DE4316357A1 - Thioethers, and liquid-crystalline medium - Google Patents

Abstract

Thioethers of the formula I <IMAGE> in which R<1>, R<2>, A<1>, A<2>, Z<1>, Z<2>, L and m are as defined in Claim 1, are suitable as components of liquid-crystalline media.

Description

The invention relates to thiol ethers of the formula I,

wherein
R¹ is H, an unsubstituted, a simple alkyl or alkenyl radical having 1 to 15 C atoms which is substituted by CN or CF₃ or at least monosubstituted by halogen, where in these radicals also one or more CH₂ groups are each independently of one another 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,
R² is at least one fluorine-substituted alkyl or alkenyl radical having 1-7 C atoms, wherein in this radical one or more CH₂ groups may each be independently replaced by -O-, -S- so that O atoms do not are directly linked.

A¹ and
A² each independently

• (a) trans-1,4-cyclohexylene radical, wherein also a or several non-adjacent CH₂ groups can be replaced by -O- and / or -S-,
• (b) 1,4-phenylene radical, wherein also one or two OH 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,
Z¹ and
Each Z² is independently -CO-O-, -O-CO-, -CH₂O-, -OCH₂-, -CH₂CH₂-, -CH = CH-, -C≡C- or a single bond, one of Z¹ and Z² also - (CH₂) ₄- or -CH = CH-CH₂CH₂-,
LH or F and
in 0, 1 or 2,
means.

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

The compounds of the formula I can be liquid as components crystalline media are used, especially for Dis plays based on the principle of the twisted cell, the guest Host effect, the effect of deformation of 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 high 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. These media also have a lot good low temperature behavior.

Thioethers of the formula

are known from U.S. Pat. 4,045,229 known.

With regard to the most diverse fields of application suchi However, it was desirable for compounds with high Δn have further connections available on the specific applications precisely tailor-made properties respectively.

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 invention are characterized by their Low viscosity at the same time high Δn.  

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 a compo nenten 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.

For the sake of simplicity, the following mean

Cyc a 1,4-cyclohexylene, Dio a 1,3-dioxane-2,5-diyl radical, which is a 1,3-dithiane-2,5-diyl radical, Phe is a 1,4-phenylene radical, Pyd is a pyridine-2,5-diyl radical and Pyr is a pyrimidine-2,5-diyl radical, where Cyc and / or Phe unsubstituted or one or two times by F or CN sub can be stituiert.

A¹ and A² are preferably selected from the group Cyc, Phe, Pyr and Pyd and Dio, preferably only one the residues A¹ and A² present in the molecule, Pyr, Pyd or Dio is.

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

R¹-A²-A³-S-R² Ia

R¹-A²-Z²-A³-S-R² Ib

as well as compounds with three rings of sub-formulas Ic to Ie:

R¹-A¹-A²-A³-S-R² Ic

R¹-A¹-Z¹-A²-A³-S-R² Id

R¹-A¹-A²-Z²-A³-S-R² Ie

and compounds with four rings of the subformula Id to Ij

R¹-A¹-A²-A²-A³-S-R² If

R¹-A¹-Z¹-A²-A²-A³-S-R² Ig

R¹-A¹-A²-Z²-A²-A³-S-R² Ih

R¹-A¹-A²-A²-Z²-A³-S-R² Ii

R¹-A¹-Z¹-A²-Z²-A²-A³-S-R² Ij

R¹-A¹-A²-Z²-A²-Z²-A³-S-R² Ik

R¹-A¹-Z¹-A²-Z²-A²-Z²-A³-S-R² il

Among them, especially those of the sub-formula Ia, Ic, and Id preferred.

The preferred compounds of sub-formula Ia include those of the subformula Iaa to Iae:

R¹-Phe-A³-S-R² Iaa

R 1 -cyc-A 3 -S-R 2 Iab

R¹-Pyr-A³-S-R² Iac

R¹-Pyd-A³-S-R² Iad

R¹-Dio-A³-S-R² Iae

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

R¹-Phe-Phe-A³-S-R² Ica

R 1 -cyc-Phe-A 3 -S-R 2 Icb

R¹-Phe-Dio-A³-S-R² Icc

R¹-Phe-Cyc-A³-S-R² Icd

R¹-Pyd-Phe-A³-S-R² Ice

R¹-Pyr-Phe-A³-S-R² Icf

R¹-Phe-Pyr-A³-S-R² Icg

R¹-Phe-Pyd-A³-S-R² Me

The preferred compounds of Partial Id include those of sub-formula Ida to Idh

R¹-Phe-CH₂CH₂-Phe-A³-S-R² Ida

R¹-Phe-Z¹-Dio-A³-S-R² Idb

R¹-Phe-Z¹-Cyc-A³-S-R² Idc

R¹-Pyd-Z¹-Phe-A³-S-R² Idd

R 1 -pyr-Z 1 -phe-A ³ -S-R 2 ide

R¹-Phe-Z¹-Pyr-A³-S-R² Idf

R¹-Phe-Z¹-Pyd-A³-S-R² Idg

R¹-Phe-Z¹-Phe-Pyd-S-R² Idh

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

R¹-Phe-Phe-Z²-A³-S-R² Iea

R¹-Phe-Phe-CH₂CH₂-A³-S-R² Ieb

R¹-Phe-Dio-Z²-A³-S-R² Iec

R¹-Phe-Cyc-Z²-A³-S-R² Ied

R¹-Pyd-Phe-Z²-A³-S-R² Ief

R¹-Pyr-Phe-Z²-A³-S-R² Ieg

R¹-Phe-Pyr-Z²-A³-S-R² Ieh

Preference is also given to compounds of the formula I and of all Partial formulas in which A¹ and / or A² once or twice by F or monosubstituted 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 2-cyano-1,4-pheny len and 3-cyano-1,4-phenylene. In a particularly preferred Embodiment is A³ 3,5-difluoro-1,4-phenylene and in the 1 or Second

One of Z¹ and Z² is preferably a single bine tion, -CO-O-, -O-CO- and -CH₂CH₂-, secondarily preferred -CH₂O- and -OCH₂-, while the other Z¹ or Z² a Single bond is.

Particularly preferred compounds correspond to the sub-formulas I1 to I16

In the compounds of formula I, S-R 2 is preferably -S-CF₃, -S-CHF₂, -S-C₂F₅, -S-CHF-CF₃, -S-CH₂-CF₃, -S-CF₂-CHF₂, -S- CF₂-CH₂F, -S-CF₂-CH₃, -S-CHF-CHF₂, -S-CHF-CH₂F, -S-CH₂-CHF₂, SC _n H _{2n + 1,} -S- (CH₂) _n -C₂F₅, - S-CH₂-CF₂-CHF₂, -S-CF ₂ -C _n H _{2 + 1} , -S-CH₂- (CH₂) _n -CF₃, -S-CF₂-C _n H _{2n + 1} , -S- (CH₂ ) _n -CF₂-CH₃, -S-CH = CHF, -S-CF = CH₂, -S-CF = CHF, -S-CH = CF₂, -S-CF = CF₃, -S-CH = CF-CF₃ , -S-CF = CF-CF₃, -S-CH₂-CF = CF₂, -S- (CH₂) _n -CH = CF₂, -S-CF = CH-C _n H _{2n + 1} , -S-CH = CF-C _n F _{2n + 1} ,
wherein n is 1, 2, 3, 4 or 5.

If R 1 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 R¹ is an alkyl radical in which a CH₂ group is replaced by -CH = CH-, so this can be straight or be branched. Preferably, it is straight-chain and has 2 to 10 C atoms. He 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-S-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 R¹ is an alkyl radical in which a CH₂ group 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-. virtue wise, 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- (Pro poxycarbonyl) ethyl, 3- (methoxycarbonyl) propyl, 3- (ethoxycar bonyl) propyl, 4- (methoxycarbonyl) -butyl.

If R¹ is an alkyl radical in which a CH₂ group by unsubstituted or substituted -CH = CH- and a adjacent CH₂ group replaced by CO or CO-O or O-CO is, it may be straight or branched. virtue It is straight-chain and has 4 to 13 carbon atoms. He means tetra especially acryloyloxymethyl, 2-acryloyloxyethyl, 3-acryloyloxypropyl, 4-acryloyloxybutyl, 5-acryloyloxypentyl, 6-acryloyloxyhexyl, 7-acryloyloxy-heptyl, 8-acryloyloxy octyl, 9-acryloyloxynonyl, 10-acryloyloxydecyl, methacryl oyloxymethyl, 2-methacryloyloxyethyl, 3-methacryloyloxy propyl, 4-methacryloyloxy-butyl, 5-methacryloyloxypentyl, 6-methacryloyloxyhexyl, 7-methacryloyloxyheptyl, 8-methacryl oyloxyoctyl, 9-methacryloyloxynonyl.  

If R 1 is an alkyl radical which is monosubstituted by CN or CF 3 or alkenyl radical, this radical is preferably straight-chain. The substitution by CN or CF₃ is in belie biger position.

If R¹ is at least monosubstituted by halogen 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 which are above for polymerization Reactions suitable wing groups R are suitable for the preparation of liquid-crystalline polymers.

Compounds of the formula I with branched wing groups R¹ 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, 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 R¹ represents an alkyl radical in which two or more CH₂ groups are replaced by -O- and / or -CO-O-, so can this be straight-chain or branched. Preferably, he is branched and has 3 to 12 carbon atoms. He means accordingly especially 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-carboxyheptyl, 8,8- Bis-carboxy-octyl, 9,9-bis-carboxy-nonyl, 10,10-bis-carboxy decyl, bis (methoxycarbonyl) methyl, 2,2-bis (methoxycar 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 (ethoxycar ethyl), 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.  

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 Vol. IX, p. 867 ff.) are described, under reaction conditions, the known and suitable for the reactions mentioned.

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

Compounds of the invention may e.g. B. Herge as follows be placed:

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

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 cyclohexylbenes zoates, cyclohexane-carboxylic acid phenyl or cyclohexyl esters, Phenyl or cyclohexyl esters of cyclohexylbenzoic acid, Phenyl or cyclohexyl esters of Cyclohexylcyclohexancar bonsäure, Cyclohexyl-phenylester of benzoic acid, the cyclo hexanecarboxylic acid or cyclohexylcyclohexanecarboxylic acid, Phenylcyclohexanes, cyclohexylbiphenyls, phenylcyclohexylcy clohexane, cyclohexylcyclohexane, cyclohexylcyclohexylcyclo hexanes, 1,4-bis-cyclohexylbenzenes, 4,4'-bis-cyclohexyl biphenyls, 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-phenylcyclohexyl) ethanes, 1-cyclohexyl-2- biphenylylethane, 1-phenyl-2-cyclohexyl-phenylethanes, given optionally halogenated stilbenes, benzylphenyl ethers, tolans and substituted cinnamic acids. The 1,4-phenylene groups in these compounds may 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-CH₂CH₂-E-R "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 their mirror images formed group, where Phe unsubstitu substituted or fluorine-substituted 1,4-phenylene, Cyc trans-1,4-cyclohexylene or 1,4-cyclohexylene, Pyr pyrimi din-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 L and E is Cyc, Phe or Pyr. e is preferably Cyc, Phe or Phe-Cyc. Preferably ent the media of the invention one or more components selected from the compounds of the formulas 1, 2, 3, 4 and 5, wherein L and E are selected from the group Cyc, Phe and Pyr and 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 of Ver compounds of formulas 1, 2, 3, 4 and 5 each independently alkyl, alkenyl, alkoxy, alkoxyalkyl, alkenyloxy or alkanoyloxy of up to 8 carbon atoms. Hereinafter this smaller subgroup is called group A and the Compounds are treated with the subformulae 1a, 2a, 3a, 4a and 5a 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 is} Cl₁, 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 sub-formulas 1b, 2b, 3b, 4b and 5b in which R "has the meaning -F, -Cl, -NCS, -CF₃, -OCHF₂ or -OCF₃.

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 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 known from the literature methods or by analogy.

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 20 to 90%, in particular 30 to 90%
Group B: 0 to 80%, preferably 10 to 80%, in particular 10 to 65%
Group C: 0 to 80%, preferably 5 to 80%, in particular 5 to 50%

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 in particular 10% to 90%.

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

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 Liquid 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 the individual case, a code for the substituents R 1, R 2, L 1 and L 2 follows separately from the acronym for the main body with a dash:

Table A

Table B

The following examples are intended to illustrate the invention, without to limit them. Above and below mean percentanga ben weight percent. All temperatures are in degrees Celsius specified. Mp means melting point, bp = clearing point. Further K = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The information between These symbols represent the transition temperatures. Δn means optical anisotropy (589 nm, 20 ° C) and the visco sity (mm² / 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 DCC dicyclohexylcarbodiimide DDQ dichlorodicyanobenzoquinone DIBALH diisobutylaluminum KOT Potassium tert-butoxide PdCl₂ dppf 1,1'-bis (diphenylphosphino) ferrocene-palladium (II) chloride THF tetrahydrofuran pTSOH p-toluenesulfonic acid TMEDA tetramethylethylenediamine

example 1

0.09 mol of 4- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] - 2,6-difluorobenzene are in a nitrogen atmosphere in  Dissolved 100 ml of THF. It is cooled to -70 ° C and dripped to the Solution slowly 0.098 mol of n-BuLi (15% in n-hexane), wherein the reaction mixture warms up. Then it is added 2 h -70 ° C stirred. Thereafter, 0.145 mol of sulfur in portions added to the reaction mixture and a further 2 h at -70 ° C. touched. The mixture is allowed to warm to room temperature with stirring, at 0 ° C Verd. Sulfuric acid to the suspension and stirred 0.5 h. The organic phase is separated and the aqueous Phase with methyl tert. Butyl ether extracted. The unite The organic extracts are washed with water and transferred over Dried sodium sulfate. The crude product is converted into methyl tert. Butyl ether and THF dissolved in a steam bath and then with conc. NaOH solution converted to the sodium salt. One lets cool and filtered through a ball frit. The sodium Salt is dissolved in water with the addition of a little ethanol in the water Dissolved heat and with the addition of dilute hydrochloric acid again in the thiol is transferred. It is extracted with methyl tert. butyl ether, separates the organic phase and washed with water. After drying over sodium sulfate is added to the Rotavapor concentrated.

0.017 mol of thiol from Example 1a) at room temperature in Dissolved 70 ml of THF. After addition of 0.0018 mol of tetrabutylammo Niumhydrogensulfat is stirred for 0.5 h at 40 ° C. Subsequently 0.5 h, CHF₂Cl gas is passed through the solution until it boils. The mixture is heated to 50 ° C and dripped while the same continues early Frigen, 0.017 mol of NaOH solution (37%; 1.6 ml) to the mixture.  

The mixture is then stirred at 60 ° C for 4.5 h. One lets up Cool room temperature and work up as usual. The Crude product is dissolved in a dichloromethane-THF mixture in the Dissolved boiling heat and mixed with 10 g of silica gel. The Solvent is spun off and the residue is on a Silica gel column chromatographed, using as eluent n-hexane is used. The isolated product is recrystallized from ethanol crystallizes. K 70 N 84.4 I; Δε = 9.78; Δn = +0,086

Analogously, the following compounds of the formula

manufactured:

Example 2

0.095 mol of sodium hydride (60%) under nitrogen in Suspended 15 ml of THF. It is cooled to 5 ° C and put the Mixture dropwise with 0.085 mol of thioether from Example 1a) in 15 ml of THF. The mixture is stirred for 0.5 h at 5 ° C and another 45 minutes at room temperature. It is then concentrated on a Rotavapor.

0.093 mol of sodium thionate from Example 2c) are in Raumtem dissolved in 30 ml of DMEU. The solution is refluxed boiled at 140 ° C and dropwise with 0.01 mol trifluoro ethyl methyl sulfonate added. The mixture is stirred for 20 h at 140 ° C and allowed to cool to room temperature. The reaction mixture is poured onto water and treated with methyl tert. Butyl ether extra hiert. The organic phase is separated and initially with 5% sodium hydroxide solution and then extracted with water.

Finally, the organic phase is dried (Na₂SO₄) and the Solvent is removed on the Rotavapor. K 91 N (65,1) I; Δε = 3.93; Δn = +0,085

Analogously, the following compounds of the formula

manufactured:

Example 3

0.016 mol of 3,6-difluoro-4 '- (trans-4-propylcyclohexyl) biphenyl are in a nitrogen atmosphere in 30 ml of tetrahydrofuran solved. The solution is cooled to -70 ° C and dropwise with 0.017 mol n-Buli (15% in n-hexane) and about 3 h stirred at 70 ° C. After adding 0.024 mol of sulfur stirred for a further 2 h without cooling.

Allow to warm to room temperature and give Ice cooling 12.5% HCl to the suspension. The organic Phase is separated, dried over Na₂SO₄ and then over Silica gel first with petroleum ether and then with ethyl acetate cleaned. The solvent is removed and the residue is recrystallized from n-hexane. The crystals were in Dissolved THF and mixed with 32% sodium hydroxide solution, the Sodium salt precipitates, which is slipped. The salt will washed with petroleum ether and then with dilute Hydrochloric acid again transferred to the thiol. You put the Solution successively with methyl tert. Butyl ether, dichloro methane and THF. The organic phase is separated and the aqueous phase with methyl tert. Butyl ether extracted. The combined organic extracts become neutral with water washed and dried over Na₂SO₄. The solvent becomes removed and the crystallized residue from n-hexane recrystallized.

0.35 g of NaH (60%) under nitrogen in 15 ml of THF suspended. It is cooled to 5 ° C and added dropwise with a solution consisting of 0.009 mol of thiol (from Example 3a)) and 15 ml of THF. The mixture is stirred for 0.5 h at room temperature. Lastly, the solvent is removed.

The sodium salt from Example 3b) (0.01 mol) is dissolved in 30 ml DMEU dissolved at room temperature. Then heated to 140 ° C. under reflux, and 0.01 mol of trifluoroethyl is added dropwise methyl sulfonate to the solution. It is stirred overnight at 140.degree and allowed to warm to room temperature. The reaction mixture is poured onto about 150 ml of water and the organic phase with methyl tert. Butyl ether extracted. The organic phase is first with 5% sodium hydroxide solution and then with water extracted by shaking and dried over Na₂SO₄. Last is the Solvent removed on Ratovapor. K 81 I; Δn = +0.134; Δε = 7.8

Analogously, the following compounds of the formula

manufactured:

Example 4

Analogously to Example 1b) 0.015 mol of thiol (from Example 3a)) dissolved in 70 ml of THF and with 0.0017 mol of tetrabutylammonium hydrogen sulfate added. Subsequently, Frigen by the Dissolve the solution until it boils. It is heated to 50 ° C and 1.5 ml of 32% sodium hydroxide solution is added dropwise to the solution.

After completion of Frigeneinleitung the mixture for 4.5 h at Stirred 60 ° C. The work-up is carried out analogously to Example 1b). K 79 I, Δε = 12.3, Δn = + 0.141  

Analogously, the following compounds of the formula

manufactured:

Claims (13)

1. thioethers of the formula I, wherein
R¹ is H, an unsubstituted, a simple alkyl or alkenyl radical having 1 to 15 C atoms which is substituted by CN or CF₃ or at least monosubstituted by halogen, where in these radicals also one or more CH₂ groups are each independently of one another 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,
R² is at least one fluorine-substituted alkyl or alkenyl radical having 1-7 C atoms, wherein in this radical one or more CH₂ groups may each be independently replaced by -O-, -S- so that O atoms do not are directly linked. A¹ and
A² each independently

• (a) trans-1,4-cyclohexylene radical, in which also one or more non-adjacent CH₂ 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,
Z¹ and
Each Z² is independently -CO-O-, -O-CO-, -CH₂O-, -OCH₂-, -CH₂CH₂-, -CH = CH-, -C≡C- or a single bond, one of Z¹ and Z² also - (CH₂) ₄- or -CH = CH-CH₂CH₂-,
LH or F and
m 0, 1 or 2,
means. 2. thioether of formula I, wherein
-S-R² -S-CHF₂, -S-CHF-CF₃, -S-CH = CHF, -S-CF = CH₂, -S- (CH₂) _n -CF₃, -S-CH₂-CH = CH-CF₃ , -S- (CH₂) _n -C _m F _{2m + 1} , -S- (CF₂) _n -C _m H _{2m + 1} , where n and m are each independently 1,2 or 3. 3. thioether of formula I, wherein L is fluorine. 4. thioethers of the formula wherein R and L have the meaning given in claim 1. 5. thioethers of the formula wherein R and L have the meaning given in claim 1. 6. thioethers of the formula wherein R and L have the meaning given in claim 1. 7. thioethers of the formula wherein R and L have the meaning given in claim 1. 8. Use of compounds of the formula I as components liquid-crystalline media. 9. Liquid-crystalline medium with at least two liquid crystalline components, characterized that it contains at least one compound of formula I. 10. Liquid crystal display element, characterized in that it is a liquid-crystalline medium according to claim 9 contains. 11. Electro-optical display element, characterized that it is a liquid-crystalline medium as a dielectric according to claim 9 contains.