EP0407569A1

EP0407569A1 - Diphenylethanes

Info

Publication number: EP0407569A1
Application number: EP90903347A
Authority: EP
Inventors: David Ian 6 Swallow Close Bishop; Stephen Lewis; David Coates; Simon 2 Blackbird Close Greenfield; Eike Poetsch; Volker Meyer; Klaus-Peter Stahl; Volker Reiffenrath; Herbert Plach; Reinhard Hittich; Andreas WÄCHTLER
Original assignee: Merck Patent GmbH
Current assignee: Merck Patent GmbH
Priority date: 1989-01-27
Filing date: 1990-01-22
Publication date: 1991-01-16
Also published as: US5093026A; JPH03503651A; WO1990008756A1; CA2026112A1

Abstract

Des biphénylyléthanes ont la formule (I): R1-CH2-X-(CH2CH2)m-Ph-Ph-CH2CH2-Ph-Y-CH2-R2, dans laquelle R1 et R2 représentent indépendamment l'un de l'autre alkyle, alkényle ou oxaalkyle ayant jusqu'à 12 atomes de C, un des résidus R1 et R2 pouvant également représenter H; m est égal à 0 ou 1; X et Y représentent indépendamment l'un de l'autre O, S, CO-O, O-CO, O-CO-O ou une liaison simple, le résidu X pouvant également représenter 1,4-phénylène ou trans-1,4-cyclohexylène et le résidu Y également trans-1,4-cyclohexylène, et Ph représente 1,4-phénylène, un ou deux résidus Ph pouvant également représenter 2- ou 3-fluor-1,4-phénylène, à condition que dans le cas (a), où X = 1,4-phénylène et m = 1, un ou deux résidus Ph représentent 2- ou 3-fluor-1,4-phénylène et que dans le cas (b), où X = trans-1,4-cyclohexylène , m = 0 et un ou deux résidus Ph représentent 2- ou 3-fluor-1,4-phénylène. Ces composés sont utiles comme composants de phases de cristaux liquides.Biphenylylethanes have the formula (I): R1-CH2-X- (CH2CH2) m-Ph-Ph-CH2CH2-Ph-Y-CH2-R2, in which R1 and R2 independently represent one another, alkenyl or oxaalkyl having up to 12 C atoms, one of the residues R1 and R2 also being able to represent H; m is 0 or 1; X and Y independently of one another represent O, S, CO-O, O-CO, O-CO-O or a single bond, the residue X can also represent 1,4-phenylene or trans-1, 4-cyclohexylene and residue Y also trans-1,4-cyclohexylene, and Ph represents 1,4-phenylene, one or two residues Ph can also represent 2- or 3-fluor-1,4-phenylene, provided that in the case (a), where X = 1,4-phenylene and m = 1, one or two residues Ph represent 2- or 3-fluor-1,4-phenylene and that in the case (b), where X = trans -1,4-cyclohexylene, m = 0 and one or two residues Ph represent 2- or 3-fluor-1,4-phenylene. These compounds are useful as components of liquid crystal phases.

Description

Biphenylylethanes The invention relates to biphenylylethanes of the formula I, R ¹ -CH ₂ -X- (CH ₂ CH ₂ ) _m -Ph-Ph-CH ₂ CH ₂ -Ph-Y-CH ₂ -R ² I wherein R ¹ and R ² each independently of the other alkyl,

Alkenyl or oxaalkyl with up to 12 carbon atoms, one of the radicals R ¹ and R ² also H, m 0 or 1, X and Y each independently of one another O, S,

CO-O, O-CO, O-CO-O or a single bond, radical X also 1,4-phenylene or trans-1,4-cyclohexylene and radical Y also trans-1,4-cyclohexylene, and Ph 1,4 -Phenylene, one or two of the residues

Ph also means 2- or 3-fluoro-1,4-phenylene, with the proviso that in case (a) X = 1,4-phenylene and m = 1 one or two of the residues Ph 2- or 3-fluoro- Mean 1,4-phenylene and (b) in the case of X = trans-1,4-cyclohexylene, m = 0 and one or two of the radicals Ph mean 2- or 3-fluoro-1,4-phenylene. 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.

