JPH0643374B2 - Liquid crystalline compound - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid crystal compound having an optically active group having a plurality of branches, which exhibits high-speed response in image display. Therefore, the present invention is applied to an image display device or an optical printer head used for a liquid crystal television receiver or the like.

[Prior Art] Liquid crystals are now widely used as one of image display devices. As a general image display method using a liquid crystal material, a twisted nematic type (TN type) and a guest-host type (GH type) are widely adopted, but both use a nematic liquid crystal and other Image display material C
The reality is that the response speed is slower than that of RT, plasma display, electroluminescence display, and the like.

However, the image display by liquid crystal is a light receiving type display, so there is less eye fatigue compared with the light emitting type display,
It also has the advantage of low power consumption. In recent years, there is a growing need for higher density and larger size displays, and therefore there is an increasing demand for faster response of liquid crystal display devices that can form thin and lightweight displays. Ferroelectric liquid crystal has recently been developed as a liquid crystal material exhibiting such a high-speed response, and an image display device utilizing the fast optical switching phenomenon has been proposed. Ferroelectric liquid crystals were reported in 1975 by RB Meyer et al. (J. de Phy
s.Lett., 36, 69,1975), the liquid crystal classification, are said to belong to a chiral smectic C phase (S _C ^* phase) or chiral smectic G phase (S _G ^* phase). Also, NAClark
(Appl. Phys. Lett., 36 , 899.1980), p-decyloxybenzylidene-p'-amino-2-methylbutyl cinnamate (abbreviated as DOBAMBC), which is one of the ferroelectric liquid crystal compounds, is disclosed in We put it in a thin film cell and observe the optical switching phenomenon of the microsecond order. Responses to optoelectronic materials such as liquid crystal televisions, optical printer heads, and nonlinear optical elements, which take advantage of the high-speed response of ferroelectric liquid crystals, have already begun to be investigated. However, conventionally developed ferroelectric liquid crystal compounds such as DOBAMBC are not practical because the temperature range showing ferroelectricity is much higher than room temperature. Recently, “Liquid Crystals and Ordered Fluids” have become known as liquid crystal compounds that exhibit ferroelectricity in the temperature range closer to room temperature.
nd TMLeslie; Vol. 4, pages 2-31, and JP-A-59-128357.
And JP-A-60-32748. But,
The response speed of these ferroelectric liquid crystal compounds near room temperature is 1 to 2 msec, and the response speed is slow as a ferroelectric liquid crystal.

[Problems to be Solved by the Invention] In view of the present situation, the emergence of a liquid crystal compound having a stable S _C ^* phase near room temperature and exhibiting a high-speed response of about 100 μsec is desired. The present invention seeks to meet this expectation.

[Means for Solving Problems] The basic conditions for obtaining a ferroelectric liquid crystal are that the molecule is an optically active substance, that there is a dipole moment perpendicular to the long axis of the molecule, and S _C ^* Phase, S _G ^* phase or chiral smectic I phase (S _I ^* ). In search of a liquid crystal compound that satisfies these conditions,
Although many compounds are being researched and developed, all of the compounds respond at a high temperature of several microseconds to several tens of microseconds, but at room temperature, the response speed is reduced to msec order.

Therefore, the present inventors examined the molecular structure of a ferroelectric liquid crystal compound including an optically active group, showed ferroelectricity at around room temperature, and had a high-speed response of about 100 μsec or less in that temperature range. Many studies have been conducted on liquid crystal compounds. As a result, by introducing an optically active group having a plurality of branches with an optically active group having 9 or more carbon atoms, most of the obtained compounds take the S _C ^* phase at around room temperature, and have 100 μsec.
The present invention has been completed by finding that it responds at a high speed before and after.

That is, the present invention has the general formula (In the formula, R represents an alkyl group having 6 to 12 carbon atoms, R ^* is an alkyl group having a plurality of branches, and the total number of carbon atoms is 9 to 15
And having an asymmetric carbon atom, l is 1 or 2, and m and n are 0 or 1).

