DE102017010487A1 - MONOFLUORIZED CYCLOHEXANES - Google Patents

Abstract

The present invention relates to 1-fluorocyclohexyl-methoxy-aryl compounds of the formula Iworin R, R, A, A, m and n are as defined in claim 1, their preparation, their use as components in liquid-crystalline media and electro-optical display elements, the contain liquid crystalline media according to the invention. The compounds have a negative dielectric anisotropy.

Description

The present invention relates to 1-fluorocyclohexyl-methoxy-aryl compounds, a process for their preparation, liquid-crystalline media containing these derivatives and electro-optical display elements containing these liquid-crystalline media. The compounds have a negative dielectric anisotropy.

Liquid crystals have found wide application since about 40 years ago the first commercially applicable liquid crystalline compounds were found. Known applications today are simple digital displays, displays of portable and stationary computers, navigation systems and not least TVs. Particularly for video-capable displays, high demands are placed on switching times and the contrast of the images.

The spatial ordering of molecules in a liquid crystal causes many of its properties to be directional. Of particular importance for use in liquid crystal displays are the anisotropies in the optical, dielectric and elasto-mechanical behavior. Depending on whether the molecules are oriented with their longitudinal axes perpendicular or parallel to the two plates of a capacitor, this has a different capacity; the dielectric constant ε of the liquid-crystalline medium is therefore different for the two orientations. Substances whose dielectric constant is greater when the molecular longitudinal axes are oriented perpendicular to the capacitor plates than in the case of a parallel arrangement are referred to as dielectrically positive. In other words: If the dielectric constant ε _∥ parallel to the _longitudinal molecular _{axes is} greater than the dielectric constant ε _⊥ perpendicular to the _longitudinal molecular axes, the dielectric anisotropy Δε = ε _∥ - ε _{⊥ is} greater than zero. Most of the liquid crystals used in conventional displays fall into this group.

For the dielectric anisotropy both the polarizability of the molecule and permanent dipole moments play a role. When a voltage is applied to the display, the longitudinal axis of the molecules aligns to make the larger of the dielectric constants effective. The strength of the interaction with the electric field depends on the difference between the two constants.

In the case of the liquid-crystalline molecules used in conventional liquid-crystal displays, the dipole moment oriented along the molecular longitudinal axis is larger than the dipole moment oriented perpendicular to the longitudinal molecular axis of the molecule.

With liquid crystals in which the larger dipole moment is oriented parallel to the longitudinal axis of the molecule, very powerful displays have already been developed. Mixtures of 5 to 20 components are usually used to achieve a sufficiently broad temperature range of the mesophase as well as short switching times and low threshold voltages. However, the strong viewing angle dependence in liquid crystal displays, such as those used for laptops, causes difficulties. The best image quality can be achieved if the surface of the display is perpendicular to the viewing direction of the viewer. If the display is tilted relative to the viewing direction, the image quality may deteriorate drastically. For a higher comfort, it is endeavored to make as large as possible the angle by which the display can be tilted from the viewing direction of a viewer without significantly reducing the imaging quality. More recently, attempts have been made to improve the viewing angle dependence using liquid crystalline compounds whose dipole moment is greater perpendicular to the longitudinal molecular axis than parallel to the longitudinal axis of the molecule. The dielectric anisotropy Δε is negative in this case. In the field-free state, these molecules are oriented with their longitudinal axis perpendicular to the glass surface of the display. By applying an electric field, they orient themselves more or less parallel to the glass surfaces. In this way an improvement of the viewing angle dependency could be achieved. Such displays are referred to as VA-TFT displays (derived from the English: "vertically aligned").

The development in the field of liquid crystalline materials is far from complete. To improve the properties of liquid-crystalline display elements, efforts are constantly being made to develop new compounds which make it possible to optimize such displays.

In the pamphlets DE 3231707 A . DE 19831712 . US 6139773 A and DE 10219542 A1 For example, fluorocyclohexanes are disclosed for use as a liquid crystalline material. The compounds differ from the compounds according to the invention in the specific substitution of the cyclohexane radical.

An object of the present invention is to provide compounds with advantageous properties for use in liquid-crystalline media. In particular, they should have a negative dielectric anisotropy, which makes them particularly suitable for use in liquid-crystalline media for VA displays. Regardless of the type of dielectric anisotropy corresponding to the display type, compounds having a favorable combination of performance parameters are desired. These parameters to be optimized at the same time include, above all, a high clearing point, a low rotational viscosity, an optical anisotropy in the application interval, and the properties which serve to achieve mixtures with the desired liquid-crystalline phases over a broad temperature range (low melting point, good miscibility with other liquid crystalline components of the desired type). Not least, the chemical stability of the compounds and the mixtures produced with them is an important aspect in the development of new substances.

