JPH0475894B2 - - Google Patents

Description

[Detailed description of the invention]

(Object of the Invention) The present invention relates to a novel liquid crystal compound and a liquid crystal composition containing the compound. Display elements using liquid crystals are widely used in watches, calculators, etc. These liquid crystal display elements utilize the optical anisotropy and dielectric anisotropy of liquid crystal materials, and the liquid crystal phases include nematic liquid crystal phase, smectic liquid crystal phase, and cholesteric liquid crystal phase. is the most widely put into practical use. There are display types such as TN (twisted nematic) type, DS (dynamic scattering) type, guest-host type, and DAP type, depending on the electro-optic effect applied to liquid crystal displays. It is desirable that the liquid crystal material used exhibits a liquid crystal phase over as wide a natural temperature range as possible. At present, there is no single substance that satisfies such conditions, and several types of liquid crystal substances or non-liquid crystal substances are mixed and put into practical use. These substances are required to be stable against moisture, light, heat, air, etc., and it is desirable that the threshold voltage and saturation voltage required to drive the display element be as low as possible. An object of the present invention is to provide a novel liquid crystal compound useful as a component of a liquid crystal composition that satisfies the above-mentioned requirements. Here, liquid crystal compounds include tautotropic liquid crystals that exhibit an obvious liquid crystal phase, monomorphic liquid crystals that exhibit a liquid crystal phase under supercooling in a molten state, and the clearing points of mixtures with tautotropic liquid crystal substances. Compounds that can detect the clearing point of an object by extrapolation, and compounds that enhance properties specific to liquid crystals (e.g. dielectric anisotropy, optical anisotropy, etc.) when dissolved in tautotropic liquid crystals, or means a compound that enhances the characteristics exhibited by a liquid crystal element based on its unique properties. (Structure of the invention) The present invention is based on the general formula (In the formula (), R ₁ or R ₂ represents an alkyl group having 1 to 10 carbon atoms, and -X- is

[Formula] or −CH ₂ −,

【ceremony

[Formula] Also teeth

[Formula] is shown, and when -X- is -CH ₂ -,

【ceremony

A liquid crystal composition characterized by containing a naphthalene derivative represented by the following formula and the naphthalene derivative. The compounds of the present invention are produced by the method described below. In the compound of the present invention, R ₁ and R ₂ are alkyl groups, and -X- is

An example of a method for manufacturing a product with [formula] is shown in the following equation. (In these equations

[Formula] has the meaning described above. ) 2-alkylnaphthalene (compound ()) and the corresponding substituted acetyl chloride (compound ()) are subjected to a Friedel-Crafts reaction in the presence of anhydrous aluminum chloride in carbon disulfide to obtain a naphthyl ketone derivative (compound ( _a-1 )) Further, an example of a method for producing a compound of the present invention in which -X- is _-CH2- is as follows. (R ₁ , R ₂ and

[Formula] is the same as above) The naphthyl ketone derivative (compound ( _a-1 )) produced by the above method is reduced with lithium aluminum hydride and anhydrous aluminum chloride in ether to produce 2-ethylnaphthalene derivative (compound ( b)) (Effect of the invention) The compound of the present invention can be used for many other liquid crystal compounds, such as ester-based, Schiff base-based, biphenyl-based,
It has good compatibility with liquid crystal compounds such as phenylcyclohexane and heterocyclic compounds, and by adding a small amount of the compound of the present invention to a liquid crystal composition, the driving voltage of a liquid crystal display element using the liquid crystal composition can be increased. It can be lowered. (Example) The present invention will be explained in more detail with reference to the following example. Example 1 6-pentyl-2-(trans-4-butylcyclohexylacetyl)naphthalene 36 g (0.18 mol) of 6-pentylnaphthalene and 40 g of trans-4-butylcyclohexyl acetate chloride
g (0.18 mol) was dissolved in 250 ml of carbon disulfide and cooled to 0°C in an ice bath. While stirring, 28 g (0.21 mol) of anhydrous aluminum chloride powder was added little by little over 40 minutes. After that, while maintaining the temperature at 0℃
Stirred for 20 hours. This reaction mixture was mixed with 6N hydrochloric acid at 100%
ml and 500g of ice cubes while stirring,
After stirring for 30 minutes, the tan oil was extracted with toluene. This toluene layer was washed with 6N hydrochloric acid, then with a 2N aqueous sodium hydroxide solution, then with water, dried over anhydrous sodium sulfate, and then the solvent was distilled off under reduced pressure. 45 g of the resulting brown oily residue was dissolved again in 50 ml of toluene, passed through an activated alumina column to remove tar-like impurities, and the toluene was distilled off under reduced pressure. The resulting oily residue (43 g) was redissolved with ethanol. Crystallizes to give the target product 6-pentyl-2-
(trans-4-butylcyclohexylacetyl)
18.6 g (0.049 mol) of naphthalene was obtained (yield 27
%). The melting point of this substance is 84.7 to 85.7°C, and the nematic-isotropic liquid phase transition point (hereinafter abbreviated as N-point) was determined by extrapolation from the mixed system with transalkyl cyanophenyl cyclohexane crystals. ) was 38.0℃. The elemental analysis results of this compound were C: 85.89%, H: 10.30% (calculated values: C: 85.66%, H: 10.12%). Example 2 The desired product, 6-pentyl- 2
-Naphthyl-4-butylbenzyl ketone was obtained.
The melting point of this substance is 109.0-110.0℃, N
- point is -18.9℃, elemental analysis result is C: 87.34%,
H: 8.68% (calculated value C: 87.05%, H: 8.66%). Example 3 6-pentyl-2-(4-butylphenethyl)
Naphthalene 1.2 g (30 mmol) of lithium aluminum hydride in a 300 ml three-necked flask whose interior was replaced with nitrogen.
and 50 ml of dry ether were added and stirred to suspend.
Add 8.3g of anhydrous aluminum chloride here in advance.
(62 mmol) dissolved in 100 ml of dry ether was added dropwise over 5 minutes. 6-pentyl-2- produced in Example 2 was added to the off-white suspension in the flask.
Naphthalene-4-butylbenzylketone 3.7g
(10 mmol) dissolved in 50 ml of chloroform was added dropwise over 30 minutes. After the dropwise addition was completed, the mixture was heated in a water bath while stirring and gently refluxed for 18 hours. 30 ml of water was added dropwise to the reaction mixture cooled to room temperature with stirring to remove excess lithium aluminum hydride, and then 60 ml of 6N hydrochloric acid was added dropwise to dissolve the gel-like hydroxide. After minutes, the liquid organic layer was washed with 6N hydrochloric acid.
Washed with 5% aqueous sodium carbonate solution and then water,
After drying over anhydrous sodium sulfate, the solvent was distilled off under reduced pressure. The resulting residue (3.1 g) was recrystallized from ethanol to obtain the target product, 6-pentyl-2-(4-
1.8 g of butylphenethyl) naphthalene was obtained. The melting point of this product is 77.9-78.9℃, N-1 by extrapolation
The point is 27.3℃, elemental analysis result C: 90.84%, H: 9.6
% (calculated values C: 90.44%, H: 9.56%). Example 4 (Application example) Trans-4-propyl-(4-cyanophenyl)cyclohexane 24% by weight Trans-4-pentyl-(4-cyanophenyl)cyclohexane 36% by weight Trans-4-heptyl-(4-cyanophenyl) ) Cyclohexane 25% by weight 4-(trans-4-pentyl)cyclohexyl-4'-cyanobiphenyl 15% by weight (abbreviated) is 11.6, 20℃
The viscosity at is 27.8cP. As a liquid crystal cell,
A substrate with a distance between the electrodes of 10 μm was prepared by assembling opposing substrates with silicon oxide coated and rubbed tin oxide transparent electrodes. When we measured the characteristics, the threshold voltage (hereinafter abbreviated as Vth) was 1.75V, and the saturation voltage (hereinafter abbreviated as Vsat).
was 2.40V. 85% by weight of this liquid crystal mixture (A) was added 6% by weight as shown in Example 1.
A composition in which 15% by weight of -pentyl-2-(trans-4-butylcyclohexylacetyl)naphthalene was dissolved had an N-point of 60.2°C, a Δε of 10.1, and a viscosity at 20°C of 30.3 cP. Regarding the characteristics of the same liquid crystal cell as described above using this composition, Vth is
1.58V, Vsat was 2.01V.

Claims (1)

[Claims] 1. General formula (In the formula, R ₁ or R ₂ represents an alkyl group having 1 to 10 carbon atoms, -X- represents [formula] or -CH ₂ -, [formula] represents [formula] or [formula], When -X- is -CH ₂ -, [Formula] is [Formula]) A naphthalene derivative represented by the following formula. 2 General formula (In the formula, R ₁ or R ₂ represents an alkyl group having 1 to 10 carbon atoms, -X- represents [formula] or -CH ₂ -, [formula] represents [formula] or [formula], When -X- is -CH ₂ -, [Formula] is [Formula]] A liquid crystal composition characterized by containing a naphthalene derivative represented by the following formula.