CARBOCYLIC ESTERS HAVING LIQUID-CRYSTAL PROPERTIES AT HIGH TEMPERATURES

Abstract: New liquid-crystalline ester compounds which exhibit a liquid-crystalline phase within a broad temperature range and have a positive, dielectric anisotropy, and a liquid-crystalline composition comprising the same are provided, the ester compounds being expressed by the general formula wherein R represents a hydrogen atom or an alkyl group of 1 to 10 carbon atoms; each represent X represents --O- or -O-; Y represents a hydrogen atom, F, Cℓ or CN; and Z represent F, Cℓ or CN.

Description: Carbocylic esters having liquid-crystal properties at high temperatures This invention realtes to novel carbocyclic esters exhibiting a liquld-crystalline phase over a broad temperature range and also having a positive dielectric anisotropy, and to liquid-crystalline compositions containing the same. Display elements using liquid crystals have come to be widely used for watches, desk calculators, etc. Such liquid-crystalline display elements utilize the properties of optical anisotropy and dielectric anisotropy of liquid-crystalline substances, and the term liquid-crystalline phase includes nematic, hectic and cholesteric liquid-crystalline phases. However, display elements utilizing nematic liquid crystals have had the wildest practical use. The display modes of such display elements include the TN type (twisted nematic type), the DS type (dynamic scattering type), the guest-host type, the DAD type, etc. and the properties required for the liquid-crystalline substances to be used for each of the respective types are different. However, it is nearly always preferred that the liquid-crystalline substances used for these display elements exhibit liquid-crystalline properties within as broad a temperature range as possible in the natural world. At present, however, no single compound is known which satisfies by itself such conditions, and it is the present state of the art that the substances which are at present available for practical use have been obtained by blending several liquid-crystalline and/or non-liquid-crystalline compounds. Further, these substances should, of course, be stable to moisture, light, heat, air, etc. and also it is preferred for them that the threshold voltage and saturation voltage required for driving such display elements be as low as possible and their viscosities be as low as possible in order to make the response speed higher. As compounds for satisfying such requirement, such compounds as expressed by the formulas EMI2.1 (where R1 represents an alkyl group; X represents EMI3.1 and R2 represents an alkyl group, an alkoxy group or CN) disclosed in U.S.P. 4,229,315 are well known and have had practical use. However, requirements for liquid-crystalline display elements have become more severe, and in order to satisfy the requirements, liquid-crystalline compositions which exhibit liquid-crystai properties over a range extending from a lower temperature to a higher temperature have become necessary. Now, in order to broaden the liquid-crystalline temperature range toward higher temperatures, it is necessary to use as a component liquid-crystalline substances having a higher melting point. However, such liquid-crystalline substances having a higher melting point generally have a higher viscosity and hence liquid-crystalline compositions containing them also have a higher viscosity. Thus the response speeds, particularly that at lower temperatures, of liquid-crystalline display elements which are usable up to higher temperatures such as 8O0C have been liable to be notably reduced. The present inventors have made strenuous studies for obtaining liquid-crytalline substances satisfying the above-mentioned requirement, and have found liquid-crystalline substances which exhibit a liquid-crystalline phase up to higher temperatures and nevertheless have a lower viscosity. The present invention resides in liquid-crystalline ester compounds expressed by the general formula EMI4.1 wherein R represents a hydrogen atom,or an alkyl group of 1 to 10 carbon atoms; EMI4.2 and EMI4.3 each represent EMI4.4 X represents EMI4.5 Y represents a hydrogen atom , F, C or CN, and Z represents F, C or CN. and liquid-crystalline compositions containing at least one member of said ester compounds. The compounds of the present invention exhibit a dielectric anisotropy value (±) which is as small as about +0.5 to 10; they also exhibit a liquid-crystalline phase up to higher temperatures; they can elevate the N-I point of liquid crystalline compositions by being added in a small amount to the compositions; further particularly in the case of their halogen-substitutes, the values of threshold and saturation voltages are unchanged or not increased so much in spite of their De values being reduced down to small values and also their viscosities are not elevated so much. Thus they are very useful compounds. Further they have superior stability to moisture, heat, light, air, etc. The compounds of the formula (I) are concretely classified into those expressed by the following 17 formulas (II) - (XVIII) (wherein each R has the same definition as in the formula (I)): EMI5.1 (wherein Z represents F, C2 or CN; this applies to the following formulas (III) and (IV)) EMI5.2 (wherein Y and Z each represent F or C; this applies to the following formulas (VI) (XII)) EMI5.3 EMI6.1 (wherein Z represents F, Cl or CN; this applies to the following formula (XIV)) EMI6.2 Next, the methods for preparing the compounds of the present invention will be described. Preparations of 4- < trans-4(trans-4- alkylcyclohexyl) cyclohexyl) benzoic acids and trans-4"-alkyl-trans-octaecahydro- p-terphenyl-trans-4-carboxylic acids From bromobenzene and metallic Mg is prepared phenylmagnesium bromide, which is then reacted with a 4- (trans-4-alkylcyclohexyl) cyclohexanone to obtain a 4- (trans-4-alkylcyclohexyl) cyclohexan- l-ol-benzene, which is then dehydrated in the presence of potassium hydrogen sulfate as a catalyst to obtain a 4-(trans-4-alkylcyclohexyl) cyclohexen-l-yl-benzene, which is then hydrogenated in the presence of Raney Ni as a catalyst to obtain a trans-4-(trans-4-alkylcyclohexyl)cyclohexylbenzene. This material may also be obtained directly by hydrogenation in the presence of Raney Ni. The material is then halogenated with iodic acid periodic acid or the lie to obtain a 4- ±trans-4- (trans-4-alkylcyclohexyl) cyclohexyl) halogenobenzene, which is then cyanogenated with cuprous cyanide to obtain a 4-ttrans-4-(trans-4- alkylcyclohexyl)cyclohexyl3 benzonitrile, which is then hydrolyzed in a KOH aqueous solutiondiethylene glycol system to prepare a 4-ttrans-4- (trans-4-alkylcyclohexyl)cyclohexyl]benzoic acid (XIX). This benzoic acid derivative is reduced with metallic sodium in isoamyl alcohol to obtain a trans-4-alkyl-trans-octadecahydro- p-terphenyl-trans-4-carboxylic acid (XX). The above preparation is illustrated by the following chemical equations: EMI8.1 <tb> O <SEP> -Br <SEP> The <SEP> ' <SEP> O <SEP> .uSBr <tb> OH <SEP> IGISO <tb> <SEP> 1 <SEP> Raney <SEP> Ni <tb> &num;ff· <SEP> · <SEP> ffThi <tb> Cu2 <SEP> cCN) <SEP> 2 <SEP> &num;mff-CN <SEP> KOH-1120 <tb> <SEP> DisStyleSe <SEP> glycol <tb> Hr0-0 <SEP> OI-t <SEP> Na <SEP> R( <SEP> 0il <tb> <SEP> - <SEP> It <SEP> Isoamy <tb> <SEP> (XIX) <SEP> alcohol <SEP> (XX) <tb> Further, trans-4-[4-(trans-4-alkylcyclohex yl)phenylcyclohexanecarboxylic acids are prepared by reducing 4- (trans-4-alkylcyclohexyl) biphenyl -4-carboxylic acids with metallic sodium in isoamyl alcohol, as in the above reduction from (XIX) into (XX). This preparation is illustrated by the following chemical equation: EMI9.1 Next, preparations of 4-[trans-4-(trans-4- alkylcyclohexyl)cyclohexyl] phenols and trans-4alkyl-4"-hydroxy-trans-octadecahydro-p-terphenyls are shown below. First, 4-bromoarisole is reacted with metallic Mg to obtain 4-methoxyphenylmagnesium bromide, which is then reacted with a 4-(trans-4-alkylcyclo- hexyl)cyclohexanone to obtain a 4-methoxy-El- hydroxy-4-(trans-4"-alkylcyclohexyl)cyclohexyl benzene, which is then dehydrated in the presence of potassium hydrogen sulfate as a catalyst to obtain a 4-methoxy-[4-(trans-4-alkylcyclohexyl) cyclohexen-l-yljbenzene, which is then reduced with Raney Ni as a catalyst in ethanol solvent under the atmospheric pressure at 300C to obtain a 4-methoxy- L4- (trans-4-alkylcyclohexyl)cyclohexyl benzene which is a mixture of trans-form and cis-form and recrystallized from ethanol to obtain a 4-methoxy-[trans-4-(trans-4-alkylcyclohexyl) cyclohexyl benzene, which is then demethylated with hydrobromic acid to obtain a 4- trans-4- (trans-4-alkylcyclohexyl) cyclohexyll phenol (XXIII), which is then subjected to catalytic reduction in the presence of ruthenium as a catalyst in ethanol solvent at 180 C under 50 kg/cmê to obtain a trans-4-alkyl-trans-4 "-hydroxy-trans-octadecahydro- p-terphenyl (XXIV). The above preparations are illustrated by the following chemical equations: EMI10.1 <tb> <SEP> C <SEP> KJ <SEP> O <SEP> Ms <SEP> -------r <tb> <SEP> THS <tb> R·mO <SEP> O <SEP> ,O <SEP> H <SEP> R: <SEP> SO( <tb> <SEP> OCH3 <tb> <SEP> R-Ni <tb> R <SEP> /-aa- <SEP> 0 <SEP> CH <tb> <SEP> Ethanol <tb> R <SEP> z <SEP> O <SEP> Cv3 <SEP> E <SEP> ¯r <SEP> j·3r <SEP> R <SEP> < <SEP> O <SEP> H <tb> <SEP> (XXIII) <tb> <SEP> B2(Ru/C) <tb> <SEP> A <SEP> -pC <SEP> jA <SEP> - <SEP> OH <tb> <SEP> (XXIV) <tb> Among the compounds having 3 six-member-rings, prepared as above, carboxylic acid compounds are converted into acid chlorides with thionyl chloride or the like, which is then subjected to esterification with a commercially available phenol corresponding to the final objective compound, in a conventional manner to obtain the objective ester compounds ((II) - (XII)). Further, phenols having 3 six-member-rings are subjected to esterification with a commercially available acid chloride corresponding to the objective compound in a conventional manner to obtain the objective ester compounds ((XIII) - (XVIII)). The above preparations are illustrated by the following chemical equations: EMI11.1 <tb> R <SEP> &num;-O-OB- <SEP> COHM·2R <SEP> R <SEP> -0 <SEP> - <SEP> ¯ <SEP> CC <tb> <SEP> O <SEP> O <tb> HO- <SEP> \-Z <SEP> ,' <SEP> R <SEP> -Z <SEP> CO <SEP> ((11) <SEP> (xII) <SEP> ) <tb> (pyridine) <SEP> 0 <tb> R <SEP> &num;-&num;0B <SEP> OH <SEP> "" <SEP> + <SEP> OE <SEP> Z <SEP> 2 <SEP> - <SEP> - <SEP> CCR <tb> <SEP> y <tb> R <SEP> R <SEP> - <SEP> C <SEP> - <SEP> z¯ <SEP> z- <SEP> OC <SEP> -- <SEP> Z <SEP> ((XIII) <SEP> - <SEP> (XVIII)) <tb> <SEP> ii <SEP> <tb> <SEP> o <tb> The methods for preparing the compounds of the present invention and the use examples of the compounds as applied to liquid-crystalline compositions will be described by way of Examples. Example 1 Preparation of trans- 4 "-propyl-trans -octa- decahydro-p-terphenyl-trans-4-carboxylic acid-4-fluorophenyl ester (compound of the formula (II) wherein R = C H and Z=F) Sliced Mg (3.6 g, 0.148 mol) was introduced into a three-neck flask and a solution (50 mQ) obtained by dissolving bromobenzene (23.2 g, 0.148 mol) in tetrahydrofuran was slowly dropwise added with stirring at a reaction temperature kept at 300 to 35 C in N2 current, during which reaction occurred and Mg uniformly dissolved after 3 hours to form phenylmagnesium bromide, to which a solution (50 m) obtained by dissolving 4-(trans-4propylcyclohexyl)cyclohexanone (26.2 g, 0.118 mol) in tetrahydrofuran was dropwise added as rapidly as possible at a reaction temperature kept at 10"C or lower, followed by raising the temperature up to 350C, stirring for 30 minutes, adding 3N hydrochloric acid (100 ml), transferring the reaction liquid into a separating funnel, three times extracting with n-heptane (100 mA), combining the n-heptane layers, washing with water till the washing liquid became neutral, distilling off n-heptane under reduced pressure to obtain as a residual oily substance, [4- (trans-4-propylcyclohexyl) cyclohexyl)cyclohexan-l-ollbenzene, adding potassium hydrogen sulfate (19 g) to this material, dehydrating at 170 C for 2 hours in N2 current, cooling, adding n-heptane (200 mZ), filtering off potassium hydrogen sulfate in a separating funnel, water-washing n-heptane layer till the washing liquid became neutral, distilling off n-heptane under reduced pressure, recrystalling the resulting residual oily substance from n-heptane and acetone to obtain [4-(trans-4-propylcyclohexyl)cyclohexen l-ylbenzene, dissolving this material (7.5 g) in ethanol (500 mQ), adding Raney Ni (3.2 g) as a catalyst, carrying out catalytic reduction at 50oC under the atmospheric pressure while passing hydrogen, tracing both the raw material and the product by gas chromatography, having the reduction reaction completed when the raw material disappeared, i.e. after 8 hours, to obtain an amount-of hydrogen absorbed of 800 m at that tIme, filtering off the catalyst, distilling off the solvent under reduced pressure, recrystallizing the residual crystals from ethanol to obtain [trans-4-(trans-4-propylcyclohexyl)cyclohexyl] benzene, dissolving this material (1.4 g) in acetic acid (50 mQ), adding a mixture of purified water (0.9 mQ), conc. sulfuric acid (1.0 mQ), iodic acid (0.20 g), iodine (0.50 g) and CCZ4 (0.4 ml), refluxing at 800C for 5 hours, cooling the reaction liquid, filtering off deposited crystals and recrystallizing the crystals from n-heptane to obtain 4-trans-4- (trans-4-propyl- cyclohexyl)cyclohexyl]iodobenzene exhibiting a liquid-crystalline state and having a C-S point of 119.0 C, a S-N point of 139.20C and a N-I point of 189.2 C. This material (1.2 g) was dissolved in N,N-dimethylformamide (50 ml), followed by adding Cu2(CN)2 (0.63 g) to the solution, reacting at 130 C for 4 hours, adding n-heptane (100 ml), transferring the mixture into a separating funnel, adding 30% aqueous ammonia, to effect liquid-separation, washing with water, washing with 6N hydrochloric acid, washing with water till the washing liquid became neutral, distilling off the solvent under reduced pressure and recrystallizing from n-heptane to obtain 4- trans- 4- (trans-4-propylcyclohexyl)cyclohexyl) benzonitrile (yield: 0.4 g, 45% relative to the cyanogenatlon reaction; C-S point, 73.1 C; S-N point, 81.1 C; N-I point, 242.50C). The thus obtained benzonitrile (5 g) together with a solution obtained by dissolving KOH (5 g) in water (10 ml) were added to diethylene glycol (100 mZ) and the mixture was heated and reacted at 200 C for 7 hours in a flask, followed by cooling down to room temperature, adding 6N HCZ (50 mQ) and water (100 ml), filtering off deposited crystals, sufficiently washing with water to obtain 4-ttrans- 4-(trans-4-propylcyclohexyl)cyclohexyl]bezoic acid (XIX), agitating this material (3 g) together with isoamyl alcohol (1500 ml), heating up to 900C, adding metallic Na (10 g) to initiate vigorcus reaction, further adding metallic Na (80 g) over 3 hours still under reflux, to form a uniform reaction liquid gradually, allowing the liquid to cool down to l000C, distilling off isoamyl alcohol while adding water small-portionwise (the total amount of water added: 1.52), adding 6N HCl (1Q) to completely acidify the resulting material, filtering off the resulting precipitate, sufficiently washing with water and recrysta llizing from acetic acid to obtain trans-4"propyl-trans-octadecahydro-p-terphenyl-trans4-carboxylic acid (XX) (yield: 1.9 g, 63%). This product also exhibited a liquid-crystallanity and had a C-S point of ca. 1700C, a S-N point of 2820C and a N-I point of 290 - 3000C (accompanied with decomposition) The thus prepared carboxylic acid (0.5 g) together with thionyl chloride (10 mQ) were heated to 800C for 2 hours for reaction to form a uniform reaction liquid, and the reaction was continued further for 1.5 hour, followed by distilling off excess thionyl chloride under reduced pressure to obtain an acid chloride as G residual oily substance. To this acid chloride was added a solution obtained by dissolving 4-fluorophenol (0.5 g) in pyridine (20 mZ) followed by adding toluene (100 mQ), allowing the mixture to stand over night, washing the toluene layer in a separating funnel first with 6N HCR, then with 2N NaOH solution and lastly with water till the washing liquid became neutral, drying with anhydrous sodium sulfate, distilling off toluene under reduced pressure and recrystallizing deposited crystals from ethanol and then from acetone to obtain the objective trans-4"- propyl-trans-octadecahydro-p-terphenyl-trans-4carboxylic acid-4-fluorophenyl ester (yield, 0.4 g, 62%; C-S point, 94.00C; S-N point, 220.60C; N-I point, 3000C or higher). Examples 2 - 21 In Example 1, 4(trans-4-propylcyclohexyl) cyclohexanone was replaced by 4-(trans-4alkylcyclohexyl)cyclohexanones having other alkyl groups to prepare 4-trans-4-(trans-4- alkylcyclohexyl)cyclohexyl] bezoic acids and trans-4" -alkyl-trans-octahydro-p-terphenyl-trans- 4-carboxylic acids. These compounds were converted with 4-fluorophenol, instead other halogenophenols or 4-cyanophenol into the objective compounds expressed by the formulas (11) , (III) , (V) , (VI) , (IX) and (X). The results are shown in Table 1 together with those of Example 1. Table 1 EMI18.1 <SEP> In <SEP> formula <SEP> (I) <SEP> Phase <SEP> transition <SEP> point <SEP> ( C) <tb> Example <SEP> Formula <tb> <SEP> R <SEP> -#B- <SEP> Y <SEP> Z <SEP> C-S <SEP> point <SEP> or <SEP> S-N <SEP> point <SEP> N-I <SEP> point <tb> <SEP> C-N <SEP> point <tb> <SEP> 1 <SEP> C3H7 <SEP> -#- <SEP> H <SEP> F <SEP> 94.0 <SEP> 220.6 <SEP> 300 <SEP> or <SEP> (II) <tb> <SEP> higher <tb> <SEP> 2 <SEP> C3H7 <SEP> -#- <SEP> H <SEP> Cl <SEP> 106.0 <SEP> 158.1 <SEP> 296.6 <SEP> " <tb> <SEP> 3 <SEP> C3H7 <SEP> -#- <SEP> H <SEP> CN <SEP> 119.0 <SEP> 194.3 <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> <SEP> 4 <SEP> H <SEP> -#- <SEP> H <SEP> F <SEP> 147.2 <SEP> - <SEP> 168.9 <SEP> (III) <tb> <SEP> 5 <SEP> C3H7 <SEP> -#- <SEP> H <SEP> F <SEP> 108.2 <SEP> - <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> <SEP> 6 <SEP> H <SEP> -#- <SEP> H <SEP> Cl <SEP> 152.8 <SEP> - <SEP> 192.0 <SEP> " <tb> <SEP> 7 <SEP> C3H7 <SEP> -#- <SEP> H <SEP> Cl <SEP> 134.5 <SEP> - <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> <SEP> 8 <SEP> H <SEP> -#- <SEP> H <SEP> CN <SEP> 151.6 <SEP> - <SEP> 230.0 <SEP> " <tb> <SEP> 9 <SEP> C3H7 <SEP> -#- <SEP> H <SEP> CN <SEP> 162.7 <SEP> - <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> <SEP> 10 <SEP> C3H7 <SEP> -#- <SEP> 2-Cl* <SEP> F <SEP> 92.0 <SEP> 190.1 <SEP> 256.3 <SEP> (V) <tb> <SEP> 11 <SEP> C3H7 <SEP> -#- <SEP> 2-F <SEP> Cl <SEP> 98.0 <SEP> 192.0 <SEP> 285.0 <SEP> " <tb> <SEP> 12 <SEP> C3H7 <SEP> -#- <SEP> 2-Cl <SEP> Cl <SEP> 103.0 <SEP> 134.0 <SEP> 260.7 <SEP> " <tb> Table 1 (continued) EMI19.1 <SEP> In <SEP> formula <SEP> (I) <SEP> Phase <SEP> transition <SEP> point <SEP> ( C) <tb> Example <SEP> Formula <tb> <SEP> R <SEP> -#- <SEP> Y <SEP> Z <SEP> C-S <SEP> point <SEP> or <SEP> S-N <SEP> point <SEP> N-I <SEP> point <tb> <SEP> C-N <SEP> point <tb> <SEP> 13 <SEP> C3H7 <SEP> -#- <SEP> 3-Cl <SEP> F <SEP> 84.0 <SEP> 162.4 <SEP> 265.3 <SEP> (IX) <tb> <SEP> 14 <SEP> C3H7 <SEP> -#- <SEP> 3-Cl <SEP> Cl <SEP> 107.0 <SEP> 123.3 <SEP> 268.0 <SEP> " <tb> <SEP> 15 <SEP> H <SEP> -#- <SEP> 2-Cl <SEP> F <SEP> 102.0 <SEP> - <SEP> - <SEP> (VI) <tb> <SEP> 16 <SEP> H <SEP> -#- <SEP> 2-F <SEP> Cl <SEP> 98.0 <SEP> - <SEP> - <SEP> " <tb> <SEP> 17 <SEP> C3H7 <SEP> -#- <SEP> 2-Cl <SEP> F <SEP> 77.0 <SEP> - <SEP> 231.0 <SEP> " <tb> <SEP> 18 <SEP> C3H7 <SEP> -#- <SEP> 2-F <SEP> Cl <SEP> 74.0 <SEP> - <SEP> 233.0 <SEP> " <tb> <SEP> 19 <SEP> C3H7 <SEP> -#- <SEP> 2-Cl <SEP> Cl <SEP> 76.0 <SEP> - <SEP> 228.0 <SEP> " <tb> <SEP> 20 <SEP> C3H7 <SEP> -#- <SEP> 3-Cl <SEP> F <SEP> 124.7 <SEP> - <SEP> 242.3 <SEP> (X) <tb> <SEP> 21 <SEP> C3H7 <SEP> -#- <SEP> 3-Cl <SEP> Cl <SEP> 126.3 <SEP> - <SEP> 287.8 <SEP> " <tb> * The numeral before the name of halogen refers to the position of halogen attached onto benzene ring. Example 22 Preparation of trans-4-[4-(trans-4 pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid-4-fluorophenyl ester (a compound of the formula (IV) wherein R=C5H11 and Z=F) 4-(Trans-4-pentylcyclohexyl)biphenyl-4carboxylic acid (XXI) (10 g) together with isoamyl alcohol (2,500 mQ) were heated to 90 C with stirring, followed by adding metallic Na (30 g) with a vigorous reaction being initiated, further adding metallic Na (120 g) over 3 hours while still continuing reflux to gradually form a uniform reaction liquid, allowing the liquid after the reaction to cool down to 1000C, distilling off isoamyl alcohol while adding water (2,000 mQ), adding ON HCZ (2±) for complete acidification, filtering off deposited precipitate, washing with water and recrystall zing from acetic acid to obtain trans-4-[4-trans-4-pentylcyclohexyl) phenylj cyclohexanecarboxylic acid (XXII) (4.5 g), which exhibited a liquid-crystallinity and had a C-S point of 239.1 C and a S-I point of 274.3 C (decomposition). This carboxylic acid (1 g) together with thionyl chloride (30 mA) were heated to 80 C for reaction to form a uniform reaction liquid in 2 hours, followed by continuing reaction further for 1.5 hour, distilling off excess thionyl chloride under reduced pressure to obtain an acid chloride as a residual oily substance, adding to this acid chloride, a solution obtained by dissolving 4-fluorophenol (0.5 g) in pyridine (20 mZ), adding toluene (100 mZ), allowing the mixture to stand over night, washing the toluene layer in a separating funnel first with 6N HCZ, then with 2N NaOH solution and finally with water till the washing liquid became neutral, drying with anhydrous NaSO4, distilling off the toluene layer under reduced pressure and recrystallizing deposited crystals from ethanol and then from acetone to prepare the objective trans4-[4-(trans-4-pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid-4-fluorophenyl ester (yield; 0.5 g, 40%; C-S point, 100.1 C; S-N point, 152.2 C; N-I point, 261.0 C). The fact that this compound corresponded to the objective substance was confirmed by infrared absorption spectra and NMR. Example 23 In Example 22, trans-4-l4-(trans-4- pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid was replaced by trans-4-[4-(trans-4- alkylcyclohexyl) phenyl] cyclohexanecarboxylic acids having other alkyl groups or 4'-(trans4-alkylcyclohexyl)biphenyl-4-carboxylic acid, and also fluorophenol, instead other halogenophenols or 4-cyanophenyl was used to prepare the objective compounds expressed by the formulas (IV) (VII) , (yIII) , (IX) , (XI) and (XII). The results are shown in Table 2 together with those of Example 22. Table 2 EMI23.1 <SEP> In <SEP> formula <SEP> (I) <SEP> Phase <SEP> transition <SEP> point <SEP> ( C) <tb> Example <SEP> Formula <tb> <SEP> R <SEP> -#- <SEP> Y <SEP> Z <SEP> C-S <SEP> point <SEP> or <SEP> S-N <SEP> point <SEP> N-I <SEP> point <tb> <SEP> C-N <SEP> point <tb> <SEP> 22 <SEP> C5H11 <SEP> -#- <SEP> H <SEP> F <SEP> 100.1 <SEP> 152.2 <SEP> 261.0 <SEP> (IV) <tb> <SEP> 23 <SEP> C5H11 <SEP> -#- <SEP> H <SEP> Cl <SEP> 120.3 <SEP> 129.3 <SEP> 264.3 <SEP> " <tb> <SEP> 24 <SEP> C5H11 <SEP> -#- <SEP> H <SEP> CN <SEP> 110.5 <SEP> - <SEP> 284.9 <SEP> " <tb> <SEP> 25 <SEP> C5H11 <SEP> -#- <SEP> Cl <SEP> F <SEP> 83.0 <SEP> - <SEP> 237.8 <SEP> (VII) <tb> <SEP> 26 <SEP> C5H11 <SEP> -#- <SEP> F <SEP> Cl <SEP> 106.1 <SEP> 144.0 <SEP> 263.6 <SEP> " <tb> <SEP> 27 <SEP> C5H11 <SEP> -#- <SEP> Cl <SEP> Cl <SEP> 112.0 <SEP> - <SEP> 241.7 <SEP> " <tb> <SEP> 28 <SEP> C5H11 <SEP> -#- <SEP> 3-Cl <SEP> F <SEP> 104.8 <SEP> - <SEP> 214.7 <SEP> (XI) <tb> <SEP> 29 <SEP> C5H11 <SEP> -#- <SEP> 3-Cl <SEP> Cl <SEP> 88.8 <SEP> - <SEP> 233.2 <SEP> " <tb> <SEP> 30 <SEP> C5H11 <SEP> -#- <SEP> 2-Cl <SEP> F <SEP> 74.1 <SEP> 106.4 <SEP> 279.6 <SEP> (VIII) <tb> <SEP> 31 <SEP> C5H11 <SEP> -#- <SEP> 2-F <SEP> Cl <SEP> 125.1 <SEP> 218.0 <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> <SEP> 32 <SEP> C5H11 <SEP> -#- <SEP> 2-Cl <SEP> Cl <SEP> 101.0 <SEP> (95.0) <SEP> 299.0 <SEP> " <tb> <SEP> 33 <SEP> C5H11 <SEP> -#- <SEP> 3-Cl <SEP> F <SEP> 109.5 <SEP> 182.6 <SEP> 256.6 <SEP> (XII) <tb> <SEP> 34 <SEP> C5H11 <SEP> -#- <SEP> 3-Cl <SEP> Cl <SEP> 116.0 <SEP> 196.7 <SEP> 266.8 <SEP> " <tb> Example 35 Preparation of trans-4-propyl-trans-4' (4-fluorobenzoyloxy)-octadecahydro-trans p-terphenyl (a compound of the formula (XIII) wherein R=C3H7 and Z=F) Sliced Mg (1.2 g, 0.049 mol) was Introduced into a three-neck flask and a solution (30 mQ) obtained by dissolving 4-bromoanisole (9.2 g, 0.049 mol) in tetrahydrofuran was slowly dropwise added with stirring at a react Ion temperature kept at 30 to 350C in N2 current, during which reaction occurred and Mg uniformly dissolved in 3 hours to form 4-methoxy-phenylmagnesium bromide, to which a solution (50 m±) obtained by dissolving 4-(trans-4-propylcyclohexyl)cyclohexanone (10.9 g, 0.049 mol) in tetrahydrofuran was dropwise added as rapidly as possible at a reaction temperature kept at a reaction temperature of 5 to 100C, followed by raising the temperature up to 35 C, stirring for 30 minutes, adding 3N hydrochloric acid (50 m±), transferring the reaction liquid into a separating funnel, three times extracting with toluene (200 ml), combining the toluene layers, washing with water till the washing liquid became neutral, distilling off toluene under reduced pressure to obtain as a residual oily substance, 4-methoxy-[1-hydroxy-4-(trans 4-propylcyclohexyl)cyclohexyl benzene, adding potassium hydrogen sulfate (6 g) to this material, dehydrating at 160 C for 2 hours in N2 current,cooling, adding toluene (200 m±), filtering off potassium hydrogen sulfate, water-washing toluene layer till the washing liquid became neutral, distilling off toluene under reduced pressure, recrystalling the resulting residual oily substance from ethanol to obtain 4-methoxy-04-(trans-4- propylcyclohexyl)cyclohexen-1-yl]benzene, dissolving the total amount of this material (7.0 g) in ethanol (120 m±) together with Raney Ni (1.0 g), carrying out catalytic reduction at 500C under the atmospheric pressure, to have 500 :n of hydrogen absorbed, filtering off the catalyst, recrystallizing as it was, to obtain a mixture of cis-form and trans-form, repeatedly recrystallizing to isolate the trans-form which was 4-methoxy-[trans-4-(trans-4-propylcyclohexyl) cyclohexyl]benzene (yield: 23 g, 188). This material (15 g) together with hydrobromic acid (47%) (200 mQ) and acetic acid (200 ml) were refluxed for 20 hours for reaction, followed by adding water (500 m±) , filtering off deposited crystals, suffIcIently washing with water and recrystallizing from a mixed solvent of acetone ethanol to obtain 4-gtrans-4-(trans-4-propyl- cyclohexyl)cyclohexylJphenol (XXIII) (yield: 11 g, 77%). The thus prepared 4-rtrans-4-(trans-4- propylcyclohexyl)cyclohexyl]phenyl (8 g) was dissolved in ethanol (400 mQ), followed by adding Ru/C catalyst (1.0 g) r carrying out catalytic reduction at 180 C, under 50 kg/cm2 for 5 hours, filtering off the catalyst, distilling off the solvent under reduced pressure and recrystallizing the residual crystals from acetone (1Q) to obtain trans-4propyl-trans-4"-hydroxy-octadecahydro-transp-terphenyl (XXIV) (yield: 3.8 g, 47%, m.p.: 232 - 2370C). This material (1 g) was dissolved in pyridine (50 ml) and to the solution was added 4-fluorobenzoic acid chloride (1 g), followed by allowing the mixture to stand over night, adding toluene (200 ml), washing the toluene layer in a separating funnel first with 6N HCl, then with 2N NaOH solution and finally with water till the washing liquid became neutral, drying with anhydrous Na2S04, distilling off the toluene layer under reduced pressure and recrystallizing deposited crystals from acetone to obtain the objective trans-4propyl-trans-4"-(4-fluorobenzoyloxy)-octadecahydro-trans-p-terphenyl (yield: 0.8 g, 57%, C-S point: 1020C, S-N point: 225.80C, N-I point: 297.0 C). ExamPles 36 - 57 In Example 35, trans-4-propyl-trans-4"hydroxy-octadecahydro-trans-p-terphenyl was replaced by trans-4-alkyl-trans-4"-hydroxyoctadecahydro-trans-p-terphenyls having other alkyl groups (XXIV) or 4-ttrans-4-(trans-d- alkylcylohexyl)cyclohexyl]phenols (XXIII), and also 4-fluorobenzoic acid chloride, instead other halogenobenzoic acid chlorides or 4cyanobenzoic acid chloride were used to prepare the objective compounds expressed by the formulas (XIII) , (XIV) , (XV) , (XVI) , (XVII) and (XVIII). The results are shown in Table 3 together with those of Example 35. Table 3 EMI28.1 <SEP> In <SEP> formula <SEP> (I) <SEP> Phase <SEP> transition <SEP> point <SEP> ( C) <tb> Example <SEP> Formula <tb> <SEP> R <SEP> -#- <SEP> Y <SEP> Z <SEP> C-S <SEP> point <SEP> or <SEP> S-N <SEP> point <SEP> N-I <SEP> point <tb> <SEP> C-N <SEP> point <tb> <SEP> 35 <SEP> C3H7 <SEP> -#- <SEP> H <SEP> F <SEP> 102.0 <SEP> 225.8 <SEP> 297.0 <SEP> (XIII) <tb> <SEP> 36 <SEP> C4H9 <SEP> -#- <SEP> H <SEP> F <SEP> 87.0 <SEP> 217.8 <SEP> 274.0 <SEP> " <tb> <SEP> 37 <SEP> C7H15 <SEP> -#- <SEP> H <SEP> F <SEP> 72.0 <SEP> 235.0 <SEP> 258.1 <SEP> " <tb> <SEP> 38 <SEP> C7H15 <SEP> -#- <SEP> H <SEP> Cl <SEP> 80.2 <SEP> 226.0 <SEP> 279.5 <SEP> " <tb> <SEP> 39 <SEP> C3H7 <SEP> -#- <SEP> H <SEP> CN <SEP> 159.0 <SEP> 204.3 <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> <SEP> 40 <SEP> C4H9 <SEP> -#- <SEP> H <SEP> CN <SEP> 151.8 <SEP> 209.2 <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> <SEP> 41 <SEP> C7H15 <SEP> -#- <SEP> 2-Cl <SEP> Cl <SEP> 147.3 <SEP> 214.5 <SEP> 298.1 <SEP> " <tb> <SEP> 42 <SEP> C3H7 <SEP> -#- <SEP> 2-Cl <SEP> Cl <SEP> 98.0 <SEP> 190.1 <SEP> 273.5 <SEP> (XV) <tb> <SEP> 43 <SEP> C4H9 <SEP> -#- <SEP> 2-Cl <SEP> Cl <SEP> 86.0 <SEP> 212.2 <SEP> 285.0 <SEP> " <tb> <SEP> 44 <SEP> C7H15 <SEP> -#- <SEP> 2-Cl <SEP> Cl <SEP> 90.0 <SEP> 216.3 <SEP> 268.6 <SEP> " <tb> <SEP> 45 <SEP> C3H7 <SEP> -#- <SEP> 2-Cl <SEP> Cl <SEP> 139.5 <SEP> 159.4 <SEP> 269.6 <SEP> (XVII) <tb> <SEP> 46 <SEP> C4H9 <SEP> -#- <SEP> 3-Cl <SEP> Cl <SEP> 114.0 <SEP> 189.4 <SEP> 267.1 <SEP> " <tb> <SEP> 47 <SEP> C7H15 <SEP> -#- <SEP> 3-Cl <SEP> Cl <SEP> 107.5 <SEP> 210.9 <SEP> 264.4 <SEP> " <tb> Table 3 (continued) EMI29.1 <SEP> In <SEP> formula <SEP> (I) <SEP> Phase <SEP> transition <SEP> point <SEP> ( C) <tb> Example <SEP> Formula <tb> <SEP> R <SEP> -#- <SEP> Y <SEP> Z <SEP> C-S <SEP> point <SEP> or <SEP> S-N <SEP> point <SEP> N-I <SEP> point <tb> <SEP> C-N <SEP> point <tb> <SEP> 48 <SEP> C3H7 <SEP> -#- <SEP> H <SEP> F <SEP> 107.0 <SEP> 195.8 <SEP> 300 <SEP> or <tb> <SEP> higher <SEP> (XIV) <tb> <SEP> 49 <SEP> C4H9 <SEP> -#- <SEP> H <SEP> F <SEP> 115.0 <SEP> 204.3 <SEP> 275.8 <SEP> " <tb> <SEP> 50 <SEP> C3H7 <SEP> -#- <SEP> H <SEP> Cl <SEP> 141.0 <SEP> 201.6 <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> <SEP> 51 <SEP> C4H9 <SEP> -#- <SEP> H <SEP> Cl <SEP> 140.0 <SEP> 179.7 <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> <SEP> 52 <SEP> C3H7 <SEP> -#- <SEP> H <SEP> CN <SEP> 215.0 <SEP> - <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> <SEP> 53 <SEP> C4H9 <SEP> -#- <SEP> H <SEP> CN <SEP> 206.0 <SEP> - <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> <SEP> 54 <SEP> C3H7 <SEP> -#- <SEP> 2-Cl <SEP> Cl <SEP> 108.9 <SEP> 114.2 <SEP> 279.9 <SEP> (XVI) <tb> <SEP> 55 <SEP> C4H9 <SEP> -#- <SEP> 2-Cl <SEP> Cl <SEP> 81.9 <SEP> 136.7 <SEP> 289.6 <SEP> " <tb> <SEP> 56 <SEP> C3H7 <SEP> -#- <SEP> 3-Cl <SEP> Cl <SEP> 145.0 <SEP> 185.0 <SEP> 300 <SEP> or <SEP> (XVIII) <tb> <SEP> higher <tb> <SEP> 57 <SEP> C4H9 <SEP> -#- <SEP> 3-Cl <SEP> Cl <SEP> 137.1 <SEP> 197.5 <SEP> 300 <SEP> or <SEP> " <tb> <SEP> higher <tb> Example 58 (Use example) A liquid-crystalline composition (A) gor.sist ng of trans-4-propyl-(4'-cyanophenyl)cyclohexane (28% by weight) trans-4-pentyl-(4'-cyanophenyl)cyclohexane (42% by weight), and trans-4-heptyl-(4'-cyanophenyl)cyclohexane (30% by weight) has a nematic -clearing point of 52 C. When this liquid crystalline composition was sealed in a TN cell (twisted, nematic cell) of 10 ijm thick, the resulting cell had an actuation threshold voltage of 1.53 V and a saturation voltage of 2.12 V. Its viscosity was 23 cp at 20 C and its optical anisotropy value was 0.120. When trans-4"-propyl-trans-octadecahydro-p terphenyl-trans-4 -carboxyllc acid-4-fluorophenyl ester (3 parts by weight) ("parts by weight" hereinafter being abbreviated to parts) prepared in Example 1 was added to the above liquid-crystalline composition (A) (97 parts), the resulting nematic composition had a nematic-clearing point of 6000. The threshold voltage and saturation voltage were 1.50 V and 2.09 V, respectively. Its viscosity was 23 cp at 2000. Example 59 (Use example) A liquid-crystalline composition obtained by adding 4-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]benzoic acid-4-fluorophenyl ester (5 parts) prepared in Example 5 to the liquid-crystalline composition (A) (95 parts) had a nematic-clearing point of 65 C. The threshold voltage and saturation voltage were i.55 V and 2.14 V, respectively. Its viscosity was 25 cp at 2000. Example 60 (Use example) A liquid-crystalline composition obtained by adding trans-4-[4-(trans-4-pentylcyclohexyl)phenyl]- cyclohexanecarboxylic acid-4-fluorophenyl ester (5 parts) prepared in Example 22 to the liauid- crystalline composition (A) (95 parts) had a N-I point of 62.4 C. The values of the threshold voltage and saturation voltage measured as above were 1.55 V and 2.14 V, respectively. Its viscosity was 24 cp at 200C and its optical anisotropy value was 0.120, that is, almost unchanged. Example 61 (Use example) A nematic composition obtained by adding trans4"-propyl-trans-octadecahydro-p-terphenyl-trans-4carboxylic acid-2-chloro-4-fluoropE.enyl ester (3 parts) prepared in Example 10 to the liquidcrystalline composition (A) (97 parts) had a nematicclearing point of 580C. The threshold voltage and saturation voltage were 1.50 V and 2.09 V, respectively. Its viscosity was 24 cp at 200C. Example 62 (Use example) A liquid-crystalline composition obtained by adding 4-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]benzoic acid-2-chloro-4-fluorophenyl ester (3 parts) prepared in Example 17 to the liquid-crystalline composition (A) (97 parts) had a N-I point elevated to 570C. The threshold voltage and saturation voltage were 1.54 V and 2.15 V, respectively, and its viscosity was 24 cp at 200C, that is, these values only slightly rised, respectively. Example 63 (Use example) A liquid-crystailine composition obtained by adding trans-4- [4- (trans-4-pentylcyclohexyl) phenyll - cyclohexanecarboxylic acid-2-chloro-4-fluorophenyl ester (5 parts) prepared in Example 25 to the iiquid-crystalline composition (A) (95 parts) had a N-I point of 610 C. The values of the threshold voltage and saturation voltage measured above were 1.55 V and 2.14 V, respectively. Its viscosity was 24 cp at 20 C and its optical anisotropy value was 0.120, that is, these values were almost unchanged. Example 64 (Use example) A liquid-crystalline composition (B) consisting of 4-pentyl-4'-cyanobiphenyl (45% by weight), 4-heptyl-41-cyanobiphenyl (29% by weight), 4-octyloxy-4'-cyanobiphenyl (15% by weight) and 4-pentyl-4'-cyanoterphenyl (11%) has a N-I point of 63.3 C, a viscosity of 46 cp at 20 C and a dielectric anisotropy of +12.4. This liquidcrystalline composition was sealed in a cell of 10 m thick composed of two base plates proTq ed with transparent tin oxide electrodes coated with SiO2 and subjected to rubbing treatment to prepare a liquid-crystalline cell. Itscharacteristics properties-were measured at 25 C to give a threshold voltage of 1.65 V and a saturation voltage of 2.31 V. A composition obtained by adding 4'-(trans-4 pentylcyclohexyl) biphenyl-4-carboxylic acid-2-chloro4-fluorophenyl ester (5 parts) of Example 30 of the present invention to the liquid-rystalline composition (B) (95 parts) had a N-I point raised to 74 C. Its viscosity was 45 cp at 20 C and its dielectric anisotropy value was +10.5, that is, these values were reduced. Further the threshold voltage axd saturation voltage were 1.60 V and 2.20 V, respectively, that is, these values were also reduced. Example 65 (Use example) A nematic composition obtained by adding trans-41,- propyl-trans-octadecahydro-p-terphenyl-trans-4carboxylic acid-2-chloro-4-fluorophenyl ester (3 parts) prepared in Example 13 to the liquid-crystalline composition (A) (97 parts) had a nematic-clearing point of 580C, a threshold voltage of 1.49 V and a saturation voltage of 2.09 V. Its viscosity was 24 cp at 20"C. Example 66 (Use example) A composition obtained by adding 4-[trans-4- (trans-4-propylcyclohexyl) cyclohexylbenzoic acid3-chloro-4-fluorophenyl ester (3 parts) prepared in