Compounds of the formula I are preferably also suitable for use as components in liquid-crystalline phases for displays which are based on the ECB effect. Similar liquid crystalline compounds are e.g. out

USP 4,695,131 known. However, the compounds described there have a cyclohexylethyl grouping.

Chiral compounds for ferroelectric liquid crystal mixtures of the formula

are described in JP 61-243037-A. In addition, there is a chiral connection of the structure

in EP-OS 0 259 995.

Via a connection of the structure

HA Staab and M. Haenel have reported in the synthesis of cyclophane compounds (Chem. Ber., 106 (7), 2150-2202 (1973)). GW Gray et al. finally report in Liquid Crystals, 1986, Vol. 1, No. 5, pp. 407-413, inter alia via compounds of the formula

in this connection indicate a negative effect of the separation of the π systems in this connection that is generally accepted by the liquid crystal industry.

The object of the invention was to find new stable liquid-crystalline or mesogenic compounds with high birefringence, which are suitable as components of liquid-crystalline phases with low viscosity, high nematogenicity and favorable low-temperature behavior. This object was achieved by the provision of the compounds of the formula I. 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 relatively large optical anisotropy and positive or negative dielectric anisotropy. For example, the substances of the formula I are particularly preferably suitable for use in mixtures for ECB effects.

The ECB effect (electrically controlled birefringence) or DAP effect (deformation of erected phases) was first described in 1971 (M.F. 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. 2J) (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 K ₃ / K ₁ , high values for the optical anisotropy Δn and negative values for the dielectric anisotropy Δs in order to be able to use highly Effect can be used. Electro-optical display elements based on the ECB effect have a homeotropic edge orientation, ie the liquid-crystalline phase has a negative dielectric anisotropy.

Surprisingly, it was found that the addition of compounds of the formula I gives liquid-crystalline phases which meet all of the criteria mentioned above excellently.

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

The compounds of formula I have a wide range of uses. 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 in order, for example, to optimize the dielectric and / or optical anisotropy of such a dielectric. The compounds of formula I are suitable also as intermediates for the manufacture of others

Substances that can be used as components of liquid crystalline phases.

The compounds of the formula I are colorless in the pure state and form liquid-crystalline mesophases in

a temperature range 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 and the use of these compounds as

Components of liquid crystalline phases. The invention furthermore relates to liquid-crystalline phases containing at least one compound of the formula I, and to liquid-crystal display elements which contain them

Phases included. R ¹ , R ² , X, Y and Ph have the meaning given above and below, unless expressly stated otherwise.

If R ¹ and / or R ^{2 are} alkyl radicals in which an (“oxaalkyl”) CH ₂ group can also be replaced by O atoms, they can be straight-chain or 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, 2-oxapropyl

(= Methoxyraethyl), 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, also methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, 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. The radicals R ¹ -X and / or R ² -Y, in which X and YO respectively mean an alkoxy or alkoxyalkoxy radical having 2, 3, 4, 5, 6, 7 carbon atoms.

Accordingly, they preferably mean ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, methoxy, octoxy, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy, tetradecoxy, pentadecoxy, 1,3-dioxabutyl (= methoxymethoxy), 1,3-, 1 , 4- or 2,4-dioxapentyl, 1,3-, 1,4-, 1,5-, 2,4-, 2,5- or 3,5-dioxahexyl, 1,3-, 1,4- , 1,5-, 1,6-, 2,4-, 2,5-, 2,6-, 3,5-, 3,6- or 4,6-dioxaheptyl. Alkyl radicals in which a CH ₂ group is replaced by a -CH = CH group or by -CHF- are also particularly preferred.

Compounds of formula I with branched wing groups R ¹ or R ² can occasionally because of a better

Solubility in the usual liquid-crystalline base materials can be important, but especially 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-meth.ylbutyl, isopentyl (= 3-methylbutyl), 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl,

2-propylpentyl, 2-octyl, isopropoxy, 2-methylpropoxy,

2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexoxy, 1-methylhexoxy, 1-methylheptoxy

(= 2-octyloxy), 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-methyl-3-oxapentyl, 2-methyl-3-oxahexyl. For compounds with branched wing groups, formula I includes both the optical antipodes and racemates and mixtures thereof.

