GB2270913A - Liquid crystalline compounds with a chlorodifluoromethoxyphenyl terminus - Google Patents

Abstract

Novel liquid crystalline compounds, which contain a chlorodifluoromethoxyphenyl group of the general formula <IMAGE> [wherein A<1> and A<2> each independently signify trans-1,4-cyclohexylene, trans-1,3-dioxane-2,5-diyl, pyridine-2,5-diyl, pyrimidine-2,5-diyl or 1,4-phenylene (which are unsubstituted or mono- or disubstituted with fluorine, cyano and/or methyl); Z<1> and Z<2> each independently represent an single bond, -CH2CH2-, -CH2O-, -OCH2-, -C IDENTICAL C-, -COO-, -OOC-, -(CH2)4-, -O(CH2)3-, -(CH2)3O- or the trans form of -CH=CH-, -CH=CH(CH2)2, -(CH2)2CH=CH-, -CH=CHCH2O- or -OCH2CH=CH-; R signifies alkyl or alkenyl with 1 to 12 or, respectively, 2 to 12 carbon atoms in which optionally 1 to 3 hydrogen atoms can be substituted by fluorine and/or 1-2 non-adjacent CH2 groups can be replaced by O; and X<1>,X<2>,X<3> each independently represent hydrogen or fluorine; with the provisos that (a) ring A<1> is not saturated when ring A<2> is (hetero)aromatic and/or (b) Z<1> and Z<2>, when between two (hetero)aromatic rings, signify a single covalent bond, -COO- or -OOC- only and/or (c) not more than two of the substituents X<1>,X<2> and X<3> signify fluorine] are disclosed, together with their manufacture, liquid crystalline mixtures which contain such substances and their use for optical and electro-optical purposes.

Description

The present invention is concerned with novel liquid crystalline compounds having a chlorodifluoromethoxyphenyl group, their manufacture, liquid crystalline mixtures which contain such compounds and their use for optical and electrooptical purposes.

Since the optical properties of liquid crystals can be influenced by an applied voltage, such substances are used primarily as dielectrics in indicating devices. Electro-optical devices based on liquid crystals are well-known to a person skilled in the art and can be based on various effects. The most common indicating devices are based on the Schadt-Helfrich effect and have a twisted nematic structure. Examples of such cells are TN cells ("twisted nematic"), STN cells ("super-twisted nematic") or actively addressed displays such as, for example, TFT cells ("thin film transistor").

The liquid crystal materials for such cells must have a good chemical and thermal stability and a good stability towards electric fields and electromagnetic radiation. Further, the liquid crystal materials should have a low viscosity and in the cells should give short response times, low threshold potentials and a high contrast. At usual operating temperatures they should have a suitable mesophase, for example a nematic or cholesteric mesophase for the aforementioned cells. Further, the dielectric anisotropy should be as high as possible.

Since liquid crystals are usually used as mixtures of several components, it is also important that the components have a good miscibility with one another.

The target of liquid crystal research is, inter alia, to provide components for the aforementioned uses which have as many as possible of the mentioned properties. It has now been found that compounds having a chlorodifluoromethoxyphenyl group are outstandingly suitable for the aforementioned uses.

The present invention accordingly provides compounds of the general formula

wherein A1 and A2 each independently signify trans-l ,4-cyclohexylene, trans-l ,3-dioxane-2,5-diyl, pyridine-2,5-diyl, pyrimidine-2,5-diyl or 1,4-phenylene which is unsubstituted or mono- or disubstituted with fluorine, cyano and/or methyl; Z1 and z2 each independently represent an single bond, -CH2CH2-, -CH20-, -OCH2-, -CmC-, -COO-, -OOC-, -(C H2)4-, -O(CH2)3-, -(CH2)30- or the trans form of -CH=CH-, -CH=CH(CH2)2, -(CH2)2CH=CH-, -CH=CHCH20 or -OCH2CH=CH-;; R signifies alkyl or alkenyl with 1 to 12 or, respectively, 2 to 12 carbon atoms in which optionally 1 to 3 hydrogen atoms can be substituted by fluorine and/or 1-2 non-adjacent CH2 groups can be replaced by 0; and X1,X2,X3 each independently represent hydrogen or fluorine; with the provisos that (a) ring A1 is not saturated when ring A2 is (hetero)aromatic and/or (b) Z1 ,Z2 between two (hetero)aromatic rings signify a single covalent bond, -COO- or -OOC- and/or (c) not more than two of the substituents X1,X2 and X3 signify fluorine.

The compounds in accordance with the invention are liquid crystals having comparatively high clearing points and with broad, partially with pure nematic mesophases. They are soluble with one another and with other known liquid crystals in comparatively high concentrations and are therefore especially suitable as components of nematic or cholesteric mixtures. It has surprisingly been found that the compounds in accordance with the invention in experimental mixtures scarcely bring about an increase and often bring about even a reduction of the threshold potential in spite of the desired clear increase in the clearing point and in spite of their favourable and comparatively small polarity. Moreover, the switching on times in the corresponding mixtures are comparatively short.The optical an isotropy can be varied in a wide range by suitable choice of rings in formula I; for example, the compounds of formula I in which rings A1 and A2 signify trans-1,4-cyclohexylene and/or trans-l ,3-dioxane-2,5-diyl have a low optical an isotropy and the compounds of formula I in which rings A1 and A2 signify an aromatic and/or heteroaromatic ring have a high optical an isotropy. Accordingly, such compounds can be used advantageously in mixtures for TN-LCDs or STN-LCDs in order to optimize the optical phase difference in the case of a given electrode separation of the display.The relatively low total polarity of the compounds in accordance with the invention with comparatively high dielectric anisotropy also permits their use as components of TFT mixtures.

In the above definition of the compounds of formula I the term "1,4-phenylene which is unsubstituted or mono- or disubstituted with fluorine, cyano and/or methyl" signifies, for example, groups such as 1 ,4-phenylene, 2-fluoro-1 ,4-phenylene, 2,3-difluoro-1 ,4-phenylene, 2-cyano-1,4-phenylene, 2,3-dicyano1,4-phenylene, 2-cyano-3-fluoro-1 ,4-phenylene, 2-methyl-1,4phenylene and the like.

The term "(hetero)aromatic rings" embraces in the scope of the present invention pyridine-2,5-diyl, pyrimidine-2,5-diyl and 1 ,4-phenylene which is unsubstituted or mono- or disubstituted with fluorine, cyano and/or methyl, while the term "saturated rings" signifies trans-i ,4-cyclohexylene or trans-1,3-dioxane2,5-diyl.

