JPH0629203B2 - Liquid crystalline compound - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ferroelectric liquid crystal compound as a material for a large-sized display device, which is required to have a high-speed response particularly in the property utilization of the electro-optical effect of liquid crystal. It is a thing.

[Prior Art] Most of the liquid crystals that have been put to practical use are nematic,
Among them, the twisted nematic type (TN) has been mainly used for displays with a small number of pixels such as a clock, a wristwatch and a calculator, but the number of pixels is large (for example, the number of signal electrodes is 100).
As described above, when a screen having a relatively large display area is used, there is a problem that the contrast is lowered and the viewing angle is narrowed, so that it is not practical.

Two measures were taken to solve this problem. In other words, one is a super twisted nematic type (ST with a twist angle of 90 ° to increase the contrast by increasing it to 180-270 °).
The other was the development of a new drive system called an active matrix system, which prevents deterioration of contrast by incorporating a transistor or a diode in each pixel.

With these solutions, LCD TVs with a screen size of 2 to 3 inches and a pixel number of 50,000 to 80,000 appear on the market, which is a momentum on the extension of research and development, and a display having a larger display area, such as a CRT. The flood display, which can be used as a substitute, has been set as a target.

However, in the nematic liquid crystal device, since the anisotropy of the dielectric constant is simply used as the driving force by the electric field E, only a small force of the paraelectric material is used, and a high-speed response of m · sec or more is difficult. Despite various efforts to meet the required level of detail, it became clear that the display capacity, responsiveness, and display quality are inherently limited. On the other hand, ferroelectric liquid crystals have recently attracted attention and expectations as new liquid crystals.

Ferroelectric liquid crystals were synthesized in 1975 by p-decyloxybenzylidene-p'-amino-2-methylbutyl cinnamate (DOBAMBC) by RB Meyer et al. (J. de Phys. Lett.,
36, 69, 1975), it was confirmed that the chiral smectic C phase is a ferroelectric substance having spontaneous polarization.

In 1980, NA Clark et al. (Appl.Phys.Lett., 36, 8
99, 1980) reported that DOBAMBC, which is one of the ferroelectric liquid crystal compounds in a thin film cell, exhibits high-speed switching characteristics of m · sec or less and has bistability. The potential as was noticed. The characteristics of ferroelectric liquid crystals are high-speed response and memory property, but the high-speed property showing a response time of the order of μ · sec is unprecedented in other liquid crystals.

Ferroelectricity is 1) having a dipole moment or a dipole moment component in the direction perpendicular to the long axis direction of the molecule in view of the structure of liquid crystal molecules, and 2) the molecule is a caralle molecule having an optically active group, 3) It is expressed with spontaneous polarization only when the three conditions that it is a smectic phase with a tilt angle are satisfied. The driving force of the element in the electric field E is the spontaneous polarization Ps (nC / cm ² ), and its response speed τ is represented by τ = η / Ps · E (η is the viscosity for precession motion with the tilt angle kept constant). Wrong (MA Handschy .; Appl.Phys.Lett., 41,39,19
82), it is clear that the spontaneous polarization must be large in order to obtain fast response.

Further, the following liquid crystal compounds are reported in JP-A-61-243037. However, it is still insufficient from the viewpoint of high-speed response.

[Problems to be Solved by the Invention] For practical application to devices and devices that utilize the electro-optical effect of ferroelectric liquid crystals, there are still problems such as alignment technology, cell configuration and mass production technology, and driving method. Although there are various problems required, the most important thing is the development of a fast response liquid crystal having a large spontaneous polarization in a wide temperature range.
The present invention seeks to meet this expectation.

[Means for Solving Problems] The occurrence of spontaneous polarization is due to the permanent dipole moment in the direction perpendicular to the long axis of the molecule. Approximately 1/30 of the expected value when the binding moment of> C = O is perfectly oriented
Shows only 0D.

This phenomenon is because the rotation of the molecule is not constrained like a solid, so it rotates freely, and because the positions of the asymmetric carbon and the permanent dipole are far apart, the rotation that is an internal motion of the molecule. It is said that the effective polarization of the dipole is canceled by the vibration and the vibration, and the spontaneous polarization is significantly reduced.

