JPH0784432B2 - Optically active substance and liquid crystal composition containing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel optically active substance and a liquid crystal composition containing the same.

BACKGROUND ART As various optical elements characterized by having optical activity, many are known as exemplified below.

1) Utilizing the cholesteric / nematic phase transition effect in the liquid crystal state (JJWysoki, A. Adams and WH
aas; "Physical Review Letters" (Phys.Rev.L)
ett.), 20,1024 (1968)), 2) Utilizing the white Taylor type guest-host effect in the liquid crystal state (DLWhite and GNTaylor;
"Journal of Applied Physics" (J.Ap
pl.Phys.), 45 , 4718 (1974)), 3) Chiral smectic C phase, H in liquid crystal state
Which utilizes the ferroelectric effect of phase, F phase, I phase, G phase, K phase, J phase (NAClark and ST Lagerwall; "Applied Physics Letters" (Appl.Phys.Lett.), 36 ,
899 (1980)), 4) By fixing the one having a cholesteric phase in the liquid crystal state in the matrix and utilizing its selective scattering property, it is used as a notch filter or bandpass filter (FJKahn; “Applied Physics”).・ Letters ”(Appl.Phys.Lett.), 18,231 (197)
1)), which is used as a circularly polarized beam splitter utilizing circular polarization characteristics (SDJacobs, SPIE, 37,98 (198
1)); etc.

A detailed description of each method is omitted, but all are important as a display element or a modulation element.

Also, by adding a very small amount to the nematic liquid crystal composition for twisted nematic (TN) type display element, the occurrence of stripe pattern (reverse domain) on the display surface is prevented,
It can also be effectively used to increase the uniformity of the display.

Conventionally, as an optically active intermediate for synthesizing a functional material required for an optical element characterized by having optical activity, 2-methylbutanol, secondary octyl alcohol,
Secondary butyl alcohol, p- (2-methylbutyl) chloride
Benzoic acid, secondary phenethyl alcohol, amino acid derivatives, camphor derivatives, cholesterol derivatives and the like are known.

However, these have the following problems. The optically active chain hydrocarbon derivative is difficult to change in structure, and is very expensive except for a part thereof. Amino acid derivatives are relatively inexpensive and easy to change in structure, but the hydrogen groups of amines are chemically active, and hydrogen bonds and chemical reactions easily occur, which limits the properties of functional materials. It is easy to fall. The camphor derivative / cholesterol derivative is difficult to change its structure, and also tends to adversely affect the properties of the functional material due to steric hindrance.

The above-mentioned drawbacks have been a major limitation in developing various materials.

OBJECT OF THE INVENTION The present invention has been made in view of the above points. That is, the present invention aims to provide a compound which can be bound to a functional material intermediate having an appropriate intermolecular force and shape without impairing the optical activity, and which can be freely designed in terms of molecular design. And

In addition, the present invention makes it easy to change the length of the alkyl group, which allows H. Arnold, “Zeitschrift to be changed.
Für Physica Riche Chemie "(Z.Phys.Che
m.), 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 of them as a compounding component. The purpose is to provide things. Another object of the present invention is to provide a compound capable of easily controlling a hydrophobic group when a monomolecular cumulative film is formed by the LB (Langmuir-Blodgett) film method and capable of forming a stable film. And

SUMMARY OF THE INVENTION The present invention has the general formula (I) (R ^* represents an alkyl group having an asymmetric carbon atom), and an optically active 4-alkylbenzenethiol represented by the formula, and a liquid crystal composition containing the same as at least one compounding component.

Since the compound represented by the general formula (I) has an asymmetric carbon and a thiol group through a benzene ring, it does not lose its optical activity, and thus, a thiolcarboxylic acid ester bond, a sulfide bond, a sulfoxide bond, etc. Since various derivatives can be easily synthesized, the compound is expected to be available in a very wide range. However, to date, no optically active compound as shown in formula (I) is known.

As a result of intensive studies based on the above findings, the present inventors succeeded in synthesizing the compound represented by the general formula (I) and completed the present invention.

The novel optically active substance represented by the general formula (I) of the present invention is effective in preventing a reverse domain in a twisted nematic (TN) type cell by adding it to a nematic liquid crystal. When added to nematic liquid crystal, it can be used as a chiral nematic liquid crystal in a phase transition type liquid crystal element or a white Taylor type guest / host type liquid crystal element.

In a device that utilizes the ferroelectricity of a chiral smectic phase, by adding to the liquid crystal composition,
Although it is possible to improve its characteristics, it can be used as a ferroelectric chiral smectic phase by adding an optically active substance represented by the general formula (I) of the present invention to a smectic liquid crystal as shown below. It is also possible to do.

Here, the symbols indicate the following phases, respectively.

Cryst .: crystalline phase, SmA: smectic A phase, SmB: smectic B phase, SmC: smectic C phase, N: nematic phase, Iso .: isotropic phase.

As described above, the novel optically active substance represented by the general formula (I) of the present invention is very effective as a material used for improving the performance of a ferroelectric liquid crystal element or a TN type liquid crystal element.

DETAILED DESCRIPTION OF THE INVENTION First, a method for synthesizing an optically active substance of the present invention will be described.

In order to produce the optically active 4-alkylbenzenethiol of the general formula (I) according to the present invention, it is suitable to use, for example, an optically active aliphatic alcohol as a starting material. Specifically, 3-methylpentanol, 4-methylhexanol, 1-methylheptanol, 2-methylbutanol, 2-methyloctanol, 2-methylnonanol, 2-methyldecanol and the like are used.

First, the above-mentioned optically active alcohol is halogenated or sulfonated, and then reacted with phenylmagnesium halide to chlorsulfonylate the obtained optically active alkylbenzene. By reducing the obtained optically active 4-alkylphenyl sulfonyl chloride, the optically active 4-alkylbenzene thiol of general formula (I) is obtained.

The following general formula (II) can be used by employing relatively mild conditions when reducing the above-mentioned optically active 4-alkylphenylsulfonyl chloride. (R ^* represents an alkyl group having 4 to 12 carbon atoms having an asymmetric carbon atom.) And is optically active bis (4-alkylphenyl)
It is also possible to obtain disulfides.

Further, the optically active bis- (4-alkylphenyl) disulfide of the general formula (II) thus obtained is further reduced to obtain the optically active 4- (4-alkylphenyl) disulfide of the general formula (I) of the present invention. Alkylbenzenethiol is obtained.

The above synthetic routes are summarized as follows.

Examples of the compound of the general formula (I) thus obtained include the following.

(+)-4- (2'-Methylbutyl) benzenethiol (+)-4- (1'-methylpropyl) benzenethiol (-)-4- (1'-methylpropyl) benzenethiol (+)-4- (1'-Methylhexyl) benzenethiol (-)-4- (1'-methylhexyl) benzenethiol (+)-4- (1 ', 3'-dimethylpropyl) benzenethiol (-)-4- (1 ′, 3′-Dimethylpropyl) benzenethiol (+)-4- (1′-methylbutyl) benzenethiol (−)-4- (1′-methylbutyl) benzenethiol (+)-4- (3′-methylpentyl) ) Benzenethiol (-)-4- (2'-methyloctyl) benzenethiol (-)-4- (2'-methylnonyl) benzenethiol (-)-4- (2'-methyldecyl) ) Benzenethiol (+)-4- (4'-methylhexyl) benzenethiol The optically active substance of formula (I) thus obtained prevents reverse domains in TN type cells by adding it to nematic liquid crystals. It is effective to do. In this case, it is preferable to use 0.01 to 50% by weight of the liquid crystal composition.

When added to nematic liquid crystal, it can be used as a chiral nematic liquid crystal in a phase transition type liquid crystal device or a white Taylor type guest-host type liquid crystal device as a liquid crystal composition. In this case, 0.01 ~ of the liquid crystal composition
It is preferably used in a proportion of 80% by weight.

In addition, the optically active substance of the formula (I) can improve properties such as durability by adding, for example, 0.01 to 80% by weight to a liquid crystal composition exhibiting a ferroelectric chiral smectic liquid crystal state. . Further, a liquid crystal composition exhibiting a ferroelectric chiral smectic phase can be provided by adding it to a smectic liquid crystal. In this case, 0.01 of the liquid crystal composition
It is preferable to add it at a ratio of ˜80% by weight.

Effect of the Invention 4-Alkylbenzenethiol, which is the optically active substance of the present invention represented by the above formula (I), can effectively prevent the reverse domain in a TN cell by adding it to a nematic liquid crystal.

Further, as described above, the 4-alkylbenzenethiol of the present invention can be bound to a functional material intermediate having an appropriate intermolecular force and shape without impairing the optical activity, and the molecular design can be freely performed. . In particular, by selecting the length of the alkyl group, it is possible to control the type and temperature range of the liquid crystal phase developed in the liquid crystal state.

The liquid crystal composition containing at least one 4-alkylbenzenethiol of the present invention can be effectively used for improving the performance by using it as a chiral nematic liquid crystal or a chiral smectic liquid crystal.

Hereinafter, the present invention will be described more specifically with reference to Examples and Reference Examples.

Example Reference Example 1 Bis [4- (2'-methylbutyl) phenyl] disulfide was prepared by the following first to fourth steps.

First step 197 g of 2-methylbutyl alcohol (I) was added to pyridine 1370.
After dissolving in ml and cooling to 10 ° C. or lower in an ice bath, 512 g of p-toluenesulfonyl chloride was added and stirred for 1 hour. After standing overnight in a cold place, 1500 ml of cold water was added and stirred for 2 hours. Then, it is extracted with 200 ml of benzene, washed with 5N HCl and water, dried over anhydrous sodium sulfate and evaporated to remove 510 g of 2'-methylbutyl (II) 4-methylbenzenesulfonate.
Obtained.

Second process Brombenzene 40g, magnesium 6.2g and ether 3
The phenylmagnesium bromide solution prepared from 00 ml was cooled to 5 ° C, and 4-methylbenzenesulfonic acid 2 '
A mixture of 125 g of methylbutyl (II) and 130 ml of ether was added dropwise. After stirring for 2 hours, the temperature was raised, the mixture was refluxed for 2 hours, and then left overnight. 10% H ₂ SO ₄ was added to the reaction solution to adjust the pH to 2. The organic layer was washed successively with an aqueous sodium bicarbonate solution and water, dried over anhydrous magnesium sulfate, and the solvent was evaporated. The product was subjected to vacuum distillation to obtain 48 g of 4- (2 '
-Methylbutyl) benzene (III) was obtained. The IR data is shown below.

IR (cm ^-1 ): 2960, 2940, 2880, 1600, 1500, 1465, 1430, 1380, 13
70.

Third process 49 g of 4- (2'-methylbutyl) benzene (III) was dissolved in 150 ml of chloroform, and 79 g of ClSO ₃ H was added to about 1 g at -10 ° C.
Dropped over time. Then, the mixture was stirred at room temperature for 6 hours.
After the reaction, the mixture was poured into ice and neutralized with a NaOH aqueous solution, and then the solvent was distilled off to obtain 380 g of crystals.

Dissolve the obtained crystals in 350 ml of benzene, and add PCl ₅ 7 at room temperature.
0g was added little by little. After that, after stirring at 55 ℃ for 5 hours,
It was poured on ice and the organic layer was washed with water. Further, the organic layer was separated, dried over anhydrous sodium sulfate, and the solvent was distilled off to obtain an oily substance. This oil was purified by silica gel column chromatography using n-hexane / isopropyl ether as a mobile phase, and 51 g of 4- (2 ″ -methylbutyl)
Benzene-4'-thionyl chloride (IV) was obtained. The IR and NMR data are shown below.

IR (cm ^-1 ): 2980, 2940, 2880, 1600, 1385, 1180.

NMR (ppm): 8.2-7.2 (4H), 2.7-2.5 (2H), 1.6-0.8 (9H).

Fourth process Concentrated H ₂ SO ₄ 137 g in water 410 g, cooled to −15 ° C.,
46.3 g of (2 ″ -methylbutyl) benzene-4′-thionyl chloride (IV) was added dropwise over 20 minutes, 108 g of zinc dust was added at 0 ° C. or below, and the mixture was stirred at −3 ° C. for 2.5 hours.
After returning to room temperature, the temperature was slowly raised and the mixture was stirred at 45 ° C. for 70 minutes.

The reaction mixture was extracted with isopropyl ether, washed with water,
It was dried over anhydrous sodium sulfate and the solvent was distilled off to obtain 25 g of an oily substance. This oily substance was purified by silica gel column chromatography using a mixture of n-hexane / ethyl acetate = 100: 1 as a mobile phase, and bis [4- (2 '
-Methylbutyl) phenyl] disulfide (V)
g, and 17.0 g of a 1: 1 mixture of (V) and 4- (2'-methylbutyl) benzenethiol (VI). (V)
The MNR data is shown below.

NMR (ppm): 7.4-6.9 (8H), 2.6-2.6 (4H), 1.7-0.8 (18H).

Example 1 4- (2'-methylbutyl) benzenethiol was prepared by a reduction process involving the following reactions.

68 g of concentrated H ₂ SO ₄ was added to 210 g of ice and cooled to −12 ° C. to obtain 40 g of 1.0 g of (V) obtained in Reference Example 1 and 17 g of a mixture of (V) and (VI).
Dropped in minutes. Thereafter, zinc powder (53.6 g) was added at 0 ° C or lower, and the mixture was stirred at -1 ° C for 2 hours. After returning to room temperature, the temperature was slowly raised and the mixture was stirred at 59 ° C. for 2.5 hours. The optical rotation, IR and NMR data of the product are shown below.

Optical rotation: ▲ [α] ²⁹ _D ▼ ＝ + 13.2 ° IR (cm ^-1 ): 2970, 2930, 2880, 2580, 1600, 1500, 1465, 1150, 10
85.

NMR (ppm): 7.2-6.9 (4H), 3.3 (1H), 2.5-2.3 (2H), 1.7-0.8 (9H).

Example 2 With respect to 99 parts by weight of Rixon GR-63 (biphenyl liquid crystal mixture manufactured by Chisso Corp.), (+)-4-of Example 2 was used.
Using a liquid crystal mixture added with 1 part by weight of (2'-methylbutyl) benzenethiol, twisted nematic (T
N) A cell was manufactured. It was observed that this cell had a significantly reduced reverse domain compared to the TN cell produced with Rixon GR-63 only.

Claims (2)

[Claims] 1. The following general formula (I): (R ^* represents an alkyl group having 4 to 12 carbon atoms having an asymmetric carbon atom.) An optically active 4-alkylbenzenethiol. 2. The following general formula (I) (R ^* represents an alkyl group having an asymmetric carbon atom and having 4 to 12 carbon atoms.) A liquid crystal composition comprising at least one kind of optically active 4-alkylbenzenethiol.