The term "alkyl or alkenyl with 1 to 12 or, respectively, 2 to 12 carbon atoms in which optionally 1 to 3 hydrogen atoms can be replaced by fluorine and/or 1-2 non-adjacent CH2 groups can be replaced by 0" embraces straight-chain and branched (optionally chiral) residues such as alkyl, 1 E-alkenyl, 3E-alkenyl, 4-alkenyl, alkenyl having a terminal double bond, alkoxy, alkoxyalkyl, 2E-alkenyloxy, 3-alkenyloxy, alkenyloxy having a terminal double bond, alkenyloxyalkyl, alkoxyalkenyl, 1fluoroalkyl, 1,1 -difluoroalkyl, 2-fluoroalkyl, 2-fluoroalkoxy, terminal fluoroalkyl, terminal difluoromethylalkyl, terminal trifluoromethylalkyl, terminal trifluoromethylalkoxy, 1methylalkyl, 2-methylalkyl, 1 -methylalkoxy, 2-methylalkoxy and the like.Examples of preferred residues are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 1-methylpropyl, 1methylheptyl, 2-methylbutyl, 3-methylpentyl, vinyl, 1 E-propenyl, 1 E-butenyl, 1 E-pentenyl, 1 E-hexenyl, 3-butenyl, 3E-pentenyl, 3Ehexenyl, 4-pentenyl, 4Z-hexenyl, 5-hexenyl, 6-heptenyl, 7octenyl, methoxy, ethoxy, ppropyloxy, butyloxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, 1-methylpropyloxy, 1methylheptyloxy, 2-methylbutyloxy, allyloxy, 2E-butenyloxy, 2Epentenyloxy, 3-butenyloxy, 3Z-pentenyloxy, 4-pentenyloxy, 5hexenyloxy, 6-heptenyloxy, 7-octenyloxy, 2-methoxyethyl, 3methoxypropyl, 1 E-3-methoxypropenyl, 1 -fluoropropyl, 1fluoropentyl, 2-fluoropropyl, 2,2-difluoropropyl, 3-fluoropropyl, 3,3-difluoropropyl, 3,3,3-trifluoropropyl, 2-fluoropropyloxy, 3fluoropropyloxy, 2,2-difluorovinyl, 2-(3,3-difluoro)propenyl and the like.

Preferred compounds of formula I are the compounds of the general formulae

wherein X1,X2,X3,Z1,Z2 and R have the above significances.

Preferred compounds of formulae I and la-lk are compounds in which one of the groups Z1 and z2 signifies a single bond or -CeO- and the other of the groups Z1 and z2 signifies a single bond, -CH2OH, -CH2O-, -OCH2-, -0=-C-, -COO, O or between two non-aromatic rings also the trans form of -CH=CH-.

Particularly preferred are, however, those compounds in which one of the groups Z1 and Z2 represents a single bond and the other of the groups Z1 and Z2 represents a single bond, -CH2CH2- or -CeO-.

Preferably, the residues R in the above formulae I and la-lk have a chain length of 1 to 7 or, respectively, 2 to 7 carbon atoms. The residues having 2 to 5 carbon atoms are especially preferred.

Also preferred are those compounds of general formula I in which either Xl, X2 and X3 signify hydrogen or X2 represents fluorine and the other two substituents represent hydrogen or X1 and X2 signify fluorine and X3 signifies hydrogen or X1 stands for hydrogen and the other two substituents stand for fluorine.

However, those compounds of formula I in which X1, X2 and X3 signify hydrogen or those in which X2 represents fluorine and the other two substituents represent hydrogen are particularly preferred.

The manufacture of the compounds of formula I can be effected by reaction sequences known per se starting from chlorodifluoromethoxybenzene derivatives which are appropriately functionalized in the para-position. The synthesis of such chlorodifluoromethoxybenzene derivatives is illustrated in Scheme 1. The starting materials for these syntheses are known compounds or analogues of known compounds. Moreover, many of them are commercially available.

Scheme 1

wherein X1 ,X2 and X3 have the significances given above.

For example, p-bromo derivatives of formula II can be prepared by converting the optionally fluoro-substituted phenol by reaction with chlorodifluoromethane in a strong base into the corresponding difluoromethoxy compound. This is subsequently transformed by photochlorination into the corresponding chlorodifluoromethoxy derivative, which can be converted into compound II by subsequent iron(lll)-catalyzed bromination.

Analogously, p-difluoromethoxybenzoic acid, which is known from the literature, or one of its fluorinated analogues (Ill), after prior transformation into the acid chloride, can be transformed directly by chlorination into the corresponding chlorodifluoromethoxybenzoyl chloride IV. The acetophenone derivative or formula 1Vb can be produced therefrom, if desired, by reaction with a methyl-Grignard reagent using stoichiometric amounts of zinc(ll) chloride and palladium-1 ,1 '-bis(diphenylphosphino)- ferrocene (PdCl[dppfi) as the catalyst. Phenols of formula IVd can be prepared from IVb by Baeyer-Villiger oxidation and subsequent alkaline saponification.The corresponding nitriles of formula IVa can also be prepared starting from an optionally fluoro-substituted p-cyanophenol by an analogous reaction sequence as for compounds of formula II (with omission of the bromination step). Aldehydes of formula IVc can be prepared either by Rosenmund reduction of the corresponding acid chlorides Ill or by DIBAH reduction of the corresponding nitriles IVa.

The compounds of formula I can be manufactured starting from the intermediates ll, IV, IVa-lVd described above by reaction sequences which are usually used in LC chemistry. Such reaction sequences are well-known to a person skilled in the art and are widely described in the literature. The requisite reaction partners are known from the literature or are analogues of known compounds and can be prepared according to known methods.For example, those compounds of formula I in which A1 signifies 1,4phenylene or 1 ,4-cyclohexylene and Z1 signifies a single bond or an acetylene bridge can be manufactured from intermediates of type II by coupling reactions which are presented in Scheme 2. Scheme 2

wherein R1, A1, A2, ZI, z2, X1, X2 and X3 have the significances given above.

Compounds of formula I in which ring A1 signifies 1,3dioxane-2,5-diyl and Z1 signifies a single bond are conveniently manufactured by acetal formation of suitable diols with aldehydes of formula IVc. Those compounds of formula I in which Z1 signifies the 1,2-ethylene bridge can also be manufactured from the same aldehydes by Wittig reaction with suitable Wittig salts and subsequent catalytic hydrogenation. Compounds of formula I in which ring A1 signifies pyrimidine-2,5-diyl are conveniently synthesized from the nitriles of formula IVa via the corresponding amidinium salts or from the aldehydes IVc after transformation of the aldehyde group into the malonyltetraacetal group.As a starting material for corresponding compounds of formula I in which ring A1 signifies pyridine-2,5-diyl, the acetophenone derivative IVb can be reacted in a known sequence beginning with the Mannich reaction. Compounds of formula I in which Z1 signifies the methyleneoxy group can be obtained by alkaline etherification of the phenols IVd with suitably substituted methylene halides. Esters of formula I in which Z1 respresents a carboxyl group can be manufactured by esterifying the acid chlorides IV with suitable alcohols or the phenols IVd with corresponding acid chlorides.

The compounds of formula I can be used in the form of mixtures with one another and/or with other liquid crystal components. Suitable liquid crystal components will be known in large numbers to a person skilled in the art, e.g. from D. Demus et al., Flüssige Kristalle in Tabellen, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, volumes I and II, and many of them are, moreover, commercially available.