Example 20 to the liquid-crystalline composition (A) (97 parts) had a N-I point of 560C, a threshold voltage of 1.55 V and a saturation voltage of 2.14 V. Its viscosity was 25 cp at 20 C. Example 67 (Use example) A liquid-crystalline composition obtained by adding trans-4-f4-(trans-4-pentylcyclohexyl)phenyl]- cyclohexanecarboxylic acid-3-chloro-4-fluorophenyl ester (5 parts) prepared in Example 28 to the liquid-crystalline composition (A) (95 parts) had a N-I point of 6000. The threshold voltage and saturation voltage measured as above were 1.55 V and 2.14 V, respectively. Its viscosity was 24 cp at 20"C and its optical anisotropy value was 0.120, that is, almost unchanged. Example 68 (Use example) A composition consisting of the liquid-crystalline composition (B) (97 parts) and 4'-(trans-4-pentylcyclohexyl)biphenyl-4-carboxylic acid-3-chlor -4-fluorophenyl ester (3 parts) prepared in Example 33 had a N-I point raised to 690C. Its viscosity was 47 cp at 200C and its dielectric anisotropy value was +10.5, that is, these values were reduced. Further, the threshold voltage and saturation voltage were 1.60 V and 2.20 V, respectively, that is, these values were also reduced. Example 59 (Use example) A nematic composition obtained by adding trans-4"propyl-trans-3-octadecahydro-p-terphenyl-trans-4carboxylic acid-4-cyanophenyl ester (3 parts) prepared in Example 3 to the liquid-crystalline composition (A) (97 parts) had a nematic-clearing point of 61 C, a threshold voltage of 1.54 V and a saturation voltage of 2.13 V. Its viscosity was 25 cp at 2000. Example 70 (Use example) A composition obtained by adding 4-[trans-4propylcyclohexyl)cyclohexyl]benzoic acid-4-cyanophenyl ester (2 parts) prepared in Example 9 to the liquidcrystalline composition (A) (98 parts) had a nematicclearing point of 58 C, a threshold voltage of 1.55 V and a saturation voltage of 2.14 V. Its viscosity was 25 cp at 2C C. Example 71 (Use example) A liquid-crystalline composition obtained by adding trans-4- [4- (trans-4-pentylcyclohexyl) phenyl] - cyclohexanecarboxylic acid-4-cyanophenyl ester (3 parts) prepared in Example 24 to the liquidcrystalline composition (A) (97 parts) had a N-I point of 5900. The threshold voltage and saturation voltage measured as above were 1.54 V and 2.13 V, respectively. Its viscosity was 24 cp at 20 C and its optical anisotropy value was 0.120, that is, these values were almost unchanged. Example 72 (Use example) A liquid-crystalline composition obtained by adding trans-4-propyl-trans-4"- (4-fluorobenzyloxy) octadecahydro-trans-p-terphenyl (3 parts) prepared in Example 35 to the liquid-crystalline composition (A) (97 parts) had a N-I point raised to 58 C and when this composition was made up into a TN cell as described above, the threshold voltage and saturation voltage were 1.55 V and 2.14 V, respectively. Its viscosity was 26 cp at 2000. Example 73 (Use example) A liquid-crystalline composition obtained by adding trans-4-propyl-trans-4"- (4-cyanobenzoyloxy) - octadecahydro-trans-p-terphenyl (3 parts) prepared in Example 39 to the liquid-crystalline composition (A) (97 parts) had a N-I point raised to 580C and when this composition was made up into a TN cell as described above, the threshold voltage and saturation voltage were 1.55 V and 2.14 V, respectively. Its viscosity was 28 cp at 2000. Example 74 (Use example) A liquid-crystalline composition obtained by adding 4-fluorobenzoic acid-4-[trans-4-(trans-4propylcyclohexyl)cyclohexyl]phenyl ester (3 parts) prepared in Example 48 to the liquid-crystalline composition (A) (97 parts) had a N-I point raised to 6100 and when this composition was made up into a TN cell as described above, the threshold voltage and saturation voltage were 1.55 V and 2.14 V, respectively. Its viscosity was 28 cp at 2000. Example 75 (Use example) A liquid-crystalline composition obtained by adding 4-cyanobenzoic acid-4-[trans-4-(trans-4 propylcyclohexyl)cyclohexyl]phenyl ester (2 parts) prepared in Example 52 to the liquid-crystalline composition (A) (98 parts) had a N-I point raised to 590C and when this composition Tas made up into a TN cell as described above, the threshold voltage and saturation voltage were 1.55 V and 2.14 V, respectively. Its viscosity was 29 cp at 20"C. Example 76 (Use example) A liquid-crystalline composition obtained by adding trans-4-propyl-trans-4"- (2 ,4-dicyclobenzoyloxy) octadecahydro-trans-p-terphenyl (3 parts) prepared in Example 42 to the liquid composition (A) (97 parts) had a N-I point raised to 58"C, and when this composition was made up into a TN cell as described above, the threshold voltage and saturation voltage were 1.55 V and 2.14 V, respectively. Its viscosity was 27 cp at 2000. Example 77 (Use example) A liquid-crystalline composition obtained by adding 2,4-dichlorobenzoic acid-4-[trans-4-(trans 4-propylcyclchexyl]phenyl ester (3 parts) prepared in Example 54 to the liquid-crystalline composition (A) (97 parts) had a N-I point raised to 58 C, and when this composition was made up into a TN cell as described above, the threshold voltage and saturation voltage were 1.55 V and 2.14 V, respectively. Its viscosity was 28 cp at 20at. Example 78 (Use example) A liquid-crystalline composition obtained by adding trans-4 -propyl-trans-4 "- (3 '4 -dichlorobenzoyloxy) - octadecahydro-trans-p-terphenyl (3 parts) prepared in Example 56 to the liquid-crystalline composition (A) (97 parts) had a N-I point raised to 58 C, and when this composition was made up into a TN cell as described above, the threshold voltage and saturation voltage were 1.55 V and 2.14 V, respectively. Its viscosity was 27 cp at 2000. Example 79 (Use example) A liquid-crystalline composition obtained by adding 3 ,4-dichlorobenzoic acid-4- [trans-4- (trans- 4-propylcyclohexyl) cyclohexyl]phenyl ester (3 parts) prepared in Example 56 to the -liquid-crystalline composition (A) (97 parts) had a N-I point raised to 60 C, and when this composition was made up into a TN cell as described above, the threshold voltage and saturation voltage were 1.55 V and 2.14 V, respectively. Its viscosity was 28 cp at 2000.

