DE4001022A1 - New di:fluoro-benzonitrile cpds. for use in liq. crystal medium - having large dielectric anisotropy and low viscosity - Google Patents

Abstract

New difluorobenzonitriles are of formula (I). Y = 1-12C alk(en)yl, oxaalkyl or alkenyloxy; Q = a -Cyc-Cyc-CH2CH2-Phe-, -Cyc-Phe-CH2CH2-Phe-, -Phe-Phe-CH2CH2-Phe-, -Cyc-Cyc-Phe-CH2CH2-, -Cyc-Phe-Phe-CH2CH2-, -Phe-Phe-CH2CH2-, Phe-CH2CH2OPhe, Cyc-CH2CH2-Phe-, -Cyc-Phe-, -Phe-Phe- or -Phe- gp.; (Cyc = trans-1,4-cyclohexylene; Phe = 1,4-phenylene). USE/ADVANTAGE - (I) are claimed for use in liq. crystal (LC) media, which are claimed for use as dielectrics in electro-optical displays. They are esp. useful in twisted cells, guest-host interaction, deformation aligned phase or dynamic scattering effect displays. (I) are stable, liq. crystalline or mesogenic cpds. with relatively low viscosity, very high dielectric anisotropy and good low temp. properties. They form stable LC media with wide nematic mesophase range and relatively low viscosity.

Description

The invention relates to difluorobenzonitriles of the formula I.

wherein
Y is alkyl, alkenyl, alkoxy, oxaalkyl or alkenyloxy having in each case 1 to 12 C atoms, and
Q is a radical selected from the group consisting of

means.

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

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

The invention was based on the object new stable to find liquid-crystalline or mesogenic compounds which are suitable as components of liquid-crystalline media are and in particular at the same time a comparatively have low viscosity and a very high dielectric anisotropy with good low temperature behavior.

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

Liquid crystals of the formula

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

and

known. In JP 63-2 16 858 and USP 48 53 152 finally become compounds of the formulas

and

described. With regard to a wide variety of applications it was such compounds with very high Δε however, more desirable compounds are available to have tailor-made to the particular applications Have properties.

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

The compounds of the formula I have a broad Scope of application. Depending on the selection of the Substituents may use these compounds as base materials serve, from which liquid-crystalline media for are composed predominantly; but it can also compounds of the formula I liquid-crystalline base materials added from other classes of compounds  be, for example, the dielectric and / or optical anisotropy of such a dielectric affect and / or at its threshold voltage and / or to optimize its viscosity.

The compounds of the formula I are colorless in the pure state and form liquid crystalline mesophases in a the electro-optical use conveniently located temperature range. Chemical, thermal and against light she stable.

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

The compounds of the formula I accordingly comprise Compounds of sub-formulas Ia to Il:

These include those of the formulas Ia, Ib, Id, If, Ig, Ih and Ii are particularly preferred.

Y is preferably alkyl, furthermore alkoxy.  

If Y is an alkyl radical and / or an alkoxy radical, this may be straight-chain or branched. Preferably if he is straight, has 2, 3, 4, 5, 6 or 7 C atoms and therefore preferably means ethyl, propyl, Butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, Pentoxy, hexoxy or heptoxy, furthermore methyl, octyl, nonyl, Decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, Methoxy, octoxy, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy or tetradecoxy.

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

If Y is an alkyl radical in which a CH₂ group replaced by -CH = CH-, this can be straight-chain or be branched. Preferably, it is straight-chain and has 2 to 10 carbon atoms. He therefore means special 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, nonyl-1-, 2-, 3-, 4-, 5-, 6-, 7- or non-8-enyl, Dec-1, 2-, 3-, 4-, 5-, 6-, 7-, 8- or dec-9-enyl.

Compounds of the formulas I with branched wing groups Y can occasionally because of better solubility in the usual liquid-crystalline base materials of Be important, but especially as chiral dopants, if they are optically active.  

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

Branched groups of this kind usually contain no more than a chain branch. Preferred branched Radicals Y 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.

Formula I includes both the racemates of these compounds as well as the optical Anitpoden and their mixtures.

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

The compounds of the formula I are known per se Methods presented in the literature (eg. in the standard works such as Houben-Weyl, Methods of the Organic Chemistry, Georg-Thieme-Verlag, Stuttgart Vol. IX, P. 867 ff.), Under reaction conditions, known for the reactions mentioned and are suitable. It can also be known by itself, Uses not mentioned in detail here do.  

The compounds of the invention may, for. B. manufactured, by dissolving a compound of formula II,

wherein Y and Q have the meaning given, according to metallized following reaction scheme and then reacted with a suitable electrophile:

Other synthetic methods will be apparent to those skilled in the art. For example, in the 5-position accordingly substituted 1,3-difluorobenzene compounds according to the above scheme in the 2-cyano-1,3-difluoro compounds be transferred and the rest Y-Q- subsequently by reactions customary in liquid-crystal chemistry (For example, esterification, etherification or couplings z. B. according to the article E. Poetsch, contacts (Darmstadt) 1988 (2), p. 15).

The compounds of the formula II can be, for example be prepared according to the following synthesis schemes:  

A particularly preferred method for the preferred Compounds of sub-formulas Ia, Ib and Ic are as follows Scheme indicated:

The starting materials are either known or can be prepared in analogy to known compounds become.

The liquid-crystalline media according to the invention contain preferably in addition to one or more inventive Compounds as further constituents 2 to 40, in particular 4 to 30 components. Very particularly preferably included these media in addition to one or more inventive Compounds 7 to 25 components. These others Ingredients are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, especially substances from the classes of Azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, Phenyl or cyclohexyl benzoates, cyclohexane-carboxylic acid phenyl or cyclohexyl esters, phenyl or cyclohexyl esters cyclohexylbenzoic acid, phenyl or cyclohexyl esters cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl ester benzoic acid, cyclohexanecarboxylic acid, or cyclohexylcyclohexanecarboxylic acid, phenylcyclo hexanes, cyclohexylbiphenyls, phenylcyclohexylcyclohexanes,  Cyclohexylcyclohexanes, cyclohexylcyclohexenes, cyclohexylcyclohexylcyclohexenes, 1,4-bis-cyclohexylbenzenes, 4,4'-biscyclohexylbiphenyls, Phenyl or cyclohexylpyrimidines, Phenyl- or cyclohexylpyridines, phenyl- or cyclohexyl-dioxanes, Phenyl or cyclohexyl-1,3-dithiane, 1,2-diphenylethane, 1,2-dicyclohexylethane, 1-phenyl-2-cyclohexylethane, 1-cyclohexyl-2- (4-phenyl-cyclohexyl) ethanes, 1-cyclohexyl-2-biphenylylethanes, 1-phenyl-2-cyclohexylphenylethanes, optionally halogenated stilbenes, Benzylphenyl ethers, tolans and substituted cinnamic acids. The 1,4-phenylene groups in these compounds can also be fluorinated.

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

R'-L-E-R '' 1 R'-L-COO-E-R '' 2 R'-L-OOC-E-R '' 3 R'-L-CH₂CH₂-E-R '' 4 R'-L-C≡C-E-R '' 5

In the formulas 1, 2, 3, 4 and 5, L and E, denote may be the same or different, each independently from each other a bivalent radical from the -Phe-, -Cyc, -Phe-Phe, -Phe-Cyc, -Cyc-Cyc, -Pyr-, -Dio, G-Phe and -G-Cyc and their mirror images formed Group, wherein Phe is unsubstituted or by Fluorine-substituted 1,4-phenylene, Cyc trans-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.  

