Optically active compound, antiferroelectric liquid crystal composition containing the same, process for producing the same and process for producing optically active carboxylic acid

Abstract: Disclosed is a novel optically active compound which exhibits no antiferroelectric liquid crystal phase but can be incorporated in an antiferroelectric liquid crystal having a high threshold voltage to reduce the threshold voltage thereof, an antiferroelectric liquid crystal composition containing the compound, a process for the reduction of the threshold voltage of an antiferroelectric liquid crystal composition, a process for producing the compound and a process for producing an optically active carboxylic acid as an intermediate.

Description: The present invention relates to a novel optically active compound useful as a liquid crystal material to be incorporated in an optical switching element employing a liquid crystal. More particularly the present invention relates to an antiferroelectric liquid crystal composition containing such an optically active compound. In addition, the present invention relates to a process for producing such an optically active compound and also relates to a process for producing an optically active carboxylic acid which is used for producing such an optically active compound. The antiferroelectric liquid crystal was discovered by Chandani et al. in 1988 (Chandani et al., Jpn.J.Appl.Phys., 27, L279 (1988).) and has been noted as a future liquid crystal substituting for the nematic liquid crystal which is incorporated in liquid crystal display devices at present. The switching time of the nematic liquid crystal which is incorporated in liquid crystal display devices at present is as slow as typically 30 milliseconds. Thus, these display devices are fabricated such that a driving method employing a thin film transistor (TFT) requiring a very high production cost called active matrix is used. Further, a display system called twisted nematic (TN) is disadvantageous in that it essentially gives a narrow viewing angle. The antiferroelectric liquid crystal has a switching time as fast as several tens of microseconds. In the antiferroelectric liquid crystal, liquid crystal molecules make response in plane. Thus, a wide viewing angle can be given. Further, the antiferroelectric liquid crystal exhibits a definite threshold voltage even when subjected to application of voltage and thus can be easily driven. Accordingly, the antiferroelectric liquid crystal can constitute a display device driven by a driving method requiring a low production cost called simple matrix. On the other hand, a ferroelectric liquid crystal found by Meyer et al. in 1975 (R. B. Meyer et al., J. Phys.(France), 36, L69, (1975)) was expected to constitute a high definition liquid crystal display because of its fast response. However, a full color image display with the use of ferroelectric liquid crystal has not yet been realized because of the difficulty to produce gray levels. With the antiferroelectric liquid crystal, gray scale has been realized. Therefore, a full-color animation display has already been achieved, though being made on an experimental basis. As mentioned above, the liquid crystal display employing an antiferroelectric liquid crystal is expected to realize a high definition display having a wide viewing angle with a low cost simple matrix. However, compounds exhibiting an antiferroelectric liquid crystal phase are extremely restricted from the structural point of view. The most of these compounds have a terminal structure such as 1-substituted alkyl benzoic acid ester as exemplified by the following structural formula (see Future Liquid Crystal Display and Its materials, supervised by Atsuo Fukuda, CMC, (1992)): wherein Y represents an alkyl group or a perfluoroalkyl group. The antiferroelectric liquid crystal to be incorporated in display devices must have a practical working temperature range as the nematic liquid crystal in general use and exhibit various properties concerning display quality. Thus, it is necessary that antiferroelectric liquid crystal compounds having different properties be mixed to form the desired liquid crystal composition. However, since the structure that allows the appearance of an antiferroelectric liquid crystal phase is restricted as mentioned above, allowable structural modifications are only the introduction of alicyclic group, condensed ring or heterocyclic group into the core structure and the introduction of ether bond into chiral terminal alkyl chain. The resulting compound is very akin to the original compound in properties. Thus, a practical liquid crystal composition which must have various properties can hardly be obtained. Thus, the development of liquid crystal compounds having different properties is indispensable to obtain an antiferroelectric liquid crystal having practical properties. On the other hand, the inventors have found that a compound having the following structure can exhibit an antiferroelectric liquid crystal phase (see JP-A-4-82862 (The term "JP-A" as used herein means an "unexamined published Japanese patent application")) . This compound has 2-methylalkanoic acid incorporated therein and thus exhibits a stable antiferroelectric liquid crystal phase. However, this compound exhibits a high viscosity because its core structure is similar to that of the known antiferroelectric liquid crystal and it has a high threshold voltage. These disadvantage should be improved. The inventors also have found that an antiferroelectric liquid crystal phase appears when 2-methylalkanoic acid is introduced into the core of a heterocyclic compound such as diphenylpyrimidine (see JP-A-9-31063). This compound has a lower viscosity than the foregoing ester compounds and thus is useful. However, this compound also has a high threshold voltage which should be improved. EP-A-0739884 discloses a liquid crystal compound exhibiting an antiferroelectric liquid crystal phase and a liquid crystal composition containing said compound. The liquid crystal compound is represented by the following formula: wherein R 1 represents a straight-chain or branched alkyl, alkoxy, alkoxycarbonyl, alkanoyloxy or alkoxycarbonyloxy group having 4 to 16 carbon atoms: R 2 represents a straight-chain alkyl group having 4 to 10 carbon atoms or branched alkyl group containing to 3 carbon atoms in its branch and 4 to 12 carbon atoms in total: X represents an oxygen or sulfur atom: rings A and B each represent an F-substituted or unsubstituted phenylene group, a cyclohexylene group or a divalent nitrogen-containing heterocyclic group, provided that either one of rings A and B is the nitrogen-containing heterocyclic group: ring C represents an F-substituted or unsubstituted phenylene group; and C* represents an asymmetric carbon atom. An object of the present invention is to provide a novel optically active compound which exhibits no antiferroelectric liquid crystal phase but can be incorporated in an antiferroelectric liquid crystal having a high threshold voltage to lower the threshold voltage thereof, an antiferroelectric liquid crystal composition containing such a novel optically active compound and processes for producing such a novel optically active compound and its intermediate at a low cost The inventors sought an optically active compound which can reduce the threshold voltage of the foregoing antiferroelectric liquid crystal compound having a high threshold voltage. As a result, it was found that an optically active compound which exhibits no antiferroelectric liquid crystal phase but can be incorporated in the foregoing antiferroelectric liquid crystal and antiferroelectric liquid crystal composition having a high threshold voltage to lower the threshold voltage thereof and that such an optically active compound and notably its intermediate can be produced by a low cost process. Thus, the present invention has been worked out In other words, the first aspect of the