JPS643858B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel organic compound, and more particularly to a novel liquid crystal compound that can be used as a component of a liquid crystal material. Nematic liquid crystals with positive dielectric anisotropy can be used in twisted nematic mode display devices and liquid crystal display devices that utilize the guest-host effect, as well as DS type display devices that utilize dynamic scattering effects and cholesteric-nematic phase transition. It is widely used in display elements that utilize the birefringence effect, DAP type display elements that utilize the electric field controlled birefringence effect, etc. The liquid crystal used for these is stable against moisture, air, light, heat, etc., and is preferably in a liquid crystal state not only at room temperature but also in a liquid crystal state from low to high temperatures. The present invention provides a novel liquid crystal compound that has such excellent practical properties and is useful as a component constituting a stable liquid crystal composition. That is, the compound of the present invention has the general formula (However, in the above formula, R ₁ and R ₂ represent an alkyl group having 1 to 10 carbon atoms.) 4-(trans-4'-alkylcyclohexyl)benzyl alkyl ether. Although the compound of the present invention is a nematic liquid crystal, it has a low melting point, so this compound alone is not practical for use in display devices, but it has excellent compatibility with other liquid crystal compounds and has a low viscosity, so it Type or N
It is very useful as a component that lowers the viscosity of the liquid crystal composition obtained by mixing it with a type of liquid crystal material, thereby increasing the response speed. The compound of the present invention can be synthesized by the following steps. That is, first, 4-(trans-4'-alkylcyclohexyl)benzoic acid is reacted with thionyl chloride to form an acid chloride, and then ethyl alcohol is reacted with it to form 4-(trans-4'-alkylcyclohexyl)benzoic acid ethyl ester. obtain. This was reduced with lithium aluminum hydride (LiAlH ₄ ) in tetrahydrofuran (THF) to give 4-(trans-4'-alkylcyclohexyl)benzyl alcohol, and then reacted with a mixture of concentrated sulfuric acid and hydrobromic acid to give 4-(trans-4'-alkylcyclohexyl)benzyl alcohol. (trans-4′-alkylcyclohexyl)benzyl bromide. this,
By reacting metallic sodium dissolved in anhydrous ethyl alcohol, