base, e.g. Pyridine, quinoline or triethylamine can be used as a solvent for the esterification.

  The esterification can also be carried out in the absence of a solvent, e.g. by simply heating the components in the presence of sodium acetate. The reaction temperature is usually between -50 ° and +250 °, preferably between -20 ° and +80 °. At these temperatures, the esterification reactions are usually complete after 15 minutes to 48 hours.



  Another preferred process for the preparation of the esters is a reaction of a carboxylic acid with an alcohol or phenol in the presence of a dehydrating agent, optionally with an organic base as a catalyst.



  Molecular sieves or carbodiimides such as e.g. Dicyclohexylcarbodiimides. A particularly suitable basic catalyst is 4-dimethylaminopyridine.



  In particular, the reaction conditions for the esterification largely depend on the nature of the starting materials used. A free carboxylic acid is usually reacted with a free alcohol or phenol in the presence of a strong acid, for example a mineral acid such as hydrochloric acid or sulfuric acid.

  A preferred reaction mode is the reaction of an acid anhydride or, in particular, an acid chloride with an alcohol, preferably in a basic medium, the bases being in particular alkali metal hydroxides such as sodium or potassium hydroxide, alkali metal carbonates or hydrogen carbonates such as 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, lutidine, collidine or quinoline are important.

   Another preferred embodiment of the esterification consists in first converting the alcohol or the phenol into the sodium or potassium alcoholate or phenolate, e.g. by treatment with ethanolic sodium or potassium hydroxide solution, isolate this and suspend it together with sodium hydrogen carbonate or potassium carbonate with stirring in acetone or diethyl ether and add a solution of the acid chloride or anhydride in diethyl ether, acetone or DMF to this suspension, advantageously at temperatures between about -25 ° C. and +20 DEG.



  Ethers of the formula I can be obtained by etherification of corresponding hydroxyl compounds, preferably corresponding phenols, the hydroxyl compound advantageously first being converted into a corresponding metal derivative, e.g. is converted into the corresponding alkali metal alcoholate or alkali metal phenolate by treatment with NaH, NaNH2, NaOH, KOH, Na2CO3 or K2CO3. This can then be reacted with the corresponding alkyl halide, sulfonate or dialkyl sulfate, advantageously in an inert solvent such as acetone, 1,2-dimethoxyethane, DMF or dimethyl sulfoxide or even an excess of aqueous or aqueous-alcoholic NaOH or KOH at temperatures between about 20 DEG and 100 DEG.



  Nitriles are preferably prepared from the corresponding aldehydes with hydroxylamine-O-sulfonic acid (according to J. Streith, et al. Helv. Chim. Acta 59, 2756 [1976]).



  In addition to one or more compounds according to the invention, the liquid-crystalline media according to the invention preferably contain 2 to 40, in particular 4 to 30, components as further constituents. These media very particularly preferably contain 7 to 25 components in addition to one or more compounds according to the invention.

  These further constituents are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, in particular substances from the classes of azoxybenzenes, benzylidene anilines, biphenyls, terphenyls, phenyl- or cyclohexylbenzoates, cyclohexane-carboxylic acid phenyl or cyclohexyl esters, phenyl or cyclohexyl esters Cyclohexylbenzoic acid, phenyl or cyclohexyl ester of cyclohexylcyclohexane carboxylic acid, cyclohexylphenyl ester of benzoic acid, cyclohexane carboxylic acid, or

   cyclohexylcyclohexane carboxylic acid, phenylcyclohexane, cyclohexylbiphenyl, phenylcyclohexylcyclohexane, cyclohexylcyclohexane, cyclohexylcyclohexene, cyclohexylcyclohexylcyclohexene, 1,4-biscyclohexylbenzenes, 4.4 min-bis-cyclohexyl or cyclohexyl or phenyl, phenyl or phenyl, phenyl or phenyl, phenyl or phenyl, phenyl or phenyl, phenyl or phenyl, phenyl or phenyl, phenyl or phenyl Cyclohexyl-1,3-dithiane, 1,2-diphenylethane, 1,2-dicyclohexylethane, 1-phenyl-2-cyclohexylethane, 1-cyclohexyl-2- (4-phenyl-cyclohexyl) -ethane, 1-cyclohexyl-2- biphenylylethane, 1-phenyl-2-cyclohexylphenylethane, optionally halogenated stilbenes, benzylphenyl ether, tolanes and substituted cinnamic acids. The 1,4-phenylene groups in these compounds can also be fluorinated.