present invention relates to an optically active compound selected from the compounds represented by the following general formulae (1) and (2): wherein R 1 represents an alkyl or alkoxy group of 5 to 14 carbon atoms; R 2 represents an alkyl group of 2 to 12 carbon atoms; 1 and m each represent 0 or 1; n is an integer from 2 to 4; D represents -OCO- or -OCOC*R 3 H-, with the proviso that in the case D is -OCO-, R 4 represents a fluorine atom or a trifluoromethyl group and R 5 represents a hydrogen atom or a fluorine atom; if D is -OCOC*R 3 H-, R 3 is a methyl group, R 4 is a fluorine atom, R 5 is a hydrogen atom, and C* represents an asymmetric carbon atom; and the compounds 5-(4-decylphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine, 5-(4-octylphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine, 5-(4-decyloxyphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(4-((R)-1-trifluoromethylpentyloxymethyl)phenyl)-1,3-pyrimidine, 5-(3-fluoro-4-octyloxyphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(3-fluoro-4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(4-((2S,3R)-2,3-dimethylheptanoyloxy)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(4-((2S,3S)-2,3-dimethylheptanoyloxy)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(4-((1S,2R)-2-methyl-1-cyclohexanecarbonyloxy)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(3-fluoro-4-((1S,2R)-2-methyl-1-cyclohexanecarbonyloxy)phenyl)-1,3-pyrimidine and 5-(4-octyloxyphenyl)-2-(4-((R)-1-methylbutyloxymethyl)phenyl)-1,3-pyrimidine. The second aspect of the present invention relates to an antiferroelectric liquid crystal composition containing at least one optically active compound according to the first aspect of the present invention. The third aspect of the present invention relates to a process for the reduction of the threshold voltage of an antiferroelectric liquid crystal composition which comprises incorporating at least one optically active compound according to the first aspect of the present invention into an antiferroelectric liquid crystal composition. The forth aspect of the present invention relates to a process for the production of the optically active compound represented by the general formula (1), comprising reacting a compound represented by the following general formula (3): wherein R 1 , l and m have the same meaning as above, and W represents a hydroxy group, with a compound represented by the following general formula (4): wherein R 2 has the same meaning as above and X represents COOH, COCl, -C*R 3 HCOOH, or -C*R 3 HCOCl, with the proviso that in the case X is COOH or COCl, R 4 represents a fluorine atom or a trifluoromethyl group and R 5 represents a hydrogen atom or a fluorine atom, if X is -C*R 3 HCOOH or -C*R 3 HCOCl, R 3 is a methyl group, R 4 is a fluorine atom, R 5 is a hydrogen atom, and C* represents an asymmetric carbon atom. The fifth aspect of the present invention relates to a process for the production of an optically active carboxylic acid represented by the general formula (5): wherein R 2 represents an alkyl group of 4 to 12 carbon atoms and C* represents an asymmetric carbon atom, comprising the following steps: wherein R 10 is an alkyl group of 1 to 9 carbon atoms. Fig. 1 illustrates an electro-optic response (double hysteresis) observed in an antiferroelectric liquid crystal and gives definition of threshold voltage; and Fig. 2 is a typical diagram of response of a liquid crystal molecule under the application of a rectangular or triangular wave. The present invention will be further described hereinafter. As a preferred optically active compound of the present invention there is exemplified a compound of the foregoing general formula (I) as given below. wherein R 1 , R 2 , l, and m are the same as those described previously, n is an integer from 2 to 4, R 1 is selected from the group consisting of pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group and tetradecyl group or their alkyloxy group, and R 2 is selected from the group consisting of ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group and dodecyl group, C 1-11 methyl-substituted alkyl group, C 3-10 ethyl-substituted alkyl group, C 3-10 dimethyl-substituted alkyl group, C 4-9 propyl-substituted alkyl group and trimethylalkyl group. Most of the various compounds of the present invention having the specified basic structure exhibit no antiferroelectric liquid crystal phase but can be incorporated in an antiferroelectric liquid crystal having a high threshold voltage to lower the threshold voltage thereof. Further, two or more of the various compounds may be used in admixture. Moreover, the compound of the present invention has a good miscibility with a known antiferroelectric liquid crystal compound and thus can easily form an antiferroelectric liquid crystal composition also when mixed therewith. As a preferred example of such a known antiferroelectric liquid crystal compound there may be used a compound terminated by the following groups : wherein R 8 represents a straight-chain alkyl group or an alkyl group having an ether bond. Particularly preferred examples of such a compound will be given below. wherein R 8 represents a straight-chain alkyl group or an alkyl group having an ether bond; R 9 represents an alkyl group or an alkoxy group; s represents 1 or 2; and t represents 0 or 1. Other examples of the foregoing compound include compounds obtained by substituting some of hydrogen atoms in the phenylene group in the foregoing general formulae by fluorine atoms. In the case where the optically active compounds of the present invention and the foregoing known antiferroelectric liquid crystal compounds or their compositions are mixed to obtain an antiferroelectric liquid crystal composition, the content of the optically active compounds of the present invention is preferably from 1 to 40% by weight. On the other hand, the optically active compound of the present invention has a good miscibility with a known compound which exhibits a smectic C phase or chiral smectic C phase but doesn't exhibit an antiferroelectric liquid crystal phase, such as phenylpyrimidine and phenyl benzoate. Therefore, the optically active compound of the present invention can be mixed with such a compound to obtain a ferroelectric liquid crystal composition. In addition, the resulting ferroelectric liquid crystal composition can be mixed with antiferroelectric liquid compounds or their composition so far as the layer structure of antiferroelectric liquid crystal phase can be maintained to obtain a desired antiferroelectric liquid crystal composition. In this case, the content of the optically active compound of the present invention and ferroelectric liquid crystal compounds or their composition is preferably from 1 to 40 % by weight, more preferably from 1 to 30 % by weight. Thus, the optically active compounds of the present invention exhibit no antiferroelectric liquid crystal phase but can be mixed with antiferroelectric liquid crystal compounds or their composition to reduce the threshold voltage thereof, and can be incorporated in electro-optic elements employing an antiferroelectric liquid crystal. Further, the compound of the present invention has a good miscibility with many known conventional liquid crystal compounds and thus can provide a liquid crystal material having improved temperature characteristics. Further, the optically active compound of the present invention can be incorporated in an antiferroelectric liquid crystal compound having a high threshold voltage to lower the threshold voltage thereof, making it possible to obtain an even more desirable antiferroelectric liquid crystal composition. The optically active compound of the present invention represented by the foregoing general formula (I) can be synthesized by, e.g., the following method. For example, optically active 2-fluoroalkanoic acids can be synthesized by fluorinating the corresponding 2-hydroxyalkanoates with a fluorinating agent