Dioxane liquid crystal compounds

Abstract: Novel ferromagnetic liquid crystal compounds of the invention, which comprises those showing tristable liquid crystal phase S (3 , have a wide range of phase transition points so as to be not only preferably used solely as display element material but also mixeo with any other liquid crystal to desiredly expand the above range wider and make optical response time faster. Typical compounds are represented by in which Z means CF₃, C₂F₅, CHF₂ CH₂F, CllF₂, CCl₂F, CF₃CCl₂ or C₃F₇ m′ and n′ are same or different witn each other and each is an integer of 1 - 20.

Description: BACKGROUND OF THE INVENTION AND RELATED ARTS The invention relates to liquid crystal compounds having a dioxane ring, and more particularly smectic and ferroelectric dioxane liquid crystal compounds showing a tristable phase. Liquid crystal display elements have been widely used in twisted nematic (TN) mode, guest-host (GH) mode and so on owing to the excellent properties thereof such as low voltage actuability, low energy consumption, displayability in a thin structure and so on. The liquid crystal display elements of the nematic type, however, are disadvantageous in that slow speed of response in the order of several m sec-several decades of m sec so that there are considerable limitations in the applied uses thereof. In order to solve the problem referred to above, a super twisted nematic (STN) mode has been developed, but it is still unsatisfactory in that it is necessary to precisely control a cell gap and a tilt angle and in that the time response is still low, despite of that display properties such as a display contrast and a visual field angle have been considerably improved. In order to comply with demands for novel liquid crystal displays superior in the time of response, ferroelectric liquid crystals were developed so as to provide liquid crystal devices having the far higher optical response time in the order of µsec. In the year of 1975, p-decyloxybenzilidene-p-amino-2-methylbutylcinamate (DOBAMBC) was synthesized as the ferroelectric liquid crystal by Meyer et al., and in the year of 1980 the high speed switching and memory properties of DOBAMBC were confirmed by Clark and Longwall (N.A. Clark et al., Appl. Phys. Lett. 36 , 899 (1980)) so as to attract attentions as an epoch-making liquid crystal element material capable of realizing the moving image display of a large picture in the simple matrix mode. However, there were still technical problems so as to actually use the above ferroelectric liquid crystal. Above all, satisfactory ferroelectricity at the room temperature and satisfactory control or orientation of the liquid crystal molecules which is necessary for the display device could not be attained. The inventors et al have found some ferroelectric liquid crystals showing tristable phase S (s) * which has definite threshhold and hysterisis properties relative to driving voltage so as to realize large moving picture display according to the simple matrix mode and a novel electroptical shutter owing to the particular electroclinic effect thereof, which is disclosed in A.D.L. Chandani, T. Hagiwara, Y. Suzuki, et al., Japan J. of Appl. Phys., 27 (5), 729-732 (1988), and JP-A Sho 63 (1988)-21159 and 21160. SUMMARY OF THE INVENTION It is an object of the invention, thus, to provide further novel ferroelectric liquid crystal compounds showing tristable phase S (s) * in a wider range of temperatures inclusive of the room temperature. The other objects and advantageous effects of the invention will be appreciated by those skilled in the art by studying the detailed explanation to be given hereafter. The above objects can be attained by a certain scope of compounds, each having a dioxane ring as the heterocyclic ring as definitely defined in the Claims. DESCRIPTION OF THE DRAWINGS Fig. 1 shows an infrared absorption spectrum (KBr) of (R)-(+)-4'-(1-trifluoromethylnonyloxycarbonyl)-1-phenyl 4-(5-n-pentyl-trans-1,3-dioxane-2-yl)benzoate, the objective compound in Example 1, Fig. 2 shows the spectrum of 4'-(1-trifluoromethylheptyloxycarbonyl)phenyl 4-(5-n-nonyl-trans-1,3-dioxane-2-yl)benzoate, the objective compound in Example 2, Fig. 3 shows the spectrum of (R)-(+)-4-(1-trifluoromethyl-2-ethoxycarbonyloxycarbonyl) phenyl 4-(5-n-pentyl-trans-1,3-dioxane-2-yl)benzoate, the objective compound in Example 3, Fig. 4 shows an optical response wave form of the objective compound in Example 3 according to the electroclinic effect in the S A phase, and Fig. 5 shows an optical response wave form of the objective compound in Example 2 in the S (s) * phase. DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION The invention relates to liquid crystal compounds represented by the general formula (I) R₁ means an alkyl, alkoxy, alkyloxycarbonyl or alkylcarbonyloxy group having 1 - 20 carbon atoms, preferably C n H 2n+1 , C n H 2n+1 O, wherein n is an integer of 5 - 10, and more preferably pentyl(C₅H₁₅), octyl(C₈H₁₇), nonyl(C₉H₁₉) or decyl(C₁₀H₂₁). (A) means X means wherein R' is hydrogen or a lower alkyl such as methyl and methyl, and ℓ is an integer of 1 - 16, preferably -OCH₂-, -OCH₂CH₂-, OCH₂CH₂CH₂-, -CH₂CH₂O-or -CH₂CH₂CH₂O-, and more preferably (B) means Y means -O-, -S- or -CH₂O-, and preferably R₂ means in which Z means CF₃, C₂F₅, CHF₂, CH₂F, CClF₂, CCL₂F, CF₃CCl₂ or C₃F₇, and preferably CF₃, C₂F₂ or C₃F₇; R₃ means a straight or branched alkyl, aralkyl, alkoxyalkyl, alkoxycarbonyl or alkoxycarbonylalkyl group of 1 - 20 carbon atoms, or a substituted vinyl, substituted cyclopropyl or substituted epoxy group; and m is an integer of 0 - 20 and preferably 0 - 10. R₂ preferably means in which m and n mean respectively an integer of 0 - 10. The preferable group, C n H 2n+1 is pentyl, hexyl, octyl, nonyl or decyl. More definitely, R₂ is a radical derived from any of the following optically active alcohols; 1,1,1-trifluoro-2-C₆ - C₁₆ alkanol, 1,1-difluoro-2-C₆ - C₁₆ alkanol, 1-monofluoro-2-C₆ - C₁₆ alkanol, 1,1,1,2,2-pentafluoro-3-C₆ - C₁₆ alkanol, 1-monofluoro-1,1-dichloro-2-C₆ - C₁₆ alkanol, 1,1,1-trichloro-2-C₆ - C₁₆ alkanol, 1,1-difluoro-1-monochloro-2-C₆ - C₁₆ alkanol, 1,1,1-trifluoromethyl-1-phenylmethanol, 1,1,1-trifluoromethyl-2-phenylethanol, 1,1,1-trifluoromethyl-3-phenylpropanol, 1,1,1-trifluoro-3-decene-2-al, 1,1,1-trifluoro-3-heptene-2-al, methyl-4,4,4-trifluoro-3-hydroxybutylate, ethyl-4,4,4-trifluoro-3-hydroxybutylate, propyl-4,4,4-trifluoro-3-hydroxybutylate, butyl-4,4,4-trifluoro-3-hydroxybutylate, pentyl-4,4,4-trifluoro-3-hydroxybutylate, hexyl-4,4,4-trifluoro-3-hydroxybutylate, heptyl-4,4,4-trifluoro-3-hydroxybutylate, octyl-4,4,4-trifluoro-3-hydroxybutylate, nonyl-4,4,4-trifluoro-3-hydroxybutylate, and decyl-4,4,4-trifluoro-3-hydroxybutylate. The haloalcohols may be manufactured according to disclosures in e.g. "J. Org. Chem." 52 , (15), 3211 (1987) and "Sience" 56 , (9), 531 (1986). Particularly preferable liquid crystal compounds of the invention are represented by the formula (I), in which R₁ means an alkyl, alkoxy, alkylalkoxycarbonyl or alkylcarbonyloxy group of 4 - 20 carbon atoms, preferably C n H 2n+1 , C n H 2n+1 O, and more preferably a straight chain alkyl or C n H 2n+1 in which n is an integer of 5 - 10; (A) means X means -CH₂O-, -O- or -OCH₂-, preferably (B) means Y means -O-, -S- or -CH₂O-; and R₂ means wherein Z is CF₃, C₂F₅, CHF₂, CH₂F, CClF₂, CCl₂F, CF₃CCl₂ or C₃F₇, preferably CF₃, C₂F₅ or C₃F₇; R₃ means a straight or branched alkyl or 3 - 15 carbon atoms; and m is an integer of 0 - 15, preferably 0 - 10, and R₂ more preferably means wherein C n H 2n+1 is pentyl, hexyl, octyl, nonyl or decyl and derived from the optically active alcohols comprising 1,1,1-trifluoro-2-C₆ - C₁₆ alkanol; 1,1-difluoro-2-C₆ - C₁₆ alkanol; 1-monofluoro-2-C₆ - C₁₆ alkanol; 1,1,1,2,2-pentafluoro-3-C₆ - C₁₆ alkanol; 1-monofluoro- 1,1-dichloro-2-C₆ - C₁₆ alkanol; 1,1,1-trichloro-2-C₆ - C₁₆ alkanol; and 1,1-difluoro-1-1-monochloro-2-C₆ - C₁₆ alkanol. Among the novel liquid crystal compounds of the invention represented by the formula (I), when R₁ is an alkyl, alkoxy, alkyloxycarbonyl or alkylcarbonyloxy group of 5 - 20 carbon atoms, and preferably C n H 2n+1 or C n H 2n+1 O, and more preferably C n H 2n+1 in which n is and integer of 6 - 10 (A) is X is (B) is Y is R₂ is wherein Z means CF₃, C₂F₅, CHF₂, CH₂F, CClF₂, CCl₂F or CF₃CCl₂ more preferably CF₃ or C₂F₅; R₃ means a straight or branched alkyl or 3 - 15 carbon atoms; and m is an integer of 0 - 3, preferably 0 or 1; R₂ is preferably in which C n H 2n+1 preferably means pentyl, hexyl, octyl, nonyl or decyl, which is derived from 1,1,1-trifluoro-2-C₆ - C₁₆ alkanol, 1,1-difluoro-2-C₆ - C₁₆ alkanol, 1-monofluoro-2-C₆ - C₁₆ alkanol, 1,1,1,2,2-pentafluoro-3-C₆ - C₁₆ alkanol, 1-monofluoro-1,1-dichloro-2-C₆ - C₁₆ alkanol, 1,1,1-trichloro-2-C₆ - C₁₆ alkanol and 1,1-difluoro-1-1monochloro-2-C₆ - C₁₆ alkanol, those show the tristable liquid crystal phase. The compounds of the invention may be manufactured as follows; In the formulae R₁ and R₂ mean the same as above. (a) Ethyl malonate is reacted with a sodium alcolate and an alkyl bromide to obtain a 2-alkyl-ethyl malonate, which is reduced in ether or tetrahydrofuran with hydrogenated lithium aluminum to obtain 2-alkyl-1,3-propanediol (1). The compound (1) is then reacted with 4-cyanobenzaldehyde to obtain 2-(4′-cyanophenyl)-5-alkyl-1,3-dioxane (2), of which cyano is hydrolyzed in the presence of caustic potash and ethylene glycol to obtain 2-(4′-carboxyphenyl)-5-alkyl-1,3-dioxane (3). The compound (3) is treated with thionylchloride to obtain the corresponding chloride (4). (B) Meanwhile, 4-benzyloxy-benzoic acid chloride is added with optically active 1-trifluoromethyl-1-alkanol in the presence of pyridine to obtain 1-trifluoromethyl-1-alkyl 4-benzyloxybenzoate (5), which is hydrogenated with using Pd/carbon as catalyst to obtain 1-trifluoromethyl-1-alkyl 4-hydroxybenzoate (6). (C) Then the chloride (4) of the dioxane (3) is reacted with 1-trifluoromethyl-1-alkyl 4-hydroxybenzoate (6) to obtain the objective compound, 4′-(1-trifluoromethylalkyloxycarbonyl)-phenyl 4-(5-alkyl-1,3-dioxane-2-yl)benzoate (7). Now some Examples are to be given, but the invention is of course not limited thereto. Example 1 1) Synthesis of (R)-(+)-1-trifluoromethylnonyl 4-benzyloxybenzoate 3.6 g of 4-Benzyloxy-benzoic acid-chloride and 2.2g of (R)-(+)-1,1,1-trifluoro-2-decanol ([α] d =22.3°) were added in 35 ml of pyridine to be stirred at the room temperature for 12 hours and poured into ice-water and extracted with methylene chloride. The methylene chloride phase was washed successively with 1N sodium carbonate solution, water, diluted hydrochloric acid and water to recover the organic phase, which was dried over anhydrous magnesium sulphate, distilled to remove the solvent and subjected to toluene/silica gel chromatography to obtain the compound captioned above. 2) Synthesis of (R)-(+)-1-trifluoromethylnonyl 4-hydroxylbezoate The compound obtained in 1) was dissolved in 50 ml of methanol, added with 0.2 g of 10% Pd/carbon catalyst and hydrogenated in an atmosphere of hydrogene under high pressure to obtain the captioned compound. 3) Synthesis of (R)-(+)-4′-(1-trifluoromethylnonyloxycarbonyl)-phenyl 4-(5-n-pentyl-trans-1,3-dioxane-2-yl)benzoate Thionyl in the excessive amount was reacted with 4-(5-n-pentyl-trans-1,3-dioxane-2-yl)-benzoic acid, which was obtained by alkaline hydrolysis of usually synthesized 4-(5-pentyl-1,3-dioxane-2-yl)benzonitrile in the amount of 2.2 g in ethylene glycol as solvent, under reflux for 6 hours and distilled for removing unreacted thionyl to obtain the acid chloride in the amount of 1.74 g. (R)-(+)-1-trifluoromethylnonyl 4-hydroxybenzoate obtained in 2) in the amount of 1.52 g was reacted with the above acid chloride in the amount of 1.74 g in 20 ml of pyridine at the room temperature for a whole day and might. The reaction liquid was poured into ice-water and extracted with methylene chloride. The methylene chloride phase was successively washed with 1N sodium carbonate solution, water, diluted hydrochloric acid and water. The organic phase was dried over anhydrous magnesium sulphate and distilled for removing the solvent to obtain the crude objective compound. The crude objective compound was subjected to toluene/silica gel chromatography to obtain the optically active compound ([α] d = +28.9°) in the amount of 1.1 g. This liquid crystal compound of the invention shows following phase transition points; The infrared absorption spectrum (KBr) thereof is shown in Fig. 1 of the accompanying drawings. Example 2 1) Synthesis of 1-trifluoromethylheptyl 4-benzyloxybenzoate 4-Benzyloxy-benzoic acid-chloride in the amount of 4.3 g was dissolved in 50 ml of methylene chloride, to which a solution of 2.9 g of optically active 1,1,1-trifluoro-2-octanol, 0.6 g of dimethylaminopyridine and 1.7 g of triethylamine in 50 ml of methylene chloride was gradually added under cooling with ice. The mixture was held at the room temperature for reaction for a whole day and might. The reaction liquid was taken in ice-water and extracted with methylene chloride. The methylene chloride phase was successively washed with diluted hydrochloric acid, water, 1N sodium carbonate solution and water, dried over anhydrous magnesium sulphate, and distilled for removing the solvent to obtain the crude compound captioned above, which was treated according to toluene/silica gel chromatgraphy and recrystalized with ethanol to obtain the purified compound in the amount of 3.8 g. 2) Synthesis of 1-trifluoromethylheptyl 4-hydroxybenzoate The compound obtained in 1) was dissolved in 100 ml of methanol, added with 10 % Pd/carbon catalyst and hydrogenated in hydrogen atmosphere to obtain the captioned compound in the amount of 2.8 g. 3) Synthesis of 4′-(1-trifluoromethylheptyloxycarbonyl)-phenyl 4-(5-n-nonyl-trans-1,3-dioxane-2-yl) benzoate 4-(5-Nonyl-trans-1,3-dioxane-2-yl)benzonitrile obtained according to the usual method was subjected to alkaline hydrolysis in ethylene glycol as solvent to obtain 4-(5-nonyl-trans-1,3-dioxy-2-yl)benzoic acid. This benzoic acid derivative in the amount of 0.700 g, 0.537 g of 1-trifluoromethylheptyl 4-hydroxybenzoate obtained in 2), 0.546 g of dicyclohexylcarbodiimide and a very small amount of dimethylaminopyridine were reacted in 30 ml of tetrahydrofuran at the room temperature for a whole day and night. The reaction mixture was filtered to remove the unsolved content and distilled for remove tetrahydrofuran. The residue was subjected to silica gel chromatography and recrystalized with ethanol to obtain the optically active objective compound in the amount of 0.179 g. The optical rotation thereof [α] D / 20= -30.47°. This objective liquid crystal compound shows tristable liquid crystal phase and has following phase transition points as a result of observation by means of the polarizing microscope with a hot stage. S (s) * means the tristable liquid crystal phase. The infrared absorption spectrum (KBr) thereof and the nuclear magnetic resonance spectrum are respectively shown in Fig. 2 and Table 1 given hereafter. Example 3 1) Synthesis of (R)-(+)-1,1,1-trifluoromethyl-2-ethoxycarbonylethyl 4-benzyloxybenzoate 4-Benzyloxybenzoyl chloride in the amount of 1,8 g was dissolved in 30 ml of methylene chloride to prepare a solution, to which a solution of 1,2g of (R)-(+)-ethyl-4,4,4-trifluoro-2- hydroxybutylate ([α ] d = +21.80), 0.7 g of triethylamine and 0.2 g of dimethyl aminopyridine in 20 ml of methylene chloride was gradually added under cooling with ice, after which the reaction liquid was held at the room temperature to be stirred for 12 hours. The reaction liquid was poured into ice-water and extracted with methylene chloride. The methylene chloride phase was successively washed with diluted hydrochloric acid, water, 1N sodium carbonate solution and water so as to recover an organic phase, which was dried over anhydrous magnesium sulphate, distilled for removing the solvent and subjected to toluene/silica gel chromatography to obtain the captioned compound in the amount of 1.1 g. 2) Synthesis of (R)-(+)-1-trifluoromethyl-2-ethoxycarbonylethyl 4-hydroxybenzoate The compound obtained in 1) was dissolved in 50 ml of methanol, added with 10 % Pd/carbon catalyst and hydrogenated in hydrogene atmosphere to obtain the captioned compound in the amount of 0.8 g. 3) (R)-(+)-4-(1,1,1-trifluoromethyl-2-ethoxycarbonyloxycarbonyl)-phenyl 4-(5-n-pentyl-trans-1,3-dioxane-2-yl)benzoate Separately, 1.2 g of 4-(5-pentyl-trans-1,3-dioxane-2-yl)benzonitrile prepared according to the usual method was subjected to alkaline hydrolysis with using ethylene glycol as solvent to obtain 4-(5-n-pentyl-trans-1,3-dioxane-2-yl)benzoic acid, which was reacted with thionyl in the exessive amount under reflux for 6 hours and distilled for removing unreacted thionyl to obtain the acid chloride in the amount of 0.9 g. 0.8 g of (R)-(+)-1,1,1-trifluoromethyl-2-ethoxycarbonylethyl 4-hydroxybenzoate obtained in 2), 0.3 g of triethylamine and 0.1 g of dimethylaminopyridine were dissolved in 50 ml of methylene chloride for preparing a solution, which was added to a solution of the acid chloride obtained in the above in 20 ml of methylene chloride for reaction at the room temperature for a whole day and might. The reaction liquid was poured into ice-water and extracted with methylene chloride. The methylene chloride phase was successively washed with diluted hydrochloric acid, water, 1N sodium carbonate solution and water. The organic phase was dried over anhydrous sodium sulphate and distilled for separating the crude compound. The crude compound was subjected to silica gel chromatography with using hexane/ethylacetate as developer so as to obtain purified objective compound ([α] D / 20= +24.5°) in the amount of 0.5 g. The transition phase points thereof is as follows as a result of the observation by means of a polarizing microscope with a hot stage. The infrared absorption spectrum (KBr) is shown in Fig. 3. Example 4 In a liquid crystal cell casing of 2.3 µm thickness having an indium/tinoxide substrate coated with an orientated polyimide layer, the liquid crystal compounds obtained in Example 3 was filled in the isotropic phase to prepare a liquid crystal cell. The cell was gradually cooled by a temperature gradient of 0.1 - 1.0°C/min so that the liquid crystal was orientated at the S A phase, impressed with a wave of ±15C and 10 Hz and observed by a polarizing microscope having a photomuliplier so as to detect the electrooptical respouse behavier, whereby the electroclinic effect making optical response to the impressed electric field at the S A phase was confirmed as shown in Fig. 4. The same can be applied also in respect of the liquid crystal compound obtained in Example 1. Example 5 The similar liquid crystal cell except that the liquid crystal obtained in Example 2 was used instead of that of Example 3 was mounted in the polarizing microscope having the photomultiplier of two polarizing plates so arranged as to make a right angle with each other in such a way that the molecular apsis makes an angle of 22.5° relative to the polarizer. This liquid crystal cell was gradually cooled at a temperature gradient of 0.1 - 1.0°C/min to be in the S * / C phase. In the range or a temperature of 70.0°C to 18.0°C, a triangular wave voltage of ±30V, 10 Hz was impressed, of which state is shown in Fig. 5, from which it is possible to observe tristable liquid crystal molecular orientations comprising a dark phase in case of minus impressed voltage, a medium phase in case or zero voltage and a light phase in case of the plus voltage.

Claims: Liquid crystal compounds represented by the general formula (I) in which R₁ means an alkyl, alkoxy, alkyloxycarbonyl or alkylcarbonyloxy group or 1 - 20 carbon atoms; (A) means X means wherein R' is hydrogen, methyl or ethyl and ℓ is an integer of 1 - 16; (B) means Y means -O-, -S- or -CH₂O-; and R₂ means wherein R₃ is a straight or branched alkyl, aralkyl, alkoxyalkyl, alkoxycarbonyl or alkoxycarbonylalkyl group of 1 - 20 carbon atoms, a substituted vinyl, substituted cyclopropyl or substituted epoxy group; Z is CF₃, C₂F₅, CHF₂, CH₂F, CClF₂, CCL₂F, CF₃CCl₂ or C₃F₇; and m is an integer of 0 - 20. Liquid crystal compounds as set forth in Claim 1, in the formula (I) of which R₂ means a radical derived from any of optically active alcohols; 1,1,1-trifluoro-2-C₆ - C₁₆ alkanol, 1,1-difluoro-2-C₆ - C₁₆ alkanol, 1-monofluoro-2-C₆ - C₁₆ alkanol, 1,1,1,2,2-pentafluoro-3-C₆ - C₁₆ alkanol, 1-monofluoro-1,1-dichloro-2-C₆ - C₁₆ alkanol, 1,1,1-trichloro-2-C₆ - C₁₆ alkanol, 1,1-difluoro-1-monochloro-2-C₆ - C₁₆ alkanol, 1,1,1-trifluoromethyl-1-phenylmethanol, 1,1,1-trifluoromethyl-2-phenylethanol, 1,1,1-trifluoromethyl-3-phenylpropanol, 1,1,1-trifluoro-3-decene-2-al, 1,1,1-trifluoro-3-heptene-2-al, methyl-4,4,4-trifluoro-3-hydroxybutylate, ethyl-4,4,4-trifluoro-3-hydroxybutylate, propyl-4,4,4-trifluoro-3-hydroxybutylate, butyl-4,4,4-trifluoro-3-hydroxybutylate, pentyl-4,4,4-trifluoro-3-hydroxybutylate, hexyl-4,4,4-trifluoro-3-hydroxybutylate, octyl-4,4,4-trifluoro-3-hydroxybutylate, nonyl-4,4,4-trifluoro-3-hydroxybutylate and decyl-4,4,4-trifluoro-3-hydroxybutylate. Liquid crystal compounds as set forth in Claim 1, in the formula (I) of which R₁ means an alkylo, alkoxy, alkyloxycarbonyl or alkylcarbonyloxy group of 4 - 20 carbon atoms; (A) means X means CH₂O, -O- or -OCH₂; (B) means Y means -O-, -S- or -CH₂O-; and R₂ means wherein R³ is a straight or branched alkyl group or 3 - 15 carbon atoms; Z is CH₃, C₂F₅, CHF₂, CClF₂, CCL₂F, CF₃CCL₂ or C₃F₇; and m is an integer of 0 - 15. Liquid crystal compounds as set forth in Claim 1, in the formula (I) of which R₁ means C n H 2n+1 , C n H 2n+1 O, wherein n is an integer of 5 - 10; (A) means X means (B) means Y means -O-, -S- or -CH₂O-; and R₂ means wherein R₃ is a straight or branched alkyl broup of 3 - 15 carbon atoms; Z is CF₃, C₂F₅ or C₃F₇; m is an integer of 0 - 10 and n is an integer of 5 - 10. Liquid crystal compounds as set forth in Claim 2, in the formula (I) of which R² means the radical derived from any of optically active alcohols; 1,1,1-trifluoro-2-C₆ - C₁₆ alkanol, 1,1-difluoro-2-C₆ - C₁₆ alkanol, 1-monofluoro-2-C₆ - C₁₆ alkanol, 1,1,1,2,2-pentafluoro-3-C₆ - C₁₆ alkanol, 1-monofluoro-1,1-dichloro-2-C₆ - C₁₆ alkanol, 1,1,1-trichloro-2-C₆ - C₁₆ alkanol and 1,1-diifluoro-1-monochloro-2-C₆ - C₁₆ alkanol. Liquid crystal compounds as set forth in Claim 1, in the formula (I) of which R₁ means an alkyl, alkoxy, alkyloxycarbonyl or alkylcarbonyloxy group of 5 - 20 carbon atoms; (A) means X means (B) means Y means and R₂ means wherein R³ is a straight or branched alkyl group of 3 - 15 carbon atoms, Z is CF₃, C₂F₅, CHF₂, CH₂F, CClF₂, CCl₂F or CF₃CCl₂; and m is an integer of 0 - 3, so as to show a tristable liquid crystal phase. Liquid crystal compounds as set forth in Claim 6, in which, R₁ means a straight chain alkyl or alkoxy group respectrively represented by the formula, C n H 2n+1 or C n H 2n+1 O wherein n is an integer or 6 - 10; (A) means X means (B) means Y means and R₂ means wherein Z is CF₃ or C₂F₅, m is an integer of 0 or 1 and n is an integer of 5, 6, 8, 9, or 10, so as to show a tristable liquid crystal phase. Liquid crystal compounds as set forth in Claim 6, in which R₂ means a radical derived from any of optically active alcohols; 1,1,1-trifluoro-2-C₆ - C₁₆ alkanol, 1,1-difluoro-2-C₆ - C₁₆ alkanol, 1-monofluoro-2-C₆ - C₁₆ alkanol, 1,1,1,2,2-pentafluoro-3-C₆ - C₁₆ alkanol, 1-monofluoro-1,1-dichloro-2-C₆ - C₁₆ alkanol, 1,1,1-trichloro-2-C₆ - C₁₆ alkanol and 1,1-diifluoro-1-monochloro-2-C₆ - C₁₆ alkanol. Liquid crystal compound as set forth in Claim 1, which is (R)-(+)-4'-(1-trifluoromethylnonyloxycarbonyl)phenyl 4-(5-pentyl-trans-1,3-dioxane-2-yl)benzoate of the formula; Liquid crystal compound as set forth in Claim 1, which is 4'-(1-trifluoromethylheptyloxycarbonyl)phenyl 4-(5-n-nonyl-trans-1,3-dioxane-2-yl)-benzoate showing a tristable liquid crystal phase and of the formula; Liquid crystal compound as set forth in Claim 1, which is (R)-(+)-4-(1-trifluoromethyl-2-ethoxycarbonyloxycarbonyl)-phenyl 4-(5-n-pentyl-trans-1,3-dioxane-2-yl) benzoate of the formula;

Inventors: HAGIWARA TAKASHI C O SHOWA SHE, NUMAZAWA KOICHI C O SHOWA SHEL, SUZUKI YOSHIICHI C O SHOWA SHE, HAGIWARA, TAKASHI C/O SHOWA SHELL SEKIYU K.K., NUMAZAWA, KOICHI C/O SHOWA SHELL SEKIYU K.K., SUZUKI, YOSHIICHI C/O SHOWA SHELL SEKIYU K.K.
Applicants: SHOWA SHELL SEKIYU, SHOWA SHELL SEKIYU KABUSHIKI KAISHA
Application year: 1989
Main classification: C07D319
IPC codes: C09K19, C07D319