The preferred meanings of X and Y are O or the single bond, with the single bond being particularly preferred. Compounds in which one of the radicals Ph is 2- or 3-fluoro-1,4-phenylene are particularly preferred. The radicals R ¹ -X and R ² -Y are preferably straight-chain alkyl or alkoxy. Preferred compounds of the formula I and their sub-formulas are those in which at least one of the radicals contained therein has one of the preferred meanings indicated.

Particularly preferred smaller groups of compounds according to the invention are those of the following sub-formulas:

-

(0) means 0 or a single bond

R and R 'each denote n-alkyl having up to 12 carbon atoms.

The central part of the compounds according to the invention

-Ph-Phe-CH ₂ CH ₂ -Ph- preferably has one of the following meanings:

Meaning 2 is particularly preferred.

Biphenylylethanes of the formula II are particularly preferred,

wherein R ¹ and R ^{2 have} the meaning given in claim 1, X is 0 or a single bond, one of the radicals

Ph means 2- or 3-fluoro-1,4-phenylene and the other

Radical Ph denotes 1,4-phenylene, and biphenylylethanes of the formula Ha,

wherein R ¹ and R ^{2 have} the meaning given in claim 1. The compounds of the 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), and under reaction conditions that are known and suitable for the implementations mentioned.

It is also possible to use variants which are known per se and are not mentioned here in any more 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 passed on to the

Reacts compounds of formula I.

Thus, the compounds of formula I can be prepared by using a compound of formula II or a corresponding ethyne compound

R ³ -X-Ph-Ph-CH = CH-Ph-YR ⁴ II under the conditions known to the person catalytically hydrogenated. In Formula II, X, Y and Ph have the above

indicated meanings. R ³ and R ⁴ each mean

independently of one another alkyl or oxaalkyl.

The compounds of the formula II are obtainable in a manner known per se by Wittig or by Heck coupling from corresponding styrene compounds with halogen aromatics, which are either known or can be prepared in complete analogy to known compounds.

Ethynes of the formula II can also be prepared via the coupling of alkynyl-zinc compounds with aryl halides analogously to that of A.O. King, E. Negishi, F.J. Villani and A. Silveira in J. Org. Chem. 43 (1978) 358.

Ethynes of the formula II can also be prepared via the Fritsch-Buttenberg-Wiechell rearrangement (Ann. 279, 319, 327, 332, 1984), in which 1,1-diaryl-2-halogenethylenes are rearranged to diarylacetylenes in the presence of strong bases . Ethynes of the formula II can also be prepared from 4-substituted phenyl- or cyclohexylacetylenes and aryl halides in the presence of a palladium catalyst, for example bis (triphenylphosphine) palladium (II) chloride, and copper (I) iodide (described in Synthesis (1980) 627 or Tetrahedron Letters 27 (1986) 1171).

Compounds according to the invention with alkenyl groups can be prepared in analogy to similar, known compounds by the Wittig reaction, the starting materials (corresponding to formula I, but one of the radicals

R ¹ and R ² is - (CH ₂ ) _x -CHO or, for example, - (CH ₂ ) _x -Br, X = 0 to 5) in analogy to the methods described above.

The compounds of formula I can continue to

Cross couplings according to DOS 36 08502, DOS 36 32 410 or DOS 37 36489 or by Wolff-Kishner reduction of corresponding methylene ketones which are produced

in turn from the corresponding arylacetic acid chlorides and corresponding benzene or biphenyl precursors

are accessible.

The liquid-crystalline phases according to the invention consist of 2 to 15, preferably 3 to 12 components, including at least one compound of the formula I. The other constituents are preferably selected from the nematic or nematogenic substances, in particular the known substances, from the classes of the azoxybenzenes, benzylidene anilines, Biphenyls, terphenyls, phenyl or cyclohexyl benzoates, cyclohexane-carboxylic acid phenyl or cyclohexyl esters, phenylcyclohexanes, cyclohexyl biphenyls, Cyclohexylcyclohexanes, cyclohexylnaphthalenes, 1,4-biscyclohexylbenzenes, 4,4'-biscyclohexylbiphenyls, phenyl or cyclophexylpyrimidines, phenyl- or cyclohexyldioxanes, phenyl- or cyclohexyl-1,3-dithiane, 1,2-diphenylethanes, 1,2-dicyclohexyl 1-phenyl-2-cyclohexylethanes, optionally halogenated stilbenes,

Benzylphenyl ether and substituted cinnamic acids.

The most important compounds which are possible as constituents of such liquid-crystalline phases can be characterized by the formula IV,

R ⁶ -LGER ⁷ IV in which L and E each have a carbocyclic or heterocyclic ring system consisting of 1,4-disubstituted benzene and cyclohexane rings, 4,4'-disubstituted biphenyl, phenylcyclohexane and cyclohexylcyclohexane systems, 2,5-disubstituted pyrimidine - and 1,3-dioxane rings, 2, 6-disubstituted naphthalene, di- and tetrahydronaphthalene,

Quinazoline and tetrahydroquinazoline formed group,

G -CH = CH- -N (O) = N- -CH = CY- -CH = N (O) -

-C≡C- -CH ₂ -CH ₂ -

-CO-O- -CH ₂ -O-

-CO-S- -CH ₂ -S-

-CH = N- -COO-Phe-COO- or a C-C single bond,

Y halogen, preferably chlorine, or -CN, and R ⁶ and R ⁷ denote alkyl, alkoxy, alkanoyloxy or alkoxycarbonyloxy having up to 18, preferably up to 8 carbon atoms, or one of these radicals by CN, NC, NO ₂ , CF ₃ , F, Cl or Br. Most of these compounds are R ⁶ and R ⁷ are different from one another, one of these radicals usually being an alkyl or alkoxy group. Other variants of the proposed substituents are also common. Many such substances or mixtures thereof are commercially available. All of these substances are obtainable by methods known from the literature.

The phases according to the invention contain about 0.1 to 99%, preferably 10 to 95%, of one or more compounds of the formula I. Also preferred are liquid-crystalline phases according to the invention, containing 0.1-40, preferably 0.5-30% of one or more compounds of Formula I.

The compounds of the formula I can also be used as components of smectic or chirally switched smectic liquid-crystalline phases. These phases are preferably chiral-chopped smectic liquid-crystalline phases, the achiral base mixture of which contains, in addition to compounds of the formula I, at least one other component with negative or small positive dielectric anisotropy. This further component (s) of the achiral base mixture can make up 1 to 50%, preferably 10 to 25%, of the base mixture.

The phases 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 so 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. For example, conductive salts, preferably ethyl dimethyl dodecyl ammonium 4-hexyloxybenzoate, tetrabutylammonium tetraphenylboranate or complex salts of crown ethers (see, for example, I. Haller et al., Mol. Cryst. Liq. Cryst. Volume 24, pages 249-258

(1973)) to improve the conductivity, dichroic dyes for producing colored guest-host systems or substances for changing the dielectric anisotropy, the viscosity and / or the orientation of the nematic phases are added. Such substances are e.g. in DE-OS 22 09 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430, 28 53 728 and 29 02 177.

The following examples are intended to illustrate the invention without limiting it. F. = melting point, K. = 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. example 1

A solution of 10.6 g of 1- (p-ethoxyphenyl) -2- (4'-n-pentylbiphenyl-4-yl) ethene [obtained by rear coupling 4-ethoxystyrene with 4-bromo-4'-n-pentylbiphenyl ] in 200 ml of tetrahydrofuran is hydrogenated in the presence of Pd / C until the H uptake has ended. After customary working up, 1- (p-ethoxyphenyl) -2- (4'-n-pentylbiphenyl-4-yl) -ethane is obtained, mp 81 °, K. 145 °

The following are prepared analogously: 1- (p-methylphenyl) -2- (4'-n-propylbiphenyl-4-yl) ethane, F 116 °