such as hexafluoropropene diethylamine, followed by hydrolysis. Moreover, 2-fluoroalkanoic acids can be also obtained by asymmetrically hydrogenating 2-fluoro-2-alkenoic acid. Optically active 2-trifluoromethylalkanoic acids can be obtained by optically resolving the racemates of 2- trifluoromethylalkanoic acids or derivative thereof with lipase. Further, optically active 2-trifluoromethylalkanoic acids can be synthesized also with the use of a chiral auxiliary as follows. Optically active 2-fluoro-2-trifluoromethylalkanoic acids can be obtained by optical resolution with the chiral auxiliary described above and also synthesized by the following novel process. Thus, optically active 2-fluoro-2-trifluoromethylalkanoic acids can be prepared from optically active 1-substituted allylalcohol with hexafluoropropene diethylamine. In this scheme, R 10 is an alkyl group of 1 to 9 carbon atoms and R 2 is an alkyl group of 4 to 12 carbon atoms. Further, 2,3-dialkylcarboxylic acids can be prepared with a chiral Sultam as shown in the next scheme. In addition, 2-methyl-3-fluoroalkanoic acids can be synthesized from optically active β-hydroxyacids obtained by asymmetric hydrogenation of β-ketoacids as follows. Optically active 1,1,1-trifluoro-2-alkanols can be optically resolved from the corresponding racemates with lipase. The core moiety of the compound of the present invention can be synthesized by an ordinary method. The compounds of the present invention can be obtained from the core moiety by condensation with 2-substituted alkanoic acids or with 2-alkanols. A method for the synthesis of the compound of the general formula (1) wherein D is -OCO- or -OCOC*R 3 H- will be described hereinafter. Firstly, a diphenylpyrimidine derivative is obtained from a perchlorate derivative of (3-dimethylamino-2-(4-alkyl or 4-alkoxyphenyl)propenylidene)dimethyl ammonium and a p-hydroxybenzamidine hydrochloride by a conventional method. The diphenylpyrimidine derivative prepared is then subjected to ordinary esterification with the foregoing optically active alkanoic acids to obtain the desired compound. An example of the synthesis route will be given below. EXAMPLES The present invention will be further described in the following examples. The phase transition temperature as used hereinafter was determined by visual observation under a polarizing microscope equipped with a hot stage and measurement by a differential scanning calorimeter (DSC). The identification of various liquid crystal phases was carried out by so-called miscibility test and contact method. For the evaluation of various liquid crystal compounds and compositions, a liquid crystal evaluation cell was employed, which was obtained by providing a transparent conductive film (indium tin oxide: ITO) on two sheets of glass substrates, coating these glass substrates with an oriented film made of a polyimide or a polyvinyl alcohol, rubbing these glass substrates, and then laminating these glass substrates in such an arrangement that the direction of rubbing on them are parallel to each other. The cell thus prepared had a gap of 2.3 µm. For the measurement of electro-optic effects such as threshold voltage, a temperature-controlled liquid crystal cell disposed between a polarizer and an analyzer arranged in crossed Nicols was irradiated with He-Ne laser. Under these conditions, the response of the liquid crystal to a voltage applied was determined by observing the change of transmittance measured by an photo-electron multiplier. The threshold voltage is defined as voltage required to give a transmittance of 90 % assuming that dark level corresponds to a transmittance of 0 % and bright level corresponds to a transmittance of 100 % under the application of triangular wave. The term "Tc " as used hereinafter is meant to indicate the upper limit temperature for antiferroelectric liquid crystal phase. EXAMPLE 1 Synthesis of 5-(3-fluoro-4-octyloxyphenyl)-2-(3-fluoro-4-((S)-2-fluoropeptanoyloxy)phenyl)-1,3-pyrimidine Into a reaction flask were charged 0.77 g of 5-(3-fluoro-4-octyloxyphenyl)-2-(3-fluoro-4-hydroxyphenyl)-1,3-pyrimidine, 0.41g of (S)-2-fluoroheptanoic acid, 0.86 g of dicyclohexylcarbodiimide (DCC), 116 mg of dimethylaminopyridine (DMAP) and 40 ml of 1,2-dichloroethane in a stream of nitrogen. The mixture was then stirred for 3 hours at room temperature. After the filtration of the resulting salt, the filtrate was evaporated to dryness. The raw product obtained was purified by silica gel column chromatography (toluene:ethyl acetate=10:1) and then by medium pressure liquid chromatography to obtain 0.88g of the desired compound (yield: 87.3 %). 1 H-NMR(CDCl 3 ) δ: 0.90 (t, 3H, J=7.0 Hz), 0.94 (t, 3H, J=7.2 Hz), 1.26-1.42 (m, 12H), 1.45-1.53 (m, 2H), 1.57-1.63 (m, 2H), 1. 82-1.90 (m, 2H), 2.03-2.20 (m, 2H), 4.10 (t, 2H, J=6.6 Hz), 5.23 (dt, 1H, J=48.7 Hz, J=5.9 Hz), 7.10 (t, 1H, J=8.5 Hz), 7.26-7.39 (m, 3H), 8.31-8.36 (m, 2H), 8.95 (s, 2H) MS(m/z): 542 (M + ) This compound melted and changed to a ferroelectric liquid crystal phase (SmC* phase) at a temperature of 81.3 °C and then to an isotropic phase at 140.7 °C. REFERENCE EXAMPLE 1 Synthesis of 5-(4-decylphenyl)-2-(4-((S)-2.6,-dimethylheptanoyloxy)phenyl)-1,3-pyrimidine The procedure of Example 1 was followed except that 5-(3-fluoro-4-octyloxyphenyl)-2-(3-fluoro-4-hydroxy)phenyl)-1,3-pyrimidine was replaced by 5-(4-decylphenyl)-2-(4-hydroxyphenyl)-1,3-pyrimidine and (S)-2-fluoroheptanoic acid was replaced by (S)-2,6-dimethylheptanoic acid. Thus, 5-(4-decylphenyl)-2-(4-((S)-2,6,-dimethylheptanoyloxy)phenyl)-1,3-pyrimidine was prepared. This compound melted to give an antiferroelectric liquid crystal phase at 100.7 °C, and changed to an isotropic phase at 131.7 °C. This compound was injected into a liquid crystal cell and then measured for threshold voltage at a temperature of 116.7 °C (Tc-15 °C). As a result, the threshold voltage was 59 V. EXAMPLE 2 To the compound shown in Reference Example 1 was added the compound set forth in Example 1 in an amount of 10.1 % by weight and a liquid crystal composition was obtained. This composition changed from an isotropic phase to a SmC* phase at 129.4 °C and then exhibited an antiferroelectric liquid crystal phase at 128.9 °C (Tc). This antiferroelectric liquid crystal composition thus obtained was injected to a liquid crystal cell and measured for threshold voltage at a temperature of (Tc-15 °C). As a result, the threshold voltage was 38.4 V. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 1 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 3 Synthesis of 5-(4-octylphenyl)-2-(3-fluoro-4-((S)-2-fluoroheptanoyloxy)phenyl)-1,3-pyrimidine The procedure of Example 1 was followed except that 5-(3-fluoro-4-octyloxyphenyl)-2-(3-fluoro-4-hydroxy)phenyl)-1,3-pyrimidine was replaced by 5-(4-octylphenyl)-2-(3-fluoro-4-hydroxyphenyl)-1,3-pyrimidine. Thus, the title compound was obtained. 1 H-NMR(CDCl 3 ) δ : 0.89 (t, 3H, J=7.0 Hz), 0.94 (t, 3H, J=7.1 Hz), 1.26-1.42 (m, 14H), 1.58-1.70 (m, 4H), 2.03-2.14 (m, 2H), 2.68 (t, 2H, J=7.8 Hz), 5.23 (dt, 1H, J=48.8 Hz, J=5.9 Hz), 7.30 (m, 1H), 7.35 (d, 2H, J=8.3 Hz), 7.55 (d, 2H, J=8.3 Hz), 8.32-8.37 (m, 2H), 9.00 (s, 2H) MS(m/z): 508 (M + ) This compound melted to give a ferroelectric liquid crystal phase (SmC* phase) at a temperature of 89.9 °C, exhibited a smectic A (SmA) phase at 140 °C and then changed to an isotropic phase at 165 °C. When this compound was added to the compound of Reference Example 1 in an amount of 10.0 % by weight, the liquid crystal composition was obtained. This composition changed from an isotropic phase to a smectic A phase at a temperature of 129.5 °C, exhibited SmC* phase at a temperature of 129.3 °C and then changed to an antiferroelectric liquid crystal phase at a temperature of 128 °C (Tc). This antiferroelectric liquid crystal composition was injected to a liquid crystal cell, and then measured for threshold voltage at a temperature of (Tc-15 °C). The results were 40.8 V. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 3 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 4 Synthesis of 5-(4-octyloxyphenyl)-2-(4-((S)-2-fluoroheptanoyloxy)phenyl)-1,3-pyrimidine The procedure of Example 1 was followed except that 5-(3-fluoro-4-octyloxyphenyl)-2-(3-fluoro-4-hydroxy)phenyl)-1,3-pyrimidine was replaced by 5-(4-octyloxyphenyl)-2-(4-hydroxyphenyl)-1,3-pyrimidine. Thus, the title compound was obtained. 1 H-NMR(CDCl 3 ) δ : 0.90 (t, 3H, J=7.0 Hz), 0.94 (t, 3H, J=7.1 Hz), 1.26-1.42 (m, 12H), 1.45-1.52 (m, 2H), 1.57-1.63 (m, 2H), 1.79-1.86 (m, 2H), 2.02-2.15 (m, 2H), 4.02 (t, 2H, J=6.6 Hz), 5.17 (dt, 1H, J=48.8 Hz, J=5.9 Hz), 7.05 (d, 2H, J=8.8 Hz), 7.27 (d, 2H, J=8.8 Hz), 7.56 (d, 2H, J=8.9 Hz), 8.53 (d, 2H, J=8.9 Hz), 8.97 (s, 2H) MS(m/z): 506 (M + ) This compound melted to give an unidentified smectic phase of high order at 124.6 °C, changed to another unidentified smectic phase of high order at 132.2 °C, exhibited SmC* phase at 139.6 °C and changed to SmA phase at 180.9 °C and then to an isotropic phase at 205 °C. When this compound was added to the compound of Reference Example 1 in an amount of 20.0 % by weight, the liquid crystal composition was obtained. This composition changed from an isotropic phase to a smectic A phase at 140.4 °C, exhibited SmC* phase at 139.1 °C and then changed to an antiferroelectric liquid crystal phase at a temperature of 129.7 °C (Tc). This antiferroelectric liquid crystal composition obtained was injected to a liquid crystal cell, and then measured for threshold voltage at a temperature of (Tc-15 °C). As a result the threshold voltage was 30 V. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 4 in an amount of 20% by weight also provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 5 Synthesis of 5-(4-decylphenyl)-2-(4-((S)-2-trifluoromethyloctanoyloxy)phenyl)-1,3-pyrimidine The procedure of Example 1 was followed except that 5-(3-fluoro-4-octyloxyphenyl)-2-(3-fluoro-4-hydroxy)phenyl)-1,3-pyrimidine was replaced by 5-(4-decylphenyl)-2-(4-hydroxyphenyl)-1,3-pyrimidine and (S)-2-fluoroheptanoic acid was replaced by (S)-2-trifluoromethyloctanoic acid. Thus, the desired compound was obtained. 1 H-NMR(CDCl 3 ) δ : 0.88 (t, 3H, J=6.9 Hz), 0.91 (t, 3H, J=6.9 Hz), 1.22-1.60 (m, 22H), 1.62-1.70 (m, 2H), 1.88-1.98 (m, 1H), 2.02-2.15 (m, 1H), 2.68 (t, 2H, J=7.7 Hz), 3.32-3.43 (m, 1H), 7.24 (d, 2H, J=8.9 Hz), 7.34 (d, 2H, J=8.3 Hz), 7.55 (d, 2H, J=8.3 Hz), 8.55 (d, 2H, J=8.9 Hz), 9.01 (s, 2H) MS(m/z): 582 (M + ) This compound melted to exhibit an unidentified smectic phase of high order at a temperature of 60.6 °C, and then became an isotropic phase at a temperature of 80.7 °C. When this compound was added to the compound of Reference Example 1 in an amount of 9.5 % by weight, the liquid crystal composition was obtained. This composition had the upper limit temperature of antiferroelectric liquid crystal phase (Tc) at 123.7 °C. This antiferroelectric liquid crystal composition obtained was injected to a liquid crystal cell, and then measured for threshold voltage at a temperature of (Tc-15 °C). As a result the threshold voltage was 40.8 V. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 5 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 6 Synthesis of 5-(4-decylphenyl)-2-(3-fluoro-4-((R)-2-trifluoromethyloctanoyloxy)phenyl)-1,3-pyrimidine The procedure of Example 5 was followed except that 5-(4-decylphenyl)-2-(4-hydroxyphenyl)-1,3-pyrimidine was replaced by 5-(4-decylphenyl)-2-(3-fluoro-4-hydroxyphenyl)-1,3-pyrimidine and (S)-2-trifluoromethyloctanoic acid was replaced by (R)-2-trifluoromethyloctanoic acid. Thus, the desired compound was obtained. 1 H-NMR(CDCl 3 ) δ : 0.88 (t, 3H, J=6.9 Hz), 0.91 (t, 3H, J=7.0 Hz), 1.20-1.68 (m, 22H), 1.70-1.72 (m, 2H), 1.88-1.98 (m, 1H), 2.02-2.16 (m, 1H), 2.68 (t, 2H, J=7.7 Hz), 3.38-3.48 (m, 1H), 7.25-7.28 (m, 1H), 7.35 (d, 2H, J=8.4 Hz), 7.55 (d, 2H, J=8.4 Hz), 8.32-8.37 (m, 2H), 9.00 (s, 2H) MS(m/z): 600 (M + ) This compound melted to give an unidentified smectic phase of high order at a temperature of 52 °C and then became an isotropic phase at a temperature of 71 °C. EXAMPLE 7 Synthesis of 5-(4-decyloxyphenyl)-2-(4((R)-2-trifluoromethyloctanoyloxy)phenyl)-1,3-pyrimidine The procedure of Example 6 was followed except that 5-(4-decylphenyl)-2-(3-fluoro-4-hydroxyphenyl)-1,3-pyrimidine was replaced by 5-(4-decyloxyphenyl)-2-(4-hydroxyphenyl)-1,3-pyrimidine. Thus, the desired compound was obtained. 1 H-NMR(CDCl 3 ) δ : 0.89 (t, 3H, J=6.9 Hz), 0.91 (t, 3H, J=7.1 Hz), 1.20-1.60 (m, 22H), 1.78-1.87 (m, 2H), 1.88-1.98 (m, 1H), 2.02-2.15 (m, 1H), 3.32-3.42 (m, 1H), 4.02 (t, 2H, J=6.6 Hz), 7.05 (d, 2H, J=8.9Hz), 7.24 (d, 2H, J=8.9 Hz), 7.56 (d, 2H, J=8.8 Hz), 8.54 (d, 2H, J=9.0 Hz), 8.98 (s, 2H) MS(m/z): 598 (M + ) This compound melted to exhibit an unidentified smectic phase of high order at 69 °C and then became an isotropic phase at 106 °C. REFERENCE EXAMPLE 2 Synthesis of 5-(4-decylphenyl)-2-(4-((R)-2,6,-dimethylheptanoyloxy)phenyl)-1,3-pyrimidine The procedure of Reference Example 1 was followed except that (S)-2,6-dimethylheptanoic acid was replaced by (R)-2,6-dimethylheptanoic acid. Thus, 5-(4-decylphenyl)-2-(4-((R)-2,6,-dimethylheptanoyloxy)phenyl)-1,3-pyrimidine was prepared. This compound melted to give an antiferroelectric liquid crystal phase at 100 °C and changed to an isotropic phase at 128 °C. This compound was injected into a liquid crystal cell and then measured for threshold voltage at a temperature of 113 °C (Tc-15 °C). As a result, the threshold voltage was 51.2 V. EXAMPLE 8 To the compound shown in Reference Example 2 was added the compound set forth in Example 7 in an amount of 30.1 % by weight and a liquid crystal composition was obtained. This composition changed from an isotropic phase to SmA phase at 127 °C, changed to SmC* phase at 113 °C and then exhibited an antiferroelectric liquid crystal phase at 109 °C (Tc). This antiferroelectric liquid crystal composition obtained was injected to a liquid crystal cell and measured for threshold voltage at a temperature of (Tc-15 °C). As a result, the threshold voltage was 19.2 V. The compound of Reference Example 2 has a threshold voltage of 51.2 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 7 in an amount of 30 % by weight also provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 9 Synthesis of 5-(4-decylphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine (1) Synthesis of 5-(4-decylphenyl)-2-(4-hydroxymethylphenyl)-1,3-pyrimidine Into a reaction flask were charged 1.2 g of lithium aluminium hydride (LAH) and 50 ml of THF in a stream of nitrogen. Into the mixture was added dropwise a THF (250 ml) solution of 5-(4-decylphenyl)-2-(4-ethoxycarbonylphenyl)-1,3-pyrimidine (9.1 g), keeping the temperature from 5 to 15 °C. The reaction mixture was stirred for another 2 hours at room temperature, poured into water and extracted with ethyl acetate. The organic layer was separated, washed with water, and evaporated to dryness. The raw material obtained was purified by silica gel column chromatography and recrystallized from hexane to get 4.12 g of the desired compound (Yield: 48.4 %). (2) Synthesis of 5-(4-decylphenyl)-2-(4-chloromethylphenyl)-1,3-pyrimidine Into a reaction flask were added 1.32 g of 5-(4-decylphenyl)-2-(4-hydroxymethylphenyl)-1,3-pyrimidine, 1.54 g of thionyl chloride and 20 ml of methylene chloride and the reaction mixture was maintained at 75 °C for 3 hours with stirring. The mixture was poured into water, extracted with ethyl acetate, washed with water and then concentrated. The resulting raw product was purified by silica gel column chromatography (benzene-ethyl acetate) to obtain 1.30 g of the desired compound (Yield: 94.2 %). (3) Synthesis of 5-(4-decylphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine Under nitrogen, 0.35 g of (R)-1,1,1-trifluoro-2-octanol in THF (2 ml) was added to the dispersion prepared from 0.8 g of 5-(4-decylphenyl)-2-(4-chloromethylphenyl)-1,3-pyrimidine, 10 ml of THF and 0.1 g of NaH. The mixture was stirred at 65 °C for 1 hour and further for 2 hours at 75 °C. After cooling, the resulting mixture was poured into a large amount of water, extracted with ethyl acetate, washed with water and then concentrated to get the raw product. This product was purified with silica gel column chromatography (hexane-ethyl acetate) and further purified with recrystallization from acetonitrile to get 0.55 g of the desired material (Yield: 50.9 %). 1 H-NMR(CDCl 3 ) δ : 0.85 (t, 3H, J=6.8 Hz), 0.88 (t, 3H, J=6.9 Hz), 1.20-1.40 (m, 22H), 1.60-1.78 (m, 4H), 2.68 (t, 2H, J=7.7 Hz), 3.68-3.78 (m, 1H), 4.66 (d, 1H, J=11.7 Hz), 4.93 (d, 1H, J=11.7 Hz), 7.34 (d, 2H, J=8.3 Hz), 7.48 (d, 2H, J=8.3 Hz), 7.55 (d, 2H, J=8.3 Hz), 8.49 (d, 2H, J=8.4 Hz), 9.01 (s, 2H) MS(m/z): 568 (M + ) This compound melted and charged to an isotropic phase at 75.1 °C. On cooling, SmA phase was observed monotropically. The phase transition temperature from SmA phase to an isotropic phase was 74.3 °C. This compound was added to the compound of Reference Example 1 in an amount of 20.1 % by weight and the liquid crystal composition was obtained. This composition changed from an isotropic phase to SmA phase at 119 °C, showed SmC* phase at 114.9 °C and then exhibited an antiferroelectric liquid crystal phase at 112.9 °C. This antiferroelectric liquid crystal composition obtained was injected into a liquid crystal cell and the threshold voltage of the composition was measured to be 20.4 V at a temperature of (Tc-15 °C). The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 9 in an amount of 20 % provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 10 Synthesis of 5-(-4-octylphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine The procedure of Example 9 was followed except that 5-(4-decylphenyl)-2-(4-ethoxycarbonylphenyl)-1,3-pyrimidine was replaced by 5-(4-octylphenyl)-2-(4-methoxycarbonylphenyl)-1,3-pyrimidine in the step Example 9-(1). Thus, the title compound was obtained. [α] D 25 =+36.8 ° (c=1.05, CHCl 3 ). 1 H-NMR(CDCl 3 ) δ : 0.85 (t, 3H, J=7.0 Hz), 0.89 (t, 3H, J=6.9 Hz), 1.19-1.42 (m, 16H), 1.48-1.58 (m, 2H), 1.6-1.75 (m, 4H), 2.68 (t, 2H, J=7.7 Hz), 3.66-3.76 (m, 1H), 4.66 (d, 1H, J=11.8 Hz), 4.93 (d, 1H, J=11.7 Hz), 7.34 (d, 2H, J=8.3 Hz), 7.49 (d, 2H, J=8.5 Hz), 7.55 (d, 2H, J=8.3 Hz), 8.49 (d, 2H, J=8.4 Hz), 9.01 (s, 2H) MS(m/z): 540 (M + ) This compound melted to give SmA phase at 68.5 °C, and changed to an isotropic phase at 81.9 °C. This compound was added to the compound of Reference Example 1 in an amount of 9.9 % by weight and the liquid crystal composition was obtained. This composition changed from an isotropic phase to SmA phase at 124.1 °C and then exhibited an antiferroelectric liquid crystal phase at 122.6 °C. This antiferroelectric liquid crystal composition obtained was injected into a liquid crystal cell and the threshold voltage of the composition was measured to be 45.2 V at a temperature of (Tc-15 °C). The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 10 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 11 Synthesis of 5-(4-decyloxyphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl) phenyl)-1,3-pyrimidine The title compound was synthesized in the same manner as in Example 9, except for replacing the 5-(4-decylphenyl)-2-(4-ethoxycarbonylphenyl)-1,3-pyrimidine used in Example 9-(1) with 5-(4-decyloxyphenyl)-2-(4-methoxycarbonylphenyl)-1,3-pyrimidine. [α] D 25 =+34.6 ° (c=1.15, CHCl 3 ). 1 H-NMR(CDCl 3 ) δ : 0.85 (t, 3H, J=6.9 Hz), 0.89 (t, 3H, J=6.9 Hz), 1.20-1.43 (m, 20H), 1.43-1.57 (m, 2H), 1.60-1.73 (m, 2H), 1.76-1.85 (m, 2H), 3.67-3.77 (m, 1H), 4.02 (t, 2H, J=6.6 Hz), 4.66 (d, 1H, J=11.8 Hz), 4.93 (d, 1H, J=11.7 Hz), 7.05 (d, 2H, J=8.9 Hz), 7.49 (d, 2H, J=8.5 Hz), 7.56 (d, 2H, J=8.9 Hz), 8.48 (d, 2H, J=8.5 Hz), 8.98 (s, 2H) MS(m/z): 584 (M + ) This compound melted at 65.3 °C to give SmC* phase, and changed to SmA phase at 74.9 °C, then to an isotropic phase at 101.1 °C. This compound was added to the compound of Reference Example 1 in an amount of 10.0 % to obtain a liquid crystal composition. This composition changed from an isotropic phase to SmA phase at 124.2 °C and then exhibited an antiferroelectric liquid crystal phase at 123.6 °C (Tc). This antiferroelectric liquid crystal composition obtained was injected to a liquid crystal cell to measure the threshold voltage at Tc-15 °C. As a result, the threshold voltage of the composition was 36 V. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 11 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 12 Synthesis of 5-(4-decylphenyl)-2-(4-((R)-1-trifluoromethylpentyloxymethyl)phenyl)-1,3-pyrimidine The synthetic procedure of Example 9 was followed except for replacing (R)-1,1,1-trifluoro-2-octanol used in the step Example 9-(3) with (R)- 1,1,1-trifluoro-2-hexanol to get the title compound. 1 H-NMR(CDCl 3 ) δ ppm: 0.88 (t, 3H, J=6.9 Hz), 0.89 (t, 3H, J=7.0 Hz), 1.20-1.43 (m, 16H), 1.45-1.58 (m, 2H), 1.60-1.75 (m, 4H), 2.68 (t, 2H, J=6.7 Hz), 3.67-3.77 (m, 1H), 4.66 (d, 1H, J=11.8 Hz), 4.92 (d, 1H, J=11.8 Hz), 7.34 (d, 2H, J=8.4 Hz), 7.49 (d, 2H, J=8.4 Hz), 7.54 (d, 2H, J=8.4 Hz), 8.49 (d, 2H, J=8.4 Hz), 9.01 (s, 2H) MS(m/z): 540 (M + ) This compound melted at 68.1 °C, at which it exhibited SmA phase, and changed to an isotropic phase at 87.8 °C. In addition, when this compound was cooled from SmA phase it exhibited SmC* phase at 64.6 °C. This compound was added in an amount of 10.0 % by weight to the compound of Reference Example 1 to obtain the liquid crystal composition. This composition changed from an isotropic phase at 124.1 °C to SmA phase and then exhibited an antiferroelectric liquid crystal phase at 123.4 °C (Tc). The resulting antiferroelectric liquid crystal composition was injected into a liquid crystal cell and the threshold voltage was measured to be 34.4 V at Tc-15 °C. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 12 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 13 Synthesis of 5-(3-fluoro-4-octyloxyphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine The title compound was synthesized in the same manner as in Example 9 except for replacing 5-(4-decylphenyl)-2-(4-ethoxycarbonylphenyl)-1,3-pyrimidine used in the step (1) with 5-(3-fluoro-4-octyloxyphenyl)-2-(4-methoxycarbonylphenyl)-1,3-pyrimidine. 1 H-NMR(CDCl 3 ) δ : 0.86 (t, 3H, J=6.9 Hz), 0.90 (t, 3H, J=7.0 Hz), 1.21-1.42 (m, 16H), 1.45-1.57 (m, 2H), 1.62-1.76 (m, 2H), 1.82-1.92 (m, 2H), 3.67-3.78 (m, 1H), 4.10 (t, 2H, J=6.7 Hz), 4.66 (d, 1H, J=11.7 Hz), 4.93 (d, 1H, J=11.7 Hz), 7.10 (t, 1H, J=8.6 Hz), 7.32-7.39 (m, 2H), 7.49 (d, 2H, J=8.6 Hz), 8.48 (d, 2H, J=8.5 Hz), 8.96 (s, 2H) MS(m/z): 574 (M + ) This compound melted at 72.7 °C to give SmA phase and changed to an isotropic phase at 77.3 °C. This compound was added to the compound of Reference Example 1 in an amount of 20.0 % by weight to obtain a liquid crystal composition. The composition changed from an isotropic phase at 121.7 °C to SmA phase and exhibited an antiferroelectric liquid crystal phase at 121 °C. This antiferroelectric liquid crystal composition was injected into a liquid crystal cell and the threshold voltage was measured to be 34.8 V at Tc-15 °C. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 13 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 14 Synthesis of 5-(4-decylphenyl)-2-(3-fluoro-4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine The synthetic procedure of Example 9 was followed except for replacing 5-(4-decylphenyl)-2-(4-ethoxycarbonylphenyl)-1,3-pyrimidine used in the step (1) with 5-(4-decylphenyl)-2-(3-fluoro-4-methoxycarbonylphenyl)-1,3-pyrimidine to obtain the title compound. 