JPH0541615B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a novel optically active substance and a liquid crystal composition containing the same. BACKGROUND ART There are many known optical elements, as exemplified below, as various optical elements characterized by having optical activity. 1) Those that utilize the cholesteric-nematic phase transition effect in the liquid crystal state (JJWysoki,
A.Adams and W.Haas; Phys.Rev.Lett., 20,
1024 (1968)), 2) One that utilizes the White-Taylor type guest-host effect in the liquid crystal state (DLWhite
and GNTaylor; J.Appl.Phys., 45 , 4718
(1974)), 3) Chiral smectic C in the liquid crystal state
Phase, H phase, F phase, I phase, G phase, K phase, J phase (NAClark and
STLagerwall; Appl.Phys.Lett., 36 , 899
(1980)), 4) By fixing a substance with a cholesteric phase in a liquid crystal state into a matrix, its selective scattering properties are utilized to utilize it as a notch filter or bandpass filter (F.
J. Kahn, Appl. Phys. Lett., 18, 231 (1971)),
Products used as circularly polarized beam splitters that utilize circularly polarized light characteristics (SDJacobs, SPIE,
37, 98 (1981)); etc. Although a detailed explanation of each method will be omitted, all of them are important as display elements and modulation elements. As a main component of the functional materials that make up these optical elements, or as a relatively small component,
Optically active compounds are used as important functional components. For example, H. Arnold, Z. Phys. Chem., 226,
146 (1964) describes the method of controlling the type and temperature range of the liquid crystal phase that appears in the liquid crystal state by adding other optically active substances or liquid crystal compounds to the above-mentioned optical element materials, especially liquid crystal materials. Disclose. In addition, we introduced a compound with a large dipole into the liquid crystal material that is driven by electric field response.
It is also expected that a liquid crystal material with better electric field responsiveness can be obtained. However, many of the conventionally known optically active substances are not suitable for changing the length of the introduced group and are not suitable for controlling the liquid crystal state. Further, there are almost no known compounds in which a group having a large dipole moment is directly introduced into an asymmetric carbon, and a sufficient effect for improving the electric field response of the optical element described above has not been obtained. Object of the Invention In view of the above-mentioned circumstances, the main object of the present invention is to provide an optically active compound that is useful for controlling the liquid crystal state and in which a group having a large dipole moment is directly introduced into an asymmetric carbon, and a liquid crystal composition containing the same. It's about providing things. More specifically, the present invention aims to provide a compound exhibiting excellent electric field response by introducing a group having a large dipole moment into an asymmetric carbon. In addition, in the present invention, it is easy to change the length of the alkyl group, and this allows H.Arnold, Z.Phys.
Chem., 226 , 146 (1964), a liquid crystal compound capable of controlling the type and temperature range of a liquid crystal phase developed in a liquid crystal state, and a liquid crystal composition containing at least one compounded compound thereof. The purpose is to provide Furthermore, the present invention aims to provide a compound whose hydrophobic groups can be easily controlled and which can be stably formed when a monomolecular cumulative film is produced by the LB (Langmuir-Blodgett) film method. . Summary of the Invention The present invention first describes the general formula () (Here, R is an alkyl group having 1 to 16 carbon atoms, and C ^* represents an optically active asymmetric carbon atom. m is 1 or 2, and n is 0 or 1.
A represents a removable substituent selected from an OH group, a halogen atom, a phenoxy group, a toluenesulfonic acid group, an acetyloxy group, and a trifluoroacetyloxy group. The compound represented by the formula () has the effect of controlling the liquid crystal state and improving electric field response as described above, and since the asymmetric carbon atom and the reactive substituent represented by A are separated from each other, It is also expected that various derivatives can be synthesized by combining with other functional intermediates without losing optical activity. However, to date, no optically active compound as represented by formula () is known. Based on the above knowledge, the present inventors conducted extensive research, and as a result, succeeded in synthesizing the compound represented by the above formula (), and completed the present invention. For example, the compound of the above () has the following general formula () The optically active 2-fluoro-1-alkanol represented by: is subjected to an esterification reaction with p-substituted benzoic acid or p-substituted biphenylcarboxylic acid, or the 2-fluoro-1-alkanol is subjected to a tosylation, halogen Hydroquinone after conversion, 4,
Obtained by reaction with 4'-dihydroxybiphenyl. The novel optically active substance represented by the general formula () of the present invention becomes a useful liquid crystal component by itself, as described above. For example, twisted
By adding a very small amount to nematic liquid crystal compositions for nematic (TN) type display elements, it prevents the occurrence of striped patterns (reverse domains) on the display surface.
It can also be effectively used to increase the uniformity of the display. That is, the present invention also provides a liquid crystal composition characterized by containing at least one type of optically active compound represented by the above general formula (). DETAILED DESCRIPTION OF THE INVENTION According to the present invention, in order to produce the optically active compound of the formula (), first, as a starting material, the optically active 2-fluoro-1-
Use alkanol. Such optically active 2-
Fluoro-1-alkanol is, for example, a patent application filed in 1980.
As shown in the specification of No.-232886, optical activity 1,
It can be easily obtained by adding hydrogen fluoride to 2-epoxyalkane. Next, by esterifying the optically active 2-fluoro-1-alkanol with p-substituted benzoic acid or p-substituted biphenylcarboxylic acid, an optically active compound of the formula () where n=1 is obtained. When A is an acetyloxy group, it can be easily converted to a hydroxyl group by further reacting with benzylamine. In the esterification, an equimolar amount or less of acid chloride is used to react with pyridine or triethylenediamine. The reaction may be carried out at a temperature of 30-80°C, preferably 40-60°C. The reaction time is preferably 3 hours or more. Further, p-toluenesulfonic acid ester of the optically active 2-fluoro-1-alkanol or optically active 2-fluoro-1-alkanol derived from the optically active alkonol
By reacting hydroquinone or 4,4'-dihydroxybiphenyl with fluoro-1-bromoalkane and monoetherifying it by a conventional method, an optically active compound in the formula () where n=0 can be obtained. An example of the above series of reactions can be shown by the following reaction scheme. In the optically active compound represented by the formula () of the present invention, the above R can be varied widely by changing the number of carbon atoms in the alkane moiety of 2-fluoro-1-alkanol as a starting material. , the invention provides that R is in particular an alkyl group having 1 to 16 carbon atoms. As mentioned above, the optically active compound represented by the formula () obtained in this way can be used instead of optically active chain hydrocarbon derivatives, amino acid derivatives, synthetic derivatives, cholesterol derivatives, etc., and is capable of attaching and detaching its hydroxyl group, etc. Using available groups, it can be bonded to other intermediates through ester bonds, ether bonds, urethane bonds, carbonate bonds, etc. For this reason, it is useful as an intermediate for manufacturing functional materials that form optical elements, and is also used as an intermediate for the synthesis of various natural optically active substances. Furthermore, the optically active substance of formula () is effective in preventing the occurrence of reverse domains in TN cells by adding it to nematic liquid crystals. In this case, it is preferable to use the optically active substance of formula () in a proportion of 0.01 to 50% by weight of the resulting liquid crystal composition. Furthermore, by adding it to a nematic liquid crystal or a chiral nematic liquid crystal, it can be used as a liquid crystal composition in a phase change type liquid crystal element or a White-Taylor type guest-host type liquid crystal element. In this case, it is preferable to use the optically active substance of formula () in a proportion of 0.01 to 80% by weight of the resulting liquid crystal composition. Further, the optically active substance of the formula () may be added to a liquid crystal composition exhibiting a ferroelectric chiral smectic liquid crystal state by itself in a proportion of, for example, 0.01 to 80% by weight of the obtained liquid crystal composition. By adding the optically active substance of formula (), properties such as durability can be improved. Furthermore, they can be added to smectic liquid crystals whose structural formulas and phase transition temperatures are shown below as 1) to 5) to provide a liquid crystal composition exhibiting a ferroelectric chiral smectic phase. In this case, the resulting liquid crystal composition
It is preferable to add the optically active substance of formula () in a proportion of 0.01 to 80% by weight. In order to provide a chiral smectic liquid crystal composition in this way, when the optically active substance of the formula () is added and utilized, it becomes possible to obtain a large spontaneous polarization, shorten the response time, and Threshold voltage can be lowered.

【table】

[Table] Here, the symbols indicate the following phases, respectively. Cryst.: Crystal phase, SmA: Smectic A
SmB: smectic B phase, SmC: smectic C phase, N: nematic phase, Iso.: isotropic phase. Effects of the Invention As described above, the present invention provides an optically active substance represented by the formula () in which a fluorine group having a large dipole moment is directly introduced into an asymmetric carbon atom. Furthermore, by blending at least one of these optically active substances, properties such as preventing the occurrence of reverse domains in TN liquid crystal compositions and improving electric field responsiveness of chiral nematic liquid crystals or chiral smectic liquid crystals can be improved. It is also possible to control the liquid crystal state. The compounds of the present invention will be explained in more detail below with reference to Examples. Example 1 P-acetyloxybenzoic acid (2-fluorooctyl) ester was produced according to the following reaction scheme. That is, p-acetoxybenzoic acid ( 1 above)
0.68g (3.7m.mol) with 7ml of thionyl chloride
After heating under reflux for 30 minutes, unreacted thionyl chloride was distilled off to obtain an acid chloride. Next, 0.83g (7.4m.
mol) was dissolved in 5 ml of dry benzene, potassium hydroxide was added, and the mixture was dried for about 30 minutes. This solution was mixed with (-)2-fluoro-1-octanol.
The mixture was placed in a container containing 0.66 g (4.5 m.mol), and the mixture was shaken and stirred. This solution was added dropwise to the above acid chloride under stirring, and after completion of the addition, the solution was stirred at 50°C for 2 hours. After the reaction was completed, 8 ml of IN hydrochloric acid and 30 ml of water were added.
This solution was extracted with benzene, and the aqueous layer was further extracted twice with 8 ml of benzene. In this benzene layer,
15 ml of IN aqueous sodium carbonate solution was added and benzene extraction was performed in the same manner as before, and the aqueous layer was extracted twice with 8 ml of benzene. Anhydrous sodium sulfate was added to this benzene layer and it was dried overnight. Benzene was distilled off to obtain a crude product. This was separated by silica gel column chromatography using a 1:1 mixture of benzene:hexane as an eluent to obtain 0.80 g (yield 69%) of p-acetyloxybenzoic acid (2-fluorooctyl) ester. For the product, the following specific rotation and
IR (infrared absorption) data was obtained. Specific optical rotation [α] ²⁴ _D +11.2° (c=2: benzene) IR (cm ^-1 ): 2850-2950, 1760, 1720, 1600, 1265, 1190. Example 2 p-hydroxybenzoic acid (2-fluorooctyl) ester was produced according to the following reaction scheme. That is, 0.750 g (2.5 m.mol) of the purified 3 above
was dissolved in 1.5 ml of ether. A solution of 0.27 g (2.5 m.mol) of benzylamine dissolved in 1.5 ml of ether was added thereto, and the mixture was left at room temperature overnight. Thereafter, the ether was distilled off to obtain a mixture of 4 and 5 . This was separated by silica gel column chromatography using a 1:9 mixture of ethyl acetate and methylene chloride to obtain 0.53 g of purified product 4 (78% yield). The specific rotation and IR data of the product are as follows. Specific optical rotation [α] ^27.6 _D +12.6° (c=2, benzene) IR (cm ^-1 ): 3390, 2850-2940, 1675, 1650, 1590, 1265. Example 3 p-hydroquinone mono(2
-fluorodecyl) ether was produced. That is, 2-fluorodecanol ( 6 ) 3.15
g (18 m.mol) and 4.25 g (54 m.mol) of dry pyridine.
mol) were placed in a container with a nitrogen atmosphere inside and stirred. This container was cooled with water, and 3.75 g (20 mmol) of p-toluenesulfonyl chloride was added in two portions, followed by stirring for 3 hours. After the reaction was completed, the mixture was neutralized with 2N hydrochloric acid, extracted with 10 ml of methylene chloride, and the aqueous layer was further extracted twice with 5 ml of methylene chloride. Water was added to this methylene chloride layer, and the mixture was extracted with methylene chloride in the same manner as before. Anhydrous sodium sulfate was added to this methylene chloride solution and dried overnight. Methylene chloride was distilled off and 2-fluorodecyl-
5.60g of p-toluenesulfonic acid ester ( 7 )
(yield 94%). Specific rotation and IR of product
The data are as follows. Specific optical rotation [α] ^22.0 _D +4.2° (c = 2, methylene chloride) IR (cm ^-1 ): 2850-2900, 1600, 1350, 1170, 1100, 660,
550. Hydroquinone 3.74g (34m.mol) and 1-butanol 5 were added to 5.60g (17m.mol) of 7 obtained earlier.
ml was added and stirred. Sodium hydroxide there 1.02
A solution of g (25 mm.mol) dissolved in 13 ml of 1-butanol was slowly added dropwise, and after the dropwise addition, the reaction was carried out at 130°C for 7 hours. After the reaction was completed, 40 ml of water was added and extracted with ether. Anhydrous sodium sulfate was added to this ether solution and dried overnight. The solvent was distilled off, and this was separated by silica gel column chromatography using methylene chloride to obtain 2.57 g of purified p-hydroquinone mono(2-fluorodecyl) ether (8) (yield: 56
%) was obtained. Specific optical rotation [α] ^24.0 _D +1.8° (c = 2, methylene chloride) IR (cm ^-1 ): 3600 ~ 3200, 2900, 1680, 1590, 1280, 1160,
700. Examples 4 to 11 According to Examples 1, 2, and 3 above, optically active substances of the present invention having different A, m, n, or R in the general formula (1) were obtained, and their specific optical rotations were measured.
The results are shown in the following table together with the results of Examples 1 to 3.

[Table] Example 12 5 parts by weight of the optically active substance of Example 8 was added to 95 parts by weight of p,p'-pentylazoxybenzene to obtain a liquid crystal composition. Using this liquid crystal composition
TN cell (twisted nematic cell)
observed a significant reduction in reverse domains compared to TN cells prepared without the addition of this compound. Example 13 5 parts by weight of the optically active substance of Example 9 was added to 95 parts by weight of MORA8 whose structure is shown below to obtain a liquid crystal composition. This liquid crystal composition exhibited an SmC ^* phase, had a spontaneous polarization 1.8 times that of MORA8 alone, and a response time of 25 msec under the condition of applying ±15 V, which was about 60%. MORA8

Claims (1)

[Claims] 1. The following general formula () (Here, R is an alkyl group having 1 to 16 carbon atoms, and C ^* represents an optically active asymmetric carbon atom. m is 1 or 2, and n is 0 or 1.
A is a substituent selected from the group consisting of an OH group, a halogen atom, a phenoxy group, a toluenesulfonic acid group, an acetyloxy group, and a trifluoroacetyloxy group). 2 General formula below () (Here, R is an alkyl group having 1 to 16 carbon atoms, and C ^* represents an optically active asymmetric carbon atom. m is 1 or 2, and n is 0 or 1.
(A represents a substituent selected from the group consisting of an OH group, a halogen atom, a phenoxy group, a toluenesulfonic acid group, an acetyloxy group, and a trifluoroacetyloxy group) and a liquid crystal compound. A liquid crystal composition.