JPH0248534B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to an optically active lactic acid derivative 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.Left., 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 the liquid crystal state into a matrix, its selective scattering properties can be utilized to utilize it as a notch filter or band filter (FJ
Kahn, Appl.Phys.Lett., 18, 231 (1971)), a circularly polarized beam splitter using circular polarization characteristics (SD Jacobs, SPIE, 37,
98 (1981)); et al. Although a detailed explanation of each method will be omitted, all of them are important as display elements and modulation elements. Optically active compounds are used as the main component of the functional materials constituting these optical elements. Many of such optically active functional materials are themselves synthesized via optically active intermediates. Conventionally, optically active intermediates for synthesizing functional materials required for optical elements characterized by having optical activity include 2-methylbutanol, secondary octyl alcohol, secondary butyl alcohol, and p-(chloride). Known examples include 2-methylbutylbenzoic acid, secondary phenethyl alcohol, amino acid derivatives, synthetic derivatives, and cholesterol derivatives. However, these have the following drawbacks. It is difficult to change the structure of optically active chain hydrocarbon derivatives and, with the exception of some, they are very expensive. Amino acid derivatives are relatively inexpensive and their structures can be easily changed, but the hydrogen groups of amines are chemically active and easily cause hydrogen bonds and chemical reactions, which tends to limit the properties of functional materials. . It is difficult to change the structure of chemical derivatives and cholesterol derivatives, and they tend to adversely affect the properties of functional materials due to steric hindrance. Furthermore, among optical elements characterized by having optical activity, polar groups have been introduced in order to improve responsiveness in methods using electro-responsive optical effects in a liquid crystal state. Most of the optically active intermediates had low polarity or were unable to utilize polar groups effectively. Particularly in ferroelectric liquid crystals, it is known that the response speed is proportional to the spontaneous polarization, and it is desired to increase the spontaneous polarization in order to increase the speed. From this point of view, P. Keller et al. showed that it is possible to increase spontaneous polarization and speed up the response speed by introducing a chlorine group into an asymmetric carbon (CR
Acad.Sc.Paris, 282 C, 639 (1976)). but,
Chlorine groups introduced into asymmetric carbons are not only chemically unstable but also have the disadvantage of decreasing the stability of the liquid crystal phase due to their large atomic radius, so improvements are desired. . The above-mentioned drawbacks have been a major constraint on the development of various materials. Purpose of the Invention In view of the above-mentioned circumstances, the main object of the present invention is to be able to combine functional material intermediates with appropriate intermolecular force and shape without impairing optical activity, and to freely design molecules. The purpose is to provide compounds that can perform the following steps. Furthermore, the length of the alkyl group can be easily changed in the present invention, which makes it possible to easily change the length of the alkyl group.
Phys.Chem., 226, 146 (1964), a liquid crystal compound capable of controlling the type and temperature range of the liquid crystal phase developed in a liquid crystal state, and a liquid crystal containing at least one compound thereof as a compounding component. The purpose is to provide a composition. Furthermore, it is an object of the present invention to provide a liquid crystal composition with improved electric field responsiveness such as response speed, especially when used as a ferroelectric liquid crystal, by blending a liquid crystal compound with a large spontaneous polarization. . 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 () (In the above general formula, R represents a linear alkyl group having 1 to 16 carbon atoms, n is 1 or 2, and C ^* represents an asymmetric carbon atom) It is something. The compound represented by the formula (I) has an asymmetric carbon via a reactive carboxy group and phenylene or buphenylene, so its optical activity is very stable. Therefore, various derivatives can be easily synthesized through ester bonds, amide bonds, carbonate bonds, etc. without particularly selecting reaction conditions. It also reduces carboxyl groups,
Even when converted by Grignard reaction, it does not lose its optical activity. Furthermore, even when a phenylene group or a biphenylene group is subjected to catalytic hydrogenation, the optical activity is stable, so that it can be converted into a very wide range of derivatives. Furthermore, the lactic acid derivative represented by the general formula () is not only a useful optically active intermediate as described above, but also a useful liquid crystal component by itself. For example, by adding a very small amount to a nematic liquid crystal composition for twisted nematic (TN) type display elements, it is effective to prevent the occurrence of striped patterns (reverse domains) on the display surface and increase the uniformity of the display. It can be used for. Therefore, the present invention also provides a liquid crystal composition containing at least one optically active lactic acid derivative represented by the above general formula () as a compounding component. DETAILED DESCRIPTION OF THE INVENTION In the lactic acid derivative of the present invention, R in the above general formula is a linear alkyl group having 1 to 16 carbon atoms. If it is 17 or more, it is not preferable because the viscosity and molar volume of the final functional material will increase. Further, the preferable number of carbon atoms in R is 2 to 14. In order to synthesize functional materials suitable for applications such as optical elements and modulation elements, it is necessary to combine the optically active lactic acid derivative provided by the present invention with appropriate intermolecular forces and shapes that allow molecular control. It is effective to bond the functional material intermediate without impairing the optical activity. Functional material intermediates that are effective in combination with the lactic acid derivatives of the present invention include azo or azoxy derivatives, ring-assembled hydrocarbon derivatives, fused polycyclic hydrocarbon derivatives, heterocyclic derivatives,
Condensed heterocyclic derivatives, ring assembled heterocyclic derivatives, etc., specifically azobenzene derivatives, azoxybenzene derivatives, biphenyl derivatives, terphenyl derivatives, phenylcyclohexane derivatives, benzoic acid derivatives, pyrimidine derivatives, prazine derivatives, pyridine derivatives, stilbene derivatives, tolan derivatives,
These include chalcone derivatives, bicyclohexane derivatives, and cinnamic acid derivatives. The novel optically active substance represented by the general formula () of the present invention is not only a useful optically active intermediate as described above, but also a useful liquid crystal component by itself. For example, by adding a very small amount to a nematic liquid crystal composition for twisted nematic (TN) type display elements, it is possible to prevent the occurrence of striped patterns (reverse domains) on the display surface and increase the uniformity of the display. It can also be used effectively. Next, an example of a method for synthesizing the optically active lactic acid derivative represented by the general formula () of the present invention will be shown. That is, the compound of the above formula (a) in which R is an alkyl group has a lactic acid ester and a hydrocarbon iodide.
Obtained by reaction in the presence of Ag ₂ O.
In this case, it is preferable to mix the lactic acid ester and the hydrocarbon in a container, and then add Ag ₂ O to the mixture. Furthermore, in order to synthesize the compound of the above formula (b), a method is used in which the compound of the above formula (a) is treated with a reducing agent such as LiAlH ₄ . Furthermore, in the case of substituting an OH group with a halogen atom, a method is employed in which a halogenating agent such as PBr ₃ , SOCl ₂ or PCl ₅ is allowed to act on the compound of formula (b). In the case of tosylation, a method is used in which p-toluenesulfonic acid chloride is allowed to act on the compound of formula (b). The optically active compound of the present invention is obtained by reacting the thus obtained compound of formula (c), (d), and (e) with p-hydroxybenzoic acid and p-hydroxybiphenylcarboxylic acid under alkaline conditions. Lactic acid derivatives can be obtained. In the optically active lactic acid derivative of the present invention, R can be varied widely by changing RI as a starting material, but in the present invention, R is particularly given as R having 1 to 16 carbon atoms. R.I.
Specific examples include iodobutane, iodopentane, iodohexane, iodoheptane, iodooctane, iodononane, iododecane, iodoundecane, iodododecane, iodotridecane, iodotradecane, iodopentadecane, iodohexadecane, etc. There are chain alkyl iodides. Examples of the optically active lactic acid derivatives of the present invention thus obtained are shown in Table 1 below along with their specific optical rotation data.

[Table] As mentioned above, the optically active lactic acid derivative of the formula () obtained in this way can be used instead of optically active chain hydrocarbon derivatives, amino acid derivatives, synthetic derivatives, cholesterol derivatives, etc. The group can be used to bond with other intermediates through ester bonds, amide bonds, carbonate bonds, etc., and this makes it useful as an intermediate for producing functional materials that form optical elements, as well as various other intermediates. It is also used as an intermediate in the synthesis of natural optically active substances. Furthermore, the optically active substance of the formula () is effective in preventing reverse domains in a TN cell by adding it to a nematic liquid crystal. In this case, it is preferable to use it in a proportion of 0.1 to 50% by weight of the liquid crystal composition. Furthermore, by adding it to a nematic liquid crystal, it can be used as a liquid crystal composition in a phase transition type liquid crystal element or a White-Taylor type guest-host type liquid crystal element as a chiral nematic liquid crystal.
In this case, it is preferable to use it in a proportion of 0.1 to 80% by weight of the liquid crystal composition. Furthermore, the optically active substance of the formula () can be added, for example, from 0.1 to 80% by weight to a liquid crystal composition that exhibits a ferroelectric chiral smectic liquid crystal state by itself to improve properties such as durability. . 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 liquid crystal composition
It is preferably added in a proportion of 0.1 to 80% by weight. (1) (4-nonyloxyphenyl)-4′-octyloxybiphenyl-4-carboxylate Cryst.107℃ --→ ←－ 74℃SmB117℃ ←－→ SmC160℃ ←－→ SmA195℃ ←－→ Iso. (2) 4,4-Decyloxyazoxybenzene Cryst.77℃ ---→ SmC120℃ ←--→ N123℃ ←--→ Iso. (3) 2-(4'-hexyloxyphenyl)-5-
(4-hexyloxyphenyl)pyrimidine Cryst.120℃ ---→ SmC189℃ ←--→ SmA216℃ ←--→ Iso. (4) 2-(4'-octyloxyphenyl)-5-nonylpyrimidine Cryst.33℃ ---→ SmC60℃ ←--→ SmA75℃ ←--→ Iso. (5) 4'-Pentyloxyphenyl-4-octyloxybenzoate Cryst.58℃ ―→ SmC64℃ ―→ SmA66℃ ―→ N85℃ ―→ Iso. Here, the symbols indicate the following phases, respectively. Cryst.: Crystal phase, SmA: Smectic A phase, SmB: Smectic B phase, SmC: Smectic C phase, N: Nematic phase, Iso.: Isotropic phase. Effects of the Invention As mentioned above, the lactic acid derivative of the present invention can be combined with a functional material intermediate having an appropriate intermolecular force and shape without impairing optical activity, allowing for free molecular design. be able to. Furthermore, in certain compounds of the lactic acid derivatives of the present invention, the length of the alkyl group can be changed, thereby making it possible to control the type and temperature range of the liquid crystal phase that appears in the liquid crystal state. Provides an excellent liquid crystal composition. The liquid crystal compound thus obtained and the liquid crystal composition containing at least one of it as a compounding component have an oxygen atom due to the presence of an oxygen atom adjacent to an asymmetric carbon atom, as shown in the general formula (). It becomes possible to effectively utilize dipole moments caused by atoms. Particularly when used as a ferroelectric liquid crystal, it is possible to increase spontaneous polarization and improve electric field responsiveness such as response speed. Furthermore, the lactic acid derivative of the present invention allows hydrophobic groups to be easily controlled even when a monomolecular cumulative film is produced by the LB film method. Furthermore, by blending at least one optically active lactic acid derivative of the present invention, it is possible to prevent the occurrence of reverse domains in TN liquid crystal compositions or to improve the characteristics of chiral nematic liquid crystals, chiral smectic liquid crystals, etc. . Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 p-(2-ethoxy)propioloxybenzoic acid A solution of 10 g of 2-ethoxypropanol in 59 ml of pyridine was cooled to below 5°C. 22 g of p-toluenesulfonic acid chloride was added with stirring. Thereafter, the mixture was stirred at room temperature for 5 hours and then left overnight. After adding cold water and extracting with ether, the mixture was washed with water and the ether was distilled off to obtain 24 g of p-toluenesulfonic acid 2-ethoxypropyl ester. 10.7g of p-hydroxybenzoic acid in ethanol
10.2g of 85% KOH and 12ml of water dissolved in 85ml
was added and stirred. 24 g of p-toluenesulfonic acid 2-ethoxypropyl ester obtained above was added dropwise. After the dropwise addition was completed, the temperature was raised and the mixture was refluxed for 10 hours. Ethanol was collected, 24 g of a 10% KOH aqueous solution was added, and the mixture was refluxed for 2 hours. After cooling, 6N hydrochloric acid was added and the precipitated white crystals were filtered, washed with water, recrystallized with hexane, and 6 g of p-
(2-Ethoxy)propyloxybenzoic acid was obtained. Specific optical rotation [α]D-18.3°. Examples 2, 3, 4 The same method as in Example 1 was carried out using 2-octyloxypropanol, 2-dodecyloxypropanol, and 2-hexadecylpropanol in place of 2-ethoxypropanol in Example 1, respectively. p-(2-octyloxy)propyloxybenzoic acid (Example 2), p-(2-dodecyloxy)propyloxybenzoic acid (Example 3), p-(2-hexadecyloxy)propyloxybenzoic acid (Example 4) was obtained. The specific rotation data is as described in Table 1 above. Example 5 p-(2-dodecyloxy)propyloxybiphenylcarboxylic acid A solution of 10 g of 2-dodecyloxypropanol in 25 ml of pyridine was cooled to below 5°C, and p-
9.4 g of toluenesulfonic acid chloride was added.
After stirring at room temperature for 6 hours, it was left to stand overnight. Cold water was added and the mixture was extracted with ether, washed with water, and the ether was recovered to obtain 16 g of 2-dodecyloxypropyl p-toluenesulfonic acid. 7.2 g of 4-hydroxy-4'-biphenylcarboxylic acid was added to 37 ml of ethanol, followed by 4.4 g of 85% KOH and 5.3 ml of water. There, the above p-toluenesulfonic acid 2
16 g of -dodecyloxypropyl ester was added dropwise, and the mixture was refluxed for 10 hours. Drop 16g of ethanol,
Refluxed for 10 hours. Collect ethanol and 10% KOH
10 g of an aqueous solution was added, and the mixture was further refluxed for 2 hours. After cooling
A 6N-HCl aqueous solution was added, and the precipitated white crystals were filtered and washed with water. Recrystallize with ethanol and p-(2-
3.5 g of dodecyloxy)propyloxybiphenylcarboxylic acid was obtained. Specific optical rotation [α] D-25.2°. Example 6 Instead of 2-dodecyloxypropanol,
Using 2-pentyloxypropanol, the following
4-(2-pentyloxy) in the same manner as in Example 5
Propyloxy-4'-biphenylcarboxylic acid was obtained. The specific optical rotation data of the lactic acid derivatives of the present invention obtained in the above Examples are summarized in Table 1 above. Further, infrared absorption charts (KBr method) of the lactic acid derivatives obtained in Examples 1, 2, and 5 are shown in FIGS. 1 to 3, respectively. Example 7 A liquid crystal mixture was used in which 2 parts by weight of p-(2-dodecyloxy)propyloxybiphenylcarboxylic acid obtained in Example 5 of the present invention was added to 98 parts by weight of p,p'-pentylazoxybenzene. It was observed that the reverse domain was significantly reduced in the TN cells (twisted nematic cells) prepared by adding this compound compared to the TN cells produced without the addition of this compound.

[Brief explanation of drawings]

FIGS. 1 to 3 show the above-mentioned Example 1 and FIG.
This is an infrared absorption chart (KBr method) of the lactic acid derivative of the present invention obtained in steps 2 and 5.

Claims (1)

[Claims] 1. The following general formula () (In the above general formula, R represents a linear alkyl group having 1 to 16 carbon atoms, n is 1 or 2, and C ^* represents an asymmetric carbon atom.) An optically active lactic acid derivative represented by: 2 General formula below () (In the above general formula, R represents a linear alkyl group having 1 to 16 carbon atoms, n is 1 or 2, and C ^* represents an asymmetric carbon atom.) A liquid crystal composition containing one type of compounded component.