The invention is therefore also concerned with a liquid crystalline mixture having at least two components of which at least one component is a compound of formula I.

Having regard to the good solubility of the compounds of formula I in other liquid crystal materials and having regard to their good miscibility with one another, the content of compounds of formula I in the mixtures in accordance with the invention can be relatively high and can be, for example, 1-70 wt.%. In general, a content of about 3-40 wt.%, especially about 5-30 wt.%, of compounds of formula I is preferred.

The mixtures in accordance with the invention preferably contain, in addition to one or more compounds of formula I, one or more compounds from the group of compounds of the general formulae

wherein R1,R4 signify alkyl, alkoxyalkyl, 3E-alkenyl, 4-alkenyl or on saturated rings also 1 E-alkenyl; n signifies 0 or 1: ring A3 denotes 1,4-phenyiene, pyridine-2,5-diyl, pyrimidine-2,5-diyl, trans-l ,4-cyclohexylene or trans ,3-dioxane-2,5-diyl; R2 represents cyano, isothiocyanato, fluorine, alkyl, 3E-alkenyl, 4-alkenyl, alkoxy, 2E alkenyloxy, 3-alkenyloxy or 1-alkynyl; ring A4 signifies 1,4-phenylene or trans-1,4 cyclohexylene; R3 denotes alkyl, 3E-alkenyl, 4-alkenyl or on trans 1,4-cyclohexylene also I E-alkenyl or on 1,4 phenylene also cyano, isothiocyanato, alkoxy, 2E-alkenyloxy or 3-alkenyloxy; R5 signifies alkyl, 1 E-alkenyl, 3E-alkenyl or 4 alkenyl; R6 represents cyano, alkyl, 1E-alkenyl, 3E-alkenyl, 4-alkenyl, alkoxy, 2E-alkenyloxy, 3-alkenyloxy, alkoxymethyl or (2E-alkenyl)oxymethyl; Z3,Z4 denote a single covalent bond or -CH2CH2-, with two aromatic rings always being linked by a single covalent bond; R7 signifies hydrogen, fluorine or chlorine; R8 represents cyano, fluorine or chlorine; R9 denotes hydrogen or fluorine; Rio represents fluorine or chlorine.

The aforementioned term "aromatic rings" denotes in this connection rings such as, for example, 1,4-phenylene, pyridine2,5-diyl or pyrimidine-2,5-diyl. The term "saturated rings" denotes trans-1,4-cyclohexylene or 1,3-dioxane-2,5-diyl.

Residues R1 to R6 each preferably have 1 to 12 carbon atoms, especially 1 to 7 carbon atoms. Straight-chain residues are generally preferred. The term "alkyl" preferably signifies in this connection residues with 1 to 12 carbon atoms, especially with 1 to 7 carbon atoms such as, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl or heptyl.

The term "alkyloxyalkyl" preferably signifies in this connection straight-chain residues such as, for example, methoxymethyl, ethoxymethyl, propyloxymethyl, butyloxymethyl and the like.

The term "alkyloxy" preferably signifies in this connection straight-chain residues such as, for example, methoxy, ethoxy, propyloxy, butyloxy, pentyloxy, hexyloxy, heptyloxy and the like.

The term "1 E-alkenyl" preferably signifies in this connection straight-chain alkenyl residues in which the double bond is situated in the 1-position, such as, for example, vinyl, 1 E-propenyl, 1 E-butenyl, 1 E-pentenyl, 1 E-hexenyl, 1 E-heptenyl and the like.

The term "3E-alkenyl" preferably signifies in this connection straight-chain alkenyl residues in which the double bond is situated in the 3-position, such as, for example, 3butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl and the like.

The term "4-alkenyl" preferably signifies in this connection straight-chain alkenyl residues in which the double bond is situated in the 3-position, such as, for example, 3-butenyl, 3Epentenyl, 3E-hexenyl, 3E-heptenyl and the like.

The term "4-alkenyl" preferably signifies in this connection straight-chain alkenyl residues in which the double bond is situated in the 4-position, such as, for example, 4-pentenyl, 4hexenyl, 4-heptenyl and the like.

The term "2E- or 3Z-alkenyloxy" preferably signifies in this connection straight-chain alkenyloxy residues in which the double bond is situated in the 2- or 3-position and E or Z indicates the preferred configuration, such as, for example, allyloxy, 2Ebutenyloxy, 2E-pentenyloxy, 2E-hexenyloxy, 2E-heptenyloxy, 3butenyloxy, 3Z-pentenyloxy, 3Z-hexenyloxy, 3Z-heptenyloxy, 4pentenyloxy, 5-hexenyloxy, 6-heptenyloxy and the like.

The term "1-alkynyl" preferably signifies in this connection straight-chain alkynyl residues in which the triple bond is situated in the 1-position, such as, for example, ethynyl, 1propynyl, 1-butynyl, 1-pentynyl and the like.

The mixtures in accordance with the invention can also contain optically active compounds (e.g. optically active 4'-alkylor 4'-alkoxy-4-biphenylcarbonitriles) and/or dichroic colouring substances (e.g. azo, azoxy or anthraquinone colouring substances). The content of such compounds is determined by the solubility, the desired pitch, colour, extinction and the like. In general, the content of optically active compounds and dichroic colouring substances is in each case a maximum of about 10 wt.% in the final mixture.

The manufacture of the mixtures in accordance with the invention and the manufacture of the electro-optical devices can be effected in a manner known per se.

The manufacture of the compounds of formula I and of liquid crystalline mixtures containing these compounds are illustrated in more detail by the following Examples. C signifies a crystalline phase, S signifies a smectic phase, N signifies a nematic phase and I signifies the isotropic phase. V10 denotes the voltage for 10% transmission (viewing angle perpendicular to the plate surface). ton and toff denote respectively the switching on time and the switching off time and An denotes the optical an isotropy.

Example 1 a) Chlorodifluoromethane was conducted at a velocity of about 1 bubble/sec. at 700C for 9 hrs. into a mixture of 39.2 g of o-fluorophenol, 200 ml of isopropanol and 200 ml of 25% sodium hydroxide solution. During this time a further 20 mi of 25% sodium hydroxide solution were added in order that the reaction solution was always basic. Thereafter, the reaction mixture was cooled and left to stand at room temperature for several hours.

Thereupon, the liquid phases were transferred into a separating funnel and the upper organic phase was separated. The precipitate remaining in the reactor was washed several times with ether and the ether phases were combined with the organic phase. This was then washed with 5% sodium hydroxide solution and thereafter with water until it was alkali-free, dried over magnesium sulphate, filtered and the solvent was evaporated.

Distillation of the residue in a vacuum (69-71 C, 55 mm Hg) gave 29 g of 2-fluoro-difluoromethoxybenzene.

b) 24.3 g of 2-fluorodifluoromethoxybenzene in 300 ml of dry carbon tetrachloride were placed in a quartz vessel having a gas inlet, reflux condenser and attached gas drying apparatus containing sulphuric acid. Chlorine gas was introduced for 25 hrs. under reflux and UV irradiation (mercury quartz lamp).