  The most important compounds which are suitable as further constituents of media according to the invention can be characterized by the formulas 1, 2, 3, 4 and 5:
 <tb> <TABLE> Columns = 2
 <tb> <SEP> R min -L-E-R min min <SEP> 1
 <tb> <SEP> R min -L-COO-E-R min min <SEP> 2
 <tb> <SEP> R min -L-OOC-E-R min min <SEP> 3
 <tb> <SEP> R min -L-CH2CH2-E-R min min <SEP> 4
 <tb> <SEP> R min -L-C IDENTICAL C-E-R min min <SEP> 5
 <tb> </TABLE>



  In formulas 1, 2, 3, 4 and 5, L and E, which may be the same or different, each independently represent a bivalent radical from the group consisting of -Phe-, -Cyc-, -Phe-Phe-, -Phe- Cyc-, -Cyc-Cyc-, -Pyr-, -Dio-, -G-Phe- and -G-Cyc- as well as their mirror images formed group, whereby Phe unsubstituted or substituted by fluorine-substituted 1,4-phenylene, Cyc- 1,4-cyclohexylene or 1,4-cyclohexenylene, pyr pyrimidine-2,5-diyl or pyridine-2,5-diyl, dio 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.



  One of the radicals L and E is preferably Cyc, Phe or Pyr. E is preferably Cyc, Phe or Phe-Cyc. The media according to the invention preferably contain one or more components selected from the compounds of the formulas 1, 2, 3, 4 and 5, in which 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, in which 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, in which the radicals L and E are selected from the group -Phe-Cyc-, -Cyc-Cyc-, -G-Phe- and -G-Cyc-.



  R min and R min min in the compounds of the sub-formulas 1a, 2a, 3a, 4a and 5a each independently of one another denote alkyl, alkenyl, alkoxy, alkenyloxy or alkanoyloxy with up to 8 carbon atoms. In most of these compounds, R min and R min min are different from one another, one of these radicals usually being alkyl or alkenyl. In the compounds of the sub-formulas 1b, 2b, 3b, 4b and 5b, R min denotes -CN, -CF3, F, Cl or -NCS; R has the meaning given for the compounds of the formulas 1a to 5a and is preferably alkyl or alkenyl. However, other variants of the proposed substituents in the compounds of the formulas 1, 2, 3, 4 and 5 are also common. Many such substances or mixtures thereof are commercially available. All of these substances can be obtained by methods known from the literature or by analogy.



  In addition to components from the group of compounds 1a, 2a, 3a, 4a and 5a (group 1), the media according to the invention preferably also contain components from the group of compounds 1b, 2b, 3b, 4b and 5b (group 2), the proportions of which are preferably as follows are:
 Group 1: 20 to 90%, in particular 30 to 90%,
 Group 2: 10 to 80%, in particular 10 to 50%,
 the sum of the proportions of the compounds according to the invention and of the compounds from groups 1 and 2 giving up to 100%.



   The media according to the invention preferably contain 1 to 40%, particularly 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 media according to the invention are produced in a conventional manner. As a rule, the components are dissolved in one another, expediently at elevated temperature. By means of suitable additives, the liquid-crystalline phases according to the invention can be modified such that they can be used in all types of liquid-crystal display elements which have hitherto become known. 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 substances to change the dielectric anisotropy, the viscosity and / or the orientation of the nematic phases.



  The following examples are intended to illustrate the invention without limiting it. mp. = Melting point, cp. = Clearing point. Percentages above and below mean percentages by weight; all temperatures are given in degrees Celsius. "Conventional work-up" means: water is added, the mixture is extracted with methylene chloride, the mixture is separated off, the organic phase is dried, evaporated and the product is purified by crystallization and / or chromatography.



  It also means:



  K: crystalline solid state, S: smectic phase (the index indicates the phase type), N: nematic state, Ch: cholesteric phase, I: isotropic phase. The number between two symbols indicates the transition temperature in degrees Celsius.


 example 1
 


 4-alkyl-1- (2,3-difluorophenyl) cyclohex-1-ene
 



  A mixture of 0.3 mol of 1,2-difluorobenzene, 600 ml of tetrahydrofuran and 0.3 mol of tetramethylethylenediamine is mixed at -60 ° C. to -70 ° C. with a solution of 0.3 mol of n-butyllithium in 188 ml of hexane. After stirring for 3 hours at -60 ° C., a solution of 0.32 mol of 4-pentylcyclohexanone in 100 ml of tetrahydrofuran is added. After the usual work-up, the residue is dissolved in 1000 ml of toluene and heated with 10 g of p-toluenesulfonic acid in a water separator for 3 h. After the usual work-up, 4-pentyl-1- (2,3-difluorophenyl) cyclohex-1-ene, bp: 123 ° C./0.5 torr.