worin

m

0, 1 oder 2 ist, bevorzugt 1,

n

1 oder 2 ist, bevorzugt 1,

R¹ und R²

unabhängig voneinander einen Alkyl- oder Alkoxyrest mit 1 bis 15 C-Atomen, wobei in diesen Resten auch eine oder mehrere CH₂-Gruppen jeweils unabhängig voneinander durch -C≡C- -CF₂O-, -OCF₂-, -CH=CH-,

-O-, -S-, -CO-O- oder -O-CO- so ersetzt sein können, dass O/S-Atome nicht direkt miteinander verknüpft sind, und worin auch ein oder mehrere H-Atome durch Halogen ersetzt sein können, oder H, bevorzugt unabhängig voneinander, einen unsubstituierten Alkylrest, Alkoxyrest oder Alkylsulfanylrest mit 1 bis 15 Kohlenstoffatomen oder einen Alkenyl-, Alkenyloxy-, Alkenylsulfanyl- oder Alkinylrest mit 2 bis 15 C-Atomen, welche jeweils optional ein- oder mehrfach halogeniert sind,

A¹

jeweils unabhängig voneinander einen Rest ausgewählt aus folgenden Gruppen

• a) der Gruppe bestehend aus trans-1,4-Cyclohexylen und 1,4-Cyclohexenylen , worin auch eine oder mehrere nicht benachbarte CH₂-Gruppen durch -O- und/oder -S- ersetzt sein können und worin auch ein oder mehrere H-Atome durch F oder Cl ersetzt sein können, und
• b) der Gruppe bestehend aus Tetrahydropyran-2,5-diyl, 1,3-Dioxan-2,5-diyl, Tetrahydrofuran-2,5-diyl,

Cyclobutan-1,3-diyl, Piperidin-1,4-diyl, Thiophen-2,5-diyl und Selenophen-2,5-diyl, welche auch ein oder mehrfach durch eine Gruppe L substituiert sein können,

L

bei jedem Auftreten unabhängig F, Cl, CN, SCN, SF₅ oder geradkettiges oder verzweigtes, jeweils optional fluoriertes Alkyl, Alkoxy, Alkylcarbonyl, Alkoxycarbonyl, Alkylcarbonyloxy oder Alkoxycarbonyloxy mit 1 bis 12 C-Atomen, und

A²

jeweils unabhängig voneinander einen Rest ausgewählt aus folgenden Gruppen

bedeuten.This object is achieved by compounds of the general formula I.

wherein

m

0, 1 or 2, preferably 1,

n

1 or 2, preferably 1,

R ¹ and R ²

independently of one another an alkyl or alkoxy radical having 1 to 15 C atoms, where in these radicals also one or more CH ₂ groups are each independently of one another by -C≡C- -CF ₂ O-, -OCF ₂ -, -CH = CH-,

-O-, -S-, -CO-O- or -O-CO- may be replaced so that O / S atoms are not directly linked to each other, and in which also one or more H atoms may be replaced by halogen or H, preferably independently of one another, is an unsubstituted alkyl radical, alkoxy radical or alkylsulfanyl radical having 1 to 15 carbon atoms or an alkenyl, alkenyloxy, alkenylsulfanyl or alkynyl radical having 2 to 15 C atoms, which are each optionally mono- or polyhalogenated,

A ¹

each independently a radical selected from the following groups

• a) the group consisting of trans-1,4-cyclohexylene and 1,4-cyclohexenylene, wherein also one or more non-adjacent CH ₂ groups may be replaced by -O- and / or -S- and in which also one or more H atoms can be replaced by F or Cl, and
• b) the group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl,

Cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, which may also be substituted one or more times by a group L,

L

each occurrence independently F, Cl, CN, SCN, SF ₅ or straight-chain or branched, each optionally fluorinated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 carbon atoms, and

A ²

each independently a radical selected from the following groups

mean.

Characteristics of the compounds of the formula I according to the invention are the trans-1,4-cyclohexane ring, which is axially fluorinated and the attached bridge member -CH ₂ O-, which is connected to an aromatic ring element A ² . The compounds have a pronounced negative Δε and are therefore particularly suitable for use in liquid-crystal mixtures for VA-TFT displays. The compounds according to the invention preferably have a Δε ≦ -5, more preferably Δε ≦ -6. They show good miscibility with the usual substances used in liquid crystal mixtures for displays, ie they have good solubility therein. The rotational viscosities of the compounds and the resulting liquid-crystalline mixtures are advantageously small.

The further physical, physicochemical or electro-optical parameters of the compounds according to the invention are also advantageous for the use of the compounds in liquid-crystalline media. The liquid-crystalline media containing these compounds have in particular a sufficient width of the nematic phase and good low-temperature and long-term stability and sufficiently high clearing points. The low melting points of the compounds of the invention give an indication of the advantageous mixing behavior. Furthermore, the compounds of the formula I according to the invention have very suitable values of the optical anisotropy Δn for use in VA TFT displays. The compounds according to the invention preferably have a Δn of greater than 0.05 and less than 0.10. In addition, the compounds are relatively easy to prepare and extremely chemically stable. The balanced combination of these advantageous properties represents a significant enrichment of the mixture components available for VA blends.

In the following the invention will be explained in more detail and the preferred embodiments are disclosed.

The parameters m and n of the formula I in the sum m + n preferably have a value of 1, 2 or 3, more preferably 2. Thus, m is preferably 0 or 1, more preferably 1, and n is preferably 1.

R ^{1 is} preferably an alkoxy radical, alkyl radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms.

R ^{2 is} preferably an unsubstituted alkyl radical, an S-alkyl radical (alkylsulfanyl radical), an S-alkenyl radical (alkenylsulfanyl radical) or alkoxy radical having 1 to 10 carbon atoms or an alkenyl radical, Alkenyloxy or alkynyl radical having 2 to 10 carbon atoms, which are each optionally mono- or polyhalogenated. R ² in the general formula I is particularly preferably an alkoxy radical or alkylsulfanyl radical having 1 to 7 C atoms, particularly preferably having 2 to 5 C atoms and very particularly 2 C atoms.

The sum of the number of carbon atoms in R ¹ and R ² together is preferably 3, 4, 5, 6, 7, 8, 9 or 10, particularly preferably 4, 5, 6, 7, 8 or 9.

If R ¹ and R ² in formula I each independently represent an alkyl radical, these are straight-chain or branched. Preferably, each of these radicals is straight-chain and, unless otherwise indicated, has 1, 2, 3, 4, 5, 6 or 7 carbon atoms and is therefore preferably methyl, ethyl, propyl, butyl, pentyl, hexyl or heptyl.

If R ¹ and R ² in formula I each independently represent an alkoxy radical, these are straight-chain or branched. Preferably, each of these radicals is straight-chain and, unless otherwise specified, has 1, 2, 3, 4, 5, 6 or 7 carbon atoms and is therefore preferably methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy.

If R ² in formula I in each case independently of one another represents an alkylsulfanyl radical (equivalent to S-alkyl radical), this is straight-chain or branched. Preferably, this radical is straight-chain, and has, unless stated otherwise, 1, 2, 3, 4, 5, 6 or 7 carbon atoms and is therefore preferably methylsulfanyl, ethylsulfanyl, propylsulfanyl, butylsulfanyl, pentylsulfanyl, hexylsulfanyl or heptylsulfanyl.

In addition, R ¹ and R ² in formula I can each independently be an alkenyl radical having 2 to 15 C atoms which is straight-chain or branched and has at least one C-C double bond. It is preferably straight-chain and has 2 to 7 carbon atoms. It is therefore preferably vinyl, prop-1 or prop-2-enyl, but-1, 2- or but-3-enyl, pent-1, 2-, 3- or pent-4-enyl, hexyl 1-, 2-, 3-, 4- or hex-5-enyl, hept-1, 2-, 3-, 4-, 5- or hept-6-enyl. If the two carbon atoms of the CC double bond are substituted, the alkenyl radical can be present as an E and / or Z isomer (trans / cis). In general, the respective E isomers are preferred. Among the alkenyl radicals, particular preference is given to prop-2-enyl, 2- or but-3-enyl, and 3-or pent-4-enyl.

R ¹ and R ² in formula I can independently of one another also be an alkynyl radical having 2 to 15 C atoms which is straight-chain or branched and has at least one C-C triple bond. An alkyne radical is preferably a 1- or 2-propynyl and 1-, 2- or 3-propynyl.

oder

insbesondere der Formel

The group A ¹ independently preferably represents a disubstituted ring-shaped group selected from the formulas

or

in particular the formula

oder

besonders bevorzugt eine Gruppe der Formel

The group A ² is preferably, each independently, a disubstituted ring-shaped group selected from the formulas

or

particularly preferably a group of the formula

The group L preferably denotes F, Cl, -CF ₃ or an alkyl or alkoxy group having 1, 2 or 3 carbon atoms.

Halogen in the context of the present invention means fluorine, chlorine, bromine and iodine, in particular fluorine or chlorine.

In the context of the present invention, the term "alkyl", unless otherwise defined elsewhere in this specification or in the claims, means a straight-chain or branched, saturated, aliphatic hydrocarbon radical of 1 to 15 (ie 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15) carbon atoms.

worin R¹, R², A¹ und A² die Bedeutungen wie für die Formel I oben definiert besitzen.Particular preference is given to compounds of the formula I according to the invention selected from the sub-formulas IA, IB, IC and ID

wherein R ^1, R ^2, A ¹ and A ² have the meanings as defined for formula I defined above.

worin „alkyl“ und „alkyl*“ jeweils unabhängig voneinander einen geradkettigen Alkylrest mit 1-7 C-Atomen bedeuten. „Alkyl“ bedeutet besonders bevorzugt einen Alkylrest mit 2, 3, 4, 5 oder 6, insbesondere mit 3 oder 5 C-Atomen. Alkyl* bedeutet bevorzugt einen Alkylrest mit 1, 2, 3 oder 4 C-Atomen.Preferred compounds of the formulas IA, IB, IC and ID are the compounds of the following formulas,

wherein "alkyl" and "alkyl *" each independently represent a straight-chain alkyl radical having 1-7 C atoms. "Alkyl" particularly preferably denotes an alkyl radical having 2, 3, 4, 5 or 6, in particular having 3 or 5 C atoms. Alkyl * is preferably an alkyl radical having 1, 2, 3 or 4 C atoms.

worin „alkyl“ wie oben für IA-1, IB-1 etc. definiert ist. Besonders bevorzugt sind hieraus Verbindungen der Formel IB-1-1 und IB-2-1, insbesondere worin alkyl einen n-Propylrest bedeutet.Particularly preferred compounds of the formula I are selected from those of the formulas:

wherein "alkyl" is defined as above for IA-1, IB-1, etc. Particular preference is given here to compounds of the formula IB-1-1 and IB-2-1, in particular in which alkyl is an n-propyl radical.

If radicals or substituents of the compounds according to the invention or the compounds according to the invention themselves are present as optically active or stereoisomeric radicals, substituents or compounds because they have, for example, an asymmetric center, these are also encompassed by the present invention. It is understood that the compounds of the general formula I according to the invention in isomerically pure form, for example as pure enantiomers, diastereomers, E or Z isomers, trans- or cis isomers, or as a mixture of several isomers in any ratio, for example as Racemate, E / Z isomer mixture or as a cis / trans isomer mixture may be present.

oder -Cyc- ist in den offenbarten Verbindungen für flüssigkristalline Medien bevorzugt trans-konfiguriert, d.h. die zwei Substituenten befindend sich in der thermodynamisch bevorzugten Sesselkonformation beide in äquatorialer Position. Analog gilt dies für die bevorzugte Konformation der Ringe Tetrahydropyran und Dioxan.The 1,4-substituted cyclohexyl ring of the formula

or -Cyc- is preferably trans-configured in the disclosed compounds for liquid crystalline media, ie the two substituents are both in the equatorial position in the thermodynamically preferred chair conformation. Analogously, this applies to the preferred conformation of the rings tetrahydropyran and dioxane.

bedeutet einen Ring der Formel

d.h. einen in der thermodynamisch bevorzugten Konformation in axialer Position mit F substituierten 1,4-trans-konfigurierten Cyclohexanring.The 1,4-substituted 1-fluorocyclohexyl ring of the formula

means a ring of the formula

ie, in the thermodynamically preferred conformation in the axial position with F substituted 1,4-trans-configured cyclohexane ring.

The compounds of general formula I can be prepared by methods known per se, as described in the literature (for example in the standard works such as Houben-Weyl, Methods of Organic Chemistry, Georg Thieme Verlag, Stuttgart) under reaction conditions, which are known and suitable for the said reactions. One can make use of known per se, not mentioned here variants.

The starting materials may optionally also be formed in situ, such that they are not isolated from the reaction mixture, but immediately further reacted to the compounds of general formula I.

The syntheses of compounds of the general formula I according to the invention are described by way of example in the examples. The starting materials are available according to generally available literature or commercially available.

Particularly suitable synthetic routes to the compounds of the invention are illustrated in the following scheme. The substituents R ¹ , R ² and the counters m and n have the meanings as given for the formula I in the following schemes.

The synthesis of the compounds of the formula I is advantageously carried out by epoxidation of a cyclohexanone 5 with sulfuryl nucleophiles (Corey), ring opening of the epoxide 6 with HF and subsequent etherification of the alcohol 7 with a phenol compound (see Scheme 1) to give the title compounds 8 (cf. Formula I).

The reaction shown is to be considered as an example. The partial reactions are generally familiar to the person skilled in the art. Compounds with different rings and substituents are prepared according to the sketched synthesis. The radical R in Scheme 1 is a general radical according to - [A ¹ ] _n -R ^{1 of} the general formula I. The person skilled in the art can carry out corresponding variations of the presented synthesis as well as other suitable synthetic routes to obtain compounds of the formula I. ,

According to the above-described syntheses, in one embodiment, the present invention also encompasses one or more processes for the preparation of compounds of the formula I.

worin m, A¹, R¹ unabhängig wie in Formel I definiert sind, mit einer Verbindung der Formel (B)

worin unabhängig

• A², n und R² wie in Formel I definiert sind,

umgesetzt wird.The invention thus comprises a process for the preparation of compounds of the formula I which is characterized in that it comprises a process step in which a compound of the formula (A)

wherein m, A ¹ , R ^{1 are} independently defined as in formula I, with a compound of formula (B)

where independent

• A ² , n and R ^{2 are} as defined in formula I,

is implemented.

Reaction A with B is optionally followed by further process steps which ultimately lead to a compound of formula I. The reaction preferably leads directly to a compound of the formula I.

One aspect of the present invention are also the intermediates of formula (A). Preferred species of the compounds are obtained analogously to the preferred embodiments of the compounds of the formula I disclosed hereinbefore and hereinafter.

The compounds of the formula (A) can advantageously be prepared by epoxide ring opening with HF from corresponding oxiranes, which in turn are directly accessible from cyclohexanones. The intermediate compounds of the formula (A) can be converted directly into the end compounds of the formula I. They therefore represent a valuable intermediate.

The inventive method allows the simple and independent variation of the substituents and parameters A ¹ , A ² , m, n, R ¹ and R ² , since the two rings A ¹ and A ² only at the end of a convergent synthesis in the compounds of formula I. to be united.

The process, the preceding reaction steps and the subsequent work-up of the reaction mixture can in principle be carried out as a batch reaction or in a continuous reaction mode. The continuous reaction includes z. As the reaction in a continuous stirred tank reactor, a stirred tank cascade, a loop or cross-flow reactor, a flow tube or in a microreactor. The reaction mixtures are optionally worked up as required by filtration through solid phases, chromatography, separation between immiscible phases (eg extraction), adsorption on solid supports, distilling off of solvents and / or azeotropic mixtures, selective distillation, sublimation, Crystallization, cocrystallization or by nanofiltration on membranes.

As already mentioned, the compounds of general formula I can be used in liquid-crystalline media. The present invention therefore also provides a liquid-crystalline medium having at least two liquid-crystalline compounds containing at least one compound of the general formula I.

The present invention also liquid-crystalline media containing in addition to one or more compounds of the formula I according to the invention as further constituents 2 to 40, preferably 4 to 30 components. With particular preference, these media contain, in addition to one or more compounds according to the invention, 7 to 25 components. These further constituents are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, in particular substances from the classes of azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, 1,3-dioxanes, 2,5-tetrahydropyrans, phenyl- or cyclohexylbenzoates, cyclohexanecarboxylic acid phenyl- or cyclohexyl esters, phenyl or cyclohexyl esters of cyclohexylbenzoic acid, phenyl or cyclohexyl esters of cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl esters of benzoic acid, cyclohexanecarboxylic acid or of cyclohexylcyclohexanecarboxylic acid, phenylcyclohexanes, cyclohexylbiphenyls, phenylcyclohexylcyclohexanes, cyclohexylcyclohexanes, cyclohexylcyclohexylcyclohexenes, 1,4-biscyclohexylbenzenes, 4 ', 4 '-Cyclohexylbiphenyls, 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-phe nylcyclohexyl) ethanes, 1-cyclohexyl-2-biphenylethanes, 1-phenyl-2-cyclohexylphenylethanes, optionally halogenated stilbenes, benzylphenyl ethers, tolans and substituted cinnamic acids. The 1,4-phenylene groups in these compounds may also be mono- or polyfluorinated.

The most important compounds which may be used as further constituents of media according to the invention can be characterized by the formulas (II), (III), (IV), (V) and (VI): R'-LER "(II) R'-L-COO-ER "(III) R'-L-OOC-ER "(IV) R'-L-CH ₂ CH ₂ -ER "(V) R'-L-CF ₂ O "(VI)

In the formulas (II), (III), (IV), (V) and (VI), L and E, which may be the same or different, each independently represents a bivalent radical selected from the group consisting of -Phe-, -Cyc- , -Phe-Phe, -Phe-Cyc, -Cyc-Cyc, -Pyr-, -Dio, -Thp-, -G-Phe- and -G-Cyc- and their mirror images formed group, wherein Phe unsubstituted or fluorine-substituted 1,4-phenylene, cyc trans-1,4-cyclohexylene or 1,4-cyclohexenylene, pyr pyrimidine-2,5-diyl or pyridine-2,5-diyl, dioxy-1,3-dioxane 2,5-diyl, Thp tetrahydropyran-2,5-diyl and G 2- (trans-1,4-cyclohexyl) -ethyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 1,3- Dioxane-2,5-diyl or tetrahydropyran-2,5-diyl.

Preferably, one of L and E is Cyc or Phe. E is preferably Cyc, Phe or Phe-Cyc. The media according to the invention preferably comprise one or more components selected from the compounds of the formulas (II), (III), (IV), (V) and (VI) in which L and E are selected from the group consisting of Cyc and Phe and at the same time one or a plurality of components selected from the compounds of formulas (II), (III), (IV), (V) and (VI) wherein one of L and E is selected from the group consisting of Cyc and Phe 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 (II), ( III), (IV), (V) and (VI), 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 the compounds of formulas (II), (III), (IV), (V) and (VI) each independently represent alkyl, alkenyl, alkoxy, alkoxyalkyl (oxaalkyl), alkenyloxy or alkanoyloxy Hereinafter, this smaller subgroup is called group A and the compounds are denoted by the subformulae (IIa), (IIIa), (IVa), (Va) and (VIa), in most of these compounds R 'and R "are different from each other, wherein one of these radicals is usually alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).

In a smaller subgroup of the compounds of formulas (II), (III), (IV), (V) and (VI) other than group B, E denotes

In the compounds of group B, which are designated by the sub-formulas (IIb), (IIIb), (IVb), (Vb) and (VIb), R 'and R "have the meanings for the compounds of sub-formulas (IIa) to ( VIa) and are preferably alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).

In a further smaller subgroup of the compounds of the formulas (II), (III), (IV), (V) and (VI), R "denotes -CN. This subgroup is referred to below as group C and the compounds of this subgroup become corresponding with sub-formulas (IIc), (IIIc), (IVc), (Vc) and (VIc) In the compounds of sub-formulas (IIc), (IIIc), (IVc), (Vc) and (VIc) R 'has the meaning given for the compounds of sub-formulas (IIa) to (VIa) and is preferably alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).

In addition to the preferred compounds of the groups A, B and C, other compounds of the formulas (II), (III), (IV), (V) and (VI) with other variants of the substituents provided are also customary. All these substances are available by literature methods or by analogy.

• Gruppe A:
  • 0 bis 90 %, vorzugsweise 20 bis 90 %, insbesondere 30 bis 90 %.
• Gruppe B:
  • 0 bis 80 %, vorzugsweise 10 bis 80 %, insbesondere 10 bis 70 %.
• Gruppe C:
  • 0 bis 80 %, vorzugsweise 5 bis 80 %, insbesondere 5 bis 50 %.

In addition to the compounds of the general formula I according to the invention, the media according to the invention preferably contain one or more compounds from groups A, B and / or C. The mass fractions of the compounds from these groups on the media according to the invention are as follows:

• Group A:
  • 0 to 90%, preferably 20 to 90%, especially 30 to 90%.
• Group B:
  • 0 to 80%, preferably 10 to 80%, especially 10 to 70%.
• Group C:
  • 0 to 80%, preferably 5 to 80%, especially 5 to 50%.

The media according to the invention preferably contain 1 to 40%, more preferably 5 to 30%, of the compounds of the formula I according to the invention. The media preferably comprise one, two, three, four or five compounds of the formula I according to the invention.

The preparation of the media according to the invention is carried out in a conventional manner. In general, the components are dissolved in each other, preferably at elevated temperature. By means of suitable additives, the liquid-crystalline phases of the present invention can be modified so that they can be used in all types of liquid-crystal display elements known hitherto. Such additives are known to the person skilled in the art and are described in detail in the literature (H. Kelker / R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980). For example, pleochroic dyes can be added to produce colored guest-host systems or to modify the dielectric anisotropy, viscosity and / or orientation of the nematic phases.

Because of their negative Δε, the compounds of the formula I are particularly suitable for use in VA TFT displays or passive VA displays.

The present invention therefore also provides electro-optical display elements comprising a liquid-crystalline medium according to the invention. The display element is preferably a VA TFT display element (VA: vertical alignment, TFT: thin film transistor).

Further combinations of the embodiments and variants of the invention according to the description will become apparent from the claims and from combinations of two or more of these claims.

The invention will be explained in more detail below with reference to exemplary embodiments, without, however, being restricted thereby. The person skilled in the art will be able to give details of the examples In the general description, to generalize them according to general knowledge and apply them to his specific problem.

In addition to the usual and well-known abbreviations, the following abbreviations are used: m.p .: melting point; K: crystalline phase; N: nematic phase; Sm: smectic phase (if specified in more detail); I: Isotropic phase. The numbers between these symbols represent the transition temperatures of the substance in question.

Temperatures are, unless otherwise stated, in ° C (Celsius).

The determination of physical, physicochemical or electro-optical parameters is carried out according to generally known methods, as described, inter alia, in the brochure "Merck Liquid Crystals - Licristal® - Physical Properties of Liquid Crystals - Description of the Measurements Methods", 1998, Merck KGaA, Darmstadt ,

Above and below Δn means the optical anisotropy (589 nm, 20 ° C) and Δε the dielectric anisotropy (1 kHz, 20 ° C). The dielectric anisotropy Δε is determined at 20 ° C and 1 kHz. The optical anisotropy Δn is determined at 20 ° C and a wavelength of 589.3 nm.

The Δε and An values, the extrapolated clearing point (clp) and the rotational viscosity (γ1) of the compounds according to the invention are obtained by linear extrapolation from liquid-crystalline mixtures containing from 5 to 10% of the respective compound according to the invention and to 90-95% from the commercially available liquid-crystal mixture ZLI-2857 (for Δε, Klp.) or ZLI-4792 (for Δn, γ1) exist (mixtures Fa. Merck KGaA, Darmstadt).

Examples

The starting materials can be obtained according to generally available literature or commercially available.