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

R 'and R' 'in the compounds of the sub-formulas 1a, 2a, 3a, 4a and 5a each independently Alkyl, alkenyl, alkoxy, alkenyloxy or alkanoyloxy with up to 8 carbon atoms. For most of these compounds R 'and R' 'are different from each other, where one of these radicals is usually alkyl or alkenyl. In the Compounds of sub-formulas 1b, 2b, 3b, 4b and 5b means R "-CN, -CF₃, F, Cl or -NCS; R has the case at the compounds of the sub-formulas 1a to 5a specified Meaning and is preferably alkyl or alkenyl. But also other variants of the proposed substituents in The compounds of the formulas 1, 2, 3, 4 and 5 are customary. Many such substances or mixtures of which are commercially available. All these substances are by literature methods or in analogy available.  

The media according to the invention preferably contain in addition Components from the group of compounds 1a, 2a, 3a, 4a and 5a (group I) also components from the group of Compounds 1b, 2b, 3b, 4b and 5b (group 2), their proportions preferably as follows:

Group 1: 20 to 90%, in particular 30 to 90%,

Group 2: 10 to 80%, in particular 10 to 50%,

wherein the sum of the proportions of the compounds of the invention and the compounds from groups 1 and 2 to 100% yield.

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

The preparation of the media according to the invention takes place in in the usual way. In general, the components are dissolved in each other, useful at elevated temperature. By suitable additives, the liquid-crystalline Phases modified according to the invention that in all hitherto known species of Liquid crystal display elements can be used. Such additives are known in the art and in the Literature described in detail (H. Kelker / R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980). For example, pleochroic dyes for the production of colored guest host systems or substances for changing the dielectric anisotropy, the viscosity and / or the orientation of the nematic Phases are added.  

The following examples are intended to illustrate the invention, without limiting it. Above and below mean Potencies percent by weight. All temperatures are in Degrees Celsius indicated. Mp means melting point Kp = Clearing point. Furthermore, K = crystalline state, N = nematic phase, S = smectic phase and I = isotropic Phase. The information between these symbols represents the Transition temperatures. Δn means optical anisotropy (589 nm, 20 ° C) and the viscosity (mm² / sec) was at 20 ° C determined.

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

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

example 1

A solution of 0.1M 1- (4'-n-pentylbiphenyl-4-yl) -2- (3,5-difluorophenyl) -ethane (mp 59 °, prepared according to Scheme 1) and 0.1M TMEDA in 300 ml of THF are added dropwise at about -65 ° with 0.1 M n-BuLi (1.5 M in hexane). The mixture is stirred for 30 min at this temperature and then sets a Lsg of 0.1 m J₂ in 70 ml of THF slowly. After completion of the addition is allowed to warm to -20 ° and hydrolyzed with H₂O. By adding diethyl ether, the product is completely dissolved and excess J₂ by washing with Natriumthiosulfatlsg. and H₂O removed. After evaporation, the product remains as residue and is heated without further purification with 0.12 m (CuCN) _x and 100 ml of NMP for 4 h at 170 ° C in an oil bath. After this time, the cooled reaction mixture is mixed with water and CH₂CH₂, the org. Phase, dried and evaporated. The pure product can be obtained by chromatography and crystallization. 1- (4'-n-Pentylbiphenyl-4-yl) -2- (4-cyano-3,5-difluoro-phenyl) -ethane is obtained.

Example 2 to 19

Similarly, one obtains from the corresponding precursors of Formula II the following compounds according to the invention:

Claims (4)

1. Difluorobenzonitriles of the formula I. wherein
Y is alkyl, alkenyl, alkoxy, oxaalkyl or alkenyloxy having in each case 1 to 12 C atoms, and
Q is a radical selected from the group consisting of means. 2. Use of the compounds of the formula I according to claim 1 as components of liquid-crystalline Media for electro-optical display elements.   3. Liquid-crystalline medium for electro-optical Display elements with at least two liquid-crystalline ones Components, characterized that at least one component is a compound of Formula I according to claim 1. 4. Electro-optical display element, characterized that it contains a medium according to claim 3.