TWI787298B - Thioether derivatives of dibenzothiophene and dibenzofuran - Google Patents

Abstract

The present invention relates to 4,6-dihalodibenzothiophene and 4,6-dihalodibenzofuran 3-thioether derivatives of the formula I

in which W, X, R¹ , R² , A¹ , Z¹ and m are as defined in Claim 1, to the preparation thereof, to the use thereof as components in liquid-crystalline media, and to electro-optical display elements which contain the liquid-crystalline media according to the invention.

Description

Sulfide Derivatives of Dibenzothiophene and Dibenzofuran

The present invention relates to 4,6-dihalogenated dibenzothiophene and 4,6-dihalogenated dibenzofuran 3-sulfide derivatives, their preparation methods, liquid crystal media containing these derivatives, and liquid crystal media containing these Optoelectronic display elements of liquid crystal media. These compounds have negative dielectric anisotropy.

Liquid crystals have found wide application because the first commercially available liquid crystal compounds were discovered about 30 years ago. In particular, known fields of application for customary mixtures are displays for watches and pocket calculators, and large display panels such as are used in railway stations, airports and sports arenas. Other areas of application are monitors for portable and desktop computers, navigation systems and video applications. For the last-mentioned applications, in particular, very high requirements are placed on the response time and image comparison.

The spatial arrangement of molecules in liquid crystals means that many of their properties are directionally dependent. Important for the use herein in liquid crystal displays is, in particular, anisotropy in optical, dielectric and elastomechanical behavior. Depending on whether the molecules are oriented perpendicular or parallel to the longitudinal axes of the two plates of the capacitor, they will have different capacitances; thus, the dielectric constant ε of the liquid crystal medium is different for the two orientations. A substance whose dielectric constant is greater in the case where the longitudinal axis of the molecules are oriented perpendicular to the capacitor plates than in the case of a parallel arrangement is called dielectrically positive. In other words: If the permittivity ε _|| parallel to the longitudinal axis of the molecule is greater than the permittivity ε _⊥ perpendicular to the longitudinal axis of the molecule, then the dielectric anisotropy Dε = ε _|| - ε _⊥ is greater than zero. Most liquid crystals used in conventional displays belong to this group.

Both the polarizability of the molecule and the permanent dipole moment contribute to the dielectric anisotropy. When a voltage is applied to the display, the longitudinal axes of the molecules orient themselves so that the larger of the dielectric constants becomes effective. The strength of the interaction with the electric field depends here on the difference between two constants.

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

Using liquid crystals in which the larger dipole moment is oriented parallel to the longitudinal axis of the molecule, very high performance displays have been developed. Mixtures of 5 to 20 components are mainly used here in order to achieve a sufficiently wide temperature range of the mesophase as well as short reaction times and low temporary voltages. However, the strong viewing angle dependence as in the case of liquid crystal displays used for eg laptop computers still poses difficulties. The best image quality is achieved if the display area is perpendicular to the viewer's viewing direction. If the display is tilted with respect to the viewing direction, the image quality may be drastically degraded in some cases. For greater comfort, efforts have been made to make the display tiltable from the viewer's viewing angle without significantly degrading the image quality as much as possible. Recently attempts have been made to improve viewing angle dependence using liquid crystal compounds having a larger dipole moment perpendicular to the longitudinal axis of the molecule than parallel to the longitudinal axis of the molecule. In this case, the dielectric anisotropy Δε is negative. In the field-free state, the molecules are oriented with their longitudinal axes perpendicular to the glass surface of the display. Applying an electric field causes it to orient itself more or less parallel to the glass surface. In this way, an improvement in viewing angle dependence can be achieved. This type of display is called a VA-TFT display (from English: "Vertical Alignment").

The development of liquid crystal materials still has a long way to go. In order to improve the properties of liquid crystal display elements, efforts are constantly being made to develop novel compounds that can optimize these displays.

Documents EP 2937342, WO 02/055463, DE 102005012585 and EP 1752510 disclose dibenzothiophene derivatives for use as liquid crystal materials. These compounds differ from the compounds of the present invention in the substitution of the dibenzothiophene structure. Document EP 2921487 discloses dibenzofuran derivatives as liquid crystal materials. The thioether in position 3 of the ring system is not disclosed in the citation.

It was an object of the present invention to provide compounds having advantageous properties for use in liquid-crystalline media. In particular, they should have negative dielectric anisotropy, which makes them especially suitable for use as liquid-crystalline media for VA displays. Regardless of the dielectric anisotropy corresponding to the display type, compounds with an advantageous combination of application-related parameters are desired. Among the parameters to be optimized at the same time, mention is made in particular of high clearing points, low rotational viscosities, optical anisotropy in the range of applications and for achieving mixtures with the desired liquid-crystalline phases over a broad temperature range. Properties (low melting point, good miscibility with other liquid crystal components of the desired kind).

其中 X 獨立地表示F或Cl，較佳F， W 表示S或O，較佳S， m 表示0、1或2，較佳0， R¹ 及R² 彼此獨立地表示具有1至15個C原子之烷基或烷氧基，其中另外該等基團中之一或多個CH₂ 基團在每一情形下彼此分別獨立以O原子並不直接彼此連接之方式經-C≡C-、-CF₂ O-、-OCF₂ -、-CH=CH-、

、

、

、

、-O-、-S-、-CO-O-或-O-CO-置換，且其中另外一或多個H原子可經鹵素置換， 較佳彼此獨立地表示具有1至15個碳原子之未經取代烷基或烷氧基或具有2至15個C原子之烯基、烯基氧基或炔基，其在每一情形下視情況經單鹵化或多鹵化， A¹ 在每一情形下獨立地表示選自以下之群之基團： a) 1,4-伸苯基，其中另外一或兩個CH基團可經N置換且其中另外一或多個H原子可經基團L置換， b) 由反式-1,4-伸環己基及1,4-伸環己烯基組成之群，其中另外一或多個不相鄰CH₂ 基團可經-O-及/或-S-置換且其中另外一或多個H原子可經F或Cl置換，及 c) 由四氫吡喃-2,5-二基、1,3-二噁烷-2,5-二基、四氫呋喃-2,5-二基、環丁烷-1,3-二基、六氫吡啶-1,4-二基、噻吩-2,5-二基及硒吩-2,5-二基組成之群，其另外可經基團L單取代或多取代， L 在每次出現時獨立地表示F、Cl、CN、SCN、SF₅ 或具有1至12個或較佳1至4個C原子之直鏈或具支鏈之在每一情形中視需要經氟化之烷基、烷氧基、烷基羰基、烷氧基羰基、烷基羰基氧基或烷氧基羰基氧基，且 Z¹ 彼此獨立地表示單鍵、-CF₂ O-、-OCF₂ -、-CH₂ O-、-OCH₂ -、-(CO)O-、-O(CO)-、-(CH₂ )₄ -、-CH₂ CH₂ -、-CF₂ -CF₂ -、-CF₂ -CH₂ -、-CH₂ -CF₂ -、-CH=CH-、-CF=CF-、-CF=CH-、-CH=CF-、-(CH₂ )₃ O-、-O(CH₂ )₃ -、-CºC-、-O-、-CH₂ -、-(CH₂ )₃ -或-CF₂ -。This object is achieved according to the invention by compounds of general formula I

Wherein X independently represents F or Cl, preferably F, W represents S or O, preferably S, m represents 0, 1 or 2, preferably 0, R ¹ and R ² independently represent 1 to 15 C Alkyl or alkoxy groups of atoms, wherein one or more _CH2 groups in these other groups are in each case independently of each other through -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-,

,

,

,

, -O-, -S-, -CO-O- or -O-CO-, and wherein one or more H atoms can be replaced by halogens, preferably independently of each other representing a group having 1 to 15 carbon atoms Unsubstituted alkyl or alkoxy or alkenyl, alkenyloxy or alkynyl groups having 2 to 15 C atoms, which are in each case monohalogenated or polyhalogenated, A ¹ in each case independently represents a group selected from the following group: a) 1,4-phenylene, wherein another one or two CH groups can be replaced by N and wherein another one or more H atoms can be replaced by a group L Substitution, b) the group consisting of trans-1,4-cyclohexylene and 1,4-cyclohexenyl, wherein one or more non-adjacent _CH groups can be replaced by -O- and/or -S-substituted and wherein one or more additional H atoms may be replaced by F or Cl, and c) from tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl , tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, hexahydropyridine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl The group consisting of, which may additionally be monosubstituted or polysubstituted by a group L, L independently at each occurrence represents F, Cl, CN, SCN, SF ₅ or has 1 to 12 or preferably 1 to 4 C straight-chain or branched, optionally fluorinated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy in each case, and Z ¹ each independently represents a single bond, -CF ₂ O-, -OCF ₂ -, -CH ₂ O-, -OCH ₂ -, -(CO)O-, -O(CO)-, -(CH ₂ ) ₄ -, -CH ₂ CH ₂ -, -CF ₂ -CF ₂ -, -CF ₂ -CH ₂ -, -CH ₂ -CF ₂ -, -CH=CH-, -CF=CF-, -CF=CH- , -CH=CF-, -(CH ₂ ) ₃ O-, -O(CH ₂ ) ₃ -, -CºC-, -O-, -CH ₂ -, -(CH ₂ ) ₃ -, or -CF ₂ - .

These compounds have a clearly negative Δε and are therefore particularly suitable for use in liquid-crystal mixtures for VA-TFT displays. Compounds of the invention preferably have Δε ≤ -4, more preferably Δε ≤ -7 and especially preferably Δε ≤ -9. They exhibit good miscibility with customary substances used in liquid crystal mixtures for displays, ie the compounds have good solubility in these customary substances. The rotational viscosities of the compounds and of the resulting liquid-crystalline mixtures are advantageously low without at the same time significantly lowering the clearing point of the mixture.

Other physical, physicochemical or optoelectronic parameters of the compounds according to the invention also facilitate the use of these compounds in liquid-crystalline media. In particular, liquid-crystalline media comprising these compounds have sufficient nematic width and good low-temperature and long-term stability, and a sufficiently high clearing point. The low melting points of the compounds of the invention indicate that the mixing process is facilitated. Furthermore, the compounds of the formula I according to the invention have optical anisotropy Δn values which are particularly suitable for use in VA-TFT displays. Preferably, the compounds of the invention have a Δn greater than 0.15 and less than 0.25. Furthermore, these compounds are relatively easy to prepare. A balanced combination of these favorable properties represents a significant enrichment of blending components available for VA blends.