1 H-NMR(CDCl 3 ) δ : 0.85 (t, 3H, J=7.0 Hz), 0.88 (t, 3H, J=7.1 Hz), 1.18-1.43 (m, 20H), 1.46-1.58 (m, 2H), 1.60-1.75 (m, 4H), 2.68 (t, 2H, J=7.8 Hz), 3.68-3.80 (m, 1H), 4.76 (d, 1H, J=11.9 Hz), 4.94 (d, 1H, J=12.1 Hz), 7.35 (d, 2H, J=8.3 Hz), 7.54-7.58 (m, 3H), 8.20 (dd, 1H, J=11.2 Hz, J=1.6 Hz), 8.30 (dd, 1H, J=8.0 Hz, J=1.6 Hz), 9.01 (s, 2H) MS(m/z): 587 (M + +1) This compound melted at 60.3 °C to give an isotropic phase, but on cooling, exhibited SmC* phase monotropically. The phase transition temperature from SmC* phase to an isotropic phase was 48.1 °C. This compound was added in an amount of 10.0 % by weight to the compound of Reference Example 1 to obtain the liquid crystal composition. This composition changed from an isotropic phase at 122.1 °C to SmA phase and then exhibited an antiferroelectric liquid crystal phase at 120.0 °C (Tc). The resulting antiferroelectric liquid crystal composition was injected into a liquid crystal cell and the threshold voltage was measured to be 40 V at Tc-20 °C. The compound of Reference Example 1 has a threshold voltage of more than 60 V at a temperature of (Tc-20 °C). Thus, it can be seen that the incorporation of the compound of Example 14 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 15 Synthesis of 5-(4-decylphenyl)-2-(4-((R)-2-fluoro-2-trifluoromethyloctanoyloxy)phenyl)-1,3-pyrimidine (1) Synthesis of (R)-2-fluoro-2-trifluoromethyloctanoic acid (1-1)Synthesis of 2-fluoro-2-trifluoromethyl-4-octenamide Into a reaction flask were charged 920 mg of (R)-1-hexen-3-ol (91.2%e.e.), 5.7 ml of triethylamine and 10 ml of dichloromethane and the reaction mixture was cooled to 0°C. Holding the temperature at 0°C, 3.3 ml of hexafluoropropene diethylamine was added dropwise into the mixture. After the addition, the reaction mixture was stirred for 2 hours at 0°C and 48 hours at room temperature. Into the mixture was added a saturated aqueous solution of sodium bicarbonate and the mixture was extracted with dichloromethane. The organic layer was dried with anhydrous magnesium sulphate and then concentrated. The raw product was purified by silica gel column chromatography to get 1.35 g of the desired compound. 1 H-NMR(CDCl 3 ) δ : 0.89 (t, 3H, J=7.1 Hz), 1.15 (t, 3H, J=7.1 Hz), 1.19 (t, 3H, J=6.8 Hz), 1.38 (dt, 2H, J=7.4 Hz, J=14.5 Hz), 1.99 (m, 2H), 2.61 (m, 1H), 3.07 (m, 1H), 3.29-3.60 (m, 2H), 5.33 (dt, 1H, J=7.3 Hz, J=15.3 Hz), 5.68 (dt, 1H, J=6.8 Hz, J=15.3 Hz). MS(m/z): 283 (M + ), 220, 149. (1-2) Synthesis of 2-fluoro-2-trifluoromethyloctanamide Into a solution of 1.30 g of 2-fluoro-2-trifluoromethyl-4-octenamide in 13 ml of methanol, paradium-carbon (13 mg) was added under nitrogen. After the atmosphere was replaced with hydrogen, the mixture was stiired for 24 hours. To remove catalyst, the resulting mixture was filtered with cerite and the filtrate was concectrated. The raw product was purified by silica gel column chromatography to obtain 1.0 g of the desired compound. 1 H-NMR(CDCl 3 ) δ : 0.89 (t, 3H, J=7.0 Hz), 1.17 (t, 3H, J=7.1 Hz), 1.21 (t, 3H, J=7.0 Hz), 1.24-1.55 (m, 8H), 1.92 (m, 1H), 2.38 (m, 1H), 3.29-3.70 (m, 4H). MS(m/z): 285 (M + ), 270, 256. (1-3) Synthesis of (R)-2-fluoro-2-trifluoromethyloctanoic acid Into the suspension of lithium aluminium hydride (67 mg, 1.80 mmol) in tetrahydrofuran (7.0 ml) was slowly added a solution of 1.0 g of 2-fluoro-2-trifluoromethyloctanamide (3.51 mmol) in 3.0 ml of tetrahydrofuran at -20°C and the reaction mixture was stirred for 6 hours at 0 °C. After cooling again to -20 °C, 15 ml of methanol and 133 mg (3.51 mmol) of sodium borohydride were added to the reaction mixture. The reaction mixture was stirred for 2 hours at 0°C and acidified to pH=2 with diluted hydrochloric acid. After the organic solvent was distilled away under vacuum, the residue was extracted with ethyl ether. The organic layer was washed with a saturated aqueous solution of sodium chloride and dried by anhydrous magnesium sulphate. The product was purified with silica gel column chromatography to get alcohol derivative. This compound was dissolved into 26 ml of ethyl ether and the resulting solution was cooled to 0 °C. Into the soution the John's reagent, previously prepared from 7.02 g (70.2 mmol) of CrO 3 , 7.02 ml of H 2 SO 4 and 28.1ml of H 2 O, was slowly added and the mixture was stirred for 15 hours at room temperature. The mixture was extracted with ethyl ether, washed with saturated aqueous sodium chloride solution and dried by anhydrous magnesium sulphate. The product was purified with silica gel column chromatography to obtain 420 mg of the desired product. The yield was 52.0 %. A part of this product was esterified to the methyl ester which was analyzed by gas chromatography with a chiral stationary phase to give optical purity as 85.9 %e.e. 1 H-NMR(CDCl 3 ) δ : 0.89 (t, 3H, J=7.0 Hz), 1.18-1.70 (m, 8H), 1.95-2.28 (m, 2H), 8.25 (br, 1H). MS(m/z): 231 (M + ) 211, 193. (2) Synthesis of 5-(4-decylphenyl)-2-(4-((R)-2-fluoro-2-trifluoromethyloctanoyloxy)phenyl)-1,3-pyrimidine The title compound was prepared in the same manner as in Example 1 except for replacing 5-(3-fluoro-4-octyloxyphenyl)-2-(3-fluoro-4-hydroxyphenyl)-1,3-pyrimidine with 5-(4-decylphenyl)-2-(4-hydroxyphenyl)-1,3-pyrimidine and replacing (S)-2-fluoroheptanoic acid with (R)-2-fluoro-2-trifluoromethyloctanoic acid. 1 H-NMR(CDCl 3 ) δ : 0.88 (t, 3H, J=6.9 Hz), 0.91 (t, 3H, J=7.1 Hz), 1.20-1.55 (m, 21H), 1.6-1.75 (m, 3H), 2.10-2.40 (m, 2H), 2.68 (t, 2H, J=7.7 Hz), 7.27 (d, 2H, J=9.0 Hz), 7.34 (d, 2H, J=8.4 Hz), 7.55 (d, 2H, J=8.4 Hz), 8.57 (d, 2H, J=9.0 Hz), 9.00 (s, 2H) MS(m/z): 600 (M + ) This compound melted at 45.2 °C to exhibit an unidentified smectic phase of high order, and changed to an isotropic phase at 70.8 °C. This compound was added in an amount of 10.0 % by weight to the compound of Reference Example 1 to obtain the liquid crystal composition. This composition changed from an isotropic phase at 124.6 °C to SmA phase, became SmC* phase at 121.1 °C and then exhibited an antiferroelectric liquid crystal phase at 120.9 °C (Tc). The resulting antiferroelectric liquid crystal composition was injected into a liquid crystal cell and the threshold voltage was measured to be 44.4 V at Tc-15 °C. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 15 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 16 Synthesis of 5-(4-decylphenyl)-2-(4-((R)-2-fluoro-2-trifluoromethyldecanoyloxy)phenyl)-1,3-pyrimidine (1) Synthesis of (R)-2-fluoro-2-trifluoromethyldecanoic acid (1-1) Synthesis of 2-fluoro-2-trifluoromethyl-4-decenamide Into a reaction flask were charged 2.0 g (15.6 mmol) of (R)-1-octen-3-ol (96.0 %e.e.), 4.4 ml (31.3 mmol) of triethylamine and 40 ml of dichloromethane and the reaction mixture was cooled to 0°C. Holding the temperature at 0°C, 3.5 ml (15.6 mmol) of hexafluoropropene diethylamine was added dropwise into the mixture. After the addition, the reaction mixture was stirred for 2 hours at 0°C and 48 hours at room temperature. Into the mixture was added a saturated aqueous solution of sodium bicarbonate and the mixture was extracted with dichloromethane. The organic layer was dried with anhydrous magnesium sulphate and then concentrated. The raw product was purified by silica gel column chromatography to get 3.26 g of the desired compound. Yield was 67.2 %. 1 H-NMR(CDCl 3 ) δ : 0.89 (t, 3H,J=7.1 Hz), 1.15 (t, 3H, J=7.1 Hz), 1.18 (t, 3H, J=7.1 Hz), 1.21-1.40 (m, 6H),2.00 (m, 2H), 2.61 (m, 1H), 3.07 (m, 1H), 3.30-3.59 (m, 4H), 5.32 (dt, 1H, J=7.2 Hz, J=15.3 Hz), 5.86 (dt, 1H, J=6.7 Hz, J=15.3 Hz). MS(m/z): 312 (M + +1), 220, 100. (1-2) Synthesis of 2-fluoro-2-trifluoromethyldecanamide Into a solution of 3.0 g (9.65 mmol) of 2-fluoro-2-trifluoromethyl-4-decenamide in 30 ml of methanol, paradium-carbon (75 mg) was added under nitrogen. After the atmosphere was replaced with hydrogen, the mixture stirred for 24 hours. To remove the catalyst, the resulting mixture was filtered with cerite and the filtrate was concectrated. The raw product was purified by silica gel column chromatography to obtain 3.0 g of the desired compound. Yield was 99.3 %. 