Therefore, in order to increase the spontaneous polarization, it is conceivable to bring the positions of the asymmetric carbon and the permanent dipole as close as possible, or to directly insert a halogen atom or a bond having a large polarization into the asymmetric carbon.

Under these circumstances, the present inventors have conducted various studies on the molecular structure including an optically active group in an effective liquid crystal compound having a large spontaneous polarization. As a result, the following general formula (I)
The present invention has been completed by finding that a compound represented by the formula (1) has a relatively large spontaneous polarization over a wide range.

That is, the present invention is a general formula showing ferroelectricity and excellent in high-speed response. (In the formula, R ¹ is an alkyl group having 6 to 12 carbon atoms, R ² is an alkyl group having 1 to 6 carbon atoms, and X is —CH ₂ O— or —OCH ₂ —
, M is 0 or 1, and n is 2 or 3. ) Is to provide a liquid crystal compound.

Next, a benzoic acid derivative of the general formula (I) (X = -CH ₂ O-, m
A general manufacturing method is briefly described for the synthesis of = 1).

(In the formula, n represents 2-3 and Me represents a methyl group.) First, after protecting the hydroxyl group of the oxyacid ester (2) with tetrahydropyran, the carboxyl group is reduced with lithium aluminum hydride. It is converted to methylol and treated with alkyl iodide to obtain the ether compound (5).
The alcohol (6) obtained by removing the protecting group is reacted with acetoxybenzoic acid chloride to obtain a benzoic acid derivative (7). Benzylamine is added to this to decompose it, and the phenol derivative of (8) is obtained. Next, the separately prepared 4-alkoxybiphenylmethylene chloride and the phenol derivative of (8) are subjected to an esterification reaction to obtain an ester of the general formula (I).

Next, a phenol derivative of the general formula (I) (X = -CH ₂ O-,
A general manufacturing method is briefly described for the synthesis of m = 0).

(In the formula, n represents 2 or 3, and Me represents a methyl group.) First, the oxyester (2) is converted to methanesulfonylalkyl lactate (9) with methanesulfonyl chloride. Next, the compound (9) is reacted with benzyloxyphenol to obtain the compound (10). Thereafter, this is reduced with lithium aluminum hydride to obtain the alcohol derivative (11). The alcohol body is reacted with alkyl iodide to obtain an ether body (12). Then, it is hydrogenated with palladium carbon under normal pressure to obtain a phenol body (13). The phenol body (13) is reacted with 4-alkoxybiphenylmethylene chloride to obtain a phenol derivative of the general formula (I).

Next, a benzoic acid derivative represented by the general formula (I) (X = -O-CH _2- ,
A general manufacturing method is briefly described for the synthesis of m = 1).

(In the formula, n represents 2-3.) Hydroxyalkyl ether (2 ') is reacted with p-formylbenzoyl chloride to give an ester body (3'),
This is reduced with a reducing agent to give a methylol body (4 '). Then, this methylol compound was converted to chloride (5 ') with thionyl chloride.
And then reacted with an alkoxy biphenol to obtain an ester of the general formula (I).

Next, a phenol derivative of the general formula (I) (X = -OCH ₂ ,
A general manufacturing method is briefly described for the synthesis of m = 0).

(In the formula, n represents 2 to 3.) The hydroxy group of hydroxyalkyl ether (2 ') is sulfonylated with methanesulfonyl chloride, and hydroxybenzalhydride is reacted with this to form an aldehyde body (7'). Then, this is reduced with a reducing agent to obtain a methylol body (8 '). Thereafter, the methylol compound is converted to chloride (9 ') with thionyl chloride and then reacted with alkoxyphenylphenol to obtain a phenol derivative of the general formula (I).

Representative examples of the liquid crystal compound represented by the general formula (I) are shown below.

Exemplified Compound-1 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. The liquid crystal compound according to the present invention can be used in combination with an existing ferroelectric liquid crystal or a compound that does not exhibit ferroelectricity and goes through a simple Sc phase to expand the temperature range of the Sc ^* phase.
It is possible to obtain a liquid crystal composition that can be practically used for displays and the like. Further, even if the compound according to the present invention has poor liquid crystallinity, the compound having a Sc phase or Sc ^* phase is contained in an amount of 5 to 20%.
%, It is possible to obtain a ferroelectric liquid crystal composition having a large spontaneous polarization.