Thereafter, the mixture was cooled, the solvent was evaporated and the residue was fractionated in a vacuum (83-85 C, 80 mm Hg). This gave 16.2 g of 2-fluoro-chlorodifluoromethoxybenzene, n2D: 1.4730.

c) 8.1 g of bromine were added dropwise at 30-350C within 30 min. to a mixture of 9.8 g of 2-fluoro-chlorodifluoromethoxybenzene, 40 ml of anhydrous carbon tetrachloride and 1.5 g of ion trichloride. As soon as the evolution of hydrogen bromide gas could no longer be determined, the solution was cooled, filtered, washed firstly with water, then with 5 percent sodium bisulphite solution and again with water and dried over magnesium sulphate. Evaporation of the solvent and fractional distillation (81-830C, 15 mm Hg) gave 8.8 g of 2-fluoro-4bromo-chlorodifluoromethoxybenzene, n2D: 1.4858.

The following compounds can be prepared in an analogous manner: 4-Bromo-chlorodifluoromethoxybenzene, b.p. 67-68"C (11 mm Hg), n2D: 1.4815, 2,3-difluoro-4-bromo-chlorodifluoromethoxybenzene, 2,6-difluoro-4-bromo-chlorodifluoromethoxybenzene.

Example 2 a) Chlorodifluoromethane was introduced at a velocity of about 1 bubble/sec. for 7 hrs. into a mixture of 23.8 g of 4hydroxybenzonitrile in 400 ml of dioxan and a solution of 60 g of sodium hydroxide in 300 ml of water while stirring intensively at 4000. In so doing, care was taken that the temperature did not exceed 450C. After working up analogously to Example la (without distillation) and crystallization from pentane there were obtained 23 g of 4-difluoromethoxy-benzonitrile (m.p. 41 420C) .

b) A solution of 6.76 g of 4-difluoromethoxybenzonitrile in 150 ml of anhydrous carbon tetrachloride was irradiated at reflux temperature for 4.5 hrs. while introducing chlorine gas in the apparatus described under 1 b. After completion of the reaction the solvent was evaporated and the residue was fractionated in a vacuum (115-1170C, 22 mm Hg).

This gave 5.85 g of 4-chlorodifluoromethoxy-benzonitrile, n2D: 14855.

In an analogous manner there can be prepared: 2-Fluoro-4-chlorodifluoromethoxy-benzonitrile, 2,3-difluoro-4-chlorodifluoromethoxy-benzonitrile, 2,6-difluoro-4-chlorodifluoromethoxy-benzonitrile.

Example 3 a) A mixture of 18.8 g of 4-difluoromethoxy-benzoic acid (preparation: J.A. Fialkov et al., Ukr. Khim. J. 49. 181 (1983), CA98(23):197713n) and 21 g of phosphorus pentachloride was heated to 130 C. The reaction mixture was held at 1300C with gentle oscillation until the evolution of hydrogen chloride gas had faded away. Thereafter, the mixture was cooled, the resulting phosphorus oxychloride was distilled off and the residue was fractionated in a vacuum (112-1140C, 12 mm Hg). This gave 19.6 g of 4-difluoromethoxy-benzoyl chloride.

b) Analogously to Example 1, chlorine gas was introduced for 18 hrs. under reflux and irradiation with UV light into a solution of 20.65 g of 4-difluoromethoxy-benzoyl chloride in 400 ml of an hydros carbon tetrachloride. Thereafter, the mixture was cooled, the solvent was evaporated and the residue was fractioned in a vacuum (101.10300, 13 mm Hg). This gave 20.3 g of 4-chlorodifluoromethoxy-benzoyl chloride. M.p. of the amide produced with ammonia: 14500.

In an analogous manner there can be prepared: 2-Fluoro-4-chlorodifluoromethoxy-benzoyl chloride, 2,3-difluoro-4-chlorodifluoromethoxy-benzoyl chloride, 2,6-difluoro-4-chlorodifluoromethoxy-benzoyl chloride.

Example 4 12.8 g of 4-(4-trans-propylcyclohexyl)-bromobenzene were slowly added dropwise to a mixture of 1.25 g of magnesium shavings in 25 ml of dry tetrahydrofuran and the mixture was then held under reflux for 1 hr. Then, the reaction mixture was cooled to 0 C, 0.9 g of PdCI2(dppf) catalyst was added and a solution of 13.8 g of 4-bromo-chlorodifluoromethoxybenzene was added dropwise at 000. 30 min. after carrying out the addition the reaction mixture was heated to reflux for 1 hr., then cooled to room temperature and treated with a saturated ammonium chloride solution. The reaction solution was extracted several times with benzene, the combined organic phases were dried over magnesium sulphate, filtered and the filtrate was evaporated.

Chromatography on silica gel with hexane and crystallization from alcohol gave 6.6 g of 4-chlorodifluoromethoxy-4'-(4-transpropylcyclohexyl)biphenyl, m.p. (C-S) 96"C, S-N 112.5 C, cl.p.

(N-l) 123"C.

The following compounds can be manufactured in an analogous manner: 4-Chlorodifluoromethoxy-4'-(4-trans-ethylcyclohexyl)biphenyl, 4-chlorodifluoromethoxy-4'-(4-trans-butylcyclohexyl)biphenyl, 4-chlorodifluoromethoxy-4'-(4-trans-pentylcyclohexyl)biphenyl, 4-chlorodifluoromethoxy-4'-(4-trans-vinylcyclohexyl)biphenyl, 4-chlorodifluoromethoxy-4'-[4-trans-(1 E-propenyl)cyclohexyl]biphenyl, 4-chlorodifluoromethoxy-4'-[4-trans-(1 E-butenyl)cyclohexyl]biphenyl, 4-chlorodifluoromethoxy-4'-[4-trans-(1E-pentenyl)cyclohexyl]biphenyl, 4-chlorodifluoromethoxy-4'-[4-trans-(3-butenyl)- cyclohexyl]biphenyl, 4-chlorodifluoromethoxy-4'-[4-trans.(3E.pentenyl).

