GB2264300A - Liquid crystalline phenylpyrazines - Google Patents

Liquid crystalline phenylpyrazines Download PDF

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GB2264300A
GB2264300A GB9302859A GB9302859A GB2264300A GB 2264300 A GB2264300 A GB 2264300A GB 9302859 A GB9302859 A GB 9302859A GB 9302859 A GB9302859 A GB 9302859A GB 2264300 A GB2264300 A GB 2264300A
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formula
groups
compounds
ocf3
phenylpyrazine
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GB9302859D0 (en
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John William Brown
Derek Thomas Hurst
Jacqueline Patricia O'donovan
David Coates
Simon Greenfield
Mark John Goulding
George William Gray
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Merck Patent GmbH
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Merck Patent GmbH
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D241/00—Heterocyclic compounds containing 1,4-diazine or hydrogenated 1,4-diazine rings
    • C07D241/02—Heterocyclic compounds containing 1,4-diazine or hydrogenated 1,4-diazine rings not condensed with other rings
    • C07D241/10—Heterocyclic compounds containing 1,4-diazine or hydrogenated 1,4-diazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
    • C07D241/12—Heterocyclic compounds containing 1,4-diazine or hydrogenated 1,4-diazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to ring carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/34—Non-steroidal liquid crystal compounds containing at least one heterocyclic ring
    • C09K19/3441—Non-steroidal liquid crystal compounds containing at least one heterocyclic ring having nitrogen as hetero atom
    • C09K19/345—Non-steroidal liquid crystal compounds containing at least one heterocyclic ring having nitrogen as hetero atom the heterocyclic ring being a six-membered aromatic ring containing two nitrogen atoms
    • C09K19/3452—Pyrazine

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  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Liquid Crystal Substances (AREA)

Abstract

Phenylpyrazines of the formula I <IMAGE> [wherein R is C1-15 alkyl or alkenyl (wherein one or two non-adjacent CH2 groups can also be replaced by -O-, -CO-, -O-CO-, -CO-O-, -O-COO- and/or -OH halogen)-groups> A is a trans-1,4-cyclohexylene group or a 1,4-phenylene group (which is unsubstituted or mono- or polysubstituted by F and/or Cl, and wherein one or two non-adjacent OH2 groups can also be replaced by a N atom or a single bond> n and m is 0 or 1 L<1> and L<2> are independently H or F, and X is Q - Y (wherein Y is H, F or Cl, and Q is -CF2-, -CF2CF2-, -OCF2-, -OCF2CF2- or a single bond) or -CN subject to certain provisos] are highly suitable as polar components of liquid crystalline media.