1- (p-ethoxyphenyl) -2- (4'-ethylbiphenyl-4-yl) ethane,

M. 114 °, K. 136.5 °

1- (p-propylphenyl) -2- (4'-ethylbiphenyl-4-yl) ethane,

F. 77 °, K. 121 °

1- (p-propylphenyl) -2- (4'-pentylbiphenyl-4-yl) ethane,

F. 57 °, K. 138 °

1- (p-ethoxyphenyl) -2- (4'-butoxybiphenyl-4-yl) ethane,

F. 133 °, K. 176 °

1- (p-methoxyphenyl) -2- (4'-pentylbiphenyl-4-yl) ethane,

M. 111 °, K. 131 °

1- (p-ethoxyphenyl) -2- (4'-propylbiphenyl-4-yl) ethane,

M. 94 °, K. 148 °

1- (p-butoxyphenyl) -2- (4'-pentylbiphenyl-4-yl) ethane, mp 158 ° Example 2

A solution of 1.9 g of 1- (p-ethoxyphenyl) -2- [4 '- (trans-4-n-pentylcyclohexyl) -3'-fluorobiphenyl-4-yl] ethene

[obtained by coupling 4-ethoxystyrene to the rear

4 '- (trans-4-n-pentylcyclohexyl) -3'-fluoro-4-broιabiphenyl] in 50 ml of tetrahydrofuran is hydrogenated in the presence of Pd / C. After customary working up, 1- (p-ethoxyphenyl) -2- [4 '- (trans-4-n-pentylcyclohexyl) -3'-fluorobiphenyl-4-yl) ethane is obtained. The following are produced analogously:

1- (p-ethoxyphenyl) -2- (4'-ethoxy-3'-fluoro-biphenyl-4-yl) ethane, mp 133 °, K. 155 °

Example 3

A solution of 3.2 g of 1- (p-ethylphenyl) -2- [4 '- (trans-4-n-pentylcyclohexyl) -2'-fluorobiphenyl-4-yl] ethene [obtained by rear coupling of p-ethyl styrene with 4 '- (trans-4-n-pentylcyclohexyl) -2'-fluoro-4-bromobiphenyl] in 100 ml of tetrahydrofuran is hydrogenated in the presence of Pd / C.

After customary working up, 1- (p-ethylphenyl) -2- [4 '- (txans-4-n-pentylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane is obtained.

The following are produced analogously:

1- (p-Methylphenyl) -2- [4 '- (trans-4-ethylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-ethylphenyl) -2- [4 '- (trans-4-ethylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane 1- (p-Propylphenyl) -2- [4 '- (trans-4-ethylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-pentylphenyl) -2- [4 '- (trans-4-ethylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane 1- (p-methylphenyl) -2- [4' - (trans- 4-propylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-ethylphenyl) -2- [4 '- (trans-4-propylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-Propylphenyl) -2- [4 '- (trans-4-propylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-pentylphenyl) -2- [4 * - (trans-4-propylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-methylphenyl) -2- [4 '- (trans-4-butylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-ethylphenyl) -2- [4 '- (trans-4-butylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-Propylphenyl) -2- [4 '- (trans-4-butylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-pentylphenyl) -2- [4 '- (trans-4-butylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-methylphenyl) -2- [4 '- (trans-4-pentylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-Propylphenyl) -2- [4 '- (trans-4-pentylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-Butylphenyl) -2- [4 '- (trans-4-pentylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-pentylphenyl) -2- [4 '- (trans-4-pentylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane

1- (p-Ethoxyphenyl) -2- [4 '- (trans-4-pentylcyclohexyl) -2'-fluorobiphenyl-4-yl) ethane, mp 69 °, K. 229.4 ° Example 4

A solution of 1.2 g of 1- (p-ethylphenyl) -2- [4'-pentyl-2'-fluorobiphenyl-4-yl] ethene [obtained by rear coupling of p-ethylstyrene with 4'-n-pentyl- 2'-fluoro-4-bromobiphenyl] in 50 ml of tetrahydrofuran is hydrogenated in the presence of Pd / C. After the usual work-up, 1- (p-ethylphenyl) -2- (4'-n-pentyl-2'-fluorobiphenyl-4-yl) -ethane is obtained.