  The following are produced analogously:
 4-ethyl-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-propyl-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-butyl-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-Hexyl-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-heptyl-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-octyl-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-nonyl-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-decyl-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-dodecyl-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-ethoxy-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-propoxy-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-butoxy-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-pentoxy-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-Hexoxy-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-heptoxy-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-octoxy-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-Nonoxy-1- (2,3-difluorophenyl) cyclohex-1-ene
 4-decoxy-1- (2,3-difluorophenyl) cyclohex-1-ene
 

   4-Undecoxy-1- (2,3-difluorophenyl) cyclohex-1-ene


 Example 2
 


 1- (2,3-difluorophenyl) -4- (p-alkylphenyl) cyclohex-1-ene
 



  A mixture of 0.1 mol of 1,2-difluorobenzene and 200 ml of tetrahydrofuran is mixed at -70 ° C. with 0.105 mol of n-butyllithium in 60 ml of hexane. After stirring for 6 hours, a mixture of 0.1 mol of 4- (p-propylphenyl) cyclohexanone and 50 ml of tetrahydrofuran is added. After stirring for 2 hours, warming to room temperature and working up normally, 1- (2,3-difluorophenyl) -4- (p-propylphenyl) -cyclohex-1-ene is obtained



  The following are produced analogously:
 
 1- (2,3-difluorophenyl) -4- (p-ethylphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-butylphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-pentylphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-hexylphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-heptylphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-octylphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-nonylphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-decylphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-dodecylphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-ethoxyphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-pentoxyphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-octoxyphenyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (p-dodecyloxyphenyl) cyclohex-1-ene
 



  With 4- (4-alkylcyclohexyl) cyclohexanones as starting compounds, the following are obtained analogously:
 
 1- (2,3-difluorophenyl) -4- (4-ethylcyclohexyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (4-pentylcyclohexyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (4-octylcyclohexyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (4-dodecylcyclohexyl) cyclohex-1-ene
 1- (2,3-difluorophenyl) -4- (4-pentoxycyclohexyl) cyclohex-1-ene


 Example 3
 


 1- (4-alkyl-2,3-difluorophenyl) -4-alkylcyclohex-1-ene
 



  A mixture of 0.2 mol of 1- (2,3-difluorophenyl) -4-pentylcyclohex-1-ene (prepared according to Example 1), 0.2 mol of potassium tert. Butylate and 400 ml of tetrahydrofuran are mixed at -100 ° C. with 0.2 mol of n-butyllithium in 125 ml of hexane. After stirring for a minute at -100 ° C., a solution of 0.22 mol of iodoethane, 0.22 mol of dimethylpropyleneurea and 80 ml of tetrahydrofuran is added. After warming to -40 ° C. and working up normally, 1- (4-ethyl-2,3-difluorophenyl) -4-pentylcyclohex-1-ene is obtained.



  The following are produced analogously:
 
 1- (4-propyl-2,3-difluorophenyl) -4-pentylcyclohex-1-ene
 1- (4-butyl-2,3-difluorophenyl) -4-pentylcyclohex-1-ene
 1- (4-pentyl-2,3-difluorophenyl) -4-pentylcyclohex-1-ene
 1- (4-Hexyl-2,3-difluorophenyl) -4-pentylcyclohex-1-ene
 1- (4-heptyl-2,3-difluorophenyl) -4-pentylcyclohex-1-ene
 1- (4-octyl-2,3-difluorophenyl) -4-pentylcyclohex-1-ene
 
 1- (4-propyl-2,3-difluorophenyl) -4-ethylcyclohex-1-ene
 1- (4-butyl-2,3-difluorophenyl) -4-ethylcyclohex-1-ene
 1- (4-pentyl-2,3-difluorophenyl) -4-ethylcyclohex-1-ene
 1- (4-Hexyl-2,3-difluorophenyl) -4-ethylcyclohex-1-ene
 1- (4-heptyl-2,3-difluorophenyl) -4-ethylcyclohex-1-ene
 1- (4-octyl-2,3-difluorophenyl) -4-ethylcyclohex-1-ene
 
 1- (4-propyl-2,3-difluorophenyl) -4-octylcyclohex-1-ene
 1- (4-butyl-2,3-difluorophenyl) -4-octylcyclohex-1-ene
 1- (4-pentyl-2,3-difluorophenyl) -4-octylcyclohex-1-ene
 1- (4-Hexyl-2,3-difluorophenyl) -4-octylcyclohex-1-ene
 

   1- (4-heptyl-2,3-difluorophenyl) -4-octylcyclohex-1-ene
 1- (4-octyl-2,3-difluorophenyl) -4-octylcyclohex-1-ene
 
 1- (4-Ethoxy-2,3-difluorophenyl) -4- (2- (trans-4-propylcyclohexyl) ethyl) cyclohex-1-ene
 Cr 73 DEG N 139 DEG I
 1- (4-Propoxy-2,3-difluorophenyl) -4- (2- (trans-4-propylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Butoxy-2,3-difluorophenyl) -4- (2- (trans-4-propylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Pentoxy-2,3-difluorophenyl) -4- (2- (trans-4-propylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Hexoxy-2,3-difluorophenyl) -4- (2- (trans-4-propylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Heptoxy-2,3-difluorophenyl) -4- (2- (trans-4-propylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Octoxy-2,3-difluorophenyl) -4- (2- (trans-4-propylcyclohexyl) ethyl) cyclohex-1-ene
 