cyclohexyl]biphenyl, 4-chlorodifluoromethoxy-4'-[4-trans-(4-pentenyl)- cyclohexyl]biphenyl, 4-chlorodifluoromethoxy-4'-[4-trans-(3-methoxypropyl)cyclohexyl]biphenyl, 4-chlorodifluoromethoxy-4'-(5-trans-propyl-1 ,3-dioxan-2yl)biphenyl, 4-chlorodifluoromethoxy-4'-(5-trans-pentyl-1 ,3-dioxan-2yl)biphenyl, 3-fluoro-4-clorodifluoromethoxy-4'-(4-trans-ethylcyclohexyl)biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-(4-trans-propylcyclohexyl) biphenyl, m.p. (C-N) 43 C, cl.p. (N-l) 75 C, 3-fluoro-4-chlorodifluoromethoxy-4'-(4-trans-butylcyclohexyl)biphenyl, 3-fluoro-4-clorodifluoromethoxy-4'-(4-trans-pentylcyclohexyl)biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-(4-trans-heXyl- cyclohexyl)biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-(4-trans-vinylcyclohexyl)biphenyl, 3fluoro-4-chlorodifluoromethoxy-4'-[4-trans-(1Epropenyl)cyclohexyl]biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[4-trans-(1E butenyl)cyclohexyIbiphenyI, 3-fluoro-4-chlorodifluoromethoxy.4'-[4.trans.(1 Epentenyl)cyclohexyl]biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[4.trans.(1 Ehexenyl)cyclohexyl]biphenyl, 3-fluoro-4-chlorodifluioromethoxy-4'-[4-trans-(3-butenyl)cyclohexyl]biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[4-trans-(3E pentenyl)cyciohexyl]biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[4-trans-(4- pentenyl)cyclohexyl]biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[4-trans-(3- methoxypropyl) cyclohexyl] biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-(5-trans-propyl-1,3 dioxan-2-yl)biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[5-trans-(1E-propenyl) 1 ,3-dioxan-2-yl]biphenyl, 2,3-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-propylcyclohexyl)biphenyl, 2,3-difluoro-4-chlorodifluoromethoxy-4'-(4-trans-butylcyclohexyl)biphenyl, 2,3-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-pentylcyclohexyl)biphenyl, 2,3-difluoro-4-chlorodifluoromethoxy-4'-(4-trans-vinylclohexyl)biphenyl, 2,3-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-(1 Epropenyl)cyclohexyl]biphenyl, 2,3-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-(1 Ebutenyl)cyclohexyl]biphenyl, 2,3-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-(1 E pentenyl)cyclohexyl]biphenyl, 2,3-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-(3butenyl)cyclohexyl]biphenyl, 2,3-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-(3E pentenyl)cyclohexyl]biphenyl, 2,3-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-(4pentenyl)cyclohexyl]biphenyl, 2,6-difluoro-4-chlorodifluoromethoxy-4'-(4-trans- propylcyclohexyl)biphenyl, 2,6-difluoro-4-chlorodifluoromethoxy-4'-(4-trans- butylcyclohexyl)biphenyl, 2,6-difluoro-4-chiorodifluoromethoxy-4'-(4-transpentylcyclohexyl)biphenyl, 2,6-difluoro-4-chlorodifluoromethoxy-4'-(4-trans- vinylcyclohexyl)biphenyl, 2,6-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-(1 Epropenyl)cyclohexyl]biphenyl, 2,6-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-(1 Ebutenyl)cyclohexyl]biphenyl, 2,6-difluoro-4-chlorodifluoromethoxy.4'.[4-trans.(i E pentenyl)cyclo hexyl]biphenyl, 2,6-difluoro-4-chlorodifluoromethoxy-4'.[4.trans.(3.

butenyI)cycIohexyIbiphenyl, 2,6-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-(3E pentenyl)cyclohexyl]biphenyl, 2,6-difluoro-4-chlorodifluoromethoxy-4'-[4-trans-(4pentenyl)cyclohexyl]biphenyl, 4-chlorodifluoromethoxy-4'-[2-(4-trans-propylcyclohexyl)ethyl]biphenyl, 4-chlorodifluoromethoxy-4'-[2-(4-trans-butylcycloheXyl)- ethyl]biphenyl, 4-chlorodifluoromethoxy-4'-[2-(4-trans-pentylcyclohexyl)ethyl]biphenyl, 4-chlorodifluoromethoxy-4'-[2-(4-trans-vinylcycloheXyl)- ethyl]biphenyl, 4-chlorodifluoromethoxy-4'-[2-(4-trans-(1 E-propenyl)cyclohexyl)ethyl]biphenyl, 4-chlorodifluoromethoxy-4'-[2-(4-trans-(3-butenyl)- cyclohexyl)ethyl]biphenyl, 4-chlorodifluoromethoxy-4'-[2-(5-trans-(3-butenyl)-1,3- dioxan-2-yI)ethyllbiphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[2-(4-trans-propylcyclohexyl)ethyl]biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[2-(4-trans-butylcyclohexyl)ethyl]biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[2-(4-trans-pentyl cyclohexyl)ethyl]biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[2-(4-trans-vinylcyclohexyl)ethyl]biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[2-(4-trans-(1 Epropenyl)cyclohexyl)ethyl]biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[2-(4-trans-(3- butenyl)cyclo hexyl)ethyl]biphenyl, 3-fluoro-4-chlorodifluoromethoxy-4'-[2-(5-trans-propyl 1 ,3-dioxan-2-yl)ethyi]biphenyl, 1-[trans-4-(trans-4-propylcyclohexyl) cyclohexyl]-4chlorodifluoromethoxybenzene, m.p. (C-N) 82 C. cl.p. (N-l) 133 C, 1-[trans-4-(trans-4-butylcyclohexyl) cyclohexyl]-4chlorodifluoromethoxybenzene, 1 -[trans-4-(trans-4-pentylcyclohexyl)cyclohexyl]-4.

chlorodifluoromethoxybenzene, 1-[trans-4-(trans-4-hexylcyclohexyl) cyclohexyl]-4chlorodifluoromethoxybenzene, 1-[trans-4-(trans-4-vinylcyclohexyl) cyclohexyl]-4chlorodifluoromethoxybenzene, I -(trans-4-[trans-4-(1 E-propenyl)cyclohexyl]cyclohexyl)- 4-chlorodifluoromethoxybenzene, 1 -{trans-4-[trans-4-(3-butenyl)cyclohexyl]cycloheXyl}-4- chlorodifluoromethoxybenzene, 1-{trans-4-[trans-4-(4-pentenyl) cyclohexyl] cyclohexyl}-4chlorodifluoromethoxybenzene, 1-{trans-4-[trans-4-(3-methoxypropyl) cyclohexyl] cyclohexyl).4.chlorodifluoromethoxybenzene, 1 -{trans-4-[trans-5-(1 E-propenyl)-1 ,3-dioxan-2-ylj- cyclohexyl)-4-chlorodifluoromethoxybenzene, 1-{trans-4-(trans-4-propylcyclohexyl) cyclohexyl]-3fluoro-4-chlorodifluoromethoxybenzene, 1 -[trans-4-(trans-4-butylcyclohexyl)cyclohexyl]-3-fluoro- 4-chlorodifluoromethoxybenzene, 1 -[trans-4-(trans-4-pentylcyclohexyl)cyclohexyl]-3fluoro-4-chlorodifluoromethoxybenzene, 1 -(trans-4-[trans-4-(1 E-propenyl)cyclohexyl]cyclohexyl}- 3-fluoro-4-chlorodifluoromethoxybenzene, 1-{trans-4-[trans-4-(3-butenyl) cyclohexyl] cyclohexyl}-3fluoro-4-chlorodifluoromethoxybenzene, 1-{trans-4-[trans-4-(4-pentenyl0 cyclohexyl] cyclohexyl]-3fluoro-4-chlorodifluoromethoxybenzene, 1-{trans-4-[trans-4-(3-methoxypropyl) cyclohexyl]cyclohexyl)-3-fluoro-4-chlorodifluoromethoxybenzene, 1-{trans-4-[trans-5-propyl-1,3-dioxan-2-yl] cyclohexyl}-3fluoro-4-chlorodifluoromethoxybenzene, 1 -(trans-4-[trans-5-(1 E-propenyl)-1 ,3-dioxan-2- yl]cyclohexyl)-3-fluoro-4-chlorodifluoromethoxybenzene, 1-{trans-4-[2-(trans-4-[2-(trans-4-propylcyclohexyl) ethyl] cyclohexyl}4-chlorodifluoromethoxybenzene, 1-{trans-4-[2-(trans-4-[2-(trans-4-butylcyclohexyl) ethyl] cyclohexyl}4-chlorodifluoromethoxybenzene, 1-{trans-4-[2-(trans-4-[2-(trans-4-pentylcyclohexyl) ethyl] cyclohexyl} 4-chlorodifluoromethoxybenzene, 1-{trans-4-[2-(trans-4-[2-(trans-4-vinylcyclohexyl) ethyl] cyclohexyl}4-chlorodifluoromethoxybenzene, 1 -(trans-4-[2-[trans-4-(1 E-propenyl)cyclohexyl]ethyl]- cyclohexyl).4-chlorodifluoromethoxybenzene, 1-{trans-4-[2-(trans-4-[2-[trans-4-(3-butenyl) cyclohexyl] ethyl] cyclohexyl).4-chlorodifluoromethoxybenzene, 1 -(trans-4-[2-[trans-4-(3- methoxypropyl)cyclohexyl)ethyl)cyclohexyl)-4-chlorodi- fluoromethoxybenzene, 1-{trans-4-[2-(trans-4-[2-(trans-5-propyl-1,3-dioxan-2-yl) ethyl] cyclohexyl)-4-chlorodifluoromethoxybenzene, 1-{trans-4-[2-(trans-4-[2-(trans-4-propylcyclohexyl) ethyl] cyclohexyl}3-fluoro-4-chlorodifluoromethoxybenzene, 1-{trans-4-[2-(trans-4-[2-(trans-4-butylcyclohexyl) ethyl] cyclohexyl}3-fluoro-4-chlorodifluoromethoxybenzene, 1 -(trans-4-[2-(trans-4-pentylcyclohexyl)ethyIcyclohexyl)- 3-fl uoro-4-ch lorodif luoromethoxybenzene, 1-{trans-4-[2-(trans-4-vinylcyclohexyl) ethyl] cyclohexyl}3-fluoro-4-chlorodifluoromethoxybenzene, 1 -(trans-4-[2-[trans-4-(1 E-propenyl)cyclohexyl]ethyl]cyclohexyl)-3-fluoro-4-chlorodifluoromethoxybenzene, 1 -{trans-4-[2-[trans-4-(3-butenyl)cyclohexyl]ethyl]- cyclohexyl)-3-fluoro-4-chlorodifluoromethoxybenzene, 1 -(trans-4-[2-[trans-4-(4-pentenyl)cyclohexyl]ethyl]- cyclohexyl)-3-fluoro-4-chlorodifluoromethoxybenzene, 1 -(trans-4-[2-[trans-4-(3- methoxypropyl)cyclohexyl]ethyl]cyclohexyl)-3-fluoro-4- chlorodifluoromethoxybenzene, 1 -(trans-4-[2-(trans-5-propyl.1 ,3-dioxan-2-yl)ethyl]- cyclohexyl)-3-fluoro-4-chlorodifluoromethoxybenzene, 1-{2-[trans-4-(trans-4-(trans-4-propylcyclohexyl) cyclohexyl] ethyl}4-chlorodifluoromethoxybenzene, 1-{2-[trans-4-(trans-4-(trans-4-butylcyclohexyl) cyclohexyl] ethyl}4-chlorodifluoromethoxybenzene, 1-{2-[trans-4-(trans-4-(trans-4-pentylcyclohexyl) cyclohexyl] ethyl}4-chlorodifluoromethoxybenzene, 1-{2-[trans-4-(trans-4-(trans-4-vinylcyclohexyl) cyclohexyl] ethyl} 4-chlorodifluoromethoxybenzene, 1 .{2.[trans.4.(trans.4-propylcyclohexyl)cyclohexyl]ethyl}- 3-fluoro-4-chlorodifluoromethoxybenzene, 1 -{2-[trans-4-(trans-4-butylcyclohexyl)cycloheXyl]ethyl}- 3-fluoro-4-chlorodifluoromethoxybenzene, 1-{2-[trans-4-(trans-4-vinylcyclohexyl) cyclohexyl] ethyl}3-fluoro-4-chlorodifluoromethoxybenzene, 1-{2-[trans-4-(trans-5-propyl-1,3-dioxan-2yl) cyclohexyl] ethyl}-3-fluoro-4-chlorodifluoromethoxybenzene.

Example 5 0.03 mol of 1-acrylyl-4-chlorodifluoromethoxybenzene (prepared from 4-chlorodifluoromethoxy-benzaldehyde analogously to C. Botteghi et al. Synth. Commun. 9, 69 (1979)) are mixed at OOC with 0.03 mol of 1-[2-(trans-4-propylcyclohexyl)vinyl]-piperidine and the mixture is held at room temperature for 2 hrs. Then, the mixture is treated with 90 ml of ethanol, 10 ml of water, 0.14 mol of hydroxylamine hydrochloride and 1 ml of concentrated hydrochloric acid and heated to reflux for 8 hrs. Subsequently, about 2/3 of the solvent is removed by distillation. The concentrated mixture is diluted with 150 ml of water and adjusted to pH 8 with aqueous sodium carbonate solution. The organic layer is extracted with benzene, the extract is washed neutral with water, dried over magnesium sulphate, filtered and concentrated.Chromatographic purification of the residue on silica gel with benzene/hexane (vol. 1:1) gives 2-(4-chlorodifluoromethoxyphenyl)-5-(trans-4-propylcyclohexyl)pyridine.

In an analogous manner there can be manufactured: 2-(4-Chlorodifluoromethoxyphenyl)-5-(trans-4-ethylcyclohexyl)pyridine 2-(4-chlorodifluoromethoxyphenyl)-5-(trans-4-butylcyclohexyl) pyridine, m.p. (C-S) 78 C, S-N 120.7 C, cl.p. (S-l) 129.5 C, 2-(4-chlorodifluoromethoxyphenyl)-5-(trans-4-pentyl cyclohexyl)pyridine, 2-(4-chlorodifluoromethoxyphenyl)-5-(trans-4-vinylcyclohexyl)pyridine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(trans-4- ethylcyclohexyl)pyridine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(trans-4- propylcyclohexyl)pyridine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(trans-4- butylcyclohexyl)pyridine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(trans-4- pentylcyclohexyl)pyridine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(trans-4- vinylcyclohexyl)pyridine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-[trans-4- (1 E-propenyl)cyclohexyl]pyridine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-[trans-4 (1 E-pentenyl)cyclohexyl]pyridine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-[trans-4 (3-butenyl)cyclohexyl]pyridine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-[trans-4- (4-pentenyl)cyclohexyl]pyridine, 2-(3,5-difluoro-4-chlorodifluoromethoxyphenyl)-5-(trans- 4-propylcyclohexyl)pyridine, 2-(2,3-difluoro-4-chlorodifluoromethoxyphenyl)-5-(trans4-propylcyclohexyl)pyridine, 2-(4-chlorodifluoromethoxyphenyl)-5-[2-(trans-4 propylcyclohexyl)ethyl]pyridine, 2-(4-chlorodifluoromethoxyphenyl)-5-[2-(trans-4pentylcyclohexyl)ethyl]pyridine.

Example 6 A solution of 1.85 g of sodium in 30 ml of methanol is added dropwise at room temperature to a solution of 0.43 mol of 3-ethoxy-2-(trans-4-propylcyclohexyl)-acrolein and 0.54 mol of 4-chlorodifluoromethoxybenzamidine hydrochloride (prepared analogously to A. Boller et al., Z. Naturforsch. 33b, 433, (1978)) in 150 ml of methanol. The reaction mixture is stirred at room temperature for 15 hrs., thereafter adjusted to pH 4 with 25 percent hydrochloric acid and concentrated on a rotary evaporator. The residual mixture is diluted with water, extracted with benzene and the combined organic extracts are washed with water. Thereafter, they are dried over magnesium sulphate, filtered and the solvent is evaporated.Chromatography of the residue on silica gel with a mixture of ethyl acetate in toluene gives 2-(4-chlorodifluoromethoxyphenyl)-5-(trans-4-propyl- cyclohexyl)pyrimidine.

The following compounds can be manufactured in an analogous manner: 2-(4-Chlorodifluoromethoxyphenyl)-5-(trans-4-ethyl- cyclohexyl)pyrimidine, 2-(4-chlorodifluoromethoxyphenyl)-5-(trans-4-butylcyclohexyl)pyrimidine, m.p. (C-S) 30"C, S-N 130,.6"C, cl.p. (N-l) 135.2"C 2-(4-chlorodifluoromethoxyphenyl)-5-(trans-4-pentylcyclohexyl)pyrimidine, 2-(4-chlorodifluoromethoxyphenyl)-5-(trans-4-vinylcyclohexyl)pyrimidine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(trans-4- ethylcyclohexyl)pyrimidine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(trans-4- propylcyclohexyl)pyrimidine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(trans-4- butylcyclohexyl)pyrimidine, 2-(3-f luo ro-4-chlorodifluoromethoxyphenyl)-5-(trans-4- pentylcyclohexyl)pyrimidine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(trans-4vinylcyclohexyl)pyrimidine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-[trans-4- (1 E-propenyl)cyclohexyl]pyrimidine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-[trans-4 (1 E-pentenyl)cyclohexyl]pyridine 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-[trans-4 (3-butenyl)cyclohexyl]pyrimidine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-[trans-4- (4-pentenyl)cyclohexyl]pyrimidine, 2-(3,5-difluoro-4-chlorodifluoromethoxyphenyl)-5-(trans- 4-propylcyclohexyl)pyrimidine, 2-(2,3-difluoro-4-chlorodifluoromethoxyphenyl)-5-(trans 4-propylcyclohexyl)pyrimidine, 2-(4-chlorodifluoromethoxyphenyl)-5-[2-(trans-4-propyl- cyclohexyl)ethyl]pyrimidine, 2-(4-chlorodifluoromethoxyphenyl)-5-[2-(trans-4-pentyl- cyclohexyl)ethyl]pyrimidine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(4-propyl- phenyl)pyrimidine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(4-butyl- phenyl)pyrimidine, 2-(3-fluoro-4-chlorodifluoromethoxyphenyl)-5-(4-pentyl- phenyl)pyrimidine.

Example 7 A mixture of 0.05 mol of 4-chlorodifluoromethoxyphenol, 0.05 mol of trans-4-(trans-4-propylcyclohexyl)cyclohexylmethyl tosylate, 15 g of potassium carbonate and 250 ml of butanone is heated under reflux for 2 days. Subsequently, the reaction mixture is cooled, poured into water and extracted with methylene chloride. The combined organic phases are washed with water, dried over magnesium sulphate, filtered and subsequently concentrated. Chromatography of the residue on silica gel with ethyl acetate in hexane gives 1-[trans-4-(trans- 4-propylcyclohexyl)cyclohexyl]methoxy-4-chlorodifluoro- methoxybenzene.

In an analogous manner there can be manufactured: 1 -[trans-4-(trans-4-Butylcyclohexyl)cyclohexyl]methOxy-4- chlorodifluoromethoxybenzene, 1 -[trans-4-(trans-4-pentylcyclohexyl)cyclohexyl]methoxy4-chlorodifluoromethoxybenzene, m.p. (C-N) 82"C, cl.p. (N-l) 133 C, 1 -(trans-4-[trans-4-(1 E-propenyi)cyclohexyI]cyclohexyl)- methoxy-4-chlorodifluoromethoxybenzene, 1 -[trans-4-(trans-4-butylcyclohexyl)cyclohexyl]methoxy-3fluoro-4-chlorodifluoromethoxybenzene, 1 -[trans-4-(trans-4-pentylcyclohexyl)cyclohexyl]methoxy- 3-fluoro-4-chlorodifluoromethoxybenzene, 1 -{trans-4-[trans-4-(1 E-propenyl)cyclohexyI]cyclohexyl) methoxy-3-fluoro-4-chlorodifluoromethoxybenzene.

Example 8 A solution of 2.6 g of 4-chlorodifluoromethoxy-benzoyl chloride in 5 ml of pyridine is treated with 2.3 g of trans-4 (trans-4-propylcyclohexyl)cyclohexanol and the mixture is stirred at room temperature for 12 hrs. Thereafter, the reaction mixture is poured into ice-water and extracted with diethyl ether. The organic phase is extracted in succession with 10 percent hydrochloric acid, saturated sodium bicarbonate solution and water, then dried over magnesium sulphate, filtered and concentrated. Chromatographic purification of the resulting crude product on silica gel with ethyl acetate/petroleum ether (vol. 3:97) gives 4-chlorodifluoromethoxy-benzoic acid trans-4 (trans-4-propylcyclohexyl)cyclohexyl ester, m.p. (C-S) 650C, S-N 1030C, cl.p. (N-l) 150.50C.