Description

Phenylpyrazines The invention relates to phenylpyrazines of the formula I
wherein R is an alkyl group of 1-15 C atoms, wherein one or two non-adjacent CH2 groups can also be replaced by 0 atoms and/or -CO- groups and/or -O-CO-groups and/or -CO-O- groups and/or -O-COO- groups and/or -CH-halogen groups, A is a a trans-1,4-cyclohexylene group or a 1,4-phenylene group which is unsubstituted or monosubstituted or polysubstituted by F and/or Cl atoms, wherein oneor two non-adja cent CH2 groups can also be replaced by a N atom, n and m is O or 1 L1 and L2 are each independently of each other H or F, and X is Q-Y wherein Y is H, F or C1, and Q is -CF2-, -CF2CF2-, -OCF2-, -OCF2CF2- or a single bond with the provisos that a) in the case of m = n = 0 and X = CF3 or F, L1 and L2 are F, b) in the case of m = n = 0 and X = Cl or CN, one of L1 and L2 is F, the other being H or F, c) in the case of m = 1, n = 0 and X = F, Cl or CN one of L1 and L2 is F, the other being H or F and also to liquid crystalline media being a mixture of at least 2 compounds, characterized in that at least one compound is a phenylpyrazine derivative according to formula 1.
Further aspects and embodiments of the invention are defined and described in claims 2-9 appended hereto.
The invention was based on the object of discovering new stable liquid crystal or mesogenic compounds which are suitable as components of liquid crystalline media and, in particular, have advantageous values for optical and dielectric anisotropy combined with low viscosity and high nematogenity.
Similar phenylpyrazine derivatives without lateral fluorine substitution are known from the JP 43961/1983, JP 204485/90 and J5 9l44-772A:
The following laterally fluorinated derivatives are disclosed in the J6 2234-072 A:
X is H or F Y is F or CF3 It has now been found that the compounds of formula I are highly suitable as polar components of liquid crystalline media. In particular, they have especially advantageous values of optical and dielectric anisotropy and are not strongly smectogenic. It is also possible to obtain stable liquid crystal phases with a broad nematic mesophase range including a good deep temperature behaviour, a high resistivity and a comparatively low viscosity with the aid of these compounds.
Depending on the choice of R, A, m, n, X, L1 and L2, the compounds of the formula I can be used as the base materials from which liquid crystal media are predominantly composed; however, it is also possible for compounds of the formula I to be added to liquid crystal base materials of other classes of compounds, for example in order to influence the dielectric and/or optical anisotropy and/or the viscosity and/or the nematic range of such a dielectric.
The compounds of the formula I are in particular suitable as components for liquid crystal media for displays which are based on the principle of polymer dispersed liquid crystals (pdlc) or polymer liquid crystals (pnlc) due to their favorable optical anisotropy and the dielectric anisotropy.
The compounds of the formula I are colourless in the pure state and are liquid crystalline in a temperature range which is favourably placed for electrooptical use. They are very stable towards chemicals, heat and light.
The invention thus relates to the phenylpyrazines of the formula I, to liquid crystalline media with at least two liquid crystalline components, wherein at least one component is a compound of the formula I and to liquid crystal display devices containing such media.
Above and below, R, A, m, n, L1, L2 and X have the meaning given unless expressly indicated otherwise.
The compounds of the formula I include phenylpyrazines of the formulae Ia to If:
Thereof those of the partial formula Ia, Ic, Id and If are particularly preferred.
The preferred compounds of the partial formula Ia comprise those of the partial formula Iaa to Iao
Thereof those of the partial formula Iaa, Iab, Iad and Iaj are particularly preferred.
Thereof those of the partial formulae Iba, Ibb, Ibe and Ibj are particularly preferred.
The preferred compounds of the partial formula Ic comprise those of the partial formulae Ica to Ico.
Thereof those of the partial formulae Ica, Icb, Icc, Ice, Ici and Icj are particularly preferred.
The preferred compounds of the partial formula Id comprise those of the partial formulae Ida to Ido.
Thereof those of the partial formula Ida, Idb, Idd, Ide, Idg and Idj are particularly preferred.
The preferred compounds of the partial formula Ie comprise those of the partial formulae Iea to Ieo.
Thereof those of the partial formula Iea, Ieb, Iec, Iee, Iej and Iek are particularly preferred.
R is preferably alkyl, alkoxy, oxaalkyl or alkenyl and can exhibit a straight-chain or branched structure.
Alkyl or alkoxy preferably are straight-chain and have 2, 3, 4, 5, 6 or 7 C atoms. Accordingly they are preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy, also methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octoxy, nonoxy, decoxy, undecoxy, tridecoxy or tetradecoxy.
Oxaalkyl is preferably straight-chain 2-oxypropyl (= methoxymethyl), 2-(= ethoxymethyl) or 3-oxybutyl (= 2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl or 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.
Alkenyl is preferably straight-chain and has 2 or 10 C atoms.
It is accordingly, in particular, vinyl, prop-l- or prop-2-enyl, but-l-, -2- or -3-enyl, pent-l-, -2-, -3- or -4-enyl, hex-l-, -2-, -3-, -4- or 5-enyl, hept-l-, -2-, -3-, -4-, -5or -6-enyl, oct-l-, -2-, -3-, -4-, -5-, -6- or -7-enyl, non-l-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl or dec-l-, -2-, -3-, -4-, -5-, -6-, -7-, -8- or -9-enyl.
Compounds of the formula I containing a branched terminal group can occasionally be of importance because of an improved solubility in the customary liquid crystal base materials, but in particular as chiral doping substances if they are optically active.
Branched groups of this type as a rule contain not more than one chain branching. Preferred branched radicals are isopropyl, 2-butyl (= 1-methylpropyl), isobutyl (= 2-methylpropyl), 2-methylbutyl, isopentyl, (= 3-methylbutyl), 2-methylpentyl, 2-ethylhexyl, 2-propylpentyl, 2-octyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexoxy, 2-methylhexoxy, l-methylhexoxy, l-methylheptoxy (= 2-octyloxy), 2-oxa-3-methylbutyl, 3-oxy-4-methylpentyl, 4-methylhexyl, 2-nonyl, 2-decyl, 2-dodecyl, 6-methyloctoxy, oxy, 2-methyl-3-oxapentyl and 2-methyl-3-oxyhexyl.
In the case of compounds with a branched terminal group R, formula I includes both the optical antipodes and racemates as well as mixtures thereof.
Of the compounds of the formula I and subformulae thereof, those in which at least one of the radicals contained therein has one of the preferred meanings given are preferred.
The compounds of the formula I are prepared by methods which are known per se, such as are described in the literature (for example in the standard works, such as Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Georg Thieme Verlag, Stuttgart), and in particular under reaction conditions which are known and suitable for the reactions mentioned. Variants which are known per se and are not mentioned in more detail here can also be used in this connection.
If desired, the starting materials can also be formed in situ, such that they are not isolated from the reaction mixture but are immediately reacted further to give the compounds of the formula I.
Preferred route for preparation of the phenylpyrazines are shown in the following scheme.
Scheme 1:
Scheme 2
All starting materials are known or prepared in analogy to known starting materials.
Other routes are apparent to the skilled worker All these steps and the corresponding reaction conditions are known to the skilled worker.
In addition to one or more compounds for formula I the liquid crystal media according to the invention preferably contain 2-40 components and in particular 4-30 components. Liquid crystal media being composed of one or more compounds of formula I and 7-25 other components are especially preferred.
These additional components are preferred chosen from the nematic or nematogenic (monotropic or isotropic) substances; in particular from the classes of azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, phenyl or cyclohexyl benzoates, phenyl or cyclohexyl cyclohexanecarboxylates, phenyl or cyclohexyl cyclohexylbenzoates, phenyl or cyclohexyl cyclohexylcyclohexanecarboxylates, cyclohexylphenylbenzoates, cyclohexylphenyl cyclohexanecarboxylates, cyclohexylphenyl cyclohexylcyclohexanecarboxylates, phenylcyclohexanes, cyclohexylbiphenyls, phenylcyclohexylcyclohexanes, cyclohexylcyclohexanes, cyclohexylcyclohexenes, cyclohexylcyclohexylcyclohexene, 1,4-bis-cyclohexylbenzenes, 4,4"-bis-cyclohexylbi- phenyl, phenyl- or cyclohexylpyrimidines, phenyl- or cyclohexylpyridines, phenyl- or cyclohexyldioxanes, phenyl -or cyclohexyl-1,3-dithianes, 1,2-diphenylethanes, 1,2-dicyclohexylethanes, l-phenyl-2-cyclohexylethanes, 1-cyclohex yl-2- (4-phenyl-cyclohexyl) -ethanes, l-cyclohexyl-2-biphenylethanes, l-phenyl-2-cyclohexyl-phenylethanes, optionally halogenated stilbenes, benzyl phenyl ethers, tolanes and substituted cinnamic acids.
The 1,4-phenylene groups of these compounds may be fluorinated.
The most important compounds which are possible constituents of liquid crystal media according to the invention can be characterized by the formulae 1, 2, 3, 4 and 5: R'-L-U-R" 1 R' -L-COO-U-R" 2 R' -L-OOC-U-R11 3 R'-L-CH2CH2-U-R 4 R' -L-C=C-U-R" 5 In the formulae 1, 2, 3, 4 and 5 L and U may equal or different from each other.L and U independently from each other denote a bivalent residue selected from the group consisting of -Phe-, -Cyc-, -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -Pyr-, -Dio-, -G-Phe-, -G-Cyc- and their mirror images; in this compilation of residues Phe denotes unsubstituted or fluorinated 1,4-phenylen, Cyc trans-1,4-cyclohexylene or 1,4-cyclohexenylen, Pyr pyrimidine-2,5-diyl or pyridine-2,5-diyl, Dio 1, 3-dioxane-2, 4-diyl and G 2- (trans-l, 4-cyclohexyl) -ethyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl or 1,3-dioxane-2,5diyl.
One of the residues L and U is preferably Cyc, Phe or Pyr. U preferably denotes Cyc, Phe or Phe-Cyc. The liquid crystal media according to the invention preferably contain one or more components selected from the compounds of formulae 1, 2, 3, 4 and 5 with L and U meaning Cyc, Phe and Pyr, said liquid crystal media further containing at the same time one or more components selected from the compounds of formulae 1, 2, 3, 4 and 5 with one of the residues L and U denoting Cyc, Phe and Pyr and the other residue being selected from the group consisting of -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -G-Cyc-, said liquid crystal media containing in addition to this optionally one or more components selected from the compounds of formulae 1, 2, 3, 4 and 5 with L and U being selected from the group consisting of -Phe-Cyc-, -Cyc-Cyc-, -G-Phe- and G-Cyc.
In a preferred subgroup of the compounds of formulae 1, 2, 3, 4 and 5 (subgroup 1) R' and R" are independently from each other alkyl, alkenyl, alkoxy, alkenoxy with up to 8 carbon atoms. R' and R" differ from one another in most of these compounds, one of the residues usually being alkyl or alkenyl. In another preferred subgroup of the compounds of formulae 1, 2, 3, 4 and 5 (subgroup 2) R" denotes -CN, -CF3, -OCF3, -OCHF2, -F, -Cl or -NCS while R' has the meaning indicated in subgroup 1 and is preferably alkyl or alkenyl. Other variants of the envisaged substituents in the compounds of formulae 1, 2, 3, 4 and 5 are also customary. Many such substances are commercially available. All these substances are obtainable by methods which are known from the literature or by analogous methods.
The liquid crystal media according to the invention preferably contain in addition to components selected from subgroup 1 also components of subgroup 2, the percentage of these components being as follows: subgroup 1: 20 to 90 %, in particular 30 to 90 % subgroup 2: 10 to 50 %, in particular 10 to 50 % In these liquid crystal media the percentages of the compounds according to the invention and the compounds of subgroup 1 and 2 may add up to give 100 %.
The media according to the invention preferably contain 1 to 40 %, in particular 5 to 30 % of the compounds according to the invention. Media containing more than 40 %, in particular 45 to 90 % of the compounds according to the invention are further preferred. The media contain preferably 3, 4 or 5 compounds according to the invention.
The media according to the invention is prepared in a manner which is customary per se. As a rule, the components are dissolved in one another, advantageously at elevated temperature. The liquid crystal media according to the invention can be modified by suitable additives so that they can be used in all the types of liquid crystal display devices. Such additives are known to the expert and are described in detail in the literature (H. Kelker/R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980). For example, it is possible to add pleochroic dyestuffs to prepare colored guest-host systems or substances for modifying the dielectric anisotropy, the viscosity and/or the orientation of the nematic phases.
The following examples are to be construed as merely illustrative and not limitative. m.p. = melting point, c.p. = clearing point. In the foregoing and in the following all parts and percentages are by weight and the temperatures are set forth in degrees Celsius. "Customary work-up" means that water is added, the mixture is extracted with methylene chloride, the organic phase is separated off, dried and evaporated, and the product is purified by crystallization and/or chromatography.
Further are: C: crystalline-solid state, S: smectic phase (the index denoting the type of smectic phase), N: nematic phase, Ch: cholesteric phase, I: isotropic phase. The number being embraced by 2 of these symbols denotes the temperature of phase change.
Example 1
Sten 1.1 Trifluoromethoxyphenylglyoxal hydrate (0.07 mol) in methanol was cooled to -40 OC and glycinamide hydrochloride (0.07 mol) was added to the stirred solution. The temperature was allowed to rise slowly to -30 OC and maintained while NaOH (0.186 mol in 25 ml H2O) was added dropwise. The reaction mixture was allowed to warm slowly to 200 over a period of 5 hours. After cooling to 0 the pH was adjusted to 5.0 with concentrated HCl to give an orange/brown precipitate which was filtered and washed with water. The crude product was dissolved in CH2C12, extracted into aqueous NaOH, and then re-precipitated by addition of concentrated HC1 to pH 5.
Stes 1.2 The 5-Phenylpyrazin-2-ol derivative (0.03 mol) and phosphorus pentachloride (0.03 mol) were heated together on an oil bath at 1000 until evolution of HCl ceased. The residual POCl3 was removed at reduced pressure and the crude material purified by column chromatography.
Step 1.3 Grignard reaction of the 2-Chloro-5-phenylpyrazine derivative (0.0026 mol) gave the crude product which was purified by column chromatography.
The following compounds of the formula
are prepared analogously: R Ll L2 X C2H5 F F F C2H5 H F C1 C2H5 F F Cl C2H5 F F CF3 C2H5 H F OCF3 C2H5 F F OCF3 R L1 L2 X C2H5 H F CF2H C2H5 H F CF2C1 C2H5 H F CF2CF2H C2H5 H F CF2CF3 n-C3H7 F F F n-C3H7 H F C1 n-C3H7 F F C1 n-C3H7 F F CF3 n-C3H7 H H OCF3 n-C3H7 H F OCF3 n-C3H7 F F OCF3 n-C3H7 H F CF2H n-C3H7 H F CF2C1 n-C3H7 H H CF2C1 n-C3H7 H F CF2CF2H n-C3H7 H F CF2CF3 n-C5H11 H F CN n-C5H11 F F F n-C5H11 H F Cl n-C5H11 F F Cl n-C5H11 H F CN n-C5H11 F F CF3 n-C3H11 H H OCF3 n-C5H11 H F OCF3 n-C5H11 F F OCF3 n-C5H11 H F CF2H n-C5H11 H F CF2C1 R L1 L2 X n-C5H11 H F CF2CF2H n-C5H11 H F CF2CF3 n-C5H11 H F CF2CF2C1 n-C5H11 H F OCF2H n-C5H11 H F OCF2C1 n-C5H11 H F OCF2CF2H n-C5H11 H F OCF2CF3 n-C5H11 H F OCF2CF2C1 n-C5H11 F F OCF2CF3 n-C5H11 F F OCF2H n-C5H11 H H OCF2H n-C5H11 H H OCF2CF3 CH2=CHCH2CH2 F F F CH2=CHCH2CH2 H F C1 CH2=CHCH2CH2 H H OCF3 CH2=CHCH2CH2 F F CF3 CH3OCH2 F F F CH3OCH2 H F Cl CH3OCH2 F F Cl CH3OCH2 H F OCF3 CH3OCH2 F F OCF3 CH3OCH2 F F CF3 Example 2
Sten 2.1
5 mole % excess of Mg is used to generate Grignard reagent of 4-fluorobrombenzene. The Grignard reaction is completed by 1 h reflux under N2 and added dropwise to acid chloride (1 molar equivalent) in THF solution. The product is purified by destillation.
