DE4314872A1 - Fluoromethyl ketones and liquid crystalline medium - Google Patents

Description

The invention relates to fluoromethyl ketones of the formula I,

wherein
R is an unsubstituted, an alkyl or alkenyl radical having 1 to 15 C atoms which is monosubstituted by CN or CF ₃ or at least monosubstituted by halogen, where one or more CH ₂ groups in these radicals are each independently of one another denoted by -O- , -S-,

-CO-, -CO-O-, -O-CO- or -O-CO-O- may be replaced so that O atoms are not directly linked to one another,
A ¹ and A ² each independently

• (a) trans-1,4-cyclohexylene radical, in which also one or more non-adjacent CH ₂ groups may be replaced by -O- and / or -S-,
• (b) 1,4-phenylene radical, wherein also one or two CH groups can be replaced by N,
• (c) radical from the group 1,4-cyclohexenylene, 1,4-bicyclo (2,2,2) octylene, piperidine-1,4-diyl, Naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl,

where the radicals (a) and (b) can be substituted by one or two fluorine,
Z ¹ and Z ^{2 are} each independently -CO-O-, -O-CO-, -CH ₂ O-, -OCH ₂ -, -CH ₂ CH ₂ -, -CH = CH-, -C≡C- or a single bond, one of Z ¹ and Z ² also - (CH ₂ ) ₄ - or -CH = CH-CH ₂ CH ₂ -,
X is fluorine or chlorine, and
m 0, 1 or 2
means.

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

The compounds of the formula I can be used as components liquid-crystalline media are 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 and especially at the same time a comparatively small Possess viscosity as well as a relatively high dielectric Anisotropy.

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

In DE 41 01 600 A1 compounds with a termi cal CO-CF ₂ alkyl group such. B.

mentioned.  

Compound of the formula

are described in DE-OS 40 06 921.

These compounds are not UV stable in most cases and therefore less suitable for practical applications.

With regard to the most diverse fields of application suchi However, it was desirable to add more UV-sta Bile compounds with high nematogeneity available to have, which measured on the respective applications exactly have tailored properties.

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

The compounds of the formula I have a broad application dung area. Depending on the choice of Substi These compounds can be used as base materials serve, from which liquid-crystalline media predominate the part are composed; but it can also Verbindun of the formula I liquid-crystalline base materials be added to other classes of compounds, for example example, the dielectric and / or optical anisotropy of a to influence such dielectric and / or 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 one for the Electro-optical use conveniently located Temperaturbe rich. Chemically, thermally and against light, they are 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 electro-optical Display elements containing such media.

For the sake of simplicity, Y denotes CO-CF ₂ -X,

Cyc is a 1,4-cyclohexyl radical, Che is 1,4-cyclo Hexenylenrest, Dio a 1,3-dioxane-2,5-diyl, Dit one 1,3-dithian-2,5-diyl, Phe a 1,4-phenylene, Pyd  a pyridine-2,5-diyl radical, Pyr a pyrimidine-2,5-diyl radical and Bi is a bicyclo (2,2,2) octylene radical, wherein Cyc and / or Phe unsubstituted or one or two times by F or CN may be substituted.

A ¹ and A ² are preferably selected from the group Cyc, Che, Phe, Pyr, Pyd and Dio, wherein preferably only one of the radicals A ¹ and A ² present in the molecule is Che, Phe, Pyr, Pyd or Dio.

R is preferably alkyl, furthermore alkoxy.

The compounds of the formula I accordingly comprise Compounds with two rings of subformulae Ia and Ib:

RA ² -A ³ -Y Ia

RA ² -Z ² -A ³ -Y Ib

Compounds with three rings of subformulae Ic to If:

RA ¹ -A ² -A ³ -Y Ic

RA ¹ -Z ¹ -A ² -Z ² -A ³ -Y Id

RA ¹ -Z ¹ -A ² -A ³ -Y Ie

RA ¹ -A ² -Z ² -A ³ -YIf

and compounds with four rings of the subformulae Ig to Im:

RA ¹ -A ¹ -A ² -A ³ -Y Ig

RA ¹ -Z ¹ -A ¹ -A ² -A ³ -Y Ih

RA ¹ -A ¹ -Z ¹ -A ² -A ³ -Y Ii

RA ¹ -A ¹ -A ² -Z ² -A ³ -Y Ij

RA ¹ -Z ¹ -A ¹ -Z ¹ -A ² -A ³ -Y Ik

RA ¹ -A ¹ -Z ¹ -A ² -Z ² -A ³ -Y II

RA ¹ -Z ¹ -A ¹ -Z ¹ -A ² -Z ² -A ³ -Y Im

Of these, particularly those of sub-formulas Ia, Ib, Ic, Id, Ie, If, Ii and Il are preferred.

The preferred compounds of sub-formula Ia include those of the subformulae Iaa to Iag:

R-Phe-A ³ -Y Iaa

R-Dit-A ³ -Y Iab

R-Dio-A ³ -Y Iac

R-Pyr-A ³ -Y I ad

R-Pyd-A ³ -Y Iae

R-Cyc-A ³ -Y Iaf

R-Che-A ³ -Y was

These include those of the formulas Iaa, Iad, Iae and Iaf particularly preferred.

The preferred compounds of sub-formula Ib include those of the subformulae Iba and Ibc:

AR-Cyc-CH ₂ CH ₂ -A ³ -Y Iba

R-Cyc-COO-A ³ -Y Ibb

R-Phe-COO-A ³ -Y Ibc

The preferred compounds of sub-formula Ic include those of partial formulas Ica to Icn:

AR-Phe-Phe-A ³ -Y Ica

R-Phe-Pyd-A ³ -Y Icb

R-Phe-Dio-A ³ -Y Icc

R-Cyc-Cyc-A ³ -Y Icd

R-Phe-Cyc-A ³ -Y Ice

R-Cyc-Pyd-A ³ -Y Icf

R-Pyd-Phe-A ³ -Y Icg

R-Pyr-Phe-A ³ -Y i

R-Phe-Pyr-A ³ -Y Ici

R-Cyc-Pyr-A ³ -Y Icj

R-Cyc-Phe-A ³ -Y Ick

R-dio-Phe-A ³ -Y Icl

R-Che-Phe-A ³ -Y Icm

R-Phe-Che-A ³ -Y Icn

Among them are those of the formulas Ica, Icb, Icd, Ice, I, Ici and Ick are particularly preferred.

The preferred compounds of Partial Id include those of the sub-formulas Ida to Idk:

AR-Phe-Z ¹ -Phe-Z ² -A ³ -Y Ida

R-Phe-Z ¹ -Dio-Z ² -A ³ -Y Idb

R-Cyc-Z ¹ -Cyc-Z ² -A ³ -Y Idc

R-Cyc-Z ¹ -Pyr-Z ³ -A ³ -Y Idd

R-Pyd-Z ¹ -Phe-Z ² -A ³ -Y Ide

R-Phe-Z ¹ -Pyd-Z ² -A ³ -Y Idf

R-Pyr-Z ¹ -Phe-Z ² -A ³ -Y Idg

R-Phe-Z ¹ -Pyr-Z ² -A ³ -Y Idh

R-Phe-Z ¹ -Cyc-Z ² -A ³ -Y Idi

R-Cyc-Z ¹ -Phe-Z ² -A ³ -Y Idj

R-Dio-Z ¹ -Phe-Z ² -A ³ -Y Idk

The preferred compounds of sub-formula Ie include those of the subformulae Iea to Iej:

AR-Pyr-Z ¹ -Phe-A ³ -Y Iea

R-Dio-Z ¹ -Phe-A ³ -Y Ieb

R-Phe-Z ¹ -Phe-A ³ -Y Iec

R-Cyc-Z ¹ -Phe-A ³ -Y IED

R-Phe-Z ¹ -Cyc-A ³ -Y Iee

R-Cyc-Z ¹ -Cyc-A ³ -Y Ief

R-Phe-Z ¹ -Dio-A ³ -Y Ieg

R-Pyd-Z ¹ -Phe-A ³ -Y Ieh

R-Phe-Z ¹ -pyr-A ³ -Y Iei

R-Cyc-Z ¹ -pyr-A ³ -Y Ij

The preferred compounds of the subform If include those of the sub-formulas Ifa to Ifn:

AR-Pyr-Phe-Z ² -A ³ -Y-Ifa

R-Pyr-Phe-OCH ₂ -A ³ -Y lft

R-Phe-Phe-Z ² -A ³ -Y Ifc

R-Phe-Phe-OOC-A ³ -Y Ifd

R-Cyc-Cyc-Z ² -A ³ -Y Ife

R-Cyc-Cyc-CH ₂ CH ₂ -A ³ -Y Iff

R-Pyd-Phe-Z ² -A ³ -Y Ifg

R-dio-Phe-Z ² -A ³ -Y Ifh

R-Phe-Cyc-Z ² -A ³ -Y Ifi

R-Phe-Pyd-Z ² -A ³ -Y Ifj

R-Che-Phe-Z ² -A ³ -Y-Ifk

R-Phe-Che-Z ² -A ³ -Y Ifl

R-Cyc-Phe-Z ² -A ³ -Y Ifm

R-Cyc-Phe-OOC-A ³ -Y Ifn

Preference is also given to compounds of the formula I and of all subformulae in which A ¹ and / or A ^{2 is} monosubstituted or disubstituted by F or simply by CN-substituted 1,4-phenylene. In particular, these are 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene and 3,5-difluoro-1,4-phenylene and also 2-cyano-1,4-phenylene and 3-cyano-1 , 4-phenylene. In a particularly preferred embodiment, A ^{2 is} 3,5-difluoro-1,4-phenylene and m is 1 or 2.

Z ¹ and Z ^{2 are} preferably a single bond, -CO-O-, -O-CO- and -CH ₂ CH ₂ -, secondarily preferably -CH ₂ O- and -OCH ₂ -.

If one of the radicals Z ¹ and Z ^{2 is} - (CH ₂ ) ₄ - or -CH = CH-CH ₂ CH ₂ -, the other radical Z ¹ or Z ² (if present) is preferably the single bond.

If R is an alkyl radical and / or an alkoxy radical, this may be straight-chain or branched. Preferably if it is straight-chain, has 2, 3, 4, 5, 6 or 7 carbon atoms and therefore preferably denotes ethyl, propyl, butyl, pentyl, Hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy or Heptoxy, furthermore methyl, octyl, nonyl, decyl, undecyl, Dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octoxy, Nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy or tetra decoxy.

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

If R is an alkyl radical in which a CH ₂ group is replaced by -CH = CH-, this may be straight-chain or branched. It is preferably straight-chain and has 2 to 10 C atoms. It therefore means especially vinyl, prop-1, or prop-2-enyl, but-1, 2- or but-3-enyl, pent-1, 2-, 3- or pent-4-enyl, hex 1-, 2-, 3-, 4- or hex-5-enyl, hept-1, 2-, 3-, 4-, 5- or hept-6-enyl, Oct-1, 2-, 3-, 4-, 5-, 6- or oct-7-enyl, non-1-, 2-, 3-, 4-, 5-, 6-, 7- or non-8-enyl, Dec-1 -, 2-, 3-, 4-, 5-, 6-, 7-, 8- or dec-9-enyl.

If R is an alkyl radical in which one CH ₂ group has been replaced by -O- and one by -CO-, these are preferably adjacent. Thus, these include an acyloxy group -CO-O- or an oxycarbonyl group -O-CO-. Preference, these are straight-chain and have 2 to 6 carbon atoms.

They therefore mean especially acetyloxy, propionyloxy, Butyryloxy, pentanoyloxy, hexanoyloxy, acetyloxymethyl, Propionyloxymethyl, butyryloxymethyl, pentanoyloxymethyl, 2-acetyloxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl, 3-acetyloxypropyl, 3-propionyloxypropyl, 4-acetyloxybutyl, Methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxy carbonyl, pentoxycarbonyl, methoxycarbonylmethyl, ethoxy carbonylmethyl, propoxycarbonylmethyl, butoxycarbonylmethyl, 2- (methoxycarbonyl) ethyl, 2- (ethoxycarbonyl) ethyl, 2- (propoxycarbonyl) ethyl, 3- (methoxycarbonyl) propyl, 3- (ethoxycarbonyl) propyl, 4- (methoxycarbonyl) -butyl.

If R is an alkyl radical in which a CH ₂ group is replaced by unsubstituted or substituted -CH = CH- and an adjacent CH ₂ group by CO or CO-O or O-CO, this may be straight-chain or branched. Preferably, it is straight-chain and has 4 to 13 carbon atoms. It therefore particularly means acryloyloxymethyl, 2-acryloyloxyethyl, 3-acryloyloxypropyl, 4-acryloyloxybutyl, 5-acryloyloxypentyl, 6-acryloyloxyhexyl, 7-acryloyloxyheptyl, 8-acryloyloxyoctyl, 9-acryloyloxynonyl, 10-acryloyloxydecyl, methacryloyloxymethyl, 2-methacryloyloxyethyl, 3-methacryloyloxypropyl, 4-methacryloyloxybutyl, 5-methacryloyloxypentyl, 6-methacryloyloxyhexyl, 7-methacryloyloxyheptyl, 8-methacryloyloxyoctyl, 9-methacryloyloxynonyl.

If R monosubstituted by CN or CF ₃ means an alkyl or alkenyl radical, this radical is preferably straight-chain and the substitution by CN or CF ₃ in ω-position.

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

Compounds of the formula I with branched wing groups R occasionally because of better solubility in the Of conventional liquid-crystalline base materials of importance but especially as chiral dopants, if they are are optically active. Smectic compounds of this kind eig as components for ferroelectric materials.

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

Branched groups of this type usually do not contain more than one chain branch. Preferred branched radicals R is isopropyl, 2-butyl (= 1-methylpropyl), isobutyl (= 2-methylpropyl), 2-methylbutyl, isopentyl (= 3-methyl butyl), 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-propylpentyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethyl hexoxy, 1-methylhexoxy, 1-methylheptoxy.  

If R is an alkyl radical in which two or more CH ₂ groups have been replaced by -O- and / or -CO-, this may be straight-chain or branched. Preferably, it is branched and has 3 to 12 carbon atoms. It therefore particularly means bis-carboxy-methyl, 2,2-bis-carboxy-ethyl, 3,3-bis-carboxy-propyl, 4,4-bis-carboxy-butyl, 5,5-bis-carboxy-pentyl, 6 , 6-bis-carboxyhexyl, 7,7-bis-carboxy heptyl, 8,8-bis-carboxy-octyl, 9,9-bis-carboxy-nonyl, 10,10-bis-carboxy-decyl, bis- (methoxycarbonyl) -methyl, 2,2-bis (methoxycarbonyl) -ethyl, 3,3-bis (methoxycarbonyl) propyl, 4,4-bis (methoxycarbonyl) -butyl, 5,5-bis (methoxycarbonyl ) pentyl, 6,6-bis (methoxycarbonyl) hexyl, 7,7-bis (methoxycarbonyl) heptyl, 8,8-bis (methoxycarbonyl) octyl, bis (ethoxycarbonyl) methyl, 2,2 -Bis (ethoxycarbonyl) ethyl, 3,3-bis (ethoxycarbonyl) -propyl, 4,4-bis (ethoxycarbonyl) -butyl, 5,5-bis (ethoxycarbonyl) -hexyl.

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

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

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

In the compounds of formula I those are stereo isomers are preferred in which the rings Cyc and piperidine trans-1,4-disubstituted. Those of the above named formulas containing one or more groups Pyd, Pyr and / or Dio, each enclosing the two 2,5-positional isomers.

Some especially preferred smaller groups of Compounds are those of the subformulae I1 to I20:

The 1,4-cyclohexenylene group preferably has the following structures:

The compounds of the formula I are known per se Methods presented in the literature (eg in the Standard works such as Houben-Weyl, Methods of the Organic Chemistry, Georg Thieme Verlag, Stuttgart), and Although under reaction conditions, for the aforementioned Umset tongues are known and suitable.

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

The compounds of the invention may, for. B. produced be prepared by reacting a compound of formula II,

wherein R, A ¹ , A ² , Z ¹ , Z ² and m have the meaning indicated, metallized according to the following reaction scheme and reacted with 2,2,2-trifluoro or 2,2-difluoro-2-chloroacetic acid methyl ester.

Scheme 1

Other synthetic methods are apparent to those skilled in the art. For example, in the 5-position corresponding to substituted 1,3-difluorobenzene compounds according to the above scheme can be converted into the 1,3-difluoro compounds (L = H) and the radical R- (A ¹ -Z ¹ ) _m -A ² -Z ^{2 can} then be introduced by reactions customary in liquid crystal chemistry (for example couplings, for example, according to the article E. Poetsch, Kontakte (Darmstadt) 1988 (2), p.

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

Scheme 2 (A = - (- A ¹ -Z ¹ ) _m -A ² - / Z ² = -CH ₂ CH ₂ -)

Scheme 3 (A = - (- A ¹ -Z ¹ ) _m -A ² - / Z ² = single bond)

Scheme 4

Scheme 5

Scheme 6

Esters of formula I may also correspond by esterification the carboxylic acids (or their reactive derivatives) with alcohols or phenols (or their reactive Derivatives) or by the DCC method (DCC = dicyclohexyl carbodiimide).

The corresponding carboxylic acids and alcohols or phenols are known or can be analogous to known methods getting produced.

In a further process for the preparation of the compounds of formula I is reacted with an aryl halide with an olefin in the presence of a tertiary amine and a palladium catalyst sators (see R. F. Heck, Acc Chem. Res. 12 (1979) 146). Suitable aryl halides are, for example, chlorides, Bromides and iodides, especially bromides and iodides. The for the success of the coupling reaction required tertiary Amines, such as As triethylamine, are also suitable as a solution medium. As palladium catalysts are, for example, the  Salts, in particular Pd (II) acetate, with organic phosphorus (III) compounds such. B. triarylphosphines suitable. One can do this in the presence or absence of an inert Solvent at temperatures between about 0 ° and 150 ° C, preferably between 20 ° and 100 ° C, work; as a solution medium come z. As nitriles such as acetonitrile or carbon hydrogens such as benzene or toluene into consideration. As Starting materials used aryl halides and olefins are widely available in the trade or may be literature known methods are prepared, for example by Halogenation of corresponding parent compounds or by Elimination reactions with corresponding alcohols or Halides.

Ethers of the formula I are obtainable by etherification of corresponding hydroxy compounds, preferably corresponding phenols, wherein the hydroxy compound is first expediently converted into a corresponding metal derivative, eg. B. by treatment with NaH, NaNH ₂ , NaOH, KOH, Na ₂ CO ₃ or K ₂ CO _{3 is converted} into the corresponding alkali metal or alkali metal phenolate. This can then be reacted with the corresponding alkyl halide, sulfonate or dialkyl sulfate, suitably in an inert solvent such as. As acetone, 1,2-dimethoxy ethane, DMF or dimethyl sulfoxide or with an excess shot of aqueous or aqueous-alcoholic NaOH or KOH at temperatures between about 20 ° and 100 ° C.

The starting materials are either known or can be used in Be prepared analogously to known compounds.  

The compounds of the formula I where Z ² = - (CH ₂ ) ₄ - can be prepared according to the following scheme:

Scheme 7

In the Pd (II) -catalyzed coupling reaction, either directly the target product I 'formed or a precursor, in this is completely analogous to the above methods for Verbindun gene or formula I, the radical -Y is introduced.

The compounds of formula I where Z ² = -CH = CH-CH ₂ CH ₂ - can be prepared according to Wittig according to the following scheme:

Scheme 8

The synthesis of some particularly preferred compounds is specified in the following:

Scheme 9

Scheme 10

Scheme 11

The liquid-crystalline media according to the invention contain preferably in addition to one or more inventive Compounds as further constituents 2 to 40, in particular 4 to 30 components. Very particularly preferably included these media in addition to one or more inventive Compounds 7 to 25 components. This further inventory Parts are preferably selected from nematic or  nematogenic (monotropic or isotropic) substances, esp substances from the classes of azoxybenzenes, benzylidene anilines, biphenyls, terphenyls, phenyl or cyclohexyl benzoate, cyclohexane-carboxylic acid-phenyl or cyclohexyl ester, phenyl or cyclohexyl esters of cyclohexylbenzoic acid acid, phenyl or cyclohexyl esters of cyclohexylcyclo hexanecarboxylic acid, cyclohexyl phenyl ester of benzoic acid, the Cyclohexanecarboxylic acid, or the Cyclohexylcyclohexancarbon acid, phenylcyclohexanes, cyclohexylbiphenyls, phenylcyclo hexylcyclohexanes, cyclohexylcyclohexanes, cyclohexylcyclo hexylcyclohexenes, 1,4-bis-cyclohexylbenzenes, 4,4'-bis-cyclo hexylbiphenyls, phenyl- or cyclohexylpyrimidines, phenyl- or cyclohexylpyridines, phenyl- or cyclohexyl-dioxanes, Phenyl or cyclohexyl-1,3-dithiane, 1,2-diphenylethane, 1,2-dicyclohexylethane, 1-phenyl-2-cyclohexylethane, 1-cyclo hexyl 2- (4-phenyl-cyclohexyl) -ethanes, 1-cyclohexyl-2-biphenyne Iylethanes, 1-phenyl-2-cyclohexyl-phenylethanes, optionally halogenated stilbenes, benzylphenyl ethers, tolans and substi tanned cinnamic acids. The 1,4-phenylene groups in these Ver bonds can also be fluorinated.

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

R'-L-E-R "1

R'-L-COO-E-R "2

R'-L-OOC-E-R "3

R'-L-CH ₂ CH ₂ -ER '' 4

R'-L-C≡C-E-R "5.

In formulas 1, 2, 3, 4 and 5, L and E are the same or may be different, each independently a bivalent radical from the group consisting of -Phe-, -Cyc-, -Phe-Phe-, -Phe-Cyc, -Cyc-Cyc, -Pyr-, -Dio, -G-Phe- and -G-Cyc- and whose mirror images formed group, where Phe unsubsti substituted or fluorine-substituted 1,4-phenylene, Cyc trans-1,4-cyclohexylene or 1,4-cyclohexylene, pyr pyrimidine 2-5-diyl or pyridine-2,5-diyl, Bio 1,3-dioxane-2,5-diyl and G 2- (trans-1,4-cyclohexyl) -ethyl, pyrimidine-2,5-diyl, pyridine 2,5-diyl or 1,3-dioxane-2,5-diyl.

Preferably, one of L and E is Cyc, Phe or Pyr. E is preferably Cyc, Phe or Phe-Cyc. Preferably ent keep the media of the invention one or more Kompo selected from the compounds of the formulas 1, 2, 3, 4 and 5, wherein L and E are selected from the group Cyc, Phe and Pyr and at the same time one or more components selected from the compounds of the formulas 1, 2, 3, 4 and 5, wherein one of L and E is selected from the group Cyc, Phe and Pyr and the other radical is selected from the Group -Phe-Phe, -Phe-Cyc, -Cyc-Cyc, -G-Phe and -G-Cyc-, and optionally one or more components selected from the compounds of the formulas 1, 2, 3, 4 and 5, wherein the Radicals L and E are selected from the group -Phe-Cyc-, -Cyc-Cyc, -G-Phe and -G-Cyc.

R 'and R' 'in a smaller subgroup denote the verb of the formulas 1, 2, 3, 4 and 5 are each independent of alkyl, alkenyl, alkoxy, alkoxyalkyl, alkenyloxy or Alkanoyloxy with up to 8 carbon atoms. The following will be  designated. For most of these compounds, R 'and R '' different from each other, with one of these radicals usually Alkyl, alkenyl, alkoxy or alkoxyalkyl.

In a smaller subgroup of compounds of formulas 1, 2, 3, 4 and 5, other than group B, R '' is -F, -Cl, -NCS or - (O) _i CH ₃ - _{(k + 1)} F _k Cl ₁ , where i is 0 or 1 and k + 1 is 1, 2 or 3; the compounds in which R "has this meaning are designated by the subformulae 1b, 2b, 3b, 4b and 5b. Particular preference is given to those compounds of the subformulae 1b, 2b, 3b, 4b and 5b in which R "has the meaning -F, -Cl, -NCS, -CF ₃ , -OCHF ₂ or -OCF ₃ . In the case of a substituted in 4-position benzene ring H may be substituted by F in one or both ortho positions.

In the compounds of sub-formulas 1b, 2b, 3b, 4b and 5b has R 'indicated in the compounds of the sub-formulas 1a-5a Meaning and is preferably alkyl, alkenyl, alkoxy or Alkoxyalkyl.

In another smaller subgroup of compounds of Formulas 1, 2, 3, 4 and 5 are R "-CN; this subgroup is hereinafter referred to as group C and the Verbindun of this subgroup are correspondingly subformulated 1c, 2c, 3c, 4c and 5c. In the compounds of Partial formulas 1c, 2c, 3c, 4c and 5c has R 'in the verbin of the sub-formulas 1a-5a given meaning and is preferably alkyl, alkoxy or alkenyl. In case of an in 4-position substituted benzene ring may be in one or both ortho positions H be substituted by F.  

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

The media of the invention contain in addition fiction compounds of the formula I preferably one or several compounds which are selected from the group A and / or group B and / or group C. The mass fractions of Compounds from these groups on the inventive Media are preferred

Group A: 0 to 90%, preferably 4 to 80%, especially 4 to 50% Group B: 0 to 80%, preferably 5 to 80%, especially 5 to 65% Group C: 0 to 80%, preferably 5 to 70%, especially 5 to 50%

where the sum of the mass fractions in the respective Compounds of the invention contained in the Groups A and / or B and / or C preferably 5 to 90% and especially 10 to 80%.

The media according to the invention preferably contain 5 to 80%, in particular preferably 10 to 55% of erfindungs proper connections. Further preferred are media, ent holding more than 60%, in particular 65 to 90% of inventions compounds according to the invention. The media preferably contain three, four or five compounds of the invention.  

Preferred embodiments of liquid-crystalline media are given below:

The medium contains one or more compounds in addition the formula I further compounds, preferably out searches from the following group:

in which the individual radicals have the following meanings:
R: alkyl, oxaalkyl, fluoroalkyl or alkenyl having in each case up to 7 C atoms,
X: F, Cl, CF ₃ , OCF ₃ or OCHF ₂ ,
Y and Z are each independently H or F,
r: 0 or 1.

In the formulas means

preferably

R is preferably straight-chain alkyl having 1 to 7 carbon atoms.  

The preparation of the media according to the invention takes place in usual way. In general, the components are dissolved in each other, useful at elevated temperature. By Suitable additives can after the liquid crystalline phases of the invention are modified so that they are in all hitherto have become known types of liquid crystal display elements can be used. Such additives are those skilled in the art known and described in detail in the literature (H.Kalkker / R.Hatz, Handbook of Liguid Crystals, Verlag Chemistry, Weinheim, 1980). For example, pleochroiti dyestuffs for producing colored guest-host systems or substances for changing the dielectric anisotropy pie, the viscosity and / or the orientation of the nematic Phases are added.

In the present application and in the following examples, the structures of the liquid crystal compounds are indicated by acronyms, wherein the transformation into chemical formulas according to following Tables A and B takes place. All radicals C _n H _{2n + 1} and C _m H _{2m + 1} are straight-chain alkyl radicals with n or m C atoms. The coding according to Table B is self-evident. In Table A, only the acronym for the main body is given. In individual cases, a code for the substituents R ¹ , R ² , L ¹ and L ² follows separately from the acronym for the main body with a dash:

Table A

Table B

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

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

DAST diethylaminosulfur trifluoride
DCC dicyclohexylcarbodiimide
DDQ dichlorodicyanobenzoquinone
DIBALH Diisobutylaluminum hydride
KOT potassium tertiary butoxide
THF tetrahydrofuran
pTSOH p-toluenesulfonic acid
TMEDA tetramethylethylenediamine

Example 1

0.019 mol of p- [trans-4- (trans-4-pentylcyclohexyl) cyclohexyl] - 2,6-difluorobenzene in 60 ml abs. Tetrahydrofuran are on Cooled to -70 ° C and then with 0.023 mol of butyl lithium (15% in n-hexane). It is stirred for 1.5 h and dripped then 0.02 mol of ethyl trifluoroacetate to the solution. It is stirred for a further 2 h at -70 ° C and last with about 6 ml Added 12% hydrochloric acid. The organic phase is abge separates, washed with water and worked up as usual. K 43 N 103.5 I, Δn = + 0.091, Δε = 17.45

Analogously, the following compounds of the formula

manufactured:

example 2

0.03 mol of p- [4- (trans-4-propylcyclohexyl) -phenyl] -2,6-difluoro benzene in 60 ml abs. Tetrahydrofuran are at -70 ° C cooled and then with 0.034 mol of butyllithium (15% in n-hexane). After stirring for 2 h at -70 ° C. 0.031 mol of ethyl trifluoroacetate was added dropwise.

It is allowed to stir for a further 2 h, mixed with 5 ml of 12.5% strength Hydrochloric acid and separates the organic phase. Subsequently is worked up as usual. K 57 N (49.5) I, Δn = +0.164.

Analogously, the following compounds of the formula

manufactured:

n X 1 F 1 Cl 2 F 2 Cl 3 Cl   4 F 4 Cl 5 Cl 6 F 6 Cl 8th F 8th Cl 10 F 10 Cl 12 F 12 Cl

example 3

2.0 mol NaOH cookies are dissolved in 500 ml of water and washed with 0.5 mol p- [trans-4-pentylcyclohexyl] phenylboronic acid in 1000 ml of toluene are added. Then it is 40 minutes ge stirred, the temperature of the solution does not exceed 45 ° C. should step. Thereafter, 0.5 mol of 3,5-difluorophenyl bromide and 11.5 g tetrakis (triphenylphosphine) palladium (0) given to the solution. It is allowed to reflux overnight Cook and cool to room temperature.  

The mixture is filtered off with suction, the organic phase is separated off and the aqueous phase is extracted with toluene. The combined organic extracts are washed with water and filtered through a silica gel filled ball frit. Subsequently, the solution is dried over NaSO ₄ . The solvent is removed under vacuum and the residue is recrystallized in ethanol.

The product (0.03 mol) is dissolved in THF at room temperature with stirring in a nitrogen atmosphere. It is then cooled to -70 ° C and 0.034 mol n-Buli (15% in n-hexane) added dropwise. The mixture is stirred for 2 h at -70 ° C, dropwise 0.031 mol of ethyl trifluoroacetate to the suspension and stirred for a further 2 h. Subsequently, 12.5% hydrochloric acid is added. Finally, as usual, worked up.
Klp. 70.5 ° C, Δε = 22, Δn = 0.155

Examples mix example A example B

Claims (8)

1. fluoromethyl ketones of the formula I, wherein
R is an unsubstituted, an alkyl or alkenyl radical having 1 to 15 C atoms which is monosubstituted by CN or CF ₃ or at least one halogen atom, where one or more CH ₂ groups in these radicals are also independently of each other denoted by O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- may be replaced so that O atoms are not directly linked to one another,
A ¹ and A ² each independently

• (a) trans-1,4-cyclohexylene radical, in which also one or more non-adjacent CH ₂ groups may be replaced by -O- and / or -S-,
• (b) 1,4-phenylene radical, in which also one or two CH groups may be replaced by N,
• (c) radical from the group consisting of 1,4-cyclohexenylene, 1,4-bicyclo (2,2,2) octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6- diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl,

where the radicals (a) and (b) can be substituted by one or two fluorine,
Z ¹ and Z ^{2 are} each independently -CO-O-, -O-CO-, -CH ₂ O-, -OCH ₂ -, -CH ₂ CH ₂ -, -CH = CH-, -C≡C- or a single bond, one of Z ¹ and Z ² also - (CH ₂ ) ₄ - or -CH = CH-CH ₂ CH ₂ -,
X is fluorine or chlorine, and
m 0, 1 or 2
means. 2. Compounds of the formula I1, wherein R and X have the meaning given in claim 1. 3. Compounds of the formula I3, wherein R and X have the meaning given in claim 1. 4. Use of compounds of the formula I as components liquid-crystalline media. 5. Liquid-crystalline medium with at least two liquids crystalline components, characterized in that it contains at least one compound of formula I. 6. Liquid crystal display element, characterized in that it is a liquid-crystalline medium according to claim 5 contains. 7. Electro-optical display element, characterized that it is a liquid-crystalline medium as a dielectric according to claim 5 contains.