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

Example 1 Synthesis of 3-hydroxybutyl methyl ether 37 g of 3-hydroxybutyric acid methyl ester and 30 g of 2,3-dihydropyran were reacted in ether to give a protected ester 5
6g was obtained. This was put in a tetrahydrofuran solution of 750 m, 8.3 g of lithium aluminum hydride was added, and the mixture was reduced at room temperature to be methylolated to obtain 50 g of a product. Then, 20 g of this was taken, and 29.3 g of methyl iodide and 8.3 g of sodium hydride were reacted in 220 m of tetrahydrofuran to obtain 20 g of an ether compound. This was put in 25 m of methanol, and the protecting group was removed with 0.1 g of paratoluenesulfonic acid to obtain 8.5 g of the target compound (theoretical yield: 64.2%).

Example 2 Parahydroxybenzoic acid (1-methyl-3-methoxy)
Synthesis of Propyl Ester First, 5 g of acetoxybenzoic acid was chlorinated with 19.8 g of thionyl chloride, and excess thionyl chloride was distilled off. Then, this whole amount and 3.5 g of the ether derivative obtained in Example 1 and 2.6 g of pyridine were combined. The reaction was carried out in 50 m of toluene at 0-5 ° C for 1 hour and then at room temperature for 2 hours. Then, it is diluted with water, neutralized with acidic sodium carbonate, washed well with saturated saline, and then toluene is collected, and paraacetoxybenzoic acid (1
7.1 g of -methyl-3-methoxy) propyl ester were obtained.

Next, dissolve this in 25m of ethanol, cool, add 2.8g of benzylamine, react at 20-25 ° C for 2 hours to distill off ethanol, then dissolve in a mixed solvent of chloroform and methanol, and pass through a silica gel column. Purity 99
% Target compound 4.1 g was obtained (theoretical yield 65.0%).

Example 3 Synthesis of 4- (4'-n-octyloxybiphenyl-4-methyleneoxy) benzoic acid (1-methyl-3-methoxy) propyl ester 1.5 g of the benzoic acid derivative obtained in Example 2 and n-octyl Oxybiphenylmethylene chloride 2.6g and acetone 100m
1.0 g of potassium carbonate, and at the reflux temperature
The reaction was carried out for 12 hours. After completion of the reaction, the reaction product was separated and acetone was distilled off to obtain 6.0 g of a crude product. This was dissolved in a mixed solvent of benzene and ethyl acetate, passed through a silica gel column, and recrystallized from ethanol to give a 4-mp melting point of 70 ° C.
2.3 g of (4'-n-octyloxybiphenyl-4-methyleneoxy) benzoic acid (1-methyl-3-methoxy) propyl ester (theoretical yield 66.3%) (Exemplary compound 12) was obtained.

The analytical values of this compound are shown below.

Specific rotation: ▲ [α] ²⁴ _D ▼ = −28.7 ° Ms; 518 (M ⁺ ) NMR; 0.90 (3H, t, J = 6.9Hz), 1.32 (11H, m), 1.48 (2H, m), 1.85 (3H, m), 2.01 (1H,), 3.32 (3H, s), 3.48 (2H, m), 4.02 (2H, m), 5.15 (2H, s), 5.25 (1H, m), 7.0 ( 4H, m), 7.42 (2H, m), 7.52 (2H, m), 7.80 (2H, m), 8.0 (2H, m) Example 4 4- (benzyloxy) phenyl (1-methyl-3-methoxy) ) Synthesis of propyl ether 3-hydroxybutyl methyl ether 30.3 g, ether 3
To a liquid obtained by mixing 5 m and pyridine 40 m, 35 g of methanesulfonyl chloride was added dropwise at room temperature. After reacting for 3 hours at the same temperature, the reaction solution was poured into water and extracted with ether. The ether layer was washed with water and dried, and then the ether was distilled off to obtain 50 g of methanesulfonate.