SteP 2.2
The product of step 1.1 is dissolved in 4 vols acetonitrile.
1 molar equivalent silver nitrate in acetonitrile is added and then the solution is stirred for 24 h at room temperature. The silver chloride is filtered off, the washed with ether and the combined filtrates run down under vacuum. The product is used crude in step 3.
Stes 2.3
The crude nitrate ester is dissolved in DMSO. 30 mol % sodium acetate trihydrate is added as DMSO solution and the resulting mixture is stirred for 30 min. The reaction mixture is pourred into water, extracted with ether, dried, filtered and purified by recrystallization.
Stes 2.4
Glyoxal hydrate is dissolved in methanol, cooled to -40 OC and glycinamide is added. Then 2.2 molar equivalents of 40 % sodium hydroxide solution is added dropwise maintaining temperature at -40 OC for 24 h. The product is purified by extraction with base.
Step 2.5
2 molar excess of phosphorus pentabromide and phosphorus oxybromide are added to the product of step 1.4. The reaction mixture is refluxed for 16 h under N2 and the product is purified by destillation.
SteD 2.6
1 % molar excess of 1.6 M n-BuLi in hexane is added dropwise to the product from step 1.5 at -70 OC under N2. Then 1.1 molar excess of dimethylformamide in 2 volumes THF is added dropwise, keeping temperature at -70 OC. The product is purified by column chromatography eluting with petrol/DCM over silica.
Step 2.7
Withig synthesis using 5 mol % excess of n-BuLi (1.6 molar hexane solution) and 4-propyl cyclohexyl methyl iodide with the aldehyde from step 1.6. The reaction mixture was stirred overnight and then the triphenylphosphine removed by H202 oxidation followed by column chromatography.
SteP 2.8
The hydrogenation is carried out using 5 % Pd/C in THF as solvent at atmospheric pressure. The product is isolated by filtration and column chromatography. Final crystallisation from ethanol gave the pure product.
The following compounds of the formula
are prepared analogously: R L L2 X C2H5 H H F C2H5 H H C1 C2H5 H H CF3 C2H5 H H OCF3 C2H5 H F F C2H5 H F Cl C2H5 H F CF3 C2H5 H F OCF3 C2H5 F F F C2H5 F F Cl C2H5 F F CF3 C2H5 F F OCF3 n-C3H7 H F F n-C3H7 F F F n-C3H7 H H Cl n-C3H7 H H Cl n-C3H7 F F Cl n-C3H7 H H CF2H R L1 L2 X n-C3H7 H F CF2H n-C3H7 F F CF2H n-C3H7 H H CF3 n-C3H7 H F CF3 n-C3H7 F F CF3 n-C3H7 H H CF2C1 n-C3H7 H F CF2C1 n-C3H7 F F CF2C1 n-C3H7 H H C2F4H n-C3H7 H F C2F4H n-C3H7 F F C2F4H n-C3H7 H H C2F5 n-C3H7 H F C2F5 n-C3H7 F F C2F5 n-C3H7 H H C2F4C1 n-C3H7 H F C2F4C1 n-C3H7 F F C2F4C1 n-C3H7 H H OCF2H n-C3H7 H F OCF2H n-C3H7 F F OCF2H n-C3H7 H H OCF3 n-C3H7 H F OCF3 n-C3H7 F F OCF3 n-C3H7 H H OCF2C1 n-C3H7 H F OCF2C1 n-C3H7 F F OCF2C1 n-C3H7 H H OC2F4H R L1 L2 X n-C3H7 H F OC2F4H n-C3H7 F F OC2F4H n-C3H7 H H OC2F5 n-C3H7 H F OC2F5 n-C3H7 F F OC2F5 n-C3H7 H H OC2F4C1 n-C3H7 H F OC2F4C1 n-C3H7 F F OC2F4C1 n-C5H11 H F F n-C5H11 F F F n-C5H11 H H C1 n-C5H11 H H C1 n-C5H11 F F Cl n-C5H11 H H CF2H n-C5H11 H F CF2H n-C5H11 F F CF2H n-C5H11 H H CF3 n-C5H11 H F CF3 n-C5H11 F F CF3 n-C5H11 H H CF2C1 n-C5H11 H F CF2C1 n-C5H11 F F CF2C1 n-C5H11 H H C2F4H n-C5H11 H F C2F4H n-C5H11 F F C2F4H n-C5H11 H H C2F5 n-C5H11 H F C2Fs R L1 L2 X n-C5H11 F F C2F5 n-C5H11 H H C2F4C1 n-C5H11 H F C2F4C1 n-C5H11 F F C2F4C1 n-C5H11 H H OCF2H n-C5H11 H F OCF2H n-C5H11 F F OCF2H n-C5H11 H H OCF3 n-C5H11 H F OCF3 n-C5H11 F F OCF3 n-C5H11 H H OCF2C1 n-C5H11 H F OCF2C1 n-C5H11 F F OCF2C1 n-C5H11 H H OC2F4H n-C5H11 H F OC2F4H n-C5H11 F F OC2F4H n-C5H11 H H OC2F5 n-C5H11 H F OC2F5 n-C5H11 F F OC2F5 n-C5H11 H H OC2F4C1 n-C5H11 H F OC2F4C1 n-C5H11 F F OC2F4C1 CH3CH20CH2 H H F CH3CH20CH2 H F F CH3CH20CH2 F F F CH3CH20CH2 H H C1 CH3CH20CH2 H F C1 R L L X CH3CH2OCH2 F F Cl CH3CH20CH2 H H CF3 CH3CH20CH2 H F CF3 CH3CH20CH2 F F CF3 CH3CH20CH2 H H OCF3 CH3CH20CH2 H F OCF3 CH3CH20CH2 F F OCF3 CH2=CHCH2CH2 H H F CH2=CHCH2CH2 H F F CH2=CHCH2CH2 F F F CH2=CHCH2CH2 H H C1 CH2=CHCH2CH2 H F C1 CH2=CHCH2CH2 F F Cl CH2=CHCH2CH2 H H CF3 CH2=CHCH2CH2 H F CF3 CH2=CHCH2CH2 F F CF3 CH2=CHCH2CH2 H H OCF3 CH2=CHCH2CH2 H F OCF3 CH2=CHCH2CH2 F F OCF3

