JPH0574582B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field) The present invention relates to a novel liquid crystal compound that is useful as a component of a ferroelectric liquid crystal composition and has excellent chemical stability, and a liquid crystal composition containing at least one of the liquid crystal compounds. Regarding. (Prior art) In 1980, Clark and Lagervall (Applied Physics Letters, 36 , 899, 1980) announced a display system that utilizes the optical switching phenomenon of ferroelectric liquid crystals, which was developed using conventional nematic liquid crystals. It has excellent properties not found in previous display systems, namely high-speed response, and is attracting attention as a next-generation display element. Ferroelectric liquid crystals were first discovered in 1975 by R.B. Meyer et al.
(1975)), for a liquid crystal substance to exhibit ferroelectricity, it must satisfy the following conditions. It must have an asymmetric carbon atom in its molecular structure and be optically active. Must have a permanent dipole moment perpendicular to the long axis of the molecule. Must have chiral smectic c phase (SmC ^* phase). Typical conventional ferroelectric liquid crystals are shown below in terms of their structural formula and other details.

[ka]

[ka]

[ka]

[Chemical formula] (a) is the first ferroelectric liquid crystal material discovered by Mayer et al., and (b) is known as a compound with large spontaneous polarization. Both are Schiff bases and are unstable in moisture. (c) is stable to moisture, but the temperature range of the SmC ^* phase is narrow. (Disclosure of the Invention) The present inventors have succeeded in providing a novel compound that is chemically stable and useful as a component of a ferroelectric liquid crystal composition. The novel compound according to the present invention is a chemically stable substance, and when used as a component of a liquid crystal composition, can provide a display element with a wide operating temperature range. That is, the compound according to the present invention is useful as a component that extends the temperature range of the SmC ^* phase in a liquid crystal composition. The present invention will be explained in detail below. The novel compound according to the present invention has the general formula ()

A liquid crystalline compound represented by: (wherein, R is an alkyl group having 1 to 18 carbon atoms, n represents an integer of 3 to 7, and the symbol * represents an optically active atom) It is. The compounds according to the present invention can be produced by the synthetic route shown by the following scheme. The symbols () to () shown in the diagram are all assigned to the corresponding compounds in the examples. EXAMPLES Below, the compounds according to the present invention, their production examples, and usage examples will be specifically explained with reference to Examples. Example 1 (s)-4-octylbiphenyl-4'-ylp
Synthesis of -(4-methylhexyl)oxybenzoate () (a) Synthesis of 4-acetoxy-4'-caprylylbiphenyl () Anhydrous aluminum chloride 126 g, methylene chloride 400
cc mixture, 92 g of capryline chloride was added dropwise with stirring, and then 80 g of 4-acetoxybiphenyl was added dropwise thereto as a methylene chloride solution at room temperature. After reacting at the same temperature for 5 hours,
The reaction solution was poured into diluted hydrochloric acid. The liberated methylene chloride layer was thoroughly washed with water and dried with Glauber's salt. After distilling off the solvent, the residue was recrystallized twice from ethanol to obtain 83 g of 4-acetoxy-4'-caprylylbiphenyl (). (b) Synthesis of 4-octyl-4'-hydroxybiphenyl () In a reaction vessel, add 92 g of 4-acetoxy-4'-caprylylbiphenyl () and 450 g of diethylene glycol.
cc, 60 g of 85% caustic potash (dissolved in 100 c.c. of water) and
Add 85g of 85% hydrazine hydrate, and under reflux,
Stir for hours. Next, the temperature was raised to 220° C. while distilling off the water in the reaction system, and the reaction was carried out at the same temperature for 4 hours. After cooling, the reaction solution was poured into dilute hydrochloric acid, and the precipitate was extracted with isopropyl ether (IPE).
After thoroughly washing the IPE layer with water, it was dried with Glauber's salt.
IPE was distilled off and the residue was recrystallized from ethanol to obtain 66 g of 4-octyl-4'-hydroxybiphenyl (). mp139-140℃ (c) Synthesis of (s)-methyl p-(4-methylhexyl)oxybenzoate (25) Methyl p-hydroxybenzoate in a reaction vessel
g, (s)-4-methylhexyl bromide (synthesized according to the reaction example of Mol.Cryst.Liq.Cryst 114 237-247 1984. bp71-72℃/23.5mmHg) 30g,
46g of anhydrous potassium carbonate and cyclohexanone
300 c.c. was charged and stirred at 130-140°C for 5 hours. The reaction solution was poured into water, and then the liberated organic layer was extracted with benzene. This benzene layer was thoroughly washed with water and then dried with sodium sulfate. The solvent was distilled off, and the residue was distilled under reduced pressure to obtain 37.5 g of methyl (s)-p-(4-methylhexyl)oxybenzoate (). bp136-137℃/0.4mmHg (d) Synthesis of (s)-p-(4-methylhexyl)oxybenzoic acid () In a reaction vessel, add methyl (s)-p-(4-methylhexyl)oxybenzoate () 37.5 g, methanol
200 c.c. and 18 g of 95% caustic soda (dissolved in 100 c.c. of water) were charged and stirred under reflux for 4 hours. The reaction solution was poured into dilute hydrochloric acid, and the precipitate was extracted with isopropyl ether (IPE). After thoroughly washing this IPE layer with water, it was dried with Glauber's salt. After distilling off IPE, the residue was recrystallized from hexane and (s)-p
-(4-methylhexyl)oxybenzoic acid ()
Obtained 34g. mp118-125.5℃ (e) Synthesis of (s)-p-(4-methylhexyl)oxybenzoic acid chloride () In a reaction vessel, (s)-p-(4-methylhexyl)
Prepare 34 g of oxybenzoic acid and 150 c.c. of benzene.
While stirring under reflux, 35 g of thionyl chloride was added dropwise. Then, after reacting at the same temperature for 6 hours, the solvent and excess thionyl chloride were distilled off. The residue was distilled under reduced pressure to obtain 32.7 g of (s)-p-(methylhexyl)oxybenzoic acid chloride (). bp133
°C/0.3mmHg (f) (s) Synthesis of -4-octylbiphenyl-4'-yl p-(4-methylhexyl)oxybenzoate () In a reaction vessel, 4-octyl-4'-hydroxybiphenyl () was added. ) 2g, benzene 30c.c., pyridine
Add 0.6g of (s)- at room temperature while stirring.
2 g of p-(4-methylhexyl)oxybenzoic acid chloride () was added dropwise. 2 hours at room temperature,
After further reacting under reflux for 3 hours, the reaction solution was poured into water. The liberated benzene layer was thoroughly washed with water and dried with Glauber's salt. Benzene was distilled off and the residue was recrystallized twice from acetone to give (s)-4-octylbiphenyl-
1.3 g of 4'-yl p-(4-methylhexyl)oxybenzoate () was obtained. The content of this product was 99% or more by liquid chromatography and 1 spot by thin layer chromatography. Also, according to infrared absorption spectrum measurements, the characteristic values are 2800 to 3000 cm ^-1 and 1740 cm ^-
It was ^1,1260 cm ^-1 . In addition, mass spectrometry analysis revealed a molecular ion peak at 500, supporting the chemical structure of this product. This is the Mettler Hot Stage FP-82.
When the phase change was observed using scissors and under a polarizing microscope, the following was observed. Cryst108 ---→ SmC ^* 125 ←--→ ch153 ←--→ Iso Examples 2 to 4 Various derivatives were synthesized in the same manner as in Example 1, and the results of measuring the phase transition temperature are shown in Table 1. show. [In the table, R is R in the above general formula (), thereby indicating each compound]

[Table] Example 5 (s)-4-octylbiphenyl-4'-ylp
-Synthesis of (6-methyloctyl)oxybenzoate () (a) (s) -6-methyloctyl bromide ()
13.8 g of powdered magnesium and 160 c.c. of tetrahydrofuran (purified by distillation after treatment with lithium aluminum hydride) were placed in a reaction vessel, and (s)-2-methylbutyl bromide (Mol.
According to the reaction example of Cryst. Separately, add 1,4-dibromobutane to the reaction vessel.
123 g, 350 c.c. of tetrahydrofuran (THF), and 18 c.c. of 0.1 mol/dilithium tetrachlorokyuprate-THF solution (Li ₂ CuCl ₄ /THF).
was charged, and the Grignard reagent mentioned above was added dropwise at a temperature below 0°C. After stirring for 1 hour at 0°C or lower, 1 hour at 10°C, and further 1 hour at room temperature, the reaction solution was poured into dilute hydrochloric acid. The liberated organic layer was extracted with benzene, and the benzene layer was thoroughly washed with water. After drying the benzene layer with Glauber's salt, the solvent was distilled off and the residue was distilled under reduced pressure to obtain (s)-6-methyloctylboromide ().
Obtained 60g. bp102-114℃/27mmHg (b) Synthesis of (s)-methyl p-(6-methyloctyl)oxybenzoate () 40.3 methyl p-hydroxybenzoate in a reaction vessel
g, (s)-6-methyloctyl bromide 50g,
67g of anhydrous potassium carbonate and cyclohexanone
350 c.c. was charged and stirred at 120 to 125°C for 5 hours. Next, the reaction solution was poured into water, and the liberated organic layer was extracted with ethyl ether. The ether layer was thoroughly washed with water and dried with Glauber's salt. After distilling off the solvent, the residue was distilled under reduced pressure to give (s)-p-(6-methyloctyl)
55.5 g of methyl oxybenzoate () was obtained. b.
p.169-171℃/1.0mmHg (c) Synthesis of (s)-p-(6-methyloctyl)oxybenzoic acid () In a reaction vessel, (s)-p-(6-methyloctyl)
Methyl oxybenzoate 54g, 95% caustic soda 20g
(dissolved in 200 c.c. of water) and 300 c.c. of methanol.
The mixture was stirred under reflux for 3 hours. The reaction solution was poured into dilute hydrochloric acid, and the precipitate was extracted with benzene. After thoroughly washing the benzene layer with water, it was dried with Glauber's salt. After distilling off the solvent, the residue was recrystallized from hexane to give (s)-p
-(6-methyloctyl)oxybenzoic acid ()
43.1g was obtained. mp126.5~127℃ (d) Synthesis of (s)-p-(6-methyloctyl)oxybenzoic acid chloride () Add (s)-p-(6-methyloctyl) to the reaction vessel.
48 g of oxybenzoic acid and 200 c.c. of benzene were charged, and 45 g of thionyl chloride was added dropwise while stirring under reflux. After reacting at the same temperature for 6 hours, benzene and excess thionyl chloride were distilled off. The residue was distilled under reduced pressure to obtain 48 g of (s)-p-(6-methyloctyl)oxybenzoic acid chloride (). b.
p.151℃/0.25mmHg (e) Synthesis of (s)-4-octylbiphenyl-4'-yl p-(6-methyloctyl)oxybenzoate () In a reaction vessel, 4-octyl-4'-hydroxy 2 g of biphenyl, 30 c.c. of benzene, and 0.6 g of pyridine were charged, and 2.2 g of (s)-p-(6-methyloctyl)oxybenzoic acid chloride was added dropwise while stirring. After reacting at room temperature for 2 hours and further under reflux for 3 hours, the reaction solution was poured into water. The liberated benzene layer was thoroughly washed with water and then dried with Glauber's salt. After distilling off the solvent, the residue was recrystallized twice from ethanol to obtain 1.8 g of (s)-4-octylbiphenyl-4'-yl p-(6-methyloctyl)oxybenzoate. The content of this product was 99% or more by liquid chromatography and 1 spot by thin layer chromatography. Also, according to infrared absorption spectrum measurements, the characteristic values are 2800 to 3000 cm ^-1 , 1730 cm ^-1 ,
It was 1260cm ^-1 . In mass spectral analysis,
A molecular ion peak was observed at 528, supporting the chemical structure of this product. This material was placed in a Mettlerhot stage FP-82, and the phase change was observed under a polarizing microscope, as shown below. Cryst87.9 ---→ SmC ^* 140 ←--→ Ch15.8 ←--→ Iso Examples 6 to 8 Based on Example 5, various derivatives were synthesized in the same manner, and the phase transition temperature was measured. are shown in Table 2. [In the table, R is R in the above general formula (), thereby indicating each compound]

[Table] The compounds obtained in each example have an enantiotropic SmC ^* phase over a wide temperature range, and are all effective as components for expanding the temperature range of ferroelectric liquid crystal compositions. Example 9 A liquid crystal cell was assembled by sandwiching a Mylar film between a glass substrate having two transparent electrodes, the surface of which was coated with a polyimide polymer film and subjected to rubbing treatment. Note that the rubbing directions of the two substrates were parallel to each other, and the cell interval was 9 μm.
The compounds obtained in each example were sealed in this liquid crystal cell, and slowly cooled from an isotropic liquid to an SmC ^* phase. When this liquid crystal cell was sandwiched between two polarizing plates and a voltage was applied to reverse the polarity, the display state changed. As described above, the SmC ^* phase of each compound obtained in each example exhibits ferroelectricity and can be used as an electro-optical element. The compounds according to the present invention are chemically stable and useful as components for extending the temperature range of ferroelectric liquid crystal compositions.

Claims (1)

[Claims] 1 General formula () [Chemical formula] (In the formula, R is an alkyl group having 1 to 18 carbon atoms, n represents an integer of 3 to 7, and the symbol * is
A liquid crystalline compound represented by (indicating an optically active atom). 2 General formula () [Chemical formula] (In the formula, R is an alkyl group having 1 to 18 carbon atoms, n represents an integer of 3 to 7, and the symbol * indicates an optically active atom.) A liquid crystal composition comprising at least one of the liquid crystal compounds shown below.