A solution of this methanesulfonate in 500 m of ethanol was added to 51 g of benzyloxyphenol, 17 g of caustic potash, and 40 g of water.
m and ethanol 240 m, and the mixture was reacted under reflux for 4 hours. Then, after distilling off ethanol, the mixture was extracted with ether, the ether layer was washed with water, dried and then concentrated under reduced pressure to obtain 62 g of a crude product. This was recrystallized from benzene to give 51.2 g of the target compound with a melting point of 62 ° C (theoretical yield of 66.6
%) Was obtained.

Example 5 Synthesis of p-hydroxyphenyl-1-methyl-3-methoxypropyl ether 2.6 g of lithium aluminum hydride was suspended in 200 m of tetrahydrofuran in a stream of nitrogen gas, and this solution was maintained at 10 to 15 ° C. 16 g of 4- (benzyloxy) phenyl (1-methyl-3-methoxy) propyl ether obtained in Example 4 was dissolved in 100 m of methanol, and hydrogenated at room temperature and atmospheric pressure using 0.12 g of 10% palladium carbon as a catalyst. did.

After separating the catalyst, it was dissolved in a mixed solvent of benzene and ethyl acetate and passed through a silica gel column to obtain 7.4 g of p-hydroxyphenyl-1-methyl-3-methoxypropyl ether having a purity of 99% (theoretical yield: 70.8%).

Example 6 Synthesis of 4- (4'-n-decyloxybiphenyl-4-methyleneoxy) phenyl (1-methyl-3-methoxy) propyl ether 100 ml of dimethylformamide and 0.37 g of sodium hydride
To the solution of p-hydroxyphenoxy-1 obtained in Example 5.
-Methyl-3-methoxy-propyl ether 1.5 g at 5 ° C
Then, 2.7 g of 4-n-decyloxybiphenylmethylene chloride was added at the same temperature, and the mixture was reacted at room temperature for 5 hours with stirring. After the reaction was completed, the reaction product was washed to obtain 4.3 g of a crude product. This was passed through a silica gel column using a mixed solvent of benzene and ethyl acetate, followed by recrystallization with ethanol, and purification with a melting point of 61 ° C 4-
1.6 g (theoretical yield 36.2%) of (4'-n-decyloxybiphenyl-4-methyleneoxy) phenyl (1-methyl-3-methoxy) propyl ether (Exemplary compound 2) was obtained.

The analytical values of this compound are shown below.

Specific rotation; ▲ [α] ²⁴ _D ▼ = -13.78 ° Ms; 578 (M ^* ) NMR; 0.90 (3H, t, J = 6.9Hz), 1.31 (15H, m), 1.45 (2H, m), 1.84 (3H, m), 2.03 (1H, m), 3.32 (3H, m), 3.50 (2H, m), 4.0 (2H, m), 4.70 (1H, m), 6.97 (2H, m), 7.24 (2H, m), 7.47 (2H, m), 7.58 (2H, m), 8.16 (2H, m), Example 7 Synthesis of p-hydroxybenzaldehyde (1-methyl-3-ethoxy) propyl ether 3- A solution prepared by dissolving 13.3 g of hydroxybutyl ether in 14.2 g of pyridine was maintained at 10 ° C., and 12.4 g of methanesulfonyl chloride was added dropwise to the solution over a period of about 1 hour. After completion of the reaction, extraction was carried out with ether, and the ether was distilled off to obtain methanesulfonate. Water 28m, ethanol 230m, p-
Hydroxybenzaldehyde 11.2 g and 85% caustic potash
The mixture (6.6 g) was heated to reflux (about 79 ° C.), and 20.9 g of methanesulfonate was added dropwise to the mixture over about 20 minutes. After heating under reflux for 3 hours, ethanol was distilled off and the mixture was extracted with ether. The ether layer was washed with water and purified by column chromatography to obtain 7.5 g of the target compound. (Theoretical yield 37%).

Example 8 Synthesis of 4-chloromethylphenyl (1-methyl-3-ethoxy) propyl ether p-hydroxybenzaldehyde (1-
Methyl-3-ethoxy) propyl ether (7.5 g) was dissolved in methanol (1.5 g), the temperature was kept at 10 ° C., sodium borohydride (200 m) was added dropwise, and the mixture was reacted at room temperature for 6 hours for reduction. After completion of the reaction, 100 m of water and 4 m of acetic acid were added and then extracted with chloroform. After removing chloroform, the residue was purified by column chromatography to obtain 4.7 g of methylol compound. Next, take 2.0g of this methylol body and add 5m to it.
Thionyl chloride was added and reacted at room temperature for 1.5 hours, and then excess thionyl chloride was distilled off under reduced pressure to obtain 4.7 g of the target compound.