Example 1:

Step 1

To a mixture of ketone 9 (29.0 g, 130.4 mmol) and trimethylsulfoxonium iodide (43.0 g, 195.6 mmol) in dimethyl sulfoxide (210 ml) at room temperature, a solution of potassium tert-butoxide (21.9 g, 195.6 mmol) in dimethyl sulfoxide (90 ml) was added dropwise. The resulting mixture is stirred for 36 h, then heptane (500 ml) is added and stirring is continued for 0.5 h. The heptane phase is separated, filtered through Celite®, washed with water, dried over Na ₂ SO ₄ and concentrated in vacuo. The residue (16.7 g) is purified by Puriflash (300 g SiO ₂ , heptane / methyl tert-butyl ether 9: 1). The epoxide 10 (95.8% HPLC) is obtained as colorless crystals.

step 2

To a solution of epoxide 10 (15.6 g, 61.8 mmol, HPLC: 93.7%) in dichloromethane (275 ml) at -5 ° C, a solution of HF in pyridine (65%, 5.0 ml, 185.5 mmol) was added dropwise. The resulting mixture becomes Stirred for 1 h at - 5 ° C, then filtered through a pad of SiO ₂ (1 l, washed with dichloromethane). The alcohol 11 (HPLC: 31.9%) is obtained as a colorless oil.

step 3

Diisopropyl azodicarboxylate (DIAD, 10.9 mL, 55.5 mmol) is added dropwise at 10 ° C to a stirred solution of alcohol 11 (10.2 g, 12.6 mmol, HPLC: 31.9%), phenol 12 (6.9 g, 47.8 mmol) and triphenylphosphine ( 12.5 g, 47.6 mmol) in tetrahydrofuran (THF, 161 ml). The resulting mixture is stirred for 7 days at room temperature and for 1 day at 45 ° C, then filtered through a pad of SiO ₂ (100 g) and purified twice by flash chromatography (heptane / methyl tert-butyl ether). After two recrystallizations from isopropanol, the final compound 2 (1.2 g, 25%, HPLC: 99.7%) is obtained as colorless crystals.

¹ H NMR: 0.81-1.87 (m, 24H), 2.03-2.15 (m, 2H), 2.25 (d, J = 2.1Hz, 3H), 3.98 (d, J = 16.4Hz, 2H), 6.68 (ddd, J = 8.7, 8.1, 1.9 Hz, 1H), 6.82 (ddd, J = 8.2, 8.2, 2.1 Hz, 1H); ¹⁹ F NMR: -140.6 (ddt, J = 19.3, 7.8, 1.8 Hz, 1F), - 159.0 (ddd, J = 19.4, 7.4, 2.4 Hz, 1F), -165.8 (qt, J = 24.3, 9.3 Hz, 1F); EI-MS: 382.3
Phases: K 91 N 118 I (mp 91 ° C),
Δε = -6.73, Δn = 0.0792; γ1 = 454 mPa · s.

Phasen: K 72 SmB (61) N 101 I (Schmp. 72 °C)
Δε=-6,25, Δn=0.0762; γ1 =433 mPa·s.

Phasen: K 72 N 144 I (Schmp. 72 °C)
Δε=-8,23, Δn=0.0832; γ1 =706 mPa·s.

Phasen: K 48 N (4) I (Schmp. 48 °C)
Δε=-8.25, Δn=0.0572; γ1 =71 mPa·sAnalogously to Example 1, the following compounds are prepared:

Phases: K 72 SmB (61) N 101 I (mp 72 ° C)
Δε = -6.25, Δn = 0.0762; γ1 = 433 mPa · s.

Phases: K 72 N 144 I (mp 72 ° C)
Δε = -8.23, Δn = 0.0832; γ1 = 706 mPa · s.

Phases: K 48 N (4) I (mp 48 ° C)
Δε = -8.25, Δn = 0.0572; γ1 = 71 mPa · s

Further example compounds are prepared analogously:

The radicals R ^1/2 are straight-chain, ie unbranched, unless stated otherwise. The structures of the individual compounds are shown in Table 1.

H₇C₃- -OC₄H₉ Bindung

K 35 N (5.7) I; Δε -8.56; Δn 0.0520; γ1 90 mPa s H7C3- -SC₂H₅ Bindung

K 43 I; Δε -6.66; Δn 0.0478; γ1 72 mPa s H₁₁C₅- -OC₂H₅

H7C3- -SC2H5

H7C3- -OC₄H₉

K 77 SmA 89 N 133.5 I; Δε -8.58; Δn 0.0851; γ1 794 mPa s H₁₁C₅- -OC₄H₉

H₇C₃- -OC₂H₅

H₇C₃- -OC₂H₅ Bindung

H₇C₃- -OC₄H₉ Bindung

H₁₁C₅- -OC₄H₉ Bindung

H₇C₃- -OC₂H₅ Bindung

H₇C₃- -OC₃H₇ Bindung

K 166 N (160.7) I H₁₁C₅- -OC₄H₉ Bindung

H₇C₃- -OC₄H₉ Bindung

The alkyl radicals of the formula C _n H _{2n + 1} are the unbranched alkyl radicals. Table 1. Physical data: R ¹ R ² A ¹ A ² dates H ₁₁ C ₅ - -C ₂ H ₅ binding