 1- (4-Propoxy-2,3-difluorophenyl) -4- (2- (trans-4-pentylcyclohexyl) ethyl) cyclohex-1-ene
 

   1- (4-Butoxy-2,3-difluorophenyl) -4- (2- (trans-4-pentylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Pentoxy-2,3-difluorophenyl) -4- (2- (trans-4-pentylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Hexoxy-2,3-difluorophenyl) -4- (2- (trans-4-pentylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Heptoxy-2,3-difluorophenyl) -4- (2- (trans-4-pentylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Octoxy-2,3-difluorophenyl) -4- (2- (trans-4-pentylcyclohexyl) ethyl) cyclohex-1-ene
 
 1- (4-Propoxy-2,3-difluorophenyl) -4- (2- (trans-4-octylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Butoxy-2,3-difluorophenyl) -4- (2- (trans-4-octylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Pentoxy-2,3-difluorophenyl) -4- (2- (trans-4-octylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Hexoxy-2,3-difluorophenyl) -4- (2- (trans-4-octylcyclohexyl) ethyl) cyclohex-1-ene
 1- (4-Heptoxy-2,3-difluorophenyl) -4- (2- (trans-4-octylcyclohexyl) ethyl) cyclohex-1-ene
 

   1- (4-Octoxy-2,3-difluorophenyl) -4- (2- (trans-4-octylcyclohexyl) ethyl) cyclohex-1-ene


 Example 4
 



  0.2 mol of 1- (2,3-difluorophenyl) -4-pentylcyclohex-1-ene are deprotonated according to Example 1 with n-butyllithium and reacted with 3-propylcyclohexanone. After dehydration and usual work-up, 1- (4-pentylcyclohex-1-enyl) -4- (propylcyclohex-1-enyl) -2,3-difluorobenzene is obtained.



  The following are produced analogously:
 
 1,4-di- (4-ethylcyclohex-1-enyl) -2,3-difluorobenzene
 1,4-di- (4-propylcyclohex-1-enyl) -2,3-difluorobenzene
 K 59 DEG N 120.5 DEG I
 1,4-di- (4-butylcyclohex-1-enyl) -2,3-difluorobenzene
 1,4-di- (4-pentylcyclohex-1-enyl) -2,3-difluorobenzene
 1,4-di- (4-hexylcyclohex-1-enyl) -2,3-difluorobenzene
 1,4-di- (4-heptylcyclohex-1-enyl) -2,3-difluorobenzene
 1,4-di- (4-octylcyclohex-1-enyl) -2,3-difluorobenzene
 
 1- (4-Pentylcyclohex-1-enyl) -4- (4-ethylcyclohex-1-enyl) -2,3-difluorobenzene
 1- (4-pentylcyclohex-1-enyl) -4- (4-butylcyclohex-1-enyl) -2,3-difluorobenzene
 1- (4-Pentylcyclohex-1-enyl) -4- (4-hexylcyclohex-1-enyl) -2,3-difluorobenzene
 1- (4-Pentylcyclohex-1-enyl) -4- (4-heptylcyclohex-1-enyl) -2,3-difluorobenzene
 1- (4-Pentylcyclohex-1-enyl) -4- (4-octylcyclohex-1-enyl) -2,3-difluorobenzene
 
 1- (4-Propylcyclohex-1-enyl) -4- (4-ethylcyclohex-1-enyl) -2,3-difluorobenzene
 

   1- (4-Propylcyclohex-1-enyl) -4- (4-butylcyclohex-1-enyl) -2,3-difluorobenzene
 1- (4-Propylcyclohex-1-enyl) -4- (4-hexylcyclohex-1-enyl) -2,3-difluorobenzene
 1- (4-Propylcyclohex-1-enyl) -4- (4-heptylcyclohex-1-enyl) -2,3-difluorobenzene
 1- (4-Propylcyclohex-1-enyl) -4- (4-octylcyclohex-1-enyl) -2,3-difluorobenzene


 Example 5
 


 Preparation of 1- (4-cyano-2,3-difluorophenyl) -3- (4-alkylcyclohex-1-enyl) ethanes
 


 a) 2- (2,3-difluorophenyl) ethyl bromide
 



  A mixture of 0.1 mol of 2,3-difluorophenyllithium (prepared according to Example 1), 200 ml of tetrahydrofuran, 0.1 mol of tetramethylethylenediamine and 65 ml of hexane is mixed in at -50 ° C. with 150 ml of a solution of 0.11 mol of ethylene oxide Tetrahydrofuran added. After warming up to +10 ° C., neutralization with 50 ml of a saturated ammonium chloride solution and customary working up, 2- (2,3-difluorophenyl) ethanol is obtained. A mixture of triphenylphosphine and acetonitrile and bromine are added to this alcohol in succession.