The parameter m which determines the number of adjacent ring systems A ¹ preferably has the value 0 or 1, in particular 0.

R ¹ preferably represents in each case independently of one another an alkoxy, alkyl or alkenyl group each having 1 to 7 or 2 to 7 carbon atoms. R ¹ in general formula I is especially preferably an alkoxy group or an alkyl group having 2 to 7 C atoms.

R ² preferably represents an alkyl or alkenyl group having 1 to 7 or 2 to 7 carbon atoms, respectively. R ² in general formula I is especially preferably an alkyl group having 2 to 7 C atoms.

For the case of m=0, R preferably represents ^an alkoxy group, an alkyl group or an alkenyl group, especially preferably an alkoxy group having 1 to 7 C atoms, especially preferably having 2 to 5 C atoms. The total number of carbon atoms in R ¹ and R ² is preferably 4, 5, 6, 7, 8, 9 or 10, especially preferably 6, 7, 8, 9 or 10.

For the case of m= ¹ or 2, R preferably represents an alkyl, alkoxy or alkenyl group, especially preferably an alkyl group, having 1 to 7 C atoms, especially preferably having 2 to 7 C atoms.

If R ¹ and R ² in formula I each independently represent an alkyl group, these groups are straight-chain or branched. Each of these groups is preferably straight chain and, unless otherwise stated, has 1, 2, 3, 4, 5, 6 or 7 C atoms and is therefore preferably methyl, ethyl, propyl base, butyl, pentyl, hexyl or heptyl.

If R ¹ in formula I each independently of the other represent alkoxy, this is straight-chain or branched. Each of these groups is preferably straight chain and, unless otherwise stated, has 1, 2, 3, 4, 5, 6 or 7 C atoms and is therefore preferably methoxy, ethoxy , propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy.

Furthermore, R ¹ and R ² in formula I may in each case independently of one another be straight-chain or branched alkenyl having 2 to 15 C atoms and having at least one CC double bond. It is preferably unbranched and has 2 to 7 C atoms. Therefore, it is preferably vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4 -enyl, hex-1-, -2-, -3-, -4- or -5-enyl or hept-1-, -2-, -3-, -4-, -5- or -6 -alkenyl. If the two C atoms of the CC double bond are substituted, the alkenyl group can exist in the form of E and/or Z isomers (trans/cis). In general, the respective E isomers are preferred. Among alkenyl groups, especially preferred are prop-2-enyl, but-2- or -3-enyl and pent-3- or -4-enyl.

R ¹ and R ² in formula I may also independently of each other be a linear or branched alkynyl group having 2 to 15 C atoms and having at least one CC triple bond. Preferred are 1- or 2-propynyl and 1-, 2- or 3-butynyl.

Group ^A independently preferably represents a disubstituted cyclic group selected from the following formula

The group Z ¹ preferably represents a single bond, -CH ₂ O-, -CF ₂ O- or -OCF ₂ -, especially preferably a single bond.

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

Especially preferably, m represents 0 and R ¹ represents an alkoxy group having 1 to 7 carbon atoms.

In connection with the present invention, halogen denotes fluorine, chlorine, bromine or iodine, preferably fluorine, chlorine or bromine, and in particular fluorine or chlorine.

In conjunction with the present invention, the expression "alkyl" means that there are 1 to 15 (i.e. 1, 2, 3, 4, 5, 6 1, 7, 8, 9, 10, 11, 12, 13, 14 or 15) carbon atoms straight-chain or branched, saturated, aliphatic hydrocarbon group.

其中R¹ 、R² 及A¹ 具有如上文針對式I所定義之含義，且 Z¹ 係如上文針對式I所定義之無單鍵之基團。Compounds of formula I according to the invention are preferably selected from sub-formulas IA to IF

wherein R ¹ , R ² and A ¹ have the meanings as defined above for formula I, and Z ¹ is a group without a single bond as defined above for formula I.

其中烷基及烷基*彼此獨立地表示具有1至7個C原子之直鏈烷基且烷氧基獨立地表示具有1至7個C原子之直鏈烷氧基。尤佳者係式IA-1化合物。Preferred compounds of formula IA and ID are compounds of formula IA-1 to IA-3 and ID-1 to ID-3,

wherein alkyl and alkyl* independently represent straight-chain alkyl having 1 to 7 C atoms, and alkoxy independently represent straight-chain alkoxy having 1 to 7 C atoms. Most preferred are compounds of formula IA-1.

其中烷基彼此獨立地表示具有1至7個C原子之直鏈烷基。Preferred compounds of formula IB and IC are compounds of the formula:

wherein the alkyl groups independently represent straight-chain alkyl groups having 1 to 7 C atoms.

若本發明化合物之基團或取代基或本發明化合物本身係以光學活性或立體異構物基團、取代基或化合物之形式存在(此乃因(例如)其具有不對稱中心)，則該等同樣涵蓋於本發明中。在此不言而喻，本發明之通式I化合物可以異構純形式、例如以純鏡像異構物、非鏡像異構物、E或Z異構物、反式或順式異構物形式、或以任何期望比率之複數種異構物之混合物形式、例如以外消旋物、E/Z異構物混合物形式或以順式/反式異構物混合物形式存在。A particularly preferred compound of formula I or IA-1 is selected from those compounds of formula IA-1-1 to IA-1-26:

If a group or substituent of a compound of the invention or a compound of the invention itself exists as an optically active or stereoisomer group, substituent or compound because, for example, it has an asymmetric center, then the etc. are also included in the present invention. It goes without saying here that the compounds of the general formula I according to the invention may be in isomerically pure form, for example in the form of pure enantiomers, diastereoisomers, E or Z isomers, trans or cis isomers, Or as a mixture of several isomers in any desired ratio, for example as a racemate, as a mixture of E/Z isomers or as a mixture of cis/trans isomers.

或-Cyc-之1,4-取代之環己基環 較佳具有反式構形，即位於熱力學上較佳之椅形構象之兩個取代基二者皆在赤道位。Among the disclosed compounds for use in liquid crystal media is the formula

The 1,4-substituted cyclohexyl ring of -Cyc- or -Cyc- preferably has a trans configuration, ie both substituents are in the thermodynamically preferred chair conformation with both at the equator.

Compounds of general formula I can be obtained by methods known per se, as described in the literature (e.g. standard works, e.g. Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), and in particular Said to be synthesized under known and suitable reaction conditions for the given reaction. In this connection, per se known variants which are not mentioned in more detail here can be utilized.

The starting material may also optionally be formed in situ, so that it is not isolated from the reaction mixture, but reacted further immediately to give the compound of general formula I.

The synthesis of compounds of general formula I according to the invention is illustrated in the examples. Starting materials can be obtained by commonly available literature procedures or obtained commercially.

Particularly suitable synthetic routes for the compounds of the invention are explained below with reference to the schemes. The substituents R ¹ , R ² , X, W and the index m in the following schemes have the meanings as given for formula I.

方案 1 . 二苯并噻吩之實例合成. R¹ = -OR，m = 0。The synthesis of compounds of formula I (where W = S and m = 0) starts from basic compounds according to Scheme 1 .

Scheme 1. Example synthesis of dibenzothiophene. R ¹ = -OR, m = 0.

方案 2. 式I化合物之兩種替代合成途徑. 類似地定義取代基。The synthesis of the corresponding difluorodibenzofuran compounds (W=0, m=0) is described, for example, in publication US 2015/0259602 A1.

Scheme 2. Two Alternative Synthetic Routes for Compounds of Formula I. The substituents are similarly defined.

The depicted reaction schemes are considered as examples only. Optionally, a group of the formula R ¹ -[A ¹ -Z ¹ ] _m - can also be similarly introduced into the general formula I to replace the group -OR in scheme 1. Those skilled in the art can make corresponding changes to the proposed syntheses and find other suitable synthetic routes to obtain the compounds of formula I.

The invention also includes, in one embodiment, one or more methods of preparing compounds of formula I, based on the syntheses shown above.

其中W、X、Z¹ 、A¹ 、m及R¹ 係獨立地如式I中所定義， 在OH基團與三氟甲磺酸或其反應性衍生物反應，以得到式(C)化合物

其中獨立地 OTf 表示基團O(SO₂ )CF₃ ， 且 W、X、Z¹ 、A¹ 、m及R¹ 係獨立地如式I中、特定而言如針對式(B)所定義， 且在一或多個其他方法步驟中轉化成式I化合物。Therefore, the present invention covers a process for the preparation of compounds of formula I, characterized in that it comprises the following process steps: wherein the compound of formula (B)

wherein W, X, Z ¹ , A ¹ , m and R ¹ are independently as defined in formula I, where the OH group is reacted with trifluoromethanesulfonic acid or a reactive derivative thereof to obtain a compound of formula (C)

wherein independently OTf represents the group O(SO ₂ )CF ₃ , and W, X, Z ¹ , A ¹ , m and R ¹ are independently as defined in formula I, in particular for formula (B), and converted to a compound of formula I in one or more further process steps.

Esterification of the OH group of the compound of formula (B) with trifluoromethanesulfonic acid (derivative) is preferably carried out using trifluoromethanesulfonyl chloride (TfCl) or trifluoromethanesulfonic anhydride (TfOTf).

The disclosed process steps and work-up of the reaction mixture can in principle be carried out as a batch reaction or in continuous reaction mode. Continuous reaction modes include, for example, reactions in continuous stirred tank reactors, stirred tank cascades, loop or cross flow reactors, flow tubes, or microreactors. The reaction mixture is worked up, optionally by solid phase filtration, chromatography, separation of immiscible phases (e.g. extraction), adsorption onto a solid support, distillative removal of solvents and/or azeotropes, selective Distillation, sublimation, crystallization, co-crystallization or by nanofiltration through membranes.

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

The invention also provides liquid-crystalline media which, in addition to one or more compounds of the formula I according to the invention, comprise as further constituents 2 to 40, preferably 4 to 30, components. These media preferably comprise 7 to 25 components in addition to one or more compounds according to the invention. These other constituents are preferably selected from nematic or nematic (monomorphic or isotropic) substances, in particular from the following classes: oxyazobenzene, benzylidene aniline, biphenyl, Terphenyl, 1,3-dioxane, 2,5-tetrahydropyran, phenyl benzoate or cyclohexyl benzoate, phenyl cyclohexanecarboxylate or cyclohexylcyclohexanecarboxylate , phenyl or cyclohexyl ester of cyclohexylbenzoic acid, phenyl or cyclohexyl ester of cyclohexylcyclohexanecarboxylic acid, benzoic acid, cyclohexanecarboxylic acid or cyclohexylbenzene of cyclohexylcyclohexanecarboxylic acid base ester, phenylcyclohexane, cyclohexylbiphenyl, phenylcyclohexylcyclohexane, cyclohexylcyclohexane, 1,4-bicyclohexylbenzene, 4',4'-bicyclohexylbiphenyl, phenylpyrimidine or cyclohexylpyrimidine, phenylpyridine or cyclohexylpyridine, phenyldioxane or cyclohexyldioxane, phenyl- or cyclohexyl-1,3-dithiarone, 1,2-diphenylethane, 1,2-Dicyclohexylethane, 1-phenyl-2-cyclohexylethane, 1-cyclohexyl-2-(4-phenylcyclohexyl)ethane, 1-cyclohexyl-2-biphenylethyl alkanes, 1-phenyl-2-cyclohexylphenylethane, optionally halogenated stilbenes, benzylphenyl ethers, tolans, and substituted cinnamic acids. The 1,4-phenylene groups in these compounds may also be monofluorinated or polyfluorinated.

The most important compounds suitable as other components of the medium of the invention can be characterized by the formulas (II), (III), (IV), (V) and (VI): R'-LE-R'' (II) R'- L-COO-E-R'' (III) R'-L-OOC-E-R'' (IV) R'-L-CH ₂ CH ₂ -E-R'' ( V ) R'-L- CF ₂ OE-R'' (VI) In formulas (II), (III), (IV), (V) and (VI), L and E may be the same or different, and in each case independently of each other represent Derived from -Phe-, -Cyc-, -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -Pyr-, -Dio-, -Thp-, -G-Phe- and -G-Cyc - and the divalent group of the group formed by its mirror image, wherein Phe represents unsubstituted or fluorine-substituted 1,4-phenylene, Cyc represents trans-1,4-cyclohexyl or 1,4- Cyclohexenyl, Pyr means pyrimidine-2,5-diyl or pyridine-2,5-diyl, Dio means 1,3-dioxane-2,5-diyl, Thp means tetrahydropyran-2 ,5-diyl, and G represents 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.

One of the groups L and E is preferably Cyc or Phe. E is preferably Cyc, Phe or Phe-Cyc. The medium of the present invention preferably comprises one or more components selected from the compounds of formulas (II), (III), (IV), (V) and (VI), wherein L and E are selected from the groups Cyc and Phe; And at the same time one or more components are selected from compounds of formula (II), (III), (IV), (V) and (VI), wherein one of the groups L and E is selected from the group Cyc and Phe and another group is selected from the group -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -G-Phe- and -G-Cyc-; and optionally one or more components are Compounds selected from formulas (II), (III), (IV), (V) and (VI), wherein the groups L and E are selected from the group -Phe-Cyc-, -Cyc-Cyc-, -G -Phe- and -G-Cyc-.

R' and R'' in relatively small subgroups of compounds of formulas (II), (III), (IV), (V) and (VI) represent in each instance independently of each other having up to 8 C atoms Alkyl, alkenyl, alkoxy, alkoxyalkyl (oxaalkyl), alkenyloxy or alkyloxy. This smaller subgroup is hereinafter referred to as Group A, and the compounds are referred to by the subformulas (IIa), (IIIa), (IVa), (Va) and (VIa). In the case of most of these compounds, R' and R'' are different from each other, and one of these groups is in most cases an alkyl, alkenyl, alkoxy or alkoxyalkyl ( oxaalkyl).

。In another relatively small subgroup of compounds of formulas (II), (III), (IV), (V) and (VI), called group B, E represents

.

In the compounds of group B mentioned by subformulas (IIb), (IIIb), (IVb), (Vb) and (VIb), R' and R'' have the The meanings given in the case of compounds are preferably alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).

In another relatively small subgroup of compounds of formulas (II), (III), (IV), (V) and (VI), R'' represents -CN. This subgroup is hereinafter referred to as group C and the compounds of this subgroup are correspondingly illustrated by sub-formulas (IIc), (IIIc), (IVc), (Vc) and (VIc). In the compounds of the subformulas (IIc), (IIIc), (IVc), (Vc) and (VIc), R' has the meaning given in the case of the compounds of the subformulas (IIa) to (VIa) and is greater than Preferable is alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).

Besides the preferred compounds of groups A, B and C, other compounds of the formulas (II), (III), (IV), (V) and (VI) with other variants of the mentioned substituents are also common. All these substances can be obtained by methods known from the literature or in a manner analogous thereto.

The medium according to the invention preferably comprises, in addition to the compounds of general formula I according to the invention, one or more compounds from groups A, B and/or C. The weight fractions of compounds from these groups in the medium of the invention are: 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 70%. Group C: 0% to 80%, preferably 5% to 80%, in particular 5% to 50%.

The medium according to the invention preferably comprises from 1% to 40%, in particular from 5% to 30%, of a compound of formula I according to the invention. The medium preferably comprises one, two, three, four or five compounds of formula I according to the invention.

The preparation of the medium according to the invention is carried out in a manner customary per se. In general, it is preferred to dissolve the components in each other at elevated temperature. The liquid-crystalline phases according to the invention can be modified by means of suitable additives so that the liquid-crystalline phases according to the invention can be used in all types of liquid-crystal display elements known hitherto. Additives of this type are known to those 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 for creating colored guest-host systems or substances for changing the dielectric anisotropy, viscosity and/or orientation of the nematic phase can be added.

Based on the negative Δε of the compound of formula I, it is especially suitable for VA-TFT displays.

The invention therefore also provides optoelectronic display elements which comprise the liquid-crystal media according to the invention. The display element is preferably a VA-TFT display element (VA: Vertical Alignment; TFT: Thin Film Transistor). Furthermore, there are other types of display elements that also use media with negative dielectric anisotropy.

Other embodiments of the invention result from claimed claims and combinations of two or more of these claimed claims.

The invention is explained in more detail below by referring to working examples, however, without any intention of limiting the invention. Those skilled in the art will be able to deduce from the examples procedural details not specifically given in the general description, generalize them on the basis of general expertise and apply them to their specific objectives.

In addition to commonly used and well-known abbreviations, the following abbreviations are used: C: crystalline phase; N: nematic phase; Sm: smectic phase; I: isotropic phase. The numbers between these symbols indicate the transition temperature of the relevant substance. Temperatures are given in °C unless otherwise stated.

The physical, physicochemical or optoelectronic parameters are determined according to known methods, as described inter alia in the handbook "Merck Liquid Crystals - Licristal® - Physical Properties of Liquid Crystals - Description of the Measurement Methods", 1998, Merck KGaA, Darmstadt.

Above and below, Δn denotes optical anisotropy (589 nm, 20°C) and Δε denotes dielectric anisotropy (1 kHz, 20°C). The dielectric anisotropy Δε was measured at 20°C and 1 kHz. The optical anisotropy ∆n is measured at 20°C and a wavelength of 589.3 nm.

The Δε and Δn values, extrapolated clearing point (cl.p.) and rotational viscosity (γ ₁ ) of the compounds of the present invention are determined by free 5% to 10% of the specific compound of the present invention and 90% to 95% of the market value. It was obtained by linear extrapolation of liquid crystal mixtures composed of commercially available liquid crystal mixtures ZLI-2857 (for Δε, cl. p.) or ZLI-4792 (for ∆n, γ ₁ ) (mixtures from Merck KGaA, Darmstadt).

In the following, the abbreviations indicate: MTB methyl tertiary butyl ether THF tetrahydrofuran DMAP 4-(dimethylamino)pyridine m.p. melting point

EXAMPLES Starting materials can be obtained by commonly available literature procedures or are available commercially.

將0.058 mol之2-溴-6-氟苯酚溶解於100 ml之THF中，並與40 ml之水及0.09 mol之碳酸鉀混合。在加熱至沸點後，添加0.3 mmol之參(二亞苄基丙酮)二鈀(0)及0.9 mmol之cataCXium® A (二(1-金剛烷基)-正丁基膦)，並在半小時內逐滴添加0.062 mol之(4-乙氧基-2,3-二氟苯基)二甲氧基-硼烷溶解於100 ml之THF中之溶液。將混合物於回流溫度下再煮沸16小時，隨後與水及MTB混合並藉由萃取處理。藉由層析(溶析劑：氯丁烷)純化粗產物4'-乙氧基-3,2',3'-三氟聯苯-2-醇，從而得到白色晶體。 Example 1 Step 1

0.058 mol of 2-bromo-6-fluorophenol was dissolved in 100 ml of THF and mixed with 40 ml of water and 0.09 mol of potassium carbonate. After heating to the boiling point, add 0.3 mmol of ginseng (dibenzylideneacetone) dipalladium (0) and 0.9 mmol of cataCXium® A (two (1-adamantyl)-n-butylphosphine), and in half an hour A solution of 0.062 mol of (4-ethoxy-2,3-difluorophenyl)dimethoxy-borane dissolved in 100 ml of THF was added dropwise. The mixture was boiled at reflux temperature for a further 16 hours, then mixed with water and MTB and worked up by extraction. The crude product 4'-ethoxy-3,2',3'-trifluorobiphenyl-2-ol was purified by chromatography (eluent: chlorobutane) to obtain white crystals.

將0.022 mol之4'-乙氧基-3,2',3'-三氟聯苯-2-醇、0.036 mol之三乙胺及0.6 mmol之DMAP溶解於50 ml之二氯甲烷中。在5℃至10℃下在半小時內將0.03 mol之三氟甲磺酸酐逐滴添加至此溶液中。再將批料攪拌1小時，而不進一步冷卻，且利用二氯甲烷經由含有矽膠之管柱過濾。蒸發該濾液得到4'-乙氧基-3,2',3'-三氟聯苯-2-醇之三氟甲基磺酸酯。 step 2

0.022 mol of 4'-ethoxy-3,2',3'-trifluorobiphenyl-2-ol, 0.036 mol of triethylamine and 0.6 mmol of DMAP were dissolved in 50 ml of dichloromethane. 0.03 mol of trifluoromethanesulfonic anhydride was added dropwise to this solution at 5°C to 10°C within half an hour. The batch was stirred for an additional hour without further cooling and filtered through a column containing silica gel with dichloromethane. Evaporation of the filtrate afforded the triflate of 4'-ethoxy-3,2',3'-trifluorobiphenyl-2-ol.

將0.022 mol 4'-乙氧基-3,2',3'-三氟-聯苯-2-醇之三氟甲烷磺酸酯及0.024 mol之巰基丙酸乙酯溶解於50 ml之無水甲苯中並在回流溫度下與2.2 mmol之雙(2-二苯基膦基苯基)醚、1.1 mmol之參-(二亞苄基丙酮)二鈀(0)及0.055 mol之碳酸鉀一起煮沸24小時。將反應混合物與水及MTB混合並藉由萃取處理。濃縮有機相，並藉由管柱層析利用1-氯丁烷在矽膠上分離產物，從而得到0.014 mol之3-(4'-乙氧基-3,2',3'-三氟聯苯-2-基硫基)丙酸乙酯。 step 3

Dissolve 0.022 mol of 4'-ethoxy-3,2',3'-trifluoro-biphenyl-2-ol trifluoromethanesulfonate and 0.024 mol of ethyl mercaptopropionate in 50 ml of anhydrous toluene and boil at reflux temperature with 2.2 mmol of bis(2-diphenylphosphinophenyl)ether, 1.1 mmol of ginseng-(dibenzylideneacetone)dipalladium(0) and 0.055 mol of potassium carbonate for 24 Hour. The reaction mixture was mixed with water and MTB and worked up by extraction. Concentrate the organic phase and separate the product by column chromatography on silica gel with 1-chlorobutane to give 0.014 mol of 3-(4'-ethoxy-3,2',3'-trifluorobiphenyl -2-ylthio)propionic acid ethyl ester.

在回流溫度下將0.014 mol之3-(4'-乙氧基-3,2',3'-三氟聯苯-2-基硫基)丙酸乙酯與50 ml之THF中之0.017 mol第三丁醇鉀一起煮沸14小時。將反應混合物與水及MTB混合並藉由萃取處理。濃縮有機相，並藉由管柱層析利用1-氯丁烷在矽膠上分離產物，從而得到3-乙氧基-4,6-二氟二苯并噻吩。 step 4

0.014 mol of ethyl 3-(4'-ethoxy-3,2',3'-trifluorobiphenyl-2-ylthio)propionate was mixed with 0.017 mol of 50 ml of THF at reflux temperature Potassium tert-butoxide was boiled together for 14 hours. The reaction mixture was mixed with water and MTB and worked up by extraction. The organic phase was concentrated and the product was isolated by column chromatography on silica gel with 1-chlorobutane to give 3-ethoxy-4,6-difluorodibenzothiophene.

將0.013 mol之3-乙氧基-4,6-二氟二苯并噻吩溶解於50 ml之THF中，並在-70℃下逐滴添加11 ml (0.017 mol)之n-BuLi (1.6 M，於己烷中)。將混合物在-70℃下再攪拌30分鐘，且然後在相同溫度下添加0.017 mol之硼酸三甲酯(溶解於少量THF中)。使該反應混合物升溫至室溫，且然後添加2 ml之乙酸與2.5 ml之水之混合物。然後於最大45℃下逐滴添加3 ml之30%過氧化氫。再攪拌14小時後，將反應混合物與水及MTB混合並藉由萃取處理。濃縮有機相，並藉由管柱層析利用二氯甲烷在矽膠上分離產物，從而得到0.011 mol之7-乙氧基-4,6-二氟二苯并噻吩-3-醇。 step 5

Dissolve 0.013 mol of 3-ethoxy-4,6-difluorodibenzothiophene in 50 ml of THF, and add 11 ml (0.017 mol) of n-BuLi (1.6 M , in hexane). The mixture was stirred at -70° C. for another 30 minutes, and then 0.017 mol of trimethyl borate (dissolved in a small amount of THF) was added at the same temperature. The reaction mixture was allowed to warm to room temperature, and then a mixture of 2 ml of acetic acid and 2.5 ml of water was added. Then 3 ml of 30% hydrogen peroxide were added dropwise at a maximum of 45°C. After stirring for a further 14 hours, the reaction mixture was mixed with water and MTB and worked up by extraction. The organic phase was concentrated and the product was separated by column chromatography on silica gel with dichloromethane to give 0.011 mol of 7-ethoxy-4,6-difluorodibenzothiophen-3-ol.

The following compounds were prepared analogously:

將9.9 g (30 mmol)之酚1 (類似於實例1製備)溶解於90 ml之DCM中並與8 ml之三乙胺及150 mg之DMAP混合。於5℃下添加8 ml (48 mmol)之三氟甲烷磺酸酐。隨後將批料攪拌1 h而不冷卻。將反應溶液置於矽膠上且用DCM溶析產物2 。產率：90%。 Example 2

9.9 g (30 mmol) of phenol 1 (prepared analogously to Example 1) were dissolved in 90 ml of DCM and mixed with 8 ml of triethylamine and 150 mg of DMAP. 8 ml (48 mmol) of trifluoromethanesulfonic anhydride were added at 5°C. The batch was then stirred for 1 h without cooling. The reaction solution was placed on silica gel and the product 2 was eluted with DCM. Yield: 90%.

Under protective gas, mix 13.9 g (30 mmol) of triflate 2 with 70 ml of toluene, 4.5 ml (73 mmol) of ethanethiol, 10.5 g (76 mmol) of potassium carbonate, 1.6 g (3.1 mmol) of bis(2-diphenylphosphinophenyl)ether and 1.4 g (1.5 mmol) of ginseng(dibenzylideneacetone)dipalladium(0) were mixed and boiled overnight. The cooled batch was filtered through Celite®, concentrated and placed on silica gel. Product 3 was eluted with n-heptane. Melting point: 73°C. Phase: C73N(26)I (see also table).

除非另有說明，否則基團R^1/2 係直鏈的，即無支鏈。材料數據可參見表1。 表1.

^*) 反式異構物The following dibenzothiophene compounds were prepared analogously to Example 1:

Unless stated otherwise, the radical R ^1/2 is linear, ie unbranched. Material data can be found in Table 1. Table 1.

^*) trans isomer

除非另有說明，否則基團R^1/2 係直鏈的，即無支鏈。材料數據可參見表2。 表2.

^*) 反式異構物The following dibenzofuran compounds were prepared analogously to Example 1:

Unless stated otherwise, the radical R ^1/2 is linear, ie unbranched. Material data can be found in Table 2. Table 2.

^*) trans isomer

Other compounds:

Claims (15)

A compound of formula I,

wherein X independently represents F or Cl, W represents S or O, m represents 0, 1 or 2, R ¹ and R ² independently represent an alkyl or alkoxy group having 1 to 15 C atoms, wherein the other One or more of the _CH2 groups in each case independently of each other via -C≡C-, _-CF2O- , _-OCF2- , -CH =CH-,

, -O-, -S-, -CO-O- or -O-CO-, and wherein one or more additional H atoms may be replaced by a halogen, A ¹ in each case independently represents one selected from the following Groups of groups: a) 1,4-phenylene, wherein one or two other CH groups can be replaced by N and one or more H atoms can be replaced by a group L, b) by trans- A group consisting of 1,4-cyclohexylene and 1,4-cyclohexenyl, wherein one or more non-adjacent CH ₂ groups can be replaced by -O- and/or -S- and one of the other or multiple H atoms can be replaced by F or Cl, and c) from tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl The group consisting of cyclobutane-1,3-diyl, hexahydropyridine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, which can be additionally The group L is monosubstituted or polysubstituted, L independently at each occurrence represents F, Cl, CN, SCN, SF ₅ or a straight-chain or branched chain having 1 to 12 C atoms in each case as desired Fluorinated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy, and Z ¹ independently represent a single bond, -CF ₂ O-, - OCF ₂ -, -CH ₂ O-, -OCH ₂ -, -(CO)O-, -O(CO)-, -(CH ₂ ) ₄ -, -CH ₂ CH ₂ -, -CF ₂ -CF ₂ -, -CF ₂ -CH ₂ -, -CH ₂ -CF ₂ -, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -(CH ₂ ) ₃ O- , -O(CH ₂ ) ₃ -, -C≡C-, -O-, -CH ₂ -, -(CH ₂ ) ₃ - or -CF ₂ -. The compound of claim 1, wherein in the formula I, m has a value of 0. The compound as claimed in item 1, wherein in the formula I, R ¹ represents an unsubstituted alkyl or alkoxy group with 1 to 15 carbon atoms or an alkenyl group with 2 to 15 C atoms, an alkenyloxy group or Alkynyl, which in each case is optionally monohalogenated or polyhalogenated. The compound of claim 1, wherein in the formula I, R ² represents an alkyl group with 1 to 7 carbon atoms or an alkenyl group with 2 to 7 carbon atoms. The compound according to any one of claims 1 to 4, wherein W in the formula I represents S. A compound as claimed in item 1, wherein the compound of formula I is selected from sub-formulas IA to IC and ID to IF

Wherein R ¹ , R ² , A ¹ and Z ¹ have the same meanings as for formula I as claimed in claim 1, wherein Z ¹ here does not represent a single bond. As the compound of claim 1, wherein these compounds are selected from the compounds of formula IA-1 to IA-3 and ID-1 to ID-3,

wherein alkyl and alkyl* independently represent straight-chain alkyl having 1 to 7 C atoms, and alkoxy independently represent straight-chain alkoxy having 1 to 7 C atoms. The compound according to any one of claims 1 to 4, wherein X represents F. The compound according to any one of claims 1 to 4 and 6, wherein R ¹ represents an alkoxy group having 1 to 7 carbon atoms. A compound as claimed in any one of claims 1, 3 and 4, wherein m= ¹ or 2, and ring A is in each case independently selected from the following moieties

A use of the compound according to any one of claims 1 to 10 in liquid crystal media. A liquid-crystalline medium comprising at least two compounds, characterized in that it comprises at least one compound according to any one of claims 1 to 10. An optoelectronic display element, which contains the liquid crystal medium as claimed in claim 12. The photoelectric display device according to claim 13, which uses polymer-stabilized or polymer-induced liquid crystal alignment. A method for preparing a compound of formula I as any one of claims 1 to 10, characterized in that it comprises the following method steps: wherein the compound of formula (B)

Wherein W, X, Z ¹ , A ¹ , m and R ¹ are independently as defined in formula I of any one of claims 1 to 9, in the OH group and trifluoromethanesulfonic acid or its reactive derivatives Reaction, to obtain formula (C) compound

wherein independently OTf represents the group O(SO ₂ )CF ₃ , and W, X, Z ¹ , A ¹ , m and R ¹ are independently as defined in formula I of any one of claims 1 to 9, and In a further process step, the compound of formula I is converted.