The following compounds can be manufactured in an analogous manner: 4-Chlorodifluo romethoxybenzoic acid trans-4-(trans-4pentylylcyclohexyl)cyclohexyl ester, 3-fluoro-4-chlorodifluoromethoxybenzoic acid trans-4 (trans-4-propylcyclohexyl)cyclohexyl ester, 4-chlorodifluoromethoxybenzoic acid trans-4-[2-(trans-4propylcyclohexyl)ethyl]cyclohexyl ester, 3-fluoro-4-chlorodifluoromethoxybenzoic acid trans-4-[2 (trans-4-propylcyclohexyl)ethyl]cyclohexyl ester, 4-chlorodifluoromethoxybenzoic acid 4-(trans-4-propylcyclohexyl)phenyl ester, 4-chlorodifluoromethoxybenzoic acid 4-(trans-4-pentyl cyclohexyl)phenyl ester, 3-fluoro-4-chlorodifluoromethoxybenzoic acid 4-(trans-4propylcyclohexyl)phenyl ester.

Example 9 A solution of 3 9 of 4-(trans-4-pentylcyclohexyl)benzoyl chloride in 5 ml of pyridine is treated with 1.9 g of 4chlorodifluoromethoxyphenol and the mixture is stirred at room temperature for 12 hrs. Thereafter, the reaction mixture is poured into ice-water and extracted with diethyl ether. The organic phase is extracted in succession with 10 percent hydrochloric acid, saturated sodium bicarbonate solution and water, then dried over magnesium sulphate, filtered and concentrated. Chromatographic purification of the resulting crude product on silica gel with ethyl acetate/petroleum ether (vol. 3:97) gives 4-(trans-4-pentylcyclohexyl)benzoic acid 4chlorodifluoromethoxyphenyl ester, m.p. (C-N) 113.40C, cl.p. (N-l) 143.300.

The following compounds can be manufactured in an analogous manner: 4-(trans-4-Propylcyclohexyl)benzoic acid 4-chlorodifluoromethoxyphenyl ester, 4-(trans-4-propylcyclohexyl)benzoic acid 3-fluoro-4chlorodifluoromethoxyphenyl ester, 4-(trans-4-pentylcyclohexyl)benzoic acid 3-fluoro-4chlorodifluoromethoxyphenyl ester, 4-[2-(trans-4-propylcyclohexyl)ethyl]benzoic acid 4chlorodifluoromethoxyphenyl ester, 4-[2-(trans-4-propylcyclohexyl)ethyl]benzoic acid 3fluoro-4-chlorodifluoromethoxyphenyl ester.

Example 10 Several binary mixtures (BM) were prepared from 4-(trans4-pentylcyclohexyl)benzonitrile and in each case a compound of formula I and the influence on clearing point, V10, toff and An was investigated. V10 and toff were measured at 22 C in a TN cell having a plate separation of 8 m; the response times were determined at the 2.5-fold value of V10. The correponding values for pure 4-(trans-4-pentylcyclohexyl)benzonitrile are: cl.p. (N-l) 54.6 C, V10 = 1.62 V, toff = 42 ms, An = 0.120.

BM-1 10 wt.% of 4-chlorodifluoromethoxy-4'-(4-trans- propylcyclohexyl)biphenyl, 90 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile; cl.p. (N-l) 55.7 C, V1O = 1.58 V, toff = 47 ms, An = 0.123.

BM-2 20 wt.% of 4-chlorodifluoromethoxy-4'-(4-trans- propylcyclo hexyl)biphenyl, 80 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile; cl.p. (N-l) 57.9 C, V10 = 1.56 V, toff = 52 ms, An = 0.125.

BM-3 10 wt.% of 1-[trans-4-propylcyclohexyl)- cyclohexyl]-4-chlorodifluoromethoxybenzene, 90 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile; cl.p. (N-l) 57.7 C, V10 = 1.61 V, toff = 44 ms, An = 0.120.

BM-4 20 wt.% of 1-[trans-4-(trans-4-propylcyclohexyl)- cyclohexyl]-4-chlorodifluoromethoxybenzene, 80 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile; cl.p. (N-l) 60.5 C. V10 = 1.62 V, toff = 48 ms, An = 0.116.

BM-5 10 wt.% of 1 -{[trans-4-(trans-4-pentylcyclohexyl)cyclo- hexyl] methoxy}-4-chlorodifluoromethoxy benzene, 90 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile; cl.p. (N-l) 58.9 C, V10 = 1.63 V, toff = 50 ms, An = 0.120.

BM-6 20 wt.% of 1-{[trans-4-(trans-4-pentylcyclohexyl) cyclo- hexyl] methoxy}-4-chlorodifluoromethoxy benzene, 80 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile; cl.p. (N-l) 63.6 C, V10 = 1.67 V, toff = 63 ms, An = 0.116.

Claims (10)

Claims

1. Compounds of the general formula

wherein A1 and A2 each independently signify trans-l ,4-cyclohexylene, trans-l ,3-dioxane-2,5-diyl, pyridine-2,5-diyl, pyrimidine-2,5-diyl or 1,4-phenylene which is unsubstituted or mono- or disubstituted with fluorine, cyano and/or methyl; Z1 and Z2 each independently represent an single bond, -CH2CH2-, -CH20-, -OCH2-, -0=-C-, -COO-, -OOC-, -(CH2)4-, -O(CH2)3-, -(CH2)30- or the trans form of -CH=CH-, -CH=CH(CH2)2, -(CH2)2CH=CH-, -CH=CHCH20 or -OCH2CH=CH-;; R signifies alkyl or alkenyl with 1 to 12 or, respectively, 2 to 12 carbon atoms in which optionally 1 to 3 hydrogen atoms can be substituted by fluorine and/or 1-2 non-adjacent CH2 groups can be replaced by 0; and X1,X2,X3 each independently represent hydrogen or fluorine; with the provisos that (a) ring A1 is not saturated when ring A2 is (hetero)aromatic and/or (b) Z1 ,Z2 between two (hetero)aromatic rings signify a single covalent bond, -COO- or -OOC- and/or (c) not more than two of the substituents X1,X2 and X3 signify fluorine.

2. Compounds of the general formulae

wherein X1 ,X2,X3,Z1 ,Z2 and R have the significances given in claim 1.

3. Compounds according to claim 1 or 2, wherein one of the groups Z1 and Z2 signifies a single bond or -0=-C- and the other of the groups Z1 and z2 signifies a single bond, -CH2CH2-, -CH2O-,-OCH2-,-CaC-, -COO-, -OOC- or between two nonaromatic rings also the trans form of -CH=CH-.

4. Compounds according to claim 1, 2 or 3, wherein the residue R has a chain length of 1 to 7 or, respectively. 2 to 7 carbon atoms.

5. Compounds according to any one of claims 1 to 4, wherein the residue R has a chain length of 2 to 5 carbon atoms.

6. Compounds according to any one of claims 1 to 5, wherein X1,X2 and X3 signify hydrogen.

7. Compounds according to any one of claims 1 to 5, wherein X1 and X3 represent hydrogen and X2 represents fluorine.

8. A liquid crystalline mixture, wherein one or more components is/are a compound of I defined in claim 1.

9. The use of the compounds of formula I defined in claim 1 for optical or electro-optical purposes.

10. The use of a liquid crystalline mixture according to claim 8 for optical or electro-optical purposes.