Claims (8)

  1. Claims 1. A phenylpyrazine of the formula I
    wherein R is an alkyl group of 1-15 C atoms, wherein one or two non-adjacent CH2 groups can also be replaced by 0 atoms and/or -CO- groups and/or -O-CO-groups and/or -CO-O- groups and/or -O-COO- groups and/or -CH-halogen groups, A is a trans-1,4-cyclohexylene group or a 1,4 phenylene group which is unsubstituted or monosubstituted or polysubstituted by F and/or Cl atoms, wherein one or two non-ad jacent CH2 groups can also be replaced by a N atom, n and m is O or 1 L1 and L2 are each independently of each other H or F, and X is Q-Y wherein Y is H, F or Cl, and Q is -CF2-, -CF2CF2-, -OCF2-, -OCF2CF2- or a single bond with the provisos that a) in the case of m = n = 0 and X = CF3 or F, L1 and L2 are F, b) in the case of m = n = 0 and X = C1 or CN, one of Ll and L2 is F, the other being H or F,
    c) in the case of m = 1, n = 0 and X = F, Cl or CN one of L1 and L2 is F, the other being H or F.
  2. 2. A phenylpyrazine of the formula Ia,
    wherein R, X, L1 and L2 have the meanings given in claim 1.
  3. 3. A phenylpyrazine of the formula Id,
    wherein R, X, L1 and L2 have the meanings given in claim 1.
  4. 4. A phenylpyrazine of the formula I, wherein X is Cl, F, OCF3 or CF3.
  5. 5. Use of a compound of formula I, as claimed in claim 1 as a component of a liquid-crystalline medium.
  6. 6. A liquid-crystalline medium containing at least two liquid-crystalline components, characterized in that at least one component is a compound of the formula I, as claimed in claim 1.
  7. 7. A liquid crystal display element, characterized in that it contains a medium as claimed in claim 6.
  8. 8. An electro-optical display element comprising a liquid crystal display element as claimed in claim 7, characterized by containing a medium as claimed in claim 6 as a dielectric.
    9 A phenylpyrazine substantially as hereinbefore described in either of examples 1 and 2.
GB9302859A 1992-02-18 1993-02-12 Liquid crystalline phenylpyrazines Withdrawn GB2264300A (en)

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GB929203440A GB9203440D0 (en) 1992-02-18 1992-02-18 Phenylpyrazines

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GB9302859A Withdrawn GB2264300A (en) 1992-02-18 1993-02-12 Liquid crystalline phenylpyrazines

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1268916A (en) * 1968-11-08 1972-03-29 Mcneilab Inc Novel derivatives of pyrazinylmalonates and pyrazineacetic acids

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1268916A (en) * 1968-11-08 1972-03-29 Mcneilab Inc Novel derivatives of pyrazinylmalonates and pyrazineacetic acids

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Chem Pharm Bull, 1979, Volume 27(9), pages 2027-2041 *
Chem.Ber, 1967,Volume 100(2), pages 555-559 *
Kyushu Sangyo Daigaku Kogakubu Kenkyu Hokoku, 1987, Volume 24, pages 29-33 *

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GB9302859D0 (en) 1993-03-31

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