1 H-NMR(CDCl 3 ) δ : 0.89 (t, 3H, J=7.0 Hz), 1.17 (t, 3H, J=7.1 Hz), 1.21 (t, 3H, J=7.0 Hz), 1.27-1.54 (m, 12H), 1.90 (m, 1H), 2.35 (m, 1H), 3.30-3.70 (m, 4H). MS(m/z): 313 (M + ), 201, 100. (1-3) Synthesis of (R)-2-fluoro-2-trifluoromethyloctanoic acid Into a suspension of lithium aluminium hydride (61 mg, 1.60 mmol) in tetrahydrofuran (7.0 ml) was slowly added a solution of 1.0 g of 2-fluoro-2-trifluoromethyloctanamide (3.19 mmol) in 3.0 ml of tetrahydrofuran at -20°C and the reaction mixture was stirred for 6 hours at 0 °C. After cooling again to -20 °C, 15 ml of methanol and 182 mg (3.19 mmol) of sodium borohydride were added to the reaction mixture. The reaction mixture was stirred for 2 hours at 0°C and acidified to pH=2 with diluted hydrochloric acid. After the organic solvent was distilled away under vacuum, the residue was extracted with ethyl ether. The organic layer was washed with saturated aqueous sodium chloride solution and dried by anhydrous magnesium sulphate. The product was purified with silica gel column chromatography to get alcohol derivative. This compound was dissolved into 26 ml of ethyl ether and the resulting organic solution was cooled to 0 °C. Into the solution the John's reagent, previously prepared from 6.4 g (64 mmol) of CrO 3 , 6.4 ml of H 2 SO 4 and 26 ml of H 2 O, was slowly added and the mixture was stirred for 15 hours at room temperature. The mixture was extracted with ethyl ether, washed with a saturated aqueous solution of sodium chloride and dried by anhydrous magnesium sulphate. The product was purified with silica gel column chromatography to obtain 270 mg of the desired product. The yield was 32.1 %. A part of this product was esterified to the methyl ester which was analyzed by gas chromatography with a chiral stationary phase to give optical purity as 86.7 %e.e. [α] D 25 =+3.0 ° (c=2.0, CHCl 3 ). 1 H-NMR(CDCl 3 ) δ : 0.89 (t, 3H, J=7.1 Hz), 1.15-1.70 (m, 12H), 1.95-2.30 (m, 2H), 9.65 (br, 1H). MS(m/z): 243 (M + -CH 3 ), 174, 146. (2) Synthesis of 5-(4-decylphenyl)-2-(4-((R)-2-fluoro-2-trifluoromethyldecanoyloxy)phenyl)-1,3-pyrimidine The synthetic procedure of Example 15 was followed except for replacing (R)-2-fluoro-2-trifluoromethyloctanoic acid with (R)-2-fluoro-2-trifluoromethyldecanoic acid in the step (2). 1 H-NMR(CDCl 3 ) δ ppm: 0.88 (t, 3H, J=6.9 Hz), 0.89 (t, 3H, J=7.0 Hz), 1.20-1.55 (m, 25 H), 1.60-1.80 (m, 3 H), 2.10-2.40 (m, 2H), 2.68 (t, 2H, J=7.8 Hz), 7.27 (d, 2H, J=8.9 Hz), 7.35 (d, 2H, J=8.4 Hz), 7.55 (d, 2H, J=8.4 Hz), 8.57 (d, 2H, J=9.0 Hz), 9.01 (s, 2H) MS(m/z): 628 (M + ) This compound melted at 46.4 °C to exhibit an unidentified smectic phase of high order and changed to an isotropic phase at 66.8 °C. EXAMPLE 17 Synthesis of 5-(4-decylphenyl)-2-(4-((R)-2-fluoro-2-trifluoromethylhexanoyloxy)phenyl)-1,3-pyrimidine (1) Synthesis of (R)-2-fluoro-2-trifluoromethylhexanoic acid The synthetic procedure of Example 15 was followed except for replacing (R)-1-hexen-3-ol with (R)-1-buten-3-ol in the step (1-1) to obtain (R)-2-fluoro-2-trifluoromethylhexanoic acid. 1 H-NMR(CDCl 3 ) δ : 0.93 (t, 3H, J=7.1 Hz), 1.10-1.70 (m, 4H), 1.95-2.38 (m, 2H), 8.14 (br, 1H) MS(m/z): 202 (M + ), 134, 91. (2) Synthesis of 5-(4-decylphenyl)-2-(4-((R)-2-fluoro-2-trifluoromethylhexanoyloxy)phenyl)-1,3-pyrimidine The synthetic procedure of Example 15 (2) was followed except for replacing (R)-2-fluoro-2-trifluoromethyloctanoic acid with (R)-2-fluoro-2-trifluoromethylhexanoic acid to get the title compound. 1 H-NMR(CDCl 3 ) δ ppm : 0.88 (t, 3H, J=6.9 Hz), 0.99 (t, 3H, J=7.2 Hz), 1.20-1.40 (m, 14 H), 1.42-1.55 (m, 3 H), 1.63-1.75 (m, 3 H), 2.10-2.42 (m, 2H), 2.68 (t, 2H, J=7.7 Hz), 7.28 (d, 2H, J=9.0 Hz), 7.35 (d, 2H, J=8.3 Hz), 7.55 (d, 2H, J=8.3 Hz), 8.57 (d, 2H, J=8.9 Hz), 9.01 (s, 2H) MS(m/z): 572 (M + ) This compound melted to give an unidentified smectic phase of high order at 56.8 °C, changed to another unidentified smectic phase of high order at 71.1 °C, and exhibited an isotropic phase at 83.6 °C. EXAMPLE 18 Synthesis of 5-(4-decylphenyl)-2-(4-((2S,3R)-2,3-dimethylheptanoyloxy)phenyl)-1,3-pyrimidin The synthetic procedure of Example 15 (2) was followed except for replacing (R)-2-fluoro-2-trifluoromethyloctanoic acid with (2S,3R)-2,3-dimethylheptanoic acid to get the title compound. 1 H-NMR(CDCl 3 ) δ ppm: 0.88 (t, 3H, J=7.0 Hz), 0.93 (t, 3H, J=7.0 Hz), 0.99 (d, 3H, J=6.8 Hz), 1.23 (d, 3H, J=7.1 Hz), 1.20-1.50 (m, 20H), 1.60-1.72 (m, 2H), 2.00-2.12 (m, 1H), 2.63-2.72 (m, 3H), 7.21 (d, 2H, J=8.9 Hz), 7.34 (d, 2H, J=8.3 Hz), 7.55 (d, 2H, J=8.3 Hz), 8.52 (d, 2H, J=8.9 Hz), 8.99 (s, 2H) MS(m/z): 528 (M + ) This compound melted at 70.3 °C to give SmC* phase and changed to SmA phase at 111.7 °C, and then to an isotropic phase at 113.2 °C. EXAMPLE 19 Synthesis of 5-(4-decylphenyl)-2-(4-((2S,3S)-2,3-dimethylheptanoyloxy)phenyl)-1,3-pyrimidine The synthetic procedure of Example 15 was followed except for replacing (R)-2-fluoro-2-trifluoromethyloctanoic acid with (2S,3S)-2,3-dimethylheptanoic acid to obtain the title compound. 1 H-NMR(CDCl 3 ) δ ppm: 0.88 (t, 3H, J=6.9 Hz), 0.93 (t, 3H, J=7.0 Hz), 1.06(d, 3H, J=6.8 Hz), 1.28 (d, 3H, J=7.0 Hz), 1.20-1.47 (m, 22H), 1.60-1.70 (m, 2H), 1.87-1.98 (m, 1H), 2.60-2.72 (m, 3H), 7.22 (d, 2H, J=8.9 Hz), 7.34 (d, 2H, J=8.3 Hz), 7.55 (d, 2H, J=8.3 Hz), 8.52 (d, 2H, J=8.9 Hz), 8.99 (s, 2H) MS(m/z): 529 (M + +1) This compound melted at 89.8 °C to give SmC* phase and changed to SmA phase at 130 °C and then to an isotropic phase at 135.6 °C. This compound was added in an amount of 30.0 % by weight to the compound of Reference Example 1 to obtain the liquid crystal composition. This composition changed from an isotropic phase at 129.5 °C to SmA phase and then exhibited an antiferroelectric liquid crystal phase at 122.1 °C (Tc). The resulting antiferroelectric liquid crystal composition was injected into a liquid crystal cell and the threshold voltage was measured to be 33.6 V at Tc-15 °C. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 19 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 20 Synthesis of 5-(4-decylphenyl)-2-(4-((1S,2R)-2-methyl-1-cyclohexanecarbonyloxy)phenyl)-1,3-pyrimidine The synthetic procedure of Example 15 was followed except for replacing (R)-2-fluoro-2-trifluoromethyloctanoic acid with (1S,2R)-2-methyl-1-cyclohexanecarboxylic acid to obtain the title compound. 1 H-NMR(CDCl 3 ) δ ppm : 0.88 (t, 3H, J=6.9 Hz), 1.09 (d, 3H, J=7.0 Hz), 1.18-2.00 (m, 24H), 2.36 (m, 1H), 2.67 (t, 2H, J=7.7 Hz), 2.76-2.85 (m, 1H), 7.22 (d, 2H, J=8.9 Hz), 7.33 (d, 2H, J=8.3 Hz), 7.54 (d, 2H, J=8.3 Hz), 8.51 (d, 2H, J=8.8 Hz), 8.99 (s, 2H) MS(m/z): 512 (M + ) This compound melted at 123.5 °C to give SmC* phase and changed to SmA phase at 149.8 °C and then to an isotropic phase at 152.2 °C. EXAMPLE 21 Synthesis of 5-(4-decylphenyl)-2-(3-fluoro-4-((1S,2R)-2-methyl-1-cyclohexanecarbonyloxy)phenyl)-1,3-pyrimidine The title compound was synthesized in the same manner as in Example 20 except for replacing 5-(4-decylphenyl)-2-(4-hydroxyphenyl)-1,3-pyrimidine used in Example 20 with 5-(4-decylphenyl)-2-(3-fluoro-4-hydroxyphenyl)-1,3-pyrimidine. 1 H-NMR(CDCl 3 ) δ ppm : 0.88 (t, 3H, J=6.9 Hz), 1.10 (d, 3H, J=7.1 Hz), 1.18-2.00 (m, 24H), 2.33 (m, 1H), 2.68 (t, 2H, J=7.7 Hz), 2.82-2.90 (m, 1H), 7.08-7.25 (m, 1H), 7.34 (d, 2H, J=8.2 Hz), 7.54 (d, 2H, J=8.3 Hz), 8.28-8.33 (m, 2H), 8.99 (s, 2H) MS(m/z): 531 (M + +1) This compound melted at 112.3 °C to show an unidentified smectic phase of high order, exhibited SmC* phase at 120.9 °C and changed to SmA phase at 142.3 °C and then to an isotropic phase at 145.8 °C. This compound was added in an amount of 19.9 % by weight to the compound of Reference Example 1 to obtain the liquid crystal composition. This composition changed from an isotropic phase at 130.3 °C to SmA phase and then exhibited an antiferroelectric liquid crystal phase at 130.1 °C (Tc). The resulting antiferroelectric liquid crystal composition was injected into a liquid crystal cell and the threshold voltage was measured to be 57.6 V at Tc-15 °C. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 21 provides only a little improvement in threshold voltage, but makes it possible to obtain a stable antiferroelectric liquid crystal composition even in the case for the incorporation of the compound of Example 21 in an amount of 20 %. EXAMPLE 22 Synthesis of 5-(4-decylphenyl)-2-(3-fluoro-4-((1S,2R)-2-butyl-1-cyclohexanecarbonyloxy)phenyl)-1,3-pyrimidine The synthetic procedure of Example 20 was followed except for replacing (1S,2R)-2-methyl-1-cyclohexanecarboxylic acid with (1S,2R)-2-butyl-1-cyclohexanecarboxylic acid to obtain the title compound. 1 H-NMR(CDCl 3 ) δ ppm : 0.89 (t, 3H, J=6.9 Hz), 0.93 (t, 3H, J=7.1 Hz), 1.22-1.85 (m, 29H), 1.92-2.04 (m, 2H), 2.68 (t, 2H, J=7.7 Hz), 2.90-2.97 (m, 1H), 7.21-7.25 (m, 1H), 7.42 (d, 2H, J=8.4 Hz), 7.55 (d, 2H, J=8.3 Hz), 8.29-8.34 (m, 2H), 9.00 (s, 2H) MS(m/z): 573 (M + +1) This compound melted at 95.4 °C to give an isotropic phase. EXAMPLE 23 Synthesis of 5-(4-decylphenyl)-2-(4-((2S,3R)-2-methyl-3-fluorohexanoyloxy)phenyl)-1,3-pyrimidine The title compound was prepared in the same manner as in Example 1 except for replacing 5-(3-fluoro-4-octyloxyphenyl)-2-(3-fluoro-4-hydroxyphenyl)-1,3-pyrimidine with 5-(4-decylphenyl)-2-(4-hydroxyphenyl)-1,3-pyrimidine and replacing (S)-2-fluoroheptanoic acid with (2S,3R)-2-methyl-3-fluorohexanoic acid. 1 H-NMR(CDCl 3 ) δ ppm : 0.88 (t, 3H, J=6.9 Hz), 1.01 (t, 3H, J=7.0 Hz), 1.20-1.90 (m, 20H), 1.41 (d, 3H, J=7.1 Hz), 2.68 (t, 2H, J=7.8 Hz), 2.87-2.98 (m, 1H), 4.92 (dm, 1H, J=48.1 Hz), 7.23 (d, 2H, J=9.0 Hz), 7.34 (d, 2H, J=8.3 Hz), 7.55 (d, 2H, J=8.3 Hz), 8.53 (d, 2H, J=9.0 Hz), 9.00 (s, 2H) MS(m/z): 518 (M + ) This compound melted at 99.6 °C to give SmC* phase and changed to SmA phase at 133.9 °C and then to an isotropic phase at 141.4 °C. This compound was added in an amount of 10.0 % by weight to the compound of Reference Example 1 to obtain the liquid crystal composition. This composition changed from an isotropic phase to an antiferroelectric liquid crystal phase at 127.1 °C (Tc). The resulting antiferroelectric liquid crystal composition was injected into a liquid crystal cell and the threshold voltage was measured to be 37.2 V at Tc-15 °C. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 23 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. EXAMPLE 24 Synthesis of 5-(4-octyloxyphenyl)-2-(4-((R)-1-methylbutyloxymethyl)phenyl)-1,3-pyrimidine The procedure of Example 9 was followed except for replacing 5-(4-decylphenyl)-2-(4-ethoxycarbonylphenyl)-1,3-pyrimidine in the step Example 9-(1) with 5-(4-octyloxyphenyl)-2-(4-methoxycarbonylphenyl)-1,3-pyrimidine and replacing (R)-1,1,1-trifluoro-2-octanol used in the step Example9-(3) with (R)-2-pentanol to obtain the title compound. 1 H-NMR(CDCl 3 ) δ ppm: 0.90 (t, 3H, J=7.0 Hz), 0.92 (t, 3H, J=7.3 Hz), 1.22 (d, 3H, J=6.1 Hz), 1.25-1.70 (m, 14H), 1.78-1.88 (m, 2H), 3.50-3.60 (m, 1H), 4.02 (t, 2H, J=6.6 Hz), 4.55 (d, 1H, J=12.3 Hz), 4.66 (d, 1H, J=12.3 Hz), 7.04 (d, 2H, J=8.9 Hz), 7.48 (d, 2H, J=8.6 Hz), 7.55 (d, 2H, J=8.8 Hz), 8.44 (d, 2H, J=8.5 Hz), 8.97 (s, 2H) MS(m/z): 460 (M + ) This compound melted to exhibit an antiferroelectric liquid crystal phase at 52.0 °C and changed to SmC* phase at 115.8 °C and then to an isotropic phase at 149.4 °C. This compound was added in an amount of 19.9% by weight to the compound of Reference Example 1 to obtain the liquid crystal composition. This composition changed from an isotropic phase to SmC* phase at 128.3°C and exhibited an antiferroelectric liquid crystal phase at 125.5°C(Tc). The resulting antiferroelectric liquid crystal composition was injected into a liquid crystal cell and the threshold voltage was measured to be 47.6 V at Tc-15 °C. The compound of Reference Example 1 has a threshold voltage of 59 V at a temperature of (Tc-15 °C). Thus, it can be seen that the incorporation of the compound of Example 24 provides an improvement in threshold voltage, making it possible to obtain a stable antiferroelectric liquid crystal composition having better properties. The optically active compound of the present invention has a good miscibility with many known antiferroelectric liquid crystal compounds and thus can provide a liquid crystal material having improved threshold voltage. Further, a liquid crystal composition containing an optically active compound of the present invention can be incorporated in electro-optic elements employing an antiferroelectric liquid crystal.

Claims: An optically active compound selected from the compounds represented by the following general formulae (1) and (2): wherein R 1 represents an alkyl or alkoxy group of 5 to 14 carbon atoms; R 2 represents an alkyl group of 2 to 12 carbon atoms; 1 and m each represent 0 or 1; n is an integer from 2 to 4; D represents -OCO- or -OCOC*R 3 H-, with the proviso that in the case D is -OCO-, R 4 represents a fluorine atom or a trifluoromethyl group and R 5 represents a hydrogen atom or a fluorine atom; if D is -OCOC*R 3 H-, R 3 is a methyl group, R 4 is a fluorine atom, R 5 is a hydrogen atom, and C* represents an asymmetric carbon atom; and the compounds 5-(4-decylphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine, 5-(4-octylphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1.,3-pyrimidine, 5-(4-decyloxyphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(4-((R)-1-trifluoromethylpentyloxymethyl)phenyl)-1,3-pyrimidine, 5-(3-fluoro-4-octyloxyphenyl)-2-(4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(3-fluoro-4-((R)-1-trifluoromethylheptyloxymethyl)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(4-((2S,3R)-2,3-dimethylheptanoyloxy)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(4-((2S,3S)-2,3-dimethylheptanoyloxy)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(4-((1S,2R)-2-methyl-1-cyclohexanecarbonyloxy)phenyl)-1,3-pyrimidine, 5-(4-decylphenyl)-2-(3-fluoro-4-((1S,2R)-2-methyl-1-cyclohexanecarbonyloxy)phenyl)-1,3-pyrimidine and 5-(4-octyloxyphenyl)-2-(4-((R)-1-methylbutyloxymethyl)phenyl)-1,3-pyrimidine. An antiferroelectric liquid crystal composition containing at least one optically active compound according to claim 1. A process for the reduction of the threshold voltage of an antiferroelectric liquid crystal composition, which comprises incorporating at least one optically active compound according to claim 1 into an antiferroelectric liquid crystal composition to reduce the threshold voltage of said composition. A process for the production of the optically active compound represented by the general formula (1) according to claim 1, comprising reacting a compound represented by the following general formula (3): wherein R 1 , I and m have the same meaning as in claim 1, and W represents a hydroxy group, with a compound represented by the following general formula (4): wherein R 2 has the same meaning as in claim 1, and X represents COOH, COCl, -C*R 3 HCOOH, or -C*R 3 HCOCl, with the proviso that in the case X is COOH or COCI, R 4 represents a fluorine atom or a trifluoromethyl group and R 5 represents a hydrogen atom or a fluorine atom, if X is -C*R 3 HCOOH or -C*R 3 HCOCl, R 3 is a methyl group, R 4 is a fluorine atom, R 5 is a hydrogen atom, and C* represents an asymmetric carbon atom. A process for the production of an optically active carboxylic acid represented by the general formula (5): wherein R 2 represents an alkyl group of 4 to 12 carbon atoms and C* represents an asymmetric carbon atom, comprising the following steps: wherein R 10 is an alkyl group of 1 to 9 carbon atoms.

Inventors: HAGIWARA TOSHIMITSU, IWAYA YUKIHARU, KONDO HITOSHI, YAMADA MAMORU, YAMADA SHINYA, YAMAGUCHI AKIO, HAGIWARA, TOSHIMITSU, IWAYA, YUKIHARU, KONDO, HITOSHI, YAMADA, MAMORU, YAMADA, SHINYA, YAMAGUCHI, AKIO, Hagiwara, Toshimitsu, c/o Takasago Intern. Corp., Iwaya, Yukiharu, c/o Takasago Intern. Corp., Kondo, Hitoshi, c/o Takasago Intern. Corp., Yamada, Mamoru, c/o Takasago Intern. Corp., Yamada, Shinya, c/o Takasago Intern. Corp., Yamaguchi, Akio, c/o Takasago Intern. Corp.
Applicants: SEMICONDUCTOR ENERGY LAB, SEMICONDUCTOR ENERGY LABORATORY CO., LTD.
Application year: 1998
Main classification: C07D239
IPC codes: C07C53, C09K19, C07D239