Claims: CLAIMS: 1. Liquid-crystalline ester compounds expressed by the general formula EMI40.1 wherein R represents a hydrogen atom or an alkyl group of 1 to 10 carbon atoms; EMI40.2 and EMI40.3 each represent EMI40.4 X represents EMI40.5 represents a hydrogen atom, F, CQ or CN; and Z represents F, Cl l or CN. 2. Trans-4"-alkyl-trans-octadecahydro-p-terphenyl-trans-4 -carboxylic acid 4-substituted phenyl esters expressed by the general formula EMI40.6 wherein R and Z each have the same definitions as in claim 1. 3. 4-[Trans-4-(trans-4-alkylcyclohexyl)cyclo-hexyl]benzOic acid 4-substituted phenyl esters expressed by the general formula EMI40.7 wherein R and Z each have the same definitions as in claim 1. 4-Trans-4-[4-(trans-4-alkylcylohexyl)phenyl] cyclohexanecarboxylic acid 4-substituted phenyl esters expressed by the general formula EMI41.1 wherein R and Z each have the same definitions as in claim 1. 5. Trans-4"-alkyl-trans-octadecahydro-p-terphenyltrans-4-carboxylic acid 2 ,4-dlhalogenophenyl esters expressed by the general formula EMI41.2 wherein R has the same definition as in claim and Y and Z each represent F or Cl. 6. 4-[Trans-4-(trans-4-alkylcylohexyl)cyclohexyl] benzoic acid 2,4-dihylogenophenyl esters expressed by the general formula EMI41.3 wherein R has the same definition as in claim 1 and Y and Z each represent F or Cl. 7. Trans-4-[4-(trans-4-alkylcylohexyl)phenyl] cyclohexanecarboxylic acid 2, 4-dihalogenophenyl esters expressed by the general form EMI41.4 wherein R has the same definition as in claim 1 and Y and Z each represent F or Ci. 8. 4-(Trans-4-alkylcylohexyl)biphenyl-4carboxylic acid 2,4-dihalogenophenyl esters expressed by the general formula EMI42.1 wherein R has the same definition as in claim 1 and Y and Z each represent F or Cl. 9. Trans-4" -alkyl-trans-octadecahydro-p- terphenyl-trans-4-carboxylic acid 3,4-dihalogenophenyl esters expressed by the general formula EMI42.2 wherein R has the same definition as in claim 1 and Y and Z each represent F or CZ. 10. 4-CTrans-4-(trans-4-alkylcyclohexyl) cyclohexyli benzoic acid 3,4-dihalogenophenyl esters expressed by the general formula EMI42.3 wherein R has the same definition as in claim 1 and Y and Z each represent F or CZ. 11. Trans-4-[4-(trans-4-alkylcylohexyl) phenyl]cyclohexanecarboxylic acid 3,4-dihalogeno phenyl esters expressed by the general formula EMI43.1 wherein R has the same definition as in claim 1 and Y and Z each represent F or Cl. 12. 4-(Trans-4-alkylcylohexyl)biphenyl-4carboxylic acid 3,4-dihalogenophenyl esters expressed by the general formula EMI43.2 wherein R has the same definition as in claim 1 and v and Z each represent F or Cl. 13. Trans-4-alkyl-trans-4"-(4-substituted benzoyloxy) octadecahydro-trans-p-terphenyls expressed by the general formula EMI43.3 wherein R has the same definition as in claim 1 and Z represents F, Ct or CN. 14. 4-Substituted benzoic acid 4-trans-4- (trans-4-alkylcylohexyl)cyclohexyl]phenyl esters expressed by the general formula EMI43.4 wherein R has the same definition as In claim and Z represents F, CZ or CN. 15. Trans-4-alkyl-trans-4"-(2,4-dichlorobenzoyloxy)octadecahydro-trans-p-terphenyls expressed by formula EMI44.1 wherein R has the same definition as in claim 1. 16. 2,4-Dichlorobenzoic acid 4-ttrans-4-(trans-4- alkylcyclohexyl)cyclohexyl]phenyl esters expressed by the general formula EMI44.2 wherein R has the same definition as in claim 1. 17. Trans-4-alkyl-trans-4"-(3,4-diclorbenzoyloxy) octadecahydro-trans-p-terphenyls expressed by the general formula EMI44.3 wherein R has the same definition as in claim 1. 18. 3,4-Dichlorobenzoic acid 4-[trans-4-(trans-4- alkylcyclohexyl) cyclohexyl phenyl esters expressed by the general formula EMI44.4 wherein R represents hydrogen atom or an alkyl group of 1 to 10 carbon atoms. 19. A liquid-crystalline composition comprising at least one one compound of the formula (I) of claim 1 together with at least one other liquid-crystalline compound.

Inventors: KOJIMA, TETSUHIKO, SUGIMORI, SHIGERU
Applicants: CHISSO CORPORATION
Application year: 1983
Main classification: C07C69
IPC codes: C07C69, C09K19, C07C255