The following are produced analogously:

1- (p-ethylphenyl) -2- (4'-ethyl-2'-fluorobiphenyl-4-yl) ethane 1- (p-ethylphenyl) -2- (4'-propyl-2'-fluorobiphenyl-4- yl) -ethane 1- (p-ethylphenyl) -2- (4'-butyl-2'-fluorobiphenyl-4-yl) -ethane 1- (p-ethylphenyl) -2- (4'-heptyl-2'- fluorobiphenyl-4-yl) ethane

1- (p-methylphenyl) -2- (4'-ethyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-methylphenyl) -2- (4'-propyl-2'-fluorobiphenyl-4-yl) ethane, mp 65 °, K. 66.3 °

1- (p-methylphenyl) -2- (4 'butyl-2' fluorobiphenyl-4-yl) ethane

1- (p-methylphenyl) -2- (4'-pentyl-2'-fluorobiphenyl-4-yl) ethane, mp 41 °, K. 67.4 °

1- (p-methylphenyl) -2- (4'-heptyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-ethyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-propyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-butyl-2'-fluorobiphenyl-4-yl) ethane 1- (p-methoxyphenyl) -2- (4'-pentyl-2'-fluorobiphenyl-4-yl) ethane, mp 49 °, K. 87.5 °

1- (p-methoxyphenyl) -2- (4'-heptyl-2'-fluorobiphenyl-4-yl) ethane 1- (p-propylphenyl) -2- (4'-ethyl-2'-fluorobiphenyl-4- yl) -ethane, mp 57 °

1- (p-propylphenyl) -2- (4'-propyl-2'-fluorobiphenyl-4-yl) ethane, mp 52 °, K. 60 °

1- (p-propylphenyl) -2- (4'-butyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-propylphenyl) -2- (4'-pentyl-2'-fluorobiphenyl-4-yl) ethane, mp 37 °, K. 67 ', 5 °

1- (p-propylphenyl) -2- (4'-heptyl-2'-fluorobiphenyl-4-yl) ethane 1- (p-butylphenyl) -2- (4'-ethyl-2'-fluorobiphenyl-4- yl) -ethane

1- (p-butylphenyl) -2- (4'-propyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-butylphenyl) -2- (4'-butyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-butylphenyl) -2- (4'-pentyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-butylphenyl) -2- (4'-heptyl-2'-fluorobiphenyl-4-yl) ethane 1- (p-pentylphenyl) -2- (4l-ethyl-2'-fluorobiphenyl-4-yl ) - ethane

1- (p-pentylphenyl) -2- (4'-propyl-2'-fluorobiphenyl-4-yl) ethane, m.p. 40 °, K. 67.7 °

1- (p-pentylphenyl) -2- (4'-butyl-2'-fluorobiphenyl-4-yl) ethane 1- (p-pentylphenyl) -2- (4'-pentyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-pentylphenyl) -2- (4'-heptyl-2'-fluorobiphenyl-4-yl) ethane 1- (p-heptylphenyl) -2- (4'-ethyl-2'-fluorobiphenyl-4- yl) -ethane

1- (p-heptylphenyl) -2- (4'-propyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-heptylphenyl) -2 - (4'-butyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-heptylphenyl) -2 - (4'-pentyl-2'-fluorobiphenyl-4-yl) ethane

1- (p-heptylphenyl) -2 - (4'-heptyl-2'-fluorobiphenyl-4-yl) ethane 1- (p-propylphenyl) -2- (4'-ethyl-2-fluorobiphenyl-4-yl ) -ethane

1- (p-propylphenyl) -2- (4'-propyl-2-fluorobiphenyl-4-yl) ethane

1- (p-propylphenyl) -2- (4'-butyl-2-fluorobiphenyl-4-yl) ethane

1- (p-propylphenyl) -2- (4'-pentyl-2-fluorobiphenyl-4-yl) ethane

1- (p-propylphenyl) -2- (4'-heptyl-2-fluorobiphenyl-4-yl) ethane

1- (p-propylphenyl) -2- (4'-propoxy-2-fluorobiphenyl-4-yl) ethane

1- (p-pentylphenyl) -2- (4'-ethyl-2-fluorobiphenyl-4-yl) ethane

1- (p-pentylphenyl) -2- (4'-propyl-2-fluorobiphenyl-4-yl) ethane

1- (p-pentylphenyl) -2- (4'-butyl-2-fluorobiphenyl-4-yl) ethane 1- (p-pentylphenyl) -2- (4'-pentyl-2-fluorobiphenyl-4-yl) ethane

1- (p-pentylphenyl) -2- (4'-heptyl-2-fluorobiphenyl-4-yl) ethane

1- (p-pentylphenyl) -2- (4'-propoxy-2-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-ethyl-2-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-propyl-2-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-butyl-2-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-pentyl-2-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-heptyl-2-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-propoxy-2-fluorobiphenyl-4-yl) ethane

1- (p-propylphenyl) -2- (4'-ethyl-3-fluorobiphenyl-4-yl) ethane

1- (p-propylphenyl) -2- (4'-propyl-3-fluorobipnenyl-4-yl) ethane

1- (p-propylphenyl) -2- (4'-pentyl-3-fluorobiphenyl-4-yl) ethane

1- (p-propylphenyl) -2- (4'-heptyl-3-fluorobipbenyl-4-yl) ethane

1- (p-propylphenyl) -2- (4'-propoxy-3-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-ethyl-3-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-propyl-3-fluorobiphenyl-4-yl) ethane 1- (p-methoxyphenyl) -2- (4'-pentyl-3-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-heptyl-3-fluorobiphenyl-4-yl) ethane

1- (p-methoxyphenyl) -2- (4'-propoxy-3-fluorobiphenyl-4-yl) ethane

1- (p-propylphenyl) -2- (4'-ethoxy-2'-fluorobiphenyl-4-yl) ethane

1- (2-fluoro-4-propylphenyl) -2- (4'-ethylbiphenyl-4-yl) ethane 1- (2-fluoro-4-propylphenyl) -2- (4'-propylbiphenyl-4-yl) -ethane 1- (2-fluoro-4-propylphenyl) -2- (4'-butylbiphenyl-4-yl) -ethane 1- (2-fluoro-4-propylphenyl) -2- (4'-pentylbiphenyl-4- yl) -ethane

4,4-bis (p-propylphenylethyl) -2-fluorobiphenyl

4,4-bis (p-ethylphenylethyl) -2-fluorobiphenyl

4,4-bis (p-butylphenylethyl) -2-fluorobiphenyl

4,4-bis (p-pentylphenylethyl) -2-fluorobiphenyl

Claims

1. Biphenylylethanes of formula I

R ¹ -CH ₂ -X- (CH ₂ CH ₂ ) _m -Ph-Ph-CH ₂ CH ₂ -Ph-Y-CH ₂ -R ² wherein R ¹ and R ^{2 are} each independently alkyl,

Alkenyl or oxaalkyl with up to

12 carbon atoms, one of the radicals R ¹ and R ² also H, m 0 or 1, X and Y each independently of one another O, S,

Ph also means 2- or 3-fluoro-1,4-phenylene, with the proviso that in case (a) X = 1,4-phenylene and m = 1 one or two of the residues Ph 2- or 3-fluoro- 1,4-phenylene and (b) in the case of X = trans-1,4-cyclohexylene, m = 0 and one or two of the radicals Ph are 2- or 3-fluoro-1,4-phenylene.

2. biphenylylethanes according to claim 1, characterized by the formula II,

wherein R ¹ and R ^{2 have} the meaning given in claim 1, X is 0 or a single bond, one of the radicals is Ph 2- or 3-fluoro-1,4-phenylene and the other radical is Ph 1,4-phenylene.

3. biphenylylethane according to claim 1, characterized by the formula Ha,

wherein R ¹ and R ^{2 have} the meaning given in claim 1.

4. Biphenylylethane according to claim 1, characterized by the formula I ':

R ¹ -CH ₂ -Ph-Ph-CH ₂ CH ₂ -Ph-CH ₂ -R ² I '

5. Biphenylylethane according to claim 1, characterized by the formula I '':

6. biphenylylethane according to claim 1, characterized by the formula I ''' Biphenylylethane according to at least one of Claims 1 to 6, characterized in that -Ph-Ph-

means.

8. Use of the compounds of formula I after

Claim 1 as components of liquid crystalline

Phases.

9. Liquid-crystalline phase with at least two liquid-crystalline components, characterized in that it contains at least one compound of the formula I.

10. Liquid crystal display element, characterized in that it contains a liquid crystalline phase according to claim 9.