  After stirring for 12 hours at room temperature and working up normally, the bromine compound is obtained.


 b) 2- (2,3-difluorophenyl) -1- (4-pentylcyclohex-1-enyl) ethane
 



  2- (2,3-difluorophenyl) ethylmagnesium bromide (made from 0.1 mol of the bromine compound and 0.1 mol of magnesium) is reacted with 0.1 mol of 4-pentylcyclohexanone analogously to Example 1 and the alcohol formed likewise according to Example 1 dehydrated. After the usual work-up, the cyclohex-1-ene derivative is obtained.


 c) Introduction of the cyano group
 



  0.1 mol of 2- (2,3-difluorophenyl) -1- (4-pentylcyclohex-1-enyl) -ethane are deprotonated according to Example 1 with n-butyllithium and reacted with 0.1 mol of N-formylpiperidine. After customary working up, 1- (4-formyl-2,3-difluorophenyl) -2- (4-pentylcyclohex-1-enyl) -ethane is obtained. This is reacted with hydroxylamine-0-sulfonic acid (e.g. according to Streith et al., Helv. Chim. Acta 59, 2786 [1976]). After usual working up, 1- (4-cyano-2,3-difluorophenyl) -2- (4-pentylcyclohex-1-enyl) -ethane is obtained.



  The following are produced analogously:
 
 1- (4-Cyano-2,3-difluorophenyl) -2- (4-ethylcyclohex-1-enyl) ethane
 1- (4-Cyano-2,3-difluorophenyl) -2- (4-propylcyclohex-1-enyl) ethane
 1- (4-Cyano-2,3-difluorophenyl) -2- (4-butylcyclohex-1-enyl) ethane
 1- (4-Cyano-2,3-difluorophenyl) -2- (4-hexylcyclohex-1-enyl) ethane
 1- (4-Cyano-2,3-difluorophenyl) -2- (4-heptylcyclohex-1-enyl) ethane
 1- (4-Cyano-2,3-difluorophenyl) -2- (4-octylcyclohex-1-enyl) ethane


 Example 6
 


 Preparation of 1- (4-alkyl-2,3-difluorophenyl) -2- (4-alkylcyclohexyl-1-enyl) ethanes.
 



  0.1 mol of 2- (2,3-difluorophenyl) -1- (4-pentylcyclohex-1-enyl) -ethane (prepared according to Example 5b) is mixed according to Example 3 with n-butyllithium / potassium tert-butoxide and with 0.1 mol of iodoethane reacted. After usual working up, 1- (4-ethyl-2,3-difluorophenyl) -2- (4-pentylcyclohex-1-enyl) -ethane is obtained.



  The following are produced analogously:
 
 1- (4-ethyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-1-enyl) ethane
 1- (4-propyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-1-enyl) ethane
 1- (4-butyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-1-enyl) ethane
 1- (4-pentyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-1-enyl) ethane
 1- (4-Hexyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-1-enyl) ethane
 1- (4-heptyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-1-enyl) ethane
 1- (4-octyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-1-enyl) ethane
 
 1- (4-ethyl-2,3-difluorophenyl) -2- (4-propylcyclohex-1-enyl) ethane
 1- (4-propyl-2,3-difluorophenyl) -2- (4-propylcyclohex-1-enyl) ethane
 1- (4-butyl-2,3-difluorophenyl) -2- (4-propylcyclohex-1-enyl) ethane
 1- (4-pentyl-2,3-difluorophenyl) -2- (4-propylcyclohex-1-enyl) ethane
 1- (4-Hexyl-2,3-difluorophenyl) -2- (4-propylcyclohex-1-enyl) ethane
 1- (4-heptyl-2,3-difluorophenyl) -2- (4-propylcyclohex-1-enyl) ethane
 

   1- (4-octyl-2,3-difluorophenyl) -2- (4-propylcyclohex-1-enyl) ethane
 
 1- (4-ethyl-2,3-difluorophenyl) -2- (4-octylcyclohex-1-enyl) ethane
 1- (4-propyl-2,3-difluorophenyl) -2- (4-octylcyclohex-1-enyl) ethane
 1- (4-butyl-2,3-difluorophenyl) -2- (4-octylcyclohex-1-enyl) ethane
 1- (4-pentyl-2,3-difluorophenyl) -2- (4-octylcyclohex-1-enyl) ethane
 1- (4-Hexyl-2,3-difluorophenyl) -2- (4-octylcyclohex-1-enyl) ethane
 1- (4-heptyl-2,3-difluorophenyl) -2- (4-octylcyclohex-1-enyl) ethane
 1- (4-octyl-2,3-difluorophenyl) -2- (4-octylcyclohex-1-enyl) ethane