The optically active group in the compound represented by the general formula (I) is an alkyl group having a plurality of branches and has a total carbon number of 9 to
15 and has an asymmetric carbon atom. With such optically active groups, the appearance of a particularly stable S _C ^* phase is observed. The S _C ^* phase also appears in an optically active group having 16 or more carbon atoms, but it affects the response speed due to viscosity and is not considered to be practically preferable.

Examples of suitable optically active groups in the present invention are as follows.

2,3-dimethylheptyl group, 2,4-dimethylheptyl group,
2,5-dimethylheptyl group, 2,6-dimethylheptyl group,
3,4-dimethylheptyl group, 3,5-dimethylheptyl group,
3,6 dimethylheptyl group, 2,3-dimethyloctyl group, 2,
4-dimethyloctyl group, 2,5-dimethyloctyl group, 2,
6-dimethyloctyl group, 2,7-dimethyloctyl group, 3,
6-dimethyloctyl group, 3,7-dimethyloctyl group, 3,
6,6-trimethyloctyl group, 2,3-dimethylnonyl group,
2,4-dimethylnonyl group, 2,5-dimethylnonyl group, 2,6
-Dimethylnonyl group, 2,7-dimethylnonyl group, 2,8-dimethylnonyl group, 3,4-dimethylnonyl group, 3,5-dimethylnonyl group, 3,6-dimethylnonyl group, 3,7-dimethyl Nonyl group, 3,8-dimethylnonyl group, 2,3-dimethyldecyl group, 2,4-dimethyldecyl group, 2,5-dimethyldecyl group,
2,6-dimethyldecyl group, 2,7-dimethyldecyl group, 2,8
-Dimethyldecyl group, 2,9-dimethyldecyl group, 3,4-dimethyldecyl group, 3,5-dimethyldecyl group, 3,6-dimethyldecyl group, 3,7-dimethyldecyl group, 3,8-dimethyl Decyl group, 3,9-dimethyldecyl group, 2,3,4-trimethylhexyl group, 2,3,5-trimethylhexyl group, 2,4,5-trimethylhexyl group, 3,4,5-trimethylhexyl group , 2,
6,6-Trimethylhexyl group, 2,3,4-trimethylheptyl group, 2,3,5-trimethylheptyl group, 2,3,6-trimethylheptyl group, 2,4,5-trimethylheptyl group, 2, 4,6-
Trimethylheptyl group, 3,7-dimethyl-7-methoxyoctyl group, 3,7-dimethyl-6-octenyl group, 3,7,1
1-trimethyl-dodecyl group and the like. In general, a 2,6-dimethylheptyl group is excellent in high-speed response, and a 3,7-dimethyloctyl group is preferable because it has a wide temperature range in which it exhibits ferroelectricity.

On the other hand, R in the alkoxy group represented by RO-in the general formula (I) is an alkyl group having 6 to 12 carbon atoms, and when an alkyl group having 5 or less carbon atoms or 13 or more carbon atoms is introduced, S _C ^*
This is not preferable because the temperature range of the phase is narrowed.

The performance of liquid crystal compounds can be generally improved by mixing and using two or more thereof. Therefore, any compound other than the compound of the present invention can be used as a mixture with the compound of the present invention as long as it is a liquid crystal compound having an S _C ^* phase.

Next, a general method for producing the liquid crystal compound of the present invention will be briefly described below.

Ester Compound An ester of 4-hydroxybenzoic acid is prepared from 4-hydroxybenzoic acid and an alkyl-substituted alkanol by a conventional method. On the other hand, thionyl chloride is reacted with 4-alkyloxybenzoic acid to form an acid chloride, which is then reacted with the ester of 4-hydroxybenzoic acid to obtain a crude product of the target compound. It is purified by column chromatography and recrystallization.

Ether compound Alkyl-substituted alkanol and p-toluenesulfonyl chloride are reacted to form a corresponding sulfonate,
Alkyloxyphenol is obtained by reacting with hydroquinone under alkaline conditions. A crude product of the target compound is obtained by reacting this phenol compound with alkyloxybenzoyl chloride. It is purified by column chromatography and recrystallization.

Biphenyl derivative To the alkali metal salt of hydroxybiphenylcarboxylic acid,
An alkyl halide is reacted to obtain an alkyloxybiphenylcarboxylic acid, and thionyl chloride is reacted with this to obtain an acid chloride. A crude product of the target compound is obtained by reacting an alkyl ester of hydroxybenzoic acid with the acid chloride. It is purified by column chromatography and recrystallization.

Tricyclic Benzoic Acid Derivative Alkyloxybenzoic acid is made into an acid chloride, and this is reacted with hydroxybenzaldehyde to give alkyloxybenzaldehyde. The aldehyde is oxidized to form a benzoic acid derivative, which is further reacted with thionyl chloride to obtain an acid chloride. The alkyl ester of hydroxybenzoic acid is reacted with this acid chloride to obtain a crude product of the target compound. It is purified by column chromatography and recrystallization.

[Examples] Hereinafter, the present invention will be described more specifically with reference to Examples and application examples.

Example-1 4- (4'-octyloxybenzoyloxy) benzoic acid-2,6-dimethylheptyl ester 4-hydroxybenzoic acid 26.5 g, toluene 300 ml, 2,6-dimethylheptanol (▲ α ²⁵ _D ▼- 9.52) 30 g of sulfuric acid and 1.5 g of sulfuric acid were heated to reflux and drained for 10 hours. After completion of the reaction, the product was washed with a dilute aqueous solution of sodium carbonate and washed with water, and toluene was distilled off to obtain 48.2 g of a concentrate. 96 g of this n-heptane
And then recrystallized by standing at -20 ° C to give 4-hydroxybenzoic acid-2,6-dimethylheptyl ester 44.6 g.
Got

On the other hand, after 12.5 g of 4-octyloxybenzoic acid and 37 ml of thionyl chloride were heated under reflux for 3 hours, excess thionyl chloride was distilled off to obtain 13.2 g of acid chloride. This was dissolved in 20 ml of toluene. This acid chloride-toluene solution was added dropwise to 13.2 g of 4-hydroxybenzoic acid-2,6-dimethylheptyl ester synthesized above, 19.9 g of pyridine and 50 ml of toluene at 5 ° C. over 1 hour. Then, the mixture was stirred at room temperature for 8 hours to carry out the reaction. After completion of the reaction, the product was washed with a dilute aqueous hydrochloric acid solution, further washed with water, dehydrated with magnesium sulfate, and then toluene was distilled off to obtain a crude product.
23.9 g was obtained.

This was separated by silica gel column chromatography (chloroform was used as a developing solvent) to obtain 21.3 g of white crystals. This product was recrystallized from ethanol to give 4- (4'-octyloxybenzoyloxy) benzoic acid-2,6-dimethylheptyl ester 1 having a melting point of 31.8 ° C.
3.1 g was obtained.

The physical constants and analytical values of this compound were as follows.

▲ α ²⁰ _D ▼ −3.32 MS: 496 (M ⁺ ) NMR: 0.89 (3H, d, J = 6.6) 0.90 (6H, t, J = 6.9) 1.06 (3H, d, J
= 6.8) 1.15 to 1.60 (17H, m) 1.82 (2H, m) 1.95 (1H, m) 4.02 (2
H, t, J = 6.5) 4.19 (2H, m) 6.98 (2H, m) 7.26 (2H, m) 8.12 (4H,
m) Example-2 4- (4'-nonyloxybenzoyloxy) benzoic acid-2,6-dimethylheptyl ester In place of 4-octyloxybenzoic acid of Example-1, 8.8 g of 4-nonyloxybenzoic acid was used. Was used and synthesized in the same manner as in Example 1 to give 4- (4'-nonyloxybenzoyloxy) benzoic acid-2,6-dimethylheptyl ester 6.6 having a melting point of 52.8 ° C.
g was obtained.

Example-3 4- (4'-decyloxybenzoyloxy) benzoic acid-2,6-dimethylheptyl ester Instead of 4-octyloxybenzoic acid of Example-1, 13.9 g of 4-decyloxybenzoic acid was used, Synthesized by the same method as in Example-1, 4 (4'-decyloxybenzoyloxy) benzoic acid-2,6-dimethylheptyl ester 18.5 having a melting point of 42.6 ° C.
g was obtained.

The physical constants and analytical values of this compound were as follows.

▲ α ²⁰ _D ▼ -1.39 MS: 524 (M ⁺ ) NMR: 0.88 (3H, d, J = 6.7) 0.91 (6H, t, J = 6.9) 1.03 (3H, d, J
= 7.0) 1.17 to 1.60 (23H, m) 1.84 (2H, m) 1.95 (1H, m) 4.03 (2H
t, J = 6.5) 4.19 (2H, m) 6.97 (2H, m) 7.28 (2H, m) 8.11 (4H, m) Example-4 4- (4'-undecyloxybenzoyloxy) benzoic acid-2 4,6-Dimethylheptyl ester Example 1-4
-In place of octyloxybenzoic acid, 9.7 g of 4-undecyloxybenzoic acid was used for synthesis in the same manner as in Example-1, and 4- (4'-undecyloxybenzoyloxy) having a melting point of 55.2 ° C. 10.2 g of benzoic acid-2,6-dimethylheptyl ester was obtained.

Example-5 4- (4'-dodecyloxybenzoyloxy) benzoic acid-2,6-dimethylheptyl ester 4-of Example-1
4- (4'-dodecyloxybenzoyloxy) benzoic acid having a melting point of 55.3 ° C was synthesized in the same manner as in Example 1 except that 10.2 g of 4-dodecyloxybenzoic acid was used instead of octyloxybenzoic acid. 8.2 g of 2,6-dimethylheptyl ester was obtained.

The physical constants and analytical values of this compound were as follows.

▲ α ²⁰ _D ▼ −0.52 MS: 552 (M ⁺ ) NMR: 0.88 (3H, d, J = 6.5) 0.90 (6H, t, J = 6.9) 1.16 to 1.60
(27H, m) 1.84 (2H, m) 1.95 (1H, m) 4.03 (2H, t, J = 6.8) 4.19 (2
H, m) 7.00 (2H, m) 7.30 (2H, m) 8.13 (4H, m) Example-6 4- (4'-octyloxybenzoyloxy) benzoic acid-3,7-dimethyloctyl ester 4-hydroxy Benzoic acid (69.0 g), toluene (500 ml), 3,7-dimethyloctanol (Δα ²⁵ _D ▼ −4.87) (86.9 g) and sulfuric acid (3.5 g) were heated under reflux and drained for 10 hours. After completion of the reaction, the product was washed with a dilute aqueous solution of sodium carbonate and washed with water, and toluene was distilled off to obtain 174.2 g of a concentrate. This is n-heptane 3
It was dissolved in 00 g and recrystallized by standing at -20 ° C to give 4-hydroxybenzoic acid-3,7-dimethyloctyl ester 12
8.1 g was obtained.

Meanwhile, 50 g of 4-octyloxybenzoic acid and thionyl chloride
After heating 145 ml under reflux for 3 hours, excess thionyl chloride was distilled off to obtain 53.7 g of acid chloride. This was dissolved in 60 ml of toluene. This acid chloride-toluene solution was added dropwise to 55.6 g of 4-hydroxybenzoic acid-3,7-dimethyloctyl ester synthesized above, 79.0 g of pyridine and 150 ml of toluene at 5 ° C. over 1 hour. Then, the mixture was stirred at room temperature for 8 hours to carry out the reaction. After completion of the reaction, the product was washed with a dilute aqueous hydrochloric acid solution, further washed with water, dehydrated with magnesium sulfate, and then toluene was distilled off to obtain a crude product.
101.9 g was obtained.

This was separated by silica gel column chromatography (chloroform was used as a developing solvent) to obtain 81.5 g of white crystals. This product was recrystallized from ethanol to give 4- (4-'octyloxybenzoyloxy) benzoic acid-3,7-dimethyloctyl ester 6 having a melting point of 41.9 ° C.
9.8 g was obtained.

The analytical values of this compound were as follows.

NMR: 0.86 (3H, d, J = 6.7) 0.90
(6H, t, J = 6.9) 1.00 (3H, d, J = 6.6) 1.12 to 1.9
1 ((22H, m) 4.00 (2H, t, J = 6.8) 4.39 ((2H, m) 7.00 (2H, m) 7.3
4 (2H, m) 8.16 (4H, m) Example-7 4- (4'-decyloxybenzoyloxy) benzoic acid-3,7-dimethyloctyl ester Instead of 4-octyloxybenzoic acid of Example-6. Then, 16.2 g of 4-decyloxybenzoic acid was used for synthesis in the same manner as in Example-6, and 4- (4'-decyloxybenzoyloxy) benzoic acid-3,7-dimethyloctyl ester having a melting point of 43.0 ° C. 16.
9 g were obtained. The optical rotation of this compound was ▲ α ²⁰ _D ▼ -2.31.

Example-8 4- (4-'dodecyloxybenzoyloxy) benzoic acid-3,7-dimethyloctyl ester 4-of Example-6
Instead of octyloxybenzoic acid, 15.3 g of 4-dodecyloxybenzoic acid was used and synthesized in the same manner as in Example-6. 4- (4′-dodecyloxybenzoyloxy) benzoic acid having a melting point of 33.0 ° C. 11.2 g of 3,7-dimethyloctyl ester was obtained.

The physical constants and analytical values of this compound were as follows.

▲ α ²⁰ _D ▼ −2.32 MS: 566 (M ⁺ ) NMR: 0.88 (3H, d, J = 6.6) 0.90 (6H, t, J = 7.0) 0.97 (3H, d, J
= 6.5) 1.14 to 1.72 (27H, m) 1.85 (3H, m) 4.06 (2H, m) 4.37 (2
H, m) 6.96 (2H, m) 7.27 (2H, m) 8.11 (4H, m) Example-9 4- (4'-decyloxybenzoyloxy) benzoic acid-3,7,11-trimethyldodecyl ester Example-6, 4
In the same manner as in Example-6, 1.2 g of 4-decyloxybenzoic acid was used instead of octyloxybenzoic acid, and 1.0 g of 3,7,11-trimethyldodecanol was used instead of 3,7-dimethyloctanol. At a melting point of 40.0 ° C.
(4'-decyloxybenzoyloxy) benzoic acid-3,
1.2 g of 7,11-trimethyldodecyl ester was obtained.

Example-10 A mixture of 4- (4'-octyloxybenzoyloxy) phenyl 3,7-dimethyloctyl ether 3,7-dimethyloctanol 60g and pyridine 120g was cooled to 5-10 ° C and p-toluenesulfonyl chloride 80g. Was dripped. Then, after reacting overnight at room temperature, the reaction product is put into ice water, extracted with benzene, and washed with water,
It was dried over magnesium sulfate. Benzene was distilled off, and the residue was heated and dissolved in 50 ml of n-hexane to separate insoluble matter, and then n-hexane was recovered to obtain 106.5 g of 3,7-dimethyloctyl-p-toluenesulfonate. .

To a mixture of 75 g of hydroquinone, 23.6 g of caustic potash, 8 ml of water and 500 ml of ethanol, 3,7-dimethyloctyl-p-
Toluenesulfonate (106.5 g) was added, and the mixture was reacted under reflux for 5 hours. After collecting ethanol under reduced pressure, 500 ml of water
Was added to acidify the hydrochloric acid, and the mixture was extracted with 150 ml of toluene. After washing with water twice, toluene was distilled off. The residue was distilled under reduced pressure to obtain 43.6 g of a 4- (3,7-dimethyloctyloxy) phenol fraction having a boiling point of 135 ° C./2 mmHg.

This 4- (3,7-dimethyloctyloxy) phenol 1
To a mixture of 0 g, 50 ml of toluene and 3.5 g of pyridine, 5
A solution of 10.7 g octyloxybenzoyl chloride and 50 ml toluene was added dropwise at -10 ° C. Then, the mixture was reacted with stirring at room temperature overnight, and then poured into 200 ml of water. After liquid separation, the toluene layer is washed with water, washed with an aqueous sodium hydrogen carbonate solution, and again with water, and the toluene is distilled off to obtain a crude product.
21 g was obtained. The crude product was separated by silica gel column chromatography with chloroform and recrystallized with ethanol to give a melting point of 4
11.9 g of 4- (4'-octyloxybenzoyloxy) phenyl 3,7-dimethyloctyl ether at 7.3 ° C was obtained.

The physical constants and analytical values of this compound were as follows.

▲ α ²⁰ _D ▼ −2.36 NMR: 0.88 (3H, d, J = 6.6) 0.90 (6H, t, J = 6.9) 0.97 (3H, d, J
= 6.5) 1.12 to 1.74 (23H, m) 1.82 (3H, m) 4.02 (4H, m) 6.94 (4
H, m) 7.12 (2H, m) 8.11 (2H, m) Example-11 4- (4'-decyloxybenzoyloxy) phenyl
2,6-Dimethylheptyl ether Synthesis was carried out in the same manner as in Example-10, using 56.4 g of 2,6-dimethylheptanol in place of 3,7-dimethyloctanol of Example-9,
38.4 g of intermediate 4- (2,6-dimethylheptyloxy) phenol was obtained. Using 5.6 g of this intermediate, decyloxybenzoyl chloride was used instead of octyloxybenzoyl chloride in the same manner as in Example-10 to give 4- (4'-decyloxybenzoyloxy) phenyl 2,3 having a melting point of 38.2 ° C. 8.6 g of 6-dimethylheptyl ether was obtained.

The analytical values of this compound were as follows.

NMR: 0.86 (3H, d, J = 6.8) 0.90 (6H, t,
J = 7.0) 0.99 (3H, d, J = 0.64) 1.14 to 2.02 (26H, m) 4.06 (2H,
m) 4.38 (2H, m) 6.97 (2H, m) 7.30 (2H, m) 8.12
(4H, m) Example-12 4- (4 "-octyloxybiphenyl-4'-carbonyloxy) benzoic acid-3,7-dimethyloctyl ester 4'-hydroxybiphenyl-4-carboxylic acid 15.0 g,
85% potassium hydroxide 9.3g, water 150ml and ethanol 1500
ml was mixed and heated to reflux. To this, 14.9 g of -n-octyl bromide was added dropwise, and then reflux was continued for 17 hours. After the completion of the reaction, the reaction mixture was cooled and the precipitated result was collected and recrystallized with 250 ml of acetic acid to obtain 15.9 g of 4'-octyloxybiphenyl-4-carboxylic acid. 20 ml of thionyl chloride was added to 8.0 g of 4'-octyloxybiphenyl-4-carboxylic acid, and 3
After refluxing for an hour, the solution was concentrated and dissolved in 70 ml of toluene to prepare an acid chloride-toluene solution. 4-Hydroxybenzoic acid-3,7-dimethyloctyl ester (6.8 g) and pyridine (2.3 g) were dissolved in toluene (80 ml), and the acid chloride-toluene solution prepared above was added dropwise thereto at room temperature.
The reaction was allowed to stir for 15 hours. After the reaction was completed, it was washed with water, dried over magnesium sulfate, concentrated and dried. The obtained crude crystals were subjected to silica gel chromatography using chloroform as an eluent, and then recrystallized from ethanol to give 4- (4 ″ -octyloxybiphenyl-) having a melting point of 75.9 ° C.
9.0 g of 4'-carbonyloxy) benzoic acid-3,7-dimethyloctyl ester was obtained.

The physical constants and analytical values of this compound were as follows.

▲ α ²⁰ _D ▼ −2.32 MS: 586 (M ⁺ ) NMR: 0.88 (3H, d, J = 6.7) 0.91 (6H, t, J = 6.9) 0.99 (3H, d, J
= 6.4) 1.16 to 1.70 (21H, m) 1.82 (3H, m) 4.03 (2H, m) 4.40 (2
H, m) 6.99 (2H, m) 7.31 (2H, m) 7.58 (2H, m) 7.70 (2H, m) 8.13 (2
H, m) 8.25 (2H, m) Example-13 4- (4 "-decyloxybiphenyl-4'-carbonyloxy) benzoic acid-2,6-dimethylheptyl ester Bromide of Example-12-n- Instead of octyl, 5.7 g of -n-decyl bromide was replaced with 4-hydroxybenzoic acid-3,7-dimethyloctyl ester to give 4-hydroxybenzoic acid-2,
Using 4.2 g of 6-dimethylheptyl ester, Example-12
Synthesis was carried out in the same manner as in, and the melting point was 61.5 ° C, 4- (4 "-
2.2 g of decyloxybiphenyl-4'-carbonyloxy) benzoic acid-2,6-dimethylheptyl ester were obtained.

The analytical values of this compound were as follows.

NMR: 0.87 (3H, d, J = 6.7) 0.88 (6H, t, J = 6.9) 1.01 (3H, d, J
= 6.7) 1.13 to 1.56 (21H, m) 1.78 (2H, m) 1.93 (1H, m) 3.97 (2
H, t, J = 6.6) 4.12 (2H, m) 6.97 (2H, m) 7.30 (2H, m) 7.57 (2H,
m) 7.18 (2H, m) 8.09 (2H, m) 8.22 (2H, m) Example-14- {4 '-(4 "-octyloxybenzoyloxy) benzoyloxy} benzoic acid-3,7-dimethyl Octyl ester 4-octyloxybenzoic acid 100g to thionyl chloride 250ml
Was added, and the mixture was refluxed for 3 hours, concentrated, and dissolved in 200 ml of benzene to prepare an acid chloride solution. 4-hydroxybenzaldehyde 48.8g and pyridine 37.9g in benzene
It was dissolved in 700 ml, the acid chloride solution prepared above was added dropwise, and the mixture was refluxed for 2 hours. After completion of the reaction, the mixture was cooled, washed with water, dried over magnesium sulfate, concentrated and dried.
Recrystallize with ethanol and n-hexane to give 4- (4 '
-Octyloxybenzoyloxy) benzaldehyde
72.0 g was obtained.

4- (4'-octyloxybenzoyloxy) benzaldehyde (15.0 g) was dissolved in 80 ml of ether, and water was added to sodium dichromate (12.6 g) and sulfuric acid (17.3 g) to prepare a solution.
What was made into ml was dripped. While gently refluxing, the mixture was stirred for 3 hours to precipitate crystals, and the crystals were over-collected. This was recrystallized from 100 ml of benzene and 4- (4'-
9.1 g of octyloxybenzoyloxy) benzoic acid was obtained.

20 ml of thionyl chloride was added to 8.8 g of 4- (4'-octyloxybenzoyloxy) benzoic acid, the mixture was refluxed for 3 hours, then concentrated and dissolved in 70 ml of toluene to prepare an acid chloride solution. 4-Hydroxybenzoic acid-3,7-dimethyloctyl ester (6.6 g) and pyridine (2.3 g) were added to toluene (80 ml).
Was dissolved in, the acid chloride solution prepared above was added dropwise thereto, and the mixture was reacted by stirring at room temperature for 15 hours. After the reaction was completed, it was washed with water, dried over magnesium sulfate, concentrated and dried. The obtained crystals were subjected to silica gel column chromatography using chloroform as an eluent, and then recrystallized from ethanol to give 4- {4 '-(4 "-octyloxybenzoyloxy) benzoyloxy} benzoic acid-3 having a melting point of 87 ° C. 9.5 g of 7,7-dimethyloctyl ester was obtained.

Example-15 4- {4 '-(4 "-decyloxybenzoyloxy)
Benzoyloxy} benzoic acid-3,7-dimethyloctyl ester Instead of 4-octyloxybenzoic acid of Example-14, 4-
Synthesis was carried out in the same manner as in Example-14 using 18.8 g of decyloxybenzoic acid to give 4- {4 '-(4 "-having a melting point of 84 ° C.
7.0 g of decyloxybenzoyloxy) benzoyloxy} benzoic acid-3,7-dimethyloctyl ester were obtained.

Example-16 4- {4 '-(4 "-octyloxybenzoyloxy) benzoyloxy} benzoic acid-2,6-dimethylheptyl ester The 4-hydroxybenzoic acid-3,7-dimethyloctyl ester of Example-14. Instead of 3.8 g, 4-hydroxy-2,6-dimethylheptyl ester was used in the same manner as in Example-14 to synthesize 4- {4 ′-(4 ″) having a melting point of 81 ° C.
-Octyloxybenzoyloxy) benzoyloxy} benzoic acid-2,6-dimethylheptyl ester 4.4 g was obtained.

The analytical values of this compound were as follows.

MS: 616 (M ⁺ ) NMR: 0.88 (3H, d, J = 6.6) 0.90 (6H, t, J = 6.6) 1.05 (3H, d, J
= 6.7) 1.18 to 1.61 (17H, m) 1.86 (2H, m) 1.96 (1H, m) 4.06 (2
H, m) 4.18 (2H, m) 7.00 (2H, m) 7.32 (2H, m) 7.40 (2H, m) 8.15 (4
H, m) 8.37 (2H, m) Example-17 4- {4 '-(4 "-decyloxybenzoyloxy)
Benzoyloxy} benzoic acid-2,6-dimethylheptyl ester Instead of 4-octyloxybenzoic acid of Example-14, 4-
By replacing 4.0 g of decyloxybenzoic acid with 4-hydroxybenzoic acid-3,7-dimethyloctyl ester, 3.8 g of 4-hydroxybenzoic acid-2,6-dimethylheptyl ester was added.
Synthesis was carried out in the same manner as in Example-14 using
There were obtained 5.1 g of 4- {4 '-(4 "-decyloxybenzoyloxy) benzoyloxy} benzoic acid-2,6-dimethylheptyl ester at 0 ° C.

Next, various liquid crystal characteristics of the compound of the present invention were measured. The liquid crystal properties were measured as follows.

As a liquid crystal cell, a transparent electrode is provided on a glass plate, coated with a polymer film, rubbed in a certain direction, and then the two substrates are rubbed in parallel to each other with a spacer to give a certain thickness. I used the assembled one. The cell spacing is 3 μm. The above-mentioned liquid crystal compound was injected into this cell, a helium-neon laser and a photomultiplier tube were used, and an alternating current of ± 20 V rectangular wave was applied to observe the electro-optical effect. A high-speed response was confirmed, and it was found that it can be used as a liquid crystal display device.

Measurement of response speed was carried out at around room temperature or _T C -T = 5 ℃. (T _C is the transition temperature from the S _C ^* phase to the S _A phase.) The phase transition temperature was determined by observation with a differential scanning calorimeter and a polarizing microscope. S ₁ is an undetermined liquid crystal phase. These results are shown in Table-1 and Table-2 for representative examples.
It was shown to.

In the phase transition temperature of Table-1, the numerical value in the parentheses indicates a monotropic phase transition temperature at which the phase transition does not occur during heating and only during cooling.

Application Examples 1 to 5 In order to obtain a liquid crystal composition exhibiting a high-speed response over a wider range of actual operating temperatures of display devices, various liquid crystal compounds were mixed and the performance thereof was investigated. In addition, the response characteristics as a liquid crystal display device were evaluated by using the liquid crystalline compounds obtained in the examples. Some of the representative examples are shown in Table 2.

[Effects of the Invention] The liquid crystalline compound of the present invention exhibits high-speed response in image display and exhibits ferroelectricity in a wide range, particularly in a low operating temperature range around room temperature. It can meet the demand as a material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Mitsuhashi 5-36-31 Kamata, Ota-ku, Tokyo Inside the Takada Perfume Industrial Co., Ltd. (72) Inventor Akio Yamaguchi 5-36-31, Kamata, Ota-ku, Tokyo Takasago Fragrance Industry Co., Ltd. in Kamata Plant (72) Inventor Haruki Tsuruta 5-36-31 Kamata, Ota-ku, Tokyo Takasago Fragrance Corp. (72) Inventor Susumu Akutagawa 5-36 Kamata, Ota-ku, Tokyo −31 Takasago International Corporation Kamata Plant

Claims (1)

[Claims] 1. A general formula (In the formula, R represents an alkyl group having 6 to 12 carbon atoms, and R ^*
Is an alkyl group having a plurality of branches and has a total carbon number of 9 to 15
And having an asymmetric carbon atom, l is 1 or 2, and m and n are 0 or 1. ) A liquid crystal compound represented by: