DE4446880A1 - Pyridazinone(s) improving property profile of liquid crystal mixts. - Google Patents

Abstract

Pyridazinones of formula (I) are new (where, R1, R2 = CN, F, Cl, 1-20C alkyl, opt. with an asymmetric C atom, in which 1 or more CH2 gps. may be replaced by -O-, -CO-, -CH=CH-, -C?=C-, cyclopropan-1,2-diyl, -SiMe2-, trans-1,4-cyclohexylene or trans-1,3-cyclopentylene, without adjacent O atoms, and/or opt. mono- or poly-substd. by F, Cl, Br or -OR3; or an optically active or racemic gp. of e.g. formulae (IIA-C); or one of R1, R2 = H; R3-R7 = H, 1-16C alkyl, opt. with an asymmetric C atom, in which 1 or more CH2 gps. may be replaced by -O- or -CH=CH-, without adjacent O atoms, and/or opt. mono- or poly-substd. by F or Cl; or R4+R5 may = -(CH2)4- or -(CH2)5 if attached to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system; Q = a single bond, -CO-O- or -CH2-O-; M1 = -O-CO-, -CO-O-, -O-CH2-, -CH2-O- or a single bond; M2 = -O-(CH2)n- (n = 1-8) or a single bond; A1 = 1,4-phenylene (Phe), opt. mono- or poly-substd. by F, Cl and/or CN, 1,4-cyclohexylene (Cyc), naphthalen-2,6-diyl (Naph), 4-(cyclohexyl-1,4-diyl)phenyl, biphenyl-4,4'-diyl (Bip), opt. mono- or poly-substd. by F, 4-(pyrimidin-2,5-diyl)phenyl, 4-(pyridin-2,5-diyl)phenyl, 4-(1,3,4-thiadiazol- 2,5-diyl)phenyl, benzothiazol-2,6-diyl, or indan-2,6-diyl; A2 = Phe, opt. mono-substd. by Me or mono- or poly-substd. by F or Cl, Cyc, Naph, or pyridin-2,5-diyl (Pyd); A3 = Phe, opt. mono-substd. by Me or mono- or poly-substd. by F or Cl, Bip, opt. mono- or poly-substd. by F, 4-(cyclohexyl- 1,4-diyl)phenyl, Pyd, opt. mono-substd. by F, benzothiazol-2,6-diyl, indan-2,6-diyl, Naph, Cyc, or pyrimidin-2,5-diyl; X = H, F or Cl; Hal = Cl or F; X' = -CO- or -CH2-; Y' = CN or Me; a, b, c, d, e = 0 or 1 such that a+b+c = 1 or 2). Also claimed are liquid crystal (LC) mixts. contg. cpd(s). (I), pref. mixts. contg. 2-20 components, including 1-10 cpd(s). (I), esp. ferroelectric mixts..

Description

In addition to nematic and cholesteric liquid crystals, more recently also optically active, inclined smectic (ferroelectric) liquid crystal phases used in commercial display devices.

Clark and Lagerwall were able to show that the use of ferroelectric Liquid crystal systems in very thin cells for optoelectric switching or Display elements leads, which compared to the conventional TN ("twisted nematic ") cells have switching times that are up to a factor of 1000 faster (see e.g. EP-A 0 032 362). Because of this and others cheaper Properties, e.g. B. the bistable switching option and almost angle-independent contrast, FLCs are basically for the above-mentioned fields of application, e.g. B. via a matrix control, good suitable.

For electro-optical or completely optical components you need either connections, the inclined or orthogonal smectic phases train and are optically active themselves, or you can by doping Connections that form such smectic phases, but not themselves are optically active, with optically active compounds ferroelectric smectic Induce phases. The desired phase should be possible if possible wide temperature range to be stable.

A uniform planar orientation of the liquid crystals is necessary to achieve a good contrast ratio in electro-optical components. A good orientation in the S _A and S * _C phase can e.g. B. achieve if the phase sequence of the liquid crystal mixture with decreasing temperature is:

Isotropic → N * → S _A → S * _C

The prerequisite is that the pitch (pitch of the helix) is very high in the N * phase large (larger than 10 µm) or, even better, completely compensated (see e.g. T. Matsumoto et al., P. 468-470, Proc. of the 6th Int. Display Research Conf., Japan Display, Sept. 30 - Octo. 2, 1986, Tokyo, Japan; M. Murakami et al., ibid. P. 344-p. 347). This is achieved e.g. B. by going to the chiral Liquid crystal mixture which in the N * phase z. B. a left-turning helix has one or more optically active dopants, the one induce clockwise helix in such amounts that the helix is compensated.

For the use of the SSFLCD effect (Surface Stabilized Ferroelectric Liquid Crystal Display) from Clark and Lagerwall for uniform, planar Orientation is also a prerequisite that the pitch in the smectic C * phase is significantly larger than the thickness of the display element (Mol. Cryst. Liq. Cryst. 1983, 94, 213-134 and 1984, 114, 151-187). This is achieved as in the case of cholesteric pitch, by using dopants with the helix rotating in the opposite direction.

Ferroelectric liquid crystal displays can also be operated by using the DHF (Distorted Helix Formation) effect or the PSFLCD effect (Pitch Stabilized Ferroelectric Liquid Crystal Display, also called SBF = Short pitch Bistable Ferroelectric Effect). The DHF effect was described by BI Ostrovski in Advances in Liquid Crystal Research and Applications, Oxford / Budapest, 1980, 469 ff., The PSFLCD effect is described in DE-A 39 20 625 and EP-A 0 405 346. In contrast to the SSFLCD effect, a liquid crystalline material with a short S _C pitch is required to use these effects.

The optical switching time τ [µs] of ferroelectric liquid crystal systems, which should be as short as possible, depends on the rotational viscosity of the system γ [mPas], the spontaneous polarization P _s [nC / cm²] and the electric field strength E [V / m] according to relationship

Since the field strength E is due to the electrode spacing in the electro-optical component and is determined by the applied voltage, the ferroelectric Display medium be low viscosity and high spontaneous polarization have so that a short switching time is achieved.

Finally, in addition to thermal, chemical and photochemical stability a small optical anisotropy Δn, preferably ≈ 0.13, and a small one requires positive or preferably negative dielectric anisotropy Δε (see S.T. Lagerwall et al., "Ferroelectric Liquid Crystals for Displays" SID Symposium, Oct. Meeting 1985, San Diego, CA, USA).

All of these requirements can only be met with mixtures of several components. The basis (or matrix) used is preferably compounds which, if possible, already have the desired phase sequence I → N → S _A → S _C. Other components of the mixture are often added to lower the melting point and broaden the S _C - and usually also the N phase, to induce optical activity, to compensate for pitch and to adjust the optical and dielectric anisotropy, but, for example, do not increase the rotational viscosity if possible shall be.

Because the development, especially of ferroelectric Liquid crystal mixtures, in no way considered complete the manufacturers of displays are on the most varied  Components for mixtures interested. This u. a. also because only the interaction of the liquid crystalline mixtures with the individual Components of the display device or the cells (e.g. the orientation layer) Allows conclusions to be drawn about the quality of the liquid-crystalline mixtures.

The object of the present invention was therefore to create new compounds To provide, which are suitable in liquid crystalline mixtures, the To improve the property profile of these mixtures.

Liquid crystalline 6- (4-substituted-phenyl) -4,5-dihydro-3 (2H) pyridazinones are in Z. Chem. 1977, 17, 333. These are for practical use Connections not suitable due to the tautomerism.

1,4-substituted pyridazin-6-ones are known per se (Angew. Chemie 1975, 87, 124). Representatives of this class of substances with liquid crystalline properties are not known, however, and also the use of pyridazinones in Liquid crystal mixtures are not described.

It has now surprisingly been found that pyridazinones are components suitable for liquid crystal mixtures.

The invention therefore relates to new pyridazinones of the formula (I)

in which the symbols and indices have the following meanings:

R¹, R² are the same or different hydrogen (but not both at the same time), -CN, -F, -Cl or a straight-chain or branched Alkyl radical with 1 to 20 C atoms (with or without asymmetric C atom), where also one or more CH₂ groups by -O-, -CO-, -CH = CH-, -C≡C-, cyclopropane-1,2-diyl, -Si (CH₃) ₂-, trans-1,4-cyclohexylene or trans-1,3-cyclopentylene can be replaced can, with the proviso that oxygen atoms are not immediate may be bound to each other, and / or where also one or several H atoms of the alkyl radical by -F, -Cl, -Br, -OR³ may be substituted, or one of the following Groups (optically active or racemic):

R³, R⁴, R⁵, R⁶, R⁷ are the same or different hydrogen or a straight-chain or branched alkyl radical having 1 to 16 carbon atoms (with or without an asymmetric carbon atom), with one or more CH₂ groups by -O- or -CH = CH- can be replaced, with the proviso that oxygen atoms must not be bonded directly to one another, and / or wherein one or more H atoms of the alkyl radical can also be substituted by -F or -Cl; R⁴ and R⁵ together can also be - (CH₂) ₄- or - (CH₂) ₅- if they are bound to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system;
Q is a single bond, -CO-O- or -CH₂-O-;
M¹ -O-CO-, -CO-O-, -O-CH₂-, -CH₂-O-, or a single bond;
M² is -O- (CH₂) _n -, with n = 1 to 8, or a single bond;
A¹ is 1,4-phenylene, although one or more hydrogen atoms can also be replaced by F, Cl and / or CN, 1,4-cyclohexylene, naphthalene-2,6-diyl, 4- (cyclohexyl-1,4-diyl ) phenyl, biphenyl-4,4'-diyl, where one or more hydrogen atoms can be replaced by fluorine, 4- (pyrimidine-2,5-diyl) phenyl, 4- (pyridine-2,5-diyl) phenyl, 4 - (1,3,4-thiadiazole-2,5-diyl) phenyl, benzthiazole-2,6-diyl, indane-2,6-diyl;
A²: is 1,4-phenylene, in which a hydrogen atom can be replaced by CH₃ or one or more hydrogen atoms by F or Cl, 1,4-cyclohexylene, naphthalene-2,6-diyl, pyridine-2,5-diyl ;
A³: is 1,4-phenylene, in which one hydrogen atom can be replaced by CH₃ or one or more hydrogen atoms by F or Cl, biphenyl-4,4'-diyl, where one or more hydrogen atoms can be replaced by fluorine, 4 - (Cyclohexyl-1,4-diyl) phenyl, pyridine-2,5-diyl, where a hydrogen atom can be replaced by F, benzothiazole-2,6-diyl, indane-2,6-diyl, naphthalene-2,6 -diyl, 1,4-cyclohexylene, pyrimidine-2,5-diyl;
X is H, F or Cl;
a, b, c, d, e are zero or one;
with the following proviso:
a + b + c is 1 or 2.

Preferred compounds of the general formula (I) are those in which
R¹, R² represent the same or different hydrogen (but not both at the same time), -F, -Cl or a straight-chain or branched alkyl radical having 1 to 18 carbon atoms (with or without an asymmetric carbon atom), one or more CH₂- Groups can be replaced by -O-, -CO-, -CH = CH-, -C≡C-, cyclopropane-1,2-diyl or -Si (CH₃) ₂-, with the proviso that oxygen atoms are not directly with one another may be bound, and / or wherein one or more H atoms of the alkyl radical may be substituted by -F, or one of the following groups (optically active or racemic):

R⁴ is a straight-chain or branched alkyl radical having 1 to 16 or 3 to 16 carbon atoms (with or without an asymmetric carbon atom, it also being possible for a CH₂ group to be replaced by -O-;
and wherein A¹, A², A³, M¹ and M² have the meanings given in formula (I).

Particularly preferred compounds of the formula (I) are those of the formulas (Ia1) to (Ia38):

where the radicals R have the following meaning
R¹, R² the same or different hydrogen (but not both at the same time), -F, -Cl or a straight-chain or branched alkyl radical having 1 to 18 carbon atoms (with or without an asymmetric carbon atom), with one or more CH₂ groups can be replaced by -O-, -CO-, -CH = CH-, -C≡C-, cyclopropane-1,2-diyl or -Si (CH₃) ₂-, with the proviso that oxygen atoms are not directly bonded to one another may be, and / or where one or more H atoms of the alkyl radical may be substituted by -F, or one of the following groups (optically active or racemic):

R⁴ is a straight-chain or branched alkyl radical having 1 to 16 or 3 to 16 carbon atoms (with or without an asymmetric carbon atom, it also being possible for a CH₂ group to be replaced by -O-;
R⁸ is a straight-chain or branched alkyl radical having 1 to 16 carbon atoms, in which one or two non-adjacent CH₂ groups can be replaced by -O- and / or in which a CH₂ group by -CH = CH-, cyclopropane -1,2-diyl or -Si (CH₃) ₂- can be replaced or two adjacent CH₂ groups can be replaced by -CH (F);
R⁹ is a straight-chain or branched alkyl radical having 1 to 16 carbon atoms, in which a CH₂ group can also be replaced by -CH = CH-, cyclopropane-1,2-diyl or -Si (CH₃) ₂-; and
R¹⁰ is a straight-chain alkyl radical with 1 to 16 carbon atoms.

Further particularly preferred compounds of formula (I) are those of Formulas (Ib1) to (Ib29):

where the symbols are those given in formulas (Ia1) to (Ia38) Have meanings.

Among the compounds of the formulas (Ia) and (Ib), those are also optical active compounds of the formula (Ic1) to (Ic21) particularly preferably:

in which R¹¹ is an optically active radical of the formula R¹²-CH (F) -CH₂- or R¹²-CH (F) -CH (F) -CH₂-, where R¹² is an alkyl or alkyloxy group having 1 to 12 carbon atoms means
and in which the other symbols and indices have the meanings given in the formulas (Ia1) to (Ia38).

The synthesis of the compounds according to the invention is shown in schemes 1 to 4 described by way of example, but without referring to this procedure restrict. In these schemes, R, R ′ and R ′ ′ represent typical, the adapted to the respective reaction conditions variants (subsets) of respective radicals R¹ and R².

Scheme 1 describes the general procedure for the synthesis of mesogenic 4,5-dichloropyridazin-6-one by reacting mesogenic hydrazines (including are understood hydrazines of such substructures that are derived from mesogenic Compounds are known from the literature) with mucochloric acid. By choosing more suitable The Cl atom in position 4 is largely selective in the reaction conditions exchange, for example by reaction with an alcoholate for one Alkyloxy group or by palladium-catalyzed coupling with a Arylboronic acid against an aryl group.

This procedure is suitable in principle for all compounds according to the invention, but it is also possible to work with protective groups or placeholder groups in order to obtain partial structures for R 1, R 2 which are not directly accessible, either because they are under the reaction conditions of ring closure , the S _N reaction or the aryl-aryl coupling are not inert. This is shown in Scheme 2 using the example of a silyl ether as a protective group in the synthesis of dopants according to the invention.

Schemes 3 and 4 exemplify the synthesis of the invention Compounds with ester or ether functions as bridges between Aryl groups.  

Scheme 1

Scheme 2

Scheme 3

Scheme 4

The synthesis of the residues R¹ (A¹-M¹) _a ä (A²) _b or (M²-A³) _c -R² or suitable reactive derivatives or parts thereof is carried out according to methods known to the person skilled in the art.

So z. B. the required hydrazines (see Scheme 1, which is analogous to the production of further compounds of type (I) applies) by standard methods produce how z. B. are described in:

• - Sandler & Karo, Organic Functional Group Preparations, Vol. 1, pp. 374 Academic Press New York, 1978;
• - J. Org. Chem. 1949, 14, 813;
• - Organic Syntheses, Col. Vol. I, 442 (1941), Col. Vol. III, 475 (1955);
• - reports German Chem. Ges. 1960, 93, 540;
• - Appl. Chemistry 1956, 68, 484;
• - J. Am. Chem. Soc. 1956, 78, 5854;
• - J. Org. Chem. 1956, 21, 394.

The production takes place under reaction conditions for the above Implementations are known and suitable. It can also by itself make use of known variants not mentioned here.

For example, reference is made to DE-A 23 44 732, 24 50 088, 24 29 093, 25 02 94, 26 36 684, 27 01 591 and 27 52 975 for connections with 1,4-cyclohexylene and 1,4-phenylene groups; DE-A 26 41 724 for Compounds with pyrimidine-2,5-diyl groups; DE-A 40 26.223 and EP-A 03 91 203 for compounds with pyridine-2,5-diyl groups; DE-A 32 31 462 for compounds with pyridazine-3,6-diyl groups; EP-A 309 514 for compounds with (1,3,4) thiadiazole-2-5-diyl groups; WO-A 92/16500 for naphthalene-2,6-diyl groups.  

The production of disubstituted pyridines, disubstituted pyrazines, disubstituted pyrimidines and disubstituted pyridazines are found for example also in the corresponding volumes of the series "The Chemistry of Heterocyclic Compounds "by A. Weissberger and E.C. Taylor (editors).

Cyclic acetals are useful by reacting an appropriate one Aldehyde (or one of its reactive derivatives) with a corresponding diol (or one of its reactive derivatives), preferably in the presence of an inert solvent such as benzene or Toluene, and / or a catalyst, e.g. B. a strong acid, such as Sulfuric acid, benzene or p-toluenesulfonic acid, at temperatures between about 20 ° C and about 150 ° C, preferably between 80 ° C and 120 ° C. As reactive derivatives of the starting materials are primarily suitable for acetals.

The aldehydes and diols mentioned and their reactive derivatives are partly known, partly they can be followed without difficulty Standard methods of organic chemistry from literature Connections are made. For example, the aldehydes are through Oxidation of appropriate alcohols or by reduction of nitriles or corresponding carboxylic acids or their derivatives, the diols by reduction corresponding diester available.

Compounds in which an aromatic ring has at least one F atom is substituted, can also from the corresponding diazonium salts Exchange of the diazonium group for a fluorine atom, e.g. B. according to the methods from Balz and Schiemann.

As for the connection of the ring systems with each other, for example referred to: N. Miyaura, T. Yanagai and A. Suzuki in Synthetic Communications 11 (1981), 513-519 DE-C-39 30 663, M.J. Sharp, W. Cheng, V. Snieckus in Tetrahedron Letters 28 (1987) 5093; G.W. Gray in J. Chem. Soc. Perkin Trans II 1989, 2041  and Mol. Cryst. Liq. Cryst. 172: 165, 204 (1991) 43 and 91; EP-A 0 449 015; WO-A 89/12039; WO-A 89/03821; EP-A 0 354 434 for the direct linking of aromatics and heteroaromatics; DE-A 32 01 721 for Connections with -CH₂CH₂ bridge members and Koji Seto et al. in liquid Crystals 8 (1990) 861-870 for connections with -C≡C bridge members.

Esters of the formula (I) can also be correspondingly esterified Carboxylic acids (or their reactive derivatives) with alcohols or Phenols (or their reactive derivatives) or by the DCCl method (DCCl = dicyclohexylcarbodiimide) can be obtained.

The corresponding carboxylic acids and alcohols or phenols are known and can be produced in analogy to known processes.

Suitable reactive derivatives of the carboxylic acids mentioned are especially the acid halides, especially the chlorides and bromides the anhydrides, e.g. B. also mixed anhydrides, azides or esters, in particular Alkyl esters with 1 to 4 carbon atoms in the alkyl group.

Coming as reactive derivatives of the alcohols or phenols mentioned in particular the corresponding metal alcoholates or phenolates, preferably an alkali metal such as sodium or potassium.

The esterification is advantageous in the presence of an inert solvent carried out. Particularly suitable are ethers, such as diethyl ether, Di-n-butyl ether, THF, dioxane or anisole, ketones such as acetone, butanone or Cyclohexanone, amides, such as DMF or phosphoric acid hexamethyltriamide, Hydrocarbons, such as benzene, toluene or xylene, halogenated hydrocarbons, such as carbon tetrachloride, dichloromethane or tetrachlorethylene and sulfoxides, such as dimethyl sulfoxide or sulfolane.  

Ethers of the formula (I) are more appropriate by etherification Hydroxy compounds, preferably corresponding phenols, are available, where the hydroxy compound expediently first in a corresponding Metal derivative, e.g. B. by treatment with NaH, NaNH₂, NaOH, KOH, Na₂CO₃ or K₂CO₃ in the corresponding alkali metal alcoholate or alkali metal phenolate is transferred. This can then be combined with the corresponding alkyl halide, Sulfonate or dialkyl sulfate are implemented, advantageously in an inert Solvents such as acetone, 1,2-dimethoxyethane, DMF or dimethyl sulfoxide, or with an excess of aqueous or aqueous-alcoholic NaOH or KOH at temperatures between about 200 and 100 ° C.

As far as the synthesis of special R¹ radicals is concerned, for example refer to EP-A 0 355 008 for connections with silicon-containing Side chains and EP-A 0 292 954 and EP-A 0 398 155 for connections with Cyclopropyl groups in the side chain, on Ferroelectrics 147, 367 (1993) for optically active fluoroalkyl compounds and on Ferroelectrics 121, 213 (1991) for optically active difluoroalkyl compounds.

With the provision of compounds of formula (I), the Range of liquid crystalline substances, which are among different technical aspects for the production of liquid crystalline Mixtures are suitable, considerably widened.

In this connection, the compounds of formula (I) have a wide range Scope of application. Depending on the choice of substituents they can serve as base materials from which liquid crystalline phases for the majority are composed; but connections can also be made of the formula (I) liquid-crystalline base materials from others Classes of compound are added, for example the dielectric and / or to influence the optical anisotropy of such a dielectric and / or by its threshold voltage and / or its viscosity optimize. The use of optically active is also preferred  Compounds of formula (Ia) as dopants in ferroelectric and / or antiferroelectric liquid crystal mixtures.

The invention also relates to the use of compounds of Formula (I) in liquid crystal mixtures, preferably ferroelectric, antiferroelectric and nematic, especially ferroelectric and antiferroelectric.

The invention furthermore relates to liquid crystal mixtures, preferably ferroelectric, antiferroelectric and nematic, in particular ferroelectric, containing one or more compounds of the Formula (I).

The liquid crystal mixtures according to the invention generally contain 2 to 35, preferably 2 to 25, particularly preferably 2 to 20 components.

They generally contain 0.01 to 80 wt .-%, preferably 0.1 to 60% by weight, particularly preferably 0.1 to 30% by weight, of one or more, preferably 1 to 10, particularly preferably 1 to 5, very particularly preferably 1 to 3, the compounds of formula (I) according to the invention.

Other components of liquid crystal mixtures, the invention Compounds of formula (I) are preferably selected from the known compounds with smectic and / or nematic and / or cholesteric and / or antiferroelectric phases. These include e.g. B .:

• Derivatives of phenylpyrimidine, as for example in WO 86/06401, US-A 4 874 542,
• - Meta-substituted six-ring aromatics, such as in EP-A 0 578 054.
• Silicon compounds, as described for example in EP-A 0 355 008, mesogenic connections with only one side chain, as in  EP-A 0 541 081,
• Hydroquinone derivatives, as described for example in EP-A 0 603 786,
• Pyridylpyrimidines, as described for example in WO 92/12974,
• Phenylbenzoates, as described, for example, by P. Keller, Ferroelectrics 1984, 58, 3 and J. W. Goodby et al., Liquid Crystals and Ordered Fluids, Vol. 4, New York 1984 described and
• - Thiadiazoles, such as. B. described in EP-A 309 514.

Examples of chiral, non-racemic dopants are:

• optically active phenylbenzoates, such as, for example, P. Keller, Ferroelectrics 1984, 58, 3 and J.W. Goodby et al., Liquid Crystals and Ordered Fluids, Vol. 4, New York 1984,
• - Optically active oxirane ethers, such as in EP-A 0 263 437 and WO-A 93/13093,
• - Optically active oxirane esters, as for example in EP-A 0 292 954 described
• optically active dioxolane ethers, such as, for example, in EP-A 0 351 746 described
• - Optically active dioxolane esters, such as, for example, in EP-A 0 361 272 described, and
• - Optically active tetrahydrofuran-2-carboxylic acid esters, such as in EP-A 0 355 561.

The mixtures in turn can be used in electro-optical or completely optical elements, e.g. B. display elements, switching elements, Light modulators, elements for image processing and / or signal processing or generally in the field of nonlinear optics.

Liquid-crystalline mixtures, the compounds of the general formula (I) included, are especially for use in electro-optical switching and Suitable display devices. These displays are usually like this  built that a liquid crystal layer on both sides of layers is included, which is usually in that order starting from the LC layer, at least one orientation layer, electrodes and one Boundary disk (e.g. made of glass). They also contain Spacers, adhesive frames, polarizers and thin ones for color displays Color filter layers. Other possible components are anti-reflective, Passivation, compensation and barrier layers as well as non-linear electrical Elements such as thin film transistors (TFT) and metal insulator metal (MIM) elements ment. The structure of liquid crystal displays is already in detail relevant monographs (see, for example, E. Kaneko, "Liquid Crystal TV Displays: Principles and Applications of Liquid Crystal Displays ", KTK Scientific Publishers 1987).

Furthermore, the mixtures for field treatment, i.e. H. for operation in the Quasi-Bookshelf Geometry (QBG), (see e.g. H. Rieger et al., SID 91 Digest (Anaheim) 1991, 396).

The mixtures according to the invention are also suitable for use in ferroelectric liquid crystal displays based on the use of the DHF effect or the PSFLCD effect (Pitch Stabilized Ferroelectric Liquid Crystal Display, too SBF = Short Pitch Bistable Ferroelectric Effect).

Furthermore, the compounds according to the invention are suitable for achieving the so-called electroclinic effect in the chiral smectic A phase (S * _A phase), which can be used for light modulation (S. Garoff and RB Meyer, Phys. Rev. Lett. 38, 848 (1977)).

If an electric field is applied parallel to the layers of a chiral S _A phase (S * _A phase), the molecules tilt in the orthogonal phase. The angle of inclination θ between the director and the layer normal is proportional to the applied field E. The electroclinic coefficient (dθ / dE) indicates the strength of the linear coupling between the tilt coordinate and the field.

The electroclinic effect assumes a monostable state in the field-free space and creates a field linear for small angles and for large angles weakly curved electro-optical characteristic. The characteristic of the In contrast, ferroelectric switching is strongly non-linear.

The electroclinic effect can be controlled as a continuously through the field Deflection of the angle of inclination can be understood.

Liquid crystalline media, which form an S * _A , S * B or S * E phase, are more suitable for the practical use of the electroclinic effect in electro-optical switching and display elements, the greater the electroclinic coefficient dθ / dE and the higher the electroclinic cutoff frequency f _G.

A device based on the use of the electroclinic effect is found z. B. Andersson et al., Appl. Phys. Lett 1987, 51, 640.

The invention is illustrated by the examples, without thereby want to restrict.

Examples

The phase transition temperatures are determined using a Polarization microscope determined based on the texture changes. The The melting point, however, is determined with a DSC device carried out. The indication of the phase transition temperatures between the Phases

Isotropic (I)
Nematic (N or N *)
Smectic-C (S _C or S _C *)
Smectic-A (S _A )
Crystalline (X)
Glass transition (Tg)

takes place in ° C and the values are between the phase names in the Phase sequence. Parenthesized values are obtained on cooling.

example 1 5-chloro-1- (4-hexylphenyl) -4-octyloxypyridazin-6-one

A solution of 9.2 g of 4-hexylphenylhydrazine and 6.8 g of mucochloric acid in 80 ml of hydrochloric acid (10%) is heated to 90 ° C for 1 hour. After this Cold is extracted with 150 ml of dichloromethane, the extract with water washed and chromatographed on silica gel. After recrystallization 5.7 g of 4,5-dichloro-1- (4-hexylphenyl) pyridazin-6-one are obtained from the mp. Get 93 ° C.

To a fully reacted mixture of 1.6 ml 1-octanol and 0.42 g Sodium hydride (60%) in 30 ml of dimethylformamide are 3.2 g above at 5 ° C Dichloropyridazinons registered. After 4 hours at 5 ° C with 300 ml Ice water is added and the emulsion obtained is extracted with dichloromethane. After distilling off all solvents on silica gel with dichloromethane chromatographed. After recrystallization from 50 ml of n-hexane, 1.8 g 5-chloro-1- (4-hexylphenyl) -4-octyloxy-pyridazin-6-one as colorless crystals of Mp. 99 ° C obtained.

Example 2

5-Chloro-4-dodecyloxy-1- (4-hexylphenyl) pyridazin-6-one is analogous to Example 1 manufactured; Mp 93 ° C.

Example 3

5-Chloro-1- (4-cyclohexyl) phenyl-4-decyloxypyridazin-6-one becomes analogous Example 1 prepared; colorless crystals of mp 122 ° C.  

Example 4 5-chloro-1 - [(4-nonyloxy) phenyloxycarbonyl] phenyl-4-octyloxypyridazin - 6-one

A mixture of 3.4 g of mucochloric acid and 3.2 g of 4-hydrazino-benzoic acid in 25 ml of acetic acid is added 2 hours at 90 ° C with the addition of 5 ml of acetic anhydride heated. After cooling, the crystal slurry is diluted with 150 ml of ice water and the crystals separated. After recrystallization Ethylene glycol monomethyl ether 3.4 g of 4- (4,5-dichloro-6-oxopyridazin-1- yl) benzoic acid of mp. 314 to 316 ° C.

1.4 g of the above benzoic acid with 10 ml of thionyl chloride for 4 hours Reflux heated. After distilling off excess thionyl chloride in Dichloromethane added. This solution becomes a solution of 1.2 g 4-nonyloxyphenol, 1 g triethylamine and 0.1 g 4-dimethylaminopyridine in 25 ml Dripped dichloromethane. After 2 hours it is filtered and the filtrate over Silica gel extracted with dichloromethane. 1.1 g of 4- (4,5-dichloro-6-oxo) are obtained pyridazin-1-yl) benzoic acid (4-nonyloxy) phenyl ester, mp. 120 ° C.

This becomes a fully reacted mixture of 0.3 g at 5 ° C 1-Octanol and 0.1 g sodium hydride (60%) in 15 ml dimethylformamide. After 4 hours, the solvent is distilled off in an oak vacuum and the Chromatograph the residue on silica gel with dichloromethane. To Recrystallization from 15 ml of n-hexane 0.13 g of 5-chloro-1 - [(4- nonyloxy) phenyloxycarbonyl] -phenyl-4-octyloxypyridazin-6-one of mp. Get 85 ° C

Example 5

5-chloro-1 - [(2,3-difluoro-4-octyloxy) phenyloxycarbonyl] phenyl-4- octyloxypyridazin-6-one is obtained analogously to Example 4; Mp 113 ° C.  

Example 6

4,5-dichloro-1- [4- (5-octyl-pyrimidin-2-yl) phenyloxycarbonyl] phenylpyr-idazin-6-one is obtained analogously to Example 4; Phase sequence X 173 N 242 I.

Example 7 1- (4-Hexylphenyl) -4-octyloxypyridazin-6-one

A solution of 1.6 g of the compound from Example 1 in 20 ml of tetrahydrofuran 0.16 g of Pd (10% on activated carbon) and 0.3 g of magnesium oxide are added. At 40 ° C, hydrogen is applied under atmospheric pressure. To Filtration and distillation of the solvent is carried out on silica gel Chromatographed dichloromethane. After recrystallization from 20 ml of n-hexane 1.0 g of 1- (4-hexylphenyl) -4-octyloxy-pyridazin-6-one are colorless crystals obtained from mp. 86 ° C.

Example 8 4- (4-hexyloxyphenyl) -1- (4-hexylphenyl) pyridazin-6-one

A mixture of 1.4 g of 4,5-dichloro-1- (4-hexylphenyl) pyridazin-6-one, 0.6 g 4-hexyloxyphenylboronic acid, 0.13 g tetrakis (triphenylphosphine) palladium (0), 0.6 g sodium carbonate, 50 ml toluene, 25 ml ethanol and 20 ml water Heated to reflux for 6 hours. After phase separation, the aqueous phase extracted with tert-butyl methyl ether, the organic phases are combined and the solvents are distilled off. After chromatography on silica gel with Dichloromethane, 0.8 g of 5-chloro-4- (4-hexyloxyphenyl) -1- (4-hexylphenyl) - pyridazin-6-one obtained, which still contains about 20% 4,5-bis (4-hexyloxyphenyl) -1- (4- hexylphenyl) pyridazin-6-one are contaminated.

This crude product is dissolved in 20 ml of tetrahydrofuran, 0.1 g of magnesium oxide and 0.1 g of palladium (10% on activated carbon) are added and the mixture is hydrogenated at 40 ° C. under atmospheric pressure. After filtration, distillation of the solvent, chromatography on silica gel and recrystallization from acetonitrile, 0.19 g of 4- (4-hexyloxyphenyl) -1- (4-hexylphenyl) pyridazin-6-one as colorless crystals with the phase sequence X 83 (59 S _C 93) S _A 196 I received.

Example 9 5-chloro-1- (4-hexylphenyl) -4- (2-fluoro-octyloxy) pyridazin-6-one

A completely reacted mixture of 0.95 g of 2-fluoro-octanol, 0.22 g of sodium hydride (60%) and 15 ml of dimethylformamide is mixed with 1.46 g of 4,5-dichloro-1- (4-hexylphenyl) pyridazine- 6-one offset. After 3 hours at room temperature, it is poured onto 150 ml of ice water, adjusted to pH 6 with hydrochloric acid and extracted with dichloromethane. After chromatography on silica gel with dichloromethane and recrystallization from acetonitrile, 0.94 g of colorless crystals of mp 89 ° C. are obtained; [α] _D ²⁰: + 4.1 ° (c = 2.1; CH₂Cl₂).