 Example 7
 


  Preparation of 1- (4-alkoxy-2,3-difluorophenyl) -2- (4-alkyl-cyclohex-3-enyl) ethanes
 


 a) 4- (2- (4-Ethoxy-2,3-difluoro) ethyl) cyclohexanone
 



  A mixture of 2- (4-ethoxy-2,3-difluorophenyl) ethyl magnesium bromide (prepared from 0.1 mol of the bromine compound obtained analogously to Example 5 a) and 0.1 mol of magnesium) and 150 ml of tetrahydrofuran a mixture of 0.1 mol of the monoethylene ketal of cyclohexane-1,4-dione and 50 ml of tetrahydrofuran is added at 0 ° C. After stirring for 5 hours at room temperature, dehydration is carried out analogously to Example 1. A mixture of the cyclohexane derivative thus obtained, 100 ml of toluene and 1 g of palladium / activated carbon (10%) is hydrogenated to saturation at room temperature and normal pressure.



  After removing the solvent, the residue is heated to boiling in 200 ml of acetone with 25 ml of hydrochloric acid (concentrated) for 24 hours. After the usual working up, 4- (2- (4-ethoxy-2,3-difluoro) ethyl) cyclohexanone is obtained.


 b) Reaction with Alkylgrignard reagent
 



  0.1 mol of the cyclohexanone are reacted with pentyl magnesium bromide (made from 0.1 mol pentyl bromide and 0.1 mol magnesium). After dehydration according to Example 1 and usual work-up, 1- (4-ethoxy-2,3-difluorophenyl) -2- (4-pentylcyclohex-3-enyl) -ethane is obtained.



  The following are produced analogously:
 
 1- (4-Ethoxy-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-propoxy-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-butoxy-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-pentoxy-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-Hexoxy-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-Heptoxy-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-octoxy-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-ethyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-propyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-butyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-pentyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-Hexyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 1- (4-heptyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 

   1- (4-octyl-2,3-difluorophenyl) -2- (4-ethylcyclohex-3-enyl) ethane
 
 1- (4-ethoxy-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-propoxy-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-butoxy-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-pentoxy-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-Hexoxy-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-Heptoxy-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-octoxy-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-ethyl-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-propyl-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-butyl-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-pentyl-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-Hexyl-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 

   1- (4-heptyl-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane
 1- (4-octyl-2,3-difluorophenyl) -2- (4-heptylcyclohex-3-enyl) ethane


 Example 8
 


 Preparation of 4- (4-alkylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-alkoxybenzenes
 



  A mixture of 0.1 mol of 4-pentylcyclohex-1-enylcarboxylic acid chloride (prepared from 4-pentylcyclohexanone with sodium bisulfite and potassium cyanide by treatment with concentrated acid and phosphorus pentachloride, (according to Guha et al., B. 71, 2674 [1938]), 0 , 2 mol of pyridine and 150 ml of methylene chloride are mixed with a mixture of 0.1 mol of 2,3-difluoro-4-ethoxyphenol and 100 ml of methylene chloride at 0 ° C. After stirring for 8 hours at room temperature, 4- (4-pentylcyclohex- 1-enylcarbonyloxy) -2,3-difluoroethoxybenzene.



  The following are produced analogously:
 
 4- (4-ethylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-propylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-butylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-pentylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-Hexylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-heptylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-octylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 
 4- (4-ethylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentylbenzene
 4- (4-propylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentylbenzene
 4- (4-butylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentylbenzene
 4- (4-pentylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentylbenzene
 4- (4-Hexylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentylbenzene
 4- (4-heptylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentylbenzene
 

   4- (4-octylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentylbenzene
 
 4- (4-ethylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-propylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-butylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-pentylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-Hexylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-heptylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-octylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 
 4- (4-ethylcyclohex-1-enylcarbonyloxy) -2,3-difluoropropoxybenzene
 4- (4-propylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-propoxybenzene
 4- (4-butylcyclohex-1-enylcarbonyloxy) -2,3-difluoropropoxybenzene
 4- (4-pentylcyclohex-1-enylcarbonyloxy) -2,3-difluoropropoxybenzene
 4- (4-Hexylcyclohex-1-enylcarbonyloxy) -2,3-difluoropropoxybenzene
 

   4- (4-heptylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-propoxybenzene
 4- (4-octylcyclohex-1-enylcarbonyloxy) -2,3-difluoropropoxybenzene
 
 4- (4-ethylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-propylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-butylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-pentylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-Hexylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-heptylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-octylcyclohex-1-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 
 4- (4-ethylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 4- (4-propylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 4- (4-butylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 4- (4-pentylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 

   4- (4-Hexylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 4- (4-heptylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 4- (4-octylcyclohex-1-enylcarbonyloxy) -2,3-difluoro-octoxybenzene


 Example 9
 


 Preparation of 4- (4-alkylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-alkylbenzenes
 



  0.1 mol of triisopropyloxypentyltitanium (prepared from the corresponding Grignard reagent and triisopropylchlorotitanium) are reacted with 0.1 mol of ethyl cyclohexane-4-oncarboxylic acid according to Example 1. After dehydration and customary working up, 4-pentylcyclohex-3-enylcarboxylic acid ethyl ester is obtained. After saponification with potassium hydroxide in aqueous ethanol, this compound is esterified with 0.1 mol of 4-propyl-2,3-difluorophenol, using 0.1 mol of dicyclohexylcarbodiimide and 1 mmol of 4-N, N-dimethylaminopyridine in methylene chloride. After the usual work-up, 4- (4-pentylcyclohex-3-enylcarbonyloxy) 2,3-difluoropropylbenzene is obtained.



  The following are produced analogously:
 
 4- (4-ethylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-propylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-butylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-pentylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-Hexylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-heptylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 4- (4-octylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethylbenzene
 
 4- (4-ethylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentylbenzene
 4- (4-propylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentylbenzene
 4- (4-butylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentylbenzene
 4- (4-pentylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentylbenzene
 4- (4-Hexylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentylbenzene
 4- (4-heptylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentylbenzene
 

   4- (4-octylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentylbenzene
 
 4- (4-ethylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-propylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-butylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-pentylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-hexylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-heptylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 4- (4-octylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octylbenzene
 
 4- (4-ethylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethoxybenzene
 4- (4-propylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethoxybenzene
 4- (4-butylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethoxybenzene
 4- (4-pentylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethoxybenzene
 4- (4-Hexylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethoxybenzene
 4- (4-heptylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethoxybenzene
 

   4- (4-octylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-ethoxybenzene
 
 4- (4-ethylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-propylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-butylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-pentylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-Hexylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-heptylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 4- (4-octylcyclohex-3-enylcarbonyloxy) -2,3-difluoropentoxybenzene
 
 4- (4-ethylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 4- (4-propylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 4- (4-butylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 4- (4-pentylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 4- (4-hexylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 

   4- (4-heptylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octoxybenzene
 4- (4-octylcyclohex-3-enylcarbonyloxy) -2,3-difluoro-octoxybenzene


 Example 10
 


 Preparation of 4-propylphenyl 4- (4-pentylcyclohex -1-enyl) -2,3-difluorobenzoate
 



  0.1 mol of 4-pentyl-1- (2,3-difluorophenyl) -cyclohex-1-ene (from Example 1) is deprotonated with 0.1 mol of n-BuLi and carboxylated by adding dry ice. A mixture of the benzoic acid thus obtained, 0.1 mol of p-propylphenol and 100 ml of dichloromethane is mixed at room temperature with a mixture of 0.12 mol of dicyclohexylcarbodiimide and 30 ml of dichloromethane. After stirring for 20 hours and working up normally, the product is obtained as a colorless solid, K 51 DEG Sc 63 DEG N 150.8 DEG I.



  The following are produced analogously:
 
 4-propylphenyl 4- (4-ethylcyclohex-1-enyl) -2,3-difluorobenzoate
 4-propylphenyl 4- (4-propylcyclohex-1-enyl) -2,3-difluorobenzoate
 4-propylphenyl 4- (4-butylcyclohex-1-enyl) -2,3-difluorobenzoate
 4-propylphenyl 4- (4-hexylcyclohex-1-enyl) -2,3-difluorobenzoate
 4-propylphenyl 4- (4-heptylcyclohex-1-enyl) -2,3-difluorobenzoate
 4-propylphenyl 4- (4-octylcyclohex-1-enyl) -2,3-difluorobenzoate


 Example A:
 


 A nematic liquid crystalline phase consisting of
 
 



  13% p-trans-4-propylcyclohexyl-benzonitrile,
 20% trans-1-p-methoxyphenyl-4-propylcyclohexane,
 13% trans-1-p-butoxyphenyl-4-propylcyclohexane,
 17% 2,3-difluoro-4- (4-pentylcyclohex-1-enyl) -1-ethoxybenzene,
 3% trans-4- (trans-4-propylcyclohexyl) cyclohexane carboxylic acid (trans-4-propylcyclohexyl ester),
 3% trans-4- (trans-4-propylcyclohexyl) cyclohexane carboxylic acid (trans-4-pentylcyclohexyl ester),
 3% trans-4- (trans-4-butylcyclohexyl) cyclohexane carboxylic acid (trans-4-pentylcyclohexyl ester),

   
 3% trans-4- (trans-4-butylcyclohexyl) cyclohexane carboxylic acid (trans-4-propylcyclohexyl ester),
 5% 4.4 min - (trans-4-propylcyclohexyl) -2-fluorobiphenyl,
 4% 4.4 min - (trans-4-propylcyclohexyl) biphenyl,
 4% 4.4 min - (trans-4-pentylcyclohexyl) -2-fluorobiphenyl,
 6% 2,3-difluoro-4- [trans-4- (trans-4-pentylcyclohexyl) cyclohexyl] -1-ethoxybenzene and
 6% 4- (trans-4-pentylcyclohexyl) -4 min - (trans-4-propylcyclohexyl) biphenyl
 is characterized by a wide nematic phase range and low birefringence.


    

Claims (5)

      1. cyclohexene derivatives of the formula I,    R <1> -A <1> -Z <1> -A <2> - (Z <2> -A <3>) m-R <2>    wherein  R <1> and R <2> each independently of one another unsubstituted, simply substituted by cyan or at least simply substituted by fluorine or chlorine, alkyl with 1-15 C-atoms or alkenyl with 3-15 C-atoms, in which radicals also a CH2 Group can be replaced by -O-, -CO-, -O-CO-, -CO-O- or -O-CO-O-, one of the radicals R <1> and R <2> also CN,  m 0, 1 or 2,  A <1>, A <2> and A <3> each independently of one another 1,4-cyclohexenylene, trans-1,4-cyclohexylene, in which one or two non-adjacent CH2 groups can also be replaced by -O-, or 1,4-phenylene which is unsubstituted or substituted once or twice by fluorine, in which one or two CH groups can also be replaced by N,  Z <1> and Z <2> each independently of one another -CO-O-, -O-CO-, -CH2O-, -OCH2-,  -CH2CH2- or a single bond,  with the proviso that at least one of the groups A <1>, A <2> and A <3> 2,3-difluoro-1,4-phenylene and at least one of the remaining groups A <1>, A <2> and A is 1,4-cyclohexenylene. 2. Cyclohexene derivatives according to claim 1, characterized by the formula II,    R <1> - (A DEG) n-Che-Z <1> - (A <1> -Z <2>) m-A <2> -R <2> II    wherein  R <1>, R <2>, Z <1>, Z <2>, A <1>, A <2> and m have the meaning given and  A DEG trans-1,4-cyclohexylene,  Che EMI47.1    n means 0 or 1,  where the sum of m + n must not be three. 3. Derivatives according to claim 1 or 2, characterized in that R <1> and R <2> each independently represent straight-chain alkyl or alkoxy having 1-15 C atoms. 4th  Liquid-crystalline phase with at least two liquid-crystalline components, characterized in that at least one component is a compound according to claim 1 or 2. 5. Liquid crystal display element, characterized in that it contains a liquid crystalline phase according to claim 4.       1. cyclohexene derivatives of the formula I,    R <1> -A <1> -Z <1> -A <2> - (Z <2> -A <3>) m-R <2>    wherein  R <1> and R <2> each independently of one another unsubstituted, simply substituted by cyan or at least simply substituted by fluorine or chlorine, alkyl with 1-15 C-atoms or alkenyl with 3-15 C-atoms, in which radicals also a CH2 Group can be replaced by -O-, -CO-, -O-CO-, -CO-O- or -O-CO-O-, one of the radicals R <1> and R <2> also CN,  m 0, 1 or 2,  A <1>, A <2> and A <3> each independently of one another 1,4-cyclohexenylene, trans-1,4-cyclohexylene, in which one or two non-adjacent CH2 groups can also be replaced by -O-, or 1,4-phenylene which is unsubstituted or substituted once or twice by fluorine, in which one or two CH groups can also be replaced by N,  Z <1> and Z <2> each independently of one another -CO-O-, -O-CO-, -CH2O-, -OCH2-,  -CH2CH2- or a single bond,  with the proviso that at least one of the groups A <1>, A <2> and A <3> 2,3-difluoro-1,4-phenylene and at least one of the remaining groups A <1>, A <2> and A is 1,4-cyclohexenylene. 2. Cyclohexene derivatives according to claim 1, characterized by the formula II,    R <1> - (A DEG) n-Che-Z <1> - (A <1> -Z <2>) m-A <2> -R <2> II    wherein  R <1>, R <2>, Z <1>, Z <2>, A <1>, A <2> and m have the meaning given and  A DEG trans-1,4-cyclohexylene,  Che EMI47.1    n means 0 or 1,  where the sum of m + n must not be three. 3. Derivatives according to claim 1 or 2, characterized in that R <1> and R <2> each independently represent straight-chain alkyl or alkoxy having 1-15 C atoms. 4th  Liquid-crystalline phase with at least two liquid-crystalline components, characterized in that at least one component is a compound according to claim 1 or 2. 5. Liquid crystal display element, characterized in that it contains a liquid crystalline phase according to claim 4.