Example 9 Synthesis of 4- (4'-n-decyloxybiphenyl-4-oxymethylene) phenyl (1-methyl-3-ethoxy) propyl ether 4-n-decyloxybiphenylcarboxylic acid 2.9 g was added to dimethylformamide 100 m. 0.43 g 60 in the solution dissolved in
% Sodium hydride was added, and stirring was continued for 1 hour at room temperature to react to obtain a phenol body. The total amount of 4-chloromethylphenyl (1-methyl-3-ethoxy) propyl ether obtained in Example 8 was added thereto, and the mixture was reacted at room temperature for 3 hours. Next, methanol was added to decompose the remaining sodium hydride, and methanol and dimethylformamide were distilled off under reduced pressure. After extraction with benzene and washing the benzene layer with water, benzene was distilled off. This was purified by column chromatography with a mixed solvent of benzene / ethyl acetate 15: 1, and then recrystallized twice with ethanol for purification 4-
2.8 g of (4'-n-decyloxybiphenyl-4-oxymethylene) phenyl (1-methyl-3-ethoxy) propyl ether (theoretical yield from methylol compound 44.6%) was obtained (Exemplary Compound 19).

The analytical values of this compound are shown below.

Specific rotation; ▲ [α] ²⁴ _D ▼ ＝ ＋ 17.38 ° Ms 532 (M ^* ) NMR; 0.89 (3H, t, J = 9Hz), 1.17 (3H, t, J = 7.0Hz), 1.32 ( 17H, m), 1.47 (2H, m), 1.82 (3H, m), 3.45 (2H, m), 3.55 (2H, m), 4.0 (2H, m), 4.57 (1H, m), 5.0 (2H , s), 6.92 (4H, m), 7.2 (2H, m), 7.35 (2H, m), 7.45 (4H, m), Example 10 4- (4′-n-octyl) obtained in Example 3 Oxybiphenyl-4-methyleneoxy) benzoic acid (1-methyl-3)
Liquid crystal properties were measured for -methoxy) propyl ester. A transparent electrode is provided on the glass plate, a polymer is further coated on it, and it is rubbed in a certain direction. Then, the rubbing directions of the two substrates are made parallel, and a certain thickness is used by using a spacer. The assembled liquid crystal cell was used as a liquid crystal cell. The thickness of the cell is 3 μm.

The compound was injected into this cell, and a helium-neon laser and a photomultiplier tube were used to apply a square wave AC of ± 20 V to observe the electro-optical effect of the liquid crystal. A response was confirmed, and it was confirmed that the material could be used as a liquid crystal display device.

On the other hand, the phase transition temperature was determined by observation with a differential scanning calorimeter and a polarizing microscope. Note that S ₁ is an undetermined liquid crystal phase.
The results of these measurements are shown in Table 1.

Examples 11 to 18 The phase transition temperature and various characteristic values of the compound of the present invention were measured in the same manner as in Example 10. The results are shown in Table-1.

Application Examples 1-2 In order to obtain a liquid crystal composition exhibiting a high-speed response over a wider range of actual operating temperatures in display devices, various liquid crystal compounds were mixed and the performance thereof was investigated. In addition, the liquid crystal compounds obtained in the examples were used to evaluate the response characteristics as a liquid crystal display device. The measurement method was the same as in Example 10. Representative examples thereof are shown in Table-1 and Table-2.

The mixing ratio of the composition used in this application example is as follows.

[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 temperature range. Therefore, it is possible to meet future needs for high-density and large-sized displays. It is possible.

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Claims (1)

[Claims] 1. A general formula (In the formula, R ¹ is an alkyl group having 6 to 12 carbon atoms, R ² is an alkyl group having 1 to 6 carbon atoms, and X is —CH ₂ O— or —OCH ₂ —
, M is 0 or 1, and n is 2 or 3. ) A liquid crystal compound represented by: