JPH0645573B2 - Liquid crystal compound and liquid crystal composition - Google Patents

Description

The present invention relates to a novel optically active liquid crystal compound and a liquid crystal composition containing the liquid crystal.

(Prior Art) Various liquid crystal display devices are currently in practical use. Among them, the TN (Twisted Nematic) type display system using nematic liquid crystal has excellent performance such as extremely low power consumption and is widely used. However, this display method has a drawback that the response speed is slow.

Recent advances in industrial technology have strongly demanded high-speed response also in liquid crystal display elements, and various attempts have been made by improving liquid crystal materials to meet such requirements. In order to meet the above demand, a display device (Appl Phys Lett, 36 , 899 (1980)) utilizing the optical switching phenomenon of a ferroelectric liquid crystal has already been proposed. This ferroelectric liquid crystal is said to belong to a chiral smectic C phase (hereinafter abbreviated as SC ^* ) or a chiral smectic H phase (hereinafter abbreviated as SH ^* ) from the viewpoint of the liquid crystal structure.

(Problems to be Solved by the Invention) Table 1 shows a typical known ferroelectric liquid crystal.

However, these compounds are not preferable as a display element because they have an unstable element that they are isomerized by light within a short period of time, and are unstable to water, causing hydrolysis and not exhibiting a liquid crystal phase. An object of the present invention is to provide a ferroelectric liquid crystal having photochemical and chemical stability without such an unstable element and a composition containing the liquid crystal.

(Means for Solving the Problems) In order to achieve the above-mentioned objects, the present inventors arrived at the present invention as a result of synthesizing and examining a liquid crystal substance containing many optically active groups.

That is, the present invention is represented by the general formula (I) (In the formula, X is a hydrogen atom or a halogen atom, Y is R-, Or Z is R-, Or (W represents a hydrogen atom or a halogen atom, R represents an alkyl group, and at least one of the alkyl groups contains an asymmetric carbon atom. (Here, n is an integer of 0 to 3, m is an integer of 1 or 2, and * is an asymmetric carbon atom.) Is an alkyl group having 4 to 8 carbon atoms and the other is 6 carbon atoms.
And a liquid crystal composition containing the compound.

The compound of the present invention is typically synthesized by the following synthetic route.

(X, Y and Z are the same as above) That is, after alkylating or esterifying 2,6-hydroxynaphthalenecarboxylic acid or its halogen-substituted derivative (II) to give compound (III) or (IV), a suitable alcohol Synthesized by reacting with phenols, phenols or carboxylic acids.

More specifically, from the compound of (II) above, (III) or (I
The compound (V) can be produced and the liquid crystal compound (I) can be obtained by using these as raw materials.

Used in the production of the liquid crystal compound of the present invention (III) or (I
For producing the compound of V), for example, 6-alkyloxynaphthalene-2-carboxylic acids, 4-alkyloxyphenols, 4-alkyloxybenzoic acids, 4-hydroxybenzoic acid-4'-alkyloxyphenyl esters And 4-alkyloxybiphenyl-4'-carboxylic acids are used, and these compounds can be produced by a known method.

For example, 6-alkyloxynaphthalene-2-carboxylic acids are prepared by reacting 6-hydroxynaphthalene-2-carboxylic acids with an alkyl bromide in ethanol in the presence of potassium hydroxide (J. Chem. Soc), 1954 678), 4-alkyloxyphenols, a method of reacting hydroquinone with an alkyl bromide in the presence of potassium hydroxide in ethanol (J. Am. Chem. Soc.), 54 , 298 (193
2)), 4-alkyloxybenzoic acids can be obtained by alkylating 4-hydroxybenzoic acid (J. Chem. Soc), 1935 187.
4), 4-alkyloxybiphenyl-4'-carboxylic acids are alkylated 4-hydroxybiphenyl-4'-carboxylic acid (Journal of Chemicals
Society (J. Chem. Soc), 1955 1412), also 4
-Hydroxybenzoic acid-4'-alkyloxyphenyl esters are 4-alkyloxyphenol and hydroxybenzoic acids in toluene in the presence of concentrated sulfuric acid and boric acid.
Any of them can be produced by a reaction method or the like.

Many of the compounds of the present invention exhibit the SC ^* phase, and one of them is characterized by a relatively low temperature range of about 45 to 70 ° C.

Therefore, these compounds are suitable for obtaining a liquid crystal composition exhibiting the SC ^* phase at around room temperature by mixing.

Further, since a certain compound exhibits the SC ^* phase at a relatively high temperature of 80 to 170 ° C., it is suitable for expanding the upper limit of the temperature range of the SC ^* phase of the liquid crystal composition.

The liquid crystal composition of the present invention may be composed of at least one compound of the general formula (I), or may be a liquid crystal composition exhibiting an SC ^* phase at room temperature by mixing the compound of the general formula (I) with another smectic liquid crystal It is also possible to construct an object, and both exhibit ferroelectricity.

Further, when a compound that does not exhibit SC ^* in the general formula (I) is used in combination with a compound that exhibits an SC ^* phase as a so-called liquid crystal compound, the same effect as a liquid crystal composition can be expected.

(Examples) Hereinafter, the present invention will be specifically described with reference to Examples.

The properties of the liquid crystal compounds and liquid crystal compositions produced in the examples are shown in the table.

In these tables, C is a crystalline phase, SA is a smectic A phase,
S ^* is a chiral smectic C phase, CH is a cholesteric (chiral nematic) phase, and I is an isotropic liquid.
X represents an unidentified smectic phase, the mark and the number on the right of each phase indicate the transition temperature from that phase to the phase on the right, and the-mark indicates that the phase does not exist. The values in parentheses are monotropic phase transition temperatures.

Example 1 Preparation of 4-optically active alkyloxyphenyl-6-alkoxynaphthalene-2-carboxylic acid ester (+)-4 '-(2 "-methylbutyloxy) phenyl-
Production Example of 6-octyloxynaphthalene-2-carboxylic acid ester (Compound No. 2 in Table 2) 6-n-octyloxynaphthalene-2-carboxylic acid 1.
8 g, (+)-4- (2′-methylbutyloxy) phenol 1.1 g, N, N′-dicyclohexylcarbodiimide (hereinafter abbreviated as DCC) 1.2 g and 4-pyrrolidinopyridine (hereinafter abbreviated as PRLPY) 50 mg Was placed in 50 ml of methylene chloride and left at room temperature for 15 hours. By-produced N, N′−
After removing dicyclohexylurea, the organic layer was washed with 5% hydrochloric acid, 5% aqueous sodium hydroxide solution and water in this order and dried over anhydrous magnesium sulfate. After distilling off methylene chloride, the residue was purified by silica gel column chromatography using benzene as an eluent. The obtained crystals were recrystallized twice from ethanol to give 1.5 g of colorless needle crystals (())-4 '-(2 "-methylbutyloxy) phenyl-6-octyloxynaphthalene- 2-Carboxylic acid ester was obtained with a yield of 59%. The phase transition temperature is shown in Table 2. Various 4'-optically active alkyloxyphenyl-6-alkoxynaphthalene-2-carboxylic acid esters were prepared by the same reaction procedure. Table 2 shows the phase transition temperatures of these compounds.

Example 2 Preparation of 4'-alkoxyphenyl-6-optically active alkyloxynaphthalene-2-carboxylic acid ester Production Example of 4'-decyloxyphenyl-6-((+)-2 "-methylbutyloxy) naphthalene-2-carboxylic acid ester (Compound No. 11 in Table 3) 6-((+)-2 ′ -Methylbutyloxy) naphthalene-
2-carboxylic acid 1.0 g 4-decyloxyphenol 1.0
g, a mixture of 800 mg of DCC and 20 mg of PRLPY was put in 30 ml of methylene chloride and left at room temperature for 4 hours. By-produced N, N ′
After filtering off dicyclohexyl clair, the organic layer is 5%
It was washed with hydrochloric acid, a 5% aqueous sodium hydroxide solution, and water in this order, and dried using anhydrous magnesium sulfate. After distilling off methylene chloride, the residue was purified by silica gel column chromatography using benzene as an eluent. Further, the obtained crystals were recrystallized twice from ethanol to give 1.1 g of colorless needle-like crystals, the target 4'-decyloxyphenyl-
6-((+)-2 "-methylbutyloxy) naphthalene-
2-Carboxylic acid ester was obtained. Yield 58% The phase transition temperature is shown in Table 3. By the same reaction procedure, various 4'-alkoxyphenyl-6-optically active alkyloxy) naphthalene-2-carboxylic acid esters were obtained.
Table 3 shows the phase transition temperatures of these compounds.

Example 3 4- (6'-alkyloxy-2-naphthoyloxy)
Production of benzoic acid 4 ″ -optically active alkyloxyphenyl ester and its derivative 3-chloro-4- (6′-tetradecyloxy-2-naphthoyloxy) benzoic acid 4 ″-((+)-2-methylbutyloxy) phenyl ester (compound of compound No. 20 in Table 4) Production method 6-tetradecyloxynaphthalene-2-carboxylic acid 55
0 mg, 3-chloro-4-hydroxybenzoic acid-4'-
((+)-2 ″ -methylbutyloxy) phenyl ester 5
00 mg, DCC300 mg, and PRLPY 20 mg were reacted in 30 ml of methylene chloride at room temperature for 20 hours.

After the by-produced N, N'-dicyclohexylurea was filtered off, the organic layer was washed with 5% hydrochloric acid, 5% aqueous sodium hydroxide solution and water in this order and dried over anhydrous magnesium sulfate.

After distilling off methylene chloride, the residue was purified by silica gel column chromatography using benzene as an eluent. The obtained crystals are recrystallized from ethanol-ethyl acetate to obtain 600 mg of colorless needle crystals.
Chlor-4- (6′-tetradecyloxy-2-naphthoyloxy) benzoic acid 4 ″-((+)-2-methylbutyloxy) phenyl ester was obtained. Yield 60% The phase transition temperature is shown in Table 4. By the same reaction procedure, various 4- (6′-alkyloxy-2-naphthoyloxy) benzoic acid 4 ″ -optically active alkyloxyphenyl ester and its halogen-substituted derivative were produced. Table 4 shows the phase transition temperatures of these compounds.

Example 4 Optically active alkyl-6-alkyloxynaphthalene-2
-Production of carboxylic acid ester (+)-2'-Methylbutyl-6-octyloxynaphthalene-2-carboxylic acid ester (Compound No. 2 in Table 5
3 compound) 6-octyloxynaphthalene-2-carboxylic acid 2 g,
5 ml of thionyl chloride was heated to reflux in 50 ml of toluene for 5 hours. Toluene and excess thionyl chloride were distilled off under reduced pressure. The residue was dissolved in 20 ml of toluene and 1 g of (-)
2-Methylbutanol and 10 ml of pyridine solution were added, and the mixture was stirred at room temperature for 10 hours. The reaction mixture was washed with 20% hydrochloric acid, 10% aqueous sodium hydroxide solution and water in this order. The organic layer was dried over anhydrous magnesium sulfate.

After the toluene was distilled off, the residual oil was purified by silica gel column chromatography.

The separated oil is dissolved in 5 ml of n-hexane and cooled to -20 ° C to obtain 1.2 g of colorless plate crystals (+)-
2'-methylbutyl-6-octyloxynaphthalene-
A 2-carboxylic acid ester could be obtained. Yield 49
% The phase transition temperature of this product is as shown in Table 5.

In carrying out the above operation, various optically active alkyl-6-alkyloxynaphthalene-2 can be obtained by using various optically active instead of (-)-2-methylbutanol.
A carboxylic acid ester could be obtained.

The phase transition temperatures of some of the compounds are shown in Table 5.

Example 5 Preparation of 4- (6'-alkyloxy-2'-naphthoyloxy) benzoic acid optically active alkyl ester Preparation Example of 4- (6'-octyloxy-2'-naphthoyloxy) benzoic acid-(+)-2 "-methylbutyl ester (Compound No. 50 in Table 6) 20 g of 4-hydroxybenzoic acid and (- ) -2-Methylbutanol (20 g) and toluene (300 ml) were carefully added, and concentrated sulfuric acid (2 ml) was carefully added, followed by heating and refluxing for 15 hours while distilling off water produced as a by-product. % Sodium carbonate aqueous solution and water in that order.
After drying over anhydrous magnesium sulfate, toluene and excess
The target 4-hydroxybenzoic acid (+)-2-methylbutyl ester 31 by distilling off (-)-2-methylbutanol 31
g was obtained.

Then, 4-hydroxybenzoic acid-(+)-2'-methylbutyl ester 700 ml, 6-octyloxynaphthalene-2-carboxylic acid 1.0 g, DCC 700 mg, PRLPY 20 m
g was dissolved in 30 ml of methylene chloride and left at room temperature for 10 hours.

After the by-produced N, N'-dicyclohexylurea was filtered off, the organic layer was washed with 5% hydrochloric acid, 5% aqueous sodium hydroxide solution and water in this order and dried over anhydrous magnesium sulfate. After distilling off methylene chloride, the residue was purified by silica gel column chromatography using benzene as an eluent. The obtained crystals were recrystallized from ethanol to give 1.1 g of colorless needle-like crystals of the desired 4- (6'-octyloxy-2'-naphthoyloxy) benzoic acid-(+)-
2 ″ -methylbutyl ester was obtained. The yield was 67%, and the phase transition temperature is shown in Table 6.

Various 4-hydroxybenzoic acid-optically active alkyl esters were used for esterification to obtain various 4- (6'-alkyloxy-2'-naphthoyloxy) benzoic acid (optically active alkyl) esters. Table 6 shows the phase transition temperatures of these compounds.

Example 6 6- (4′-alkyloxybenzoyloxy) naphthalene-2-carboxylic acid (optically active alkyl) ester and 5-halogeno-6- (4′-alkyloxybenzoyloxy) naphthalene-2-carboxylic acid (optical Production of active alkyl) esters Preparation Example of 6- (4'-tetradecyloxybenzoyloxy) naphthalene-2-carboxylic acid-((+)-2 "-methylbutyl) ester (Compound No. 70 in Table 7) 6-Hydroxynaphthalene-2- 5.0 g of carboxylic acid, (-)
A mixture of 10 g of 2-methylbutanol and 1 ml of concentrated sulfuric acid
The mixture was heated and refluxed for 15 hours while distilling off water produced as a by-product in 200 ml of toluene. After cooling, the reaction mixture was washed with water,
% Sodium carbonate aqueous solution and water in that order, and dried over anhydrous magnesium sulfate. Toluene and excess (-)-2-
After distilling off methylbutanol, the residue was purified by silica gel column chromatography using benzene-ethyl acetate (15: 1 v / v) as an eluent to obtain the desired 6-hydroxynaphthalene-2-carboxylic acid-(+). 4.5 g of 2-methylbutyl ester was obtained. Yield 66%, melting point 84
˜85 ° C. Then, this 6-hydroxynaphthalene-2-carboxylic acid-(+)-2-methylbutyl ester 400 mg, tetradecyloxybenzoic acid 500 mg, DCC 320 mg and PRLPY 10 mg
The reaction was carried out in 0 ml of methyl chloride at room temperature for 10 hours.

After the by-produced N, N'-dicyclohexylurea was filtered off, the organic layer was washed with 5% hydrochloric acid, 5% aqueous sodium hydroxide solution and water in this order and dried over anhydrous magnesium sulfate. After distilling off methylene chloride, the residue was purified by silica gel column chromatography using benzene as an eluent. Further, the obtained crystals were recrystallized from ethanol to give 450 mg of colorless needle-like crystals of the desired 6- (tetradecyloxybenzoyloxy) naphthalene-2-carboxylic acid-
((+)-2 ″ -methylbutyl) ester was obtained. Yield 5
The 1% phase transition temperature is shown in Table 7.

Various 6- (4'-alkyloxybenzoyloxy) naphthalene-2-carboxylic acid (optically active alkyl) esters were obtained by the same reaction procedure as above. Table 7 shows the phase transition temperatures of these compounds. Further, in the esterification, 5-halogeno-6- (4 'was obtained by using 5-halogeno-6-hydroxynaphthalene-2-carboxylic acid optically active alkyl ester instead of 6-hydroxynaphthalene-2-carboxylic acid optically active alkyl ester. -Alkyloxybenzoyloxy) naphthalene-2-carboxylic acid (optically active alkyl) esters were produced, and the phase transition temperatures of these compounds (Compound Nos. 74 and 75) are shown in Table 7.

Example 7 6- (4 "-alkyloxybiphenyl-4'-carbonyloxy) naphthalene-2-carboxylic acid (optically active alkyl) ester and 5-halogeno-6- (4"-alkyloxybiphenyl-4'-carbonyl Production of (oxy) naphthalene-2-carboxylic acid (optically active alkyl) ester 5-chloro-6- (4 "-octyloxybiphenyl-
The method for producing 4'-carbonyloxy) naphthalene-2-carboxylic acid-((+)-2-methylbutyl) ester (Compound No. 77 in Table 8) is shown.

6.5 g of 5-chloro-6-hydroxynaphthalene-2-carboxylic acid, 15 g of (-)-2-methylbutanol and concentrated sulfuric acid 1
ml in toluene 200ml while distilling off by-product water 10
Heated to reflux for hours.

After cooling, the reaction mixture is treated with water, 5% aqueous sodium carbonate solution,
It was washed with water in that order and dried over anhydrous magnesium sulfate.
After distilling off toluene and excess (-)-2-methylbutanol, the residue was purified by silica gel column chromatography using benzene-ethyl acetate (15: 1 v / v) as an eluent to obtain the desired 5-chloro-6 6.8 g of -hydroxynaphthalene-2-carboxylic acid-(+)-2-methylbutyl ester was obtained. Yield 80%, melting point 108 ° C., and then 5-chloro-6-hydroxynaphthalene-2
-Carboxylic acid-(+)-2-methylbutyl ester 500 mg,
4'-octyloxybiphenyl-4-carboxylic acid 550m
g, 350 mg of DCC and 20 mg of PRLPY were reacted in 40 ml of methylene chloride at room temperature for 3 hours. After the by-produced N, N'-dicyclohexylurea was filtered off, the organic layer was washed with 5% hydrochloric acid, 5% aqueous sodium hydroxide solution and water in this order and dried over anhydrous magnesium sulfate. After distilling off methylene chloride,
The residue was purified by silica gel column chromatography using benzene as an eluent. The crystals were recrystallized from ethanol-ethyl acetate to give colorless prism crystals.
600 mg of 5-chloro-6- (4 "-octyloxybiphenyl-4'-carbonyloxy) naphthalene-2-carboxylic acid-((+)-2-methylbutyl) ester was obtained. Yield 59% Phase transition temperature Are shown in Table 8.

A 6- (4 ″ -alkyloxybiphenyl-4′-carbonyloxy) naphthalene-2-carboxylic acid (optically active alkyl) ester was produced by the same reaction procedure.Table 8 shows the phase transition temperatures.

Example 8 Preparation of 6- (6'-alkyloxynaphthalene-2'-carbonyloxy) naphthalene-2-carboxylic acid (optically active alkyl) ester 6- (6'-hexyloxynaphthalene-2'-carbonyloxy) naphthalene-2-carboxylic acid-((+)-
2 ″ -methylbutyl) ester (Compound No. 78 in Table 9)
Compound) 6-hexyloxynaphthalene-2-carboxylic acid 530 m
g, 6-hydroxynaphthalene-2-carboxylic acid ((+)-
2'-methylbutyl) ester 500mg, DCC 400mg and PR
20 mg of LPY was dissolved in 40 ml of methylene chloride and reacted at room temperature for 5 hours. After the N, N'-dicyclohexylurea by-produced was filtered off, the organic layer was washed with 5% hydrochloric acid, 5% aqueous sodium hydroxide solution and water in this order, and dried with anhydrous magnesium sulfate. After distilling off methylene chloride, the residue was purified by silica gel column chromatography using benzene as an eluent. The obtained crystals were recrystallized from ethanol-ethyl acetate to give 580 mg of 6- (6'-hexyloxynaphthalene-2'-carbonyloxy) naphthalene-2-carboxylic acid-((+) as colorless plate crystals. −
2 ″ -methylbutyl) ester was obtained. The phase transition temperatures are shown in Table 9.

Similarly, various 6- (6'-alkyloxynaphthalene-
2-Carbonyloxy) naphthalene-2-carboxylic acid (optically active alkyl) ester was obtained. Table 9 shows the phase transition temperatures of these compounds.

Example 9 Liquid crystal compound of the present invention And as other liquid crystal The liquid crystal composition composed of (1) shows an SC ^* phase up to 57 ° C., an SA phase from 57 ° C. to 72 ° C., and an isotropic liquid at higher temperatures, and is suitable as a display device near room temperature.

Example 10 The liquid crystal compound of Example 9 was injected into a cell in which the electrode surface was subjected to oblique vapor deposition of silica and the electrode interval was 5 μm. When a low-frequency (1 Hz) alternating current of 5 V was applied between the two polarizers in which this liquid crystal cell was arranged in the crossed Nicols state, a clear switching phenomenon was observed, and the contrast was very good and the response speed was also high. A very fast (1 msec or less) liquid crystal display device was obtained. The spontaneous polarization value Ps is 9 nC /
It was cm ² .

Example 11 Liquid crystal compound of the present invention And other liquid crystal compounds The liquid crystal compound composed of is a SC ^* phase up to 62 ° C., an SA phase up to 62 to 83 ° C., and becomes an isotropic liquid at a temperature higher than that, and is suitable as a display element near room temperature.

Example 12 The liquid crystal mixture of Example 11 was injected into a cell in which the electrode surface was subjected to oblique vapor deposition of silica and the electrode interval was 5 μm. When a low-frequency (1 Hz) alternating current of 5 V was applied between the two polarizers in which this liquid crystal cell was arranged in the crossed Nicols state, a clear switching phenomenon was observed, and the contrast was very good and the response speed was also high. Very fast (less than 1 msec)
A liquid crystal display device was obtained.

The spontaneous polarization value Ps was 8 nC / cm ² .

Claims (2)

[Claims] 1. A liquid crystal compound represented by formula (I). [In the formula, X is a hydrogen atom or a halogen atom, Y is R-, Or Z is R-, Or (W represents a hydrogen atom or a halogen atom, R represents an alkyl group, and at least one of the alkyl groups contains an asymmetric carbon atom. (Here, n is an integer of 0 to 3, m is an integer of 1 or 2, and * is an asymmetric carbon atom) is an alkyl group having 4 to 8 carbon atoms and the other is 6 carbon atoms.
To 18 alkyl groups) are shown] 2. A liquid crystal composition containing at least one liquid crystal compound represented by formula (I). [In the formula, X is a hydrogen atom or a halogen atom, Y is R-, Or Z is R-, Or (W represents a hydrogen atom or a halogen atom, R represents an alkyl group, and at least one of the alkyl groups contains an asymmetric carbon atom. (Here, n is an integer of 0 to 3, m is an integer of 1 or 2, and * is an asymmetric carbon atom) is an alkyl group having 4 to 8 carbon atoms, and another 6 carbon atoms.
To 18 alkyl groups) are shown]