Example 10 4- (2-fluorodecyloxy) -1- (4-hexylphenyl) pyridazin-6-one

A solution of 0.65 g of the compound from Example 9 in 30 ml of tetrahydrofuran is mixed with 0.11 g of magnesium oxide and 0.14 g of Pd / C (10%) and hydrogenated at 45 ° C. until the hydrogen uptake has ended. After chromatography on silica gel with dichloromethane and recrystallization from acetonitrile, 0.51 g of colorless crystals of the phase sequence X 104 (98 ⁵A 99) I are obtained; [α] _D ²⁰: + 5.9 ° (c = 1.95; CH₂Cl₂).

Example 11 4- [4- (2-Fluoro-decyloxy) phenyl] -1- (4-hexylphenyl) pyridazin-6-one

A mixture of 5 g of 4,5-dichloro-1- (4-hexylphenyl) pyridazin-6-one, 2.9 g of 4-benzyloxy-phenylboronic acid, 2.7 g of sodium carbonate, 200 ml of toluene and 100 ml of ethanol and 60 ml of water and 0.15 g of tetrakis (triphenylphosphine) palladium (0) are heated to boiling for 5 hours. After the usual work-up and chromatography on silica gel with heptane / ethyl acetate (8: 2), the organic phase gives 2.5 g of 4- (4-benzyloxy) phenyl-5-chloro-1- (4-hexylphenyl) pyridazin-6-one. This is dissolved in 100 ml of tetrahydrofuran, mixed with 0.44 g of magnesium oxide and 0.4 g of Pd / C (10%) and hydrogenated at 45 ° C. until the hydrogen uptake has ended. After chromatography on silica gel with dichloromethane / ethyl acetate (8: 2), 1.3 g of 1- (4-hexylphenyl) -4- (4-hydroxyphenyl) pyridazin-6-one are obtained as a crude product. This is dissolved in 20 ml of tetrahydrofuran, 1.44 g of triphenylphosphine, 0.86 ml of diethylazodicarboxylate and 0.98 g of 2-fluoro-decanol are added. After 5 hours the mixture is brought to dryness in vacuo and the residue is chromatographed on silica gel with heptane / ethyl acetate (6: 4). After recrystallization from acetonitrile, 0.72 g of 4- [4- (2-fluoro-decyloxy) phenyl] -1- (4-hexylphenyl) pyridazin-6-one are colorless crystals of the phase sequence X 101 S _C * 155 S _A 194 I received; [α] _D ²⁰: + 3.3 ° (c = 2.2; CH₂Cl₂).

Application example 1

A SmC base mixture (TLC 1; Hoechst AG) with the phase transition temperatures S _C / S _A 80 ° C, S _A / N 91 ° C and N / I 102 ° C is mixed with 10 wt .-% of the compound from Example 7 . The transition S _C / S _A is lowered at 2 K, S _A / N is raised by 3 K, N / I is lowered by 1 K, so that the S _A phase widened significantly.

Example of use 2

A SmC base mixture (TLC 1; Hoechst AG) with the phase transition temperatures S _C / S _A 80 ° C, S _A / N 91 ° C and N / I 102 ° C is mixed with 10 wt .-% of the compound from Example 9 . The resulting FLC mixture with the phase transition _temperatures S _C * / S _A 75 ° C, S _A / N * 83 ° C and N * / I 96 ° C has (at 40 ° C) a spontaneous polarization of 15 nC / cm².

Example of use 3

10% by weight of the compound from Example 11, dissolved in the SmC mixture (TLC 1) described above, give an FLC mixture with the phase transition _temperatures S _C * / S _A 81 ° C., S _A / N * 101 ° C. and N * / I 106 ° C; at 40 ° C the mixture has a spontaneous polarization of 29 nC / cm².

Claims (12)

1. pyridazinones of the formula (I) in which the symbols and indices have the following meanings: R¹, R² are the same or different hydrogen (but not both at the same time), -CN, -F, -Cl or a straight-chain or branched alkyl radical having 1 to 20 carbon atoms (with or without asymmetrical carbon atom), one or several CH₂ groups by -O-, -CO-, -CH = CH-, -C≡C-, cyclopropane-1,2-diyl, -Si (CH₃) ₂-, trans-1,4-cyclohexylene or trans 1,3-cyclopentylene can be replaced, with the proviso that oxygen atoms must not be bonded directly to one another, and / or wherein one or more H atoms of the alkyl radical are also substituted by -F, -Cl, -Br, -OR³ can, or also one of the following groups (optically active or racemic): R³, R⁴, R⁵, R⁶, R⁷ are the same or different hydrogen or a straight-chain or branched alkyl radical having 1 to 16 carbon atoms (with or without an asymmetric carbon atom), with one or more CH₂ groups by -O- or -CH = CH- can be replaced, with the proviso that oxygen atoms must not be bonded directly to one another, and / or wherein one or more H atoms of the alkyl radical can also be substituted by -F or -Cl; R⁴ and R⁵ together can also be - (CH₂) ₄- or - (CH₂) ₅- if they are bound to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system;
Q is a single bond, -CO-O- or -CH₂-O-;
M¹ -O-CO-, -CO-O-, -O-CH₂-, -CH₂-O-, or a single bond;
M² is -O- (CH₂) _n -, with n = 1 to 8, or a single bond;
A¹ is 1,4-phenylene, although one or more hydrogen atoms can also be replaced by F, Cl and / or CN, 1,4-cyclohexylene, naphthalene-2,6-diyl, 4- (cyclohexyl-1,4-diyl ) phenyl, biphenyl-4,4'-diyl, where one or more hydrogen atoms can be replaced by fluorine, 4- (pyrimidine-2,5-diyl) phenyl, 4- (pyridine-2,5-diyl) phenyl, 4 - (1,3,4-thiadiazole-2,5-diyl) phenyl, benzthiazole-2,6-diyl, indane-2,6-diyl;
A²: is 1,4-phenylene, in which a hydrogen atom can be replaced by CH₃ or one or more hydrogen atoms by F or Cl, 1,4-cyclohexylene, naphthalene-2,6-diyl, pyridine-2,5-diyl ;
A³: is 1,4-phenylene, in which one hydrogen atom can be replaced by CH₃ or one or more hydrogen atoms by F or Cl, biphenyl-4,4'-diyl, where one or more hydrogen atoms can be replaced by fluorine, 4 - (Cyclohexyl-1,4-diyl) phenyl, pyridine-2,5-diyl, where a hydrogen atom can be replaced by F, benzothiazole-2,6-diyl, indane-2,6-diyl, naphthalene-2,6 -diyl, 1,4-cyclohexylene, pyrimidine-2,5-diyl;
X is H, F or Cl;
a, b, c, d, e are zero or one;
with the following proviso:
a + b + c is 1 or 2. 2. Pyridazinone according to claim 1, characterized in that the symbols and indices in formula (I) have the following meaning: R¹, R² are identical or different hydrogen (but not both at the same time), -F, -Cl or a straight-chain or branched alkyl radical with 1 to 18 carbon atoms (with or without asymmetric carbon atom), one or more CH₂- Groups can be replaced by -O-, -CO-, -CH = CH-, -C≡C-, cyclopropane-1,2-diyl or -Si (CH₃) ₂-, with the proviso that oxygen atoms are not directly with one another may be bound, and / or wherein one or more H atoms of the alkyl radical may be substituted by -F, or one of the following groups (optically active or racemic): R⁴ is a straight-chain or branched alkyl radical having 1 to 16 or 3 to 16 carbon atoms (with or without an asymmetric carbon atom, it also being possible for a CH₂ group to be replaced by -O-;
A¹ 1,4-phenylene, where one or more H atoms can be replaced by F, 1,4-cyclohexylene, naphthalene-2,6-diyl, 4- (cyclohexyl-1,4-diyl) phenyl, biphenyl-4 , 4'-diyl;
A² 1,4-phenylene, in which one or more H atoms can also be replaced by F, 1,4-cyclohexylene, naphthalene-2,6-diyl, pyridine-2,5-diyl;
A³ 1,4-phenylene, in which one or more H atoms can also be replaced by F, biphenyl-4,4'-diyl, 4- (cyclohexyl-1,4-diyl) phenyl, pyridine-2,5- diyl, where one H atom can be replaced by F;
XH, F or Cl. 3. Pyridazinones according to claim 1 and / or 2, characterized by the formulas (Ia1) to (Ia38): where the radicals R have the following meanings
R¹, R² are the same or different hydrogen (but not both at the same time), -F, -Cl or a straight-chain or branched alkyl radical with 1 to 18 carbon atoms (with or without an asymmetric carbon atom), with one or more CH₂- Groups can be replaced by -O-, -CO-, -CH = CH-, -C≡C-, cyclopropane-1,2-diyl or -Si (CH₃) ₂-, with the proviso that oxygen atoms are not directly with one another may be bound, and / or wherein one or more H atoms of the alkyl radical may be substituted by -F, or one of the following groups (optically active or racemic): R⁴ is a straight-chain or branched alkyl radical having 1 to 16 or 3 to 16 carbon atoms (with or without an asymmetric carbon atom, it also being possible for a CH₂ group to be replaced by -O-;
R⁸ is a straight-chain or branched alkyl radical having 1 to 16 carbon atoms, in which one or two non-adjacent CH₂ groups can be replaced by -O- and / or in which a CH₂ group by -CH = CH-, cyclopropane -1,2-diyl or -Si (CH₃) ₂- can be replaced or two adjacent CH₂ groups can be replaced by -CH (F);
R⁹ is a straight-chain or branched alkyl radical having 1 to 16 carbon atoms, in which a CH₂ group can also be replaced by -CH = CH-, cyclopropane-1,2-diyl or -Si (CH₃) ₂-; and
R¹⁰ is a straight-chain alkyl radical with 1 to 16 carbon atoms. 4. Pyridazinones according to claim 1 and / or 2, characterized by the formulas (Ib1) to (Ib29): wherein the symbols and indices have the meanings given in the formulas (Ia1) to (Ia38) in claim 3. 5. Optically active pyridazinones according to one or more of the preceding claims, characterized by the formulas (Ic1) to (Ic21): in which R¹¹ is an optically active radical of the formula R¹²-CH (F) -CH₂- or R¹²-CH (F) -CH (F) -CH₂-, where R¹² is an alkyl or alkyloxy group having 1 to 12 carbon atoms means
and in which the other symbols and indices have the meanings given in the formulas (Ia1) to (Ia38) in claim 3. 6. Use of pyridazinone derivatives of the formula (I) according to one or several of claims 1 to 5 in liquid crystal mixtures. 7. Liquid crystal mixture containing one or more compounds of Formula (I) according to one or more of claims 1 to 5. 8. A liquid crystal mixture according to claim 7, consisting of 2 to 20 Components, characterized in that they contain 1 to 10 compounds of the Contains formula (I). 9. Liquid crystal mixture according to claim 7 and / or 8, characterized characterized that it is ferroelectric. 10. Electro-optical switching and / or display element containing one Liquid crystal mixture according to one or more of claims 7 to 9.