H ₇ C ₃ - -OC ₄ H ₉ binding

K 35 N (5.7) I; Δε -8.56; Δn 0.0520; γ1 90 mPa s H7C3- -SC ₂ H ₅ binding

K 43 I; Δε -6.66; Δn 0.0478; γ1 72 mPa s H ₁₁ C ₅ - -OC ₂ H ₅

H7C3- -SC2H5

H7C3- -OC ₄ H ₉

K 77 SmA 89 N 133.5 I; Δε -8.58; Δn 0.0851; γ1 794 mPa s H ₁₁ C ₅ - -OC ₄ H ₉

H ₇ C ₃ - -OC ₂ H ₅

H ₇ C ₃ - -OC ₂ H ₅ binding

H ₇ C ₃ - -OC ₄ H ₉ binding

H ₁₁ C ₅ - -OC ₄ H ₉ binding

H ₇ C ₃ - -OC ₂ H ₅ binding

H ₇ C ₃ - -OC ₃ H ₇ binding

K 166 N (160.7) I H ₁₁ C ₅ - -OC ₄ H ₉ binding

H ₇ C ₃ - -OC ₄ H ₉ binding

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3231707 A [0008]
• DE 19831712 [0008]
• US 6139773 A [0008]
• DE 10219542 A1 [0008]

Claims (17)

Compounds of the formula I:

wherein m is 0, 1 or 2, n is 1 or 2, R ¹ and R ^{2 are} independently an alkyl radical having 1 to 15 C atoms, wherein in these radicals also one or more CH ₂ groups each independently of one another by -C -C-, -CH = CH-,

-O-, -S-, -CO-O- or -O-CO- can be replaced so that O and S atoms are not directly linked to each other, and wherein also one or more H atoms are replaced by halogen A ^{1 can} independently of one another be selected from the following groups a) the group consisting of trans-1,4-cyclohexylene and 1,4-cyclohexenylene, in which also one or more non-adjacent CH ₂ groups is represented by -O- and / or -S- may be replaced and in which also one or more H atoms may be replaced by F or Cl, and b) the group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, Tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, which also substituted one or more times by a group L. L at each occurrence may be independently F, Cl, CN, SCN, SF ₅ or straight chain or branched, in each case optionally fluorinated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy with 1 to 12 carbon atoms, and A ^{2 are} independently a radical selected from the following groups. Connections to Claim 1 , characterized in that in the formula I, the ring A ²

means. Connections to Claim 1 or 2 , characterized in that R ^{2 is} an unsubstituted alkyl radical, an S-alkyl radical, an S-alkenyl radical or an alkoxy radical having 1 to 10 carbon atoms or an alkenyl, alkenyloxy or alkynyl radical having 2 to 10 C atoms, which are each optionally an or halogenated several times, means. Compounds according to one or more of Claims 1 to 3 , characterized in that in the formula I n = 1. Compounds according to one or more of Claims 1 to 4 , characterized in that in the formula I R ^{2 is} an alkoxy radical having 1 to 7 carbon atoms, an alkenyloxy having 2 to 7 carbon atoms, an S-alkyl radical having 1 to 7 carbon atoms or an S-alkenyl radical having 2 to 7 C. Is -atoms. Compounds according to one or more of Claims 1 to 5 , characterized in that m is 0 or 1 Compounds according to one or more of Claims 1 to 6 , characterized in that A ^{1 is} independently a radical selected from the following groups

or

means. Compounds according to one or more of Claims 1 to 7 , characterized in that the compounds of the formula I are selected from the sub-formulas IA to ID

wherein R ¹ , R ² , A ¹ and A ² and m are each independently the same as for the formula I according to Claim 1 have. Compounds according to one or more of Claims 1 to 8th , characterized in that the compounds are selected from compounds of the formulas

wherein alkyl and alkyl * each independently represent a straight-chain alkyl radical having 1-7 C atoms. Compounds according to one or more of Claims 1 to 9 , characterized in that R ¹ and R ² independently of one another are an alkoxy or alkyl radical having 1 to 7 or an alkenyl radical having 2 to 7 carbon atoms. Compounds according to one or more of Claims 1 to 10 , characterized in that the ring system A ¹ is independently selected from the substructures

or

Compounds according to one or more of Claims 1 to 11 selected from the formulas

wherein alkyl is a straight-chain alkyl radical having 1-7 C atoms. Use of one or more compounds according to one or more of Claims 1 to 12 in liquid-crystalline media. Liquid-crystalline medium containing at least two compounds, characterized in that it contains at least one compound according to one or more of the Claims 1 to 12 contains. Electro-optical display element containing a liquid-crystalline medium according to Claim 14 , A process for the preparation of compounds of the formula I according to one or more of Claims 1 to 12 characterized in that it comprises a process step wherein a compound of formula (A)

wherein m, A ¹ , R ^{1 are} independently defined as in formula I, with a compound of formula (B)

wherein independently A ² , n and R ^{2 are} as defined in formula I is reacted. Compounds of the formula (A):

wherein m, A ¹ and R ¹ independently as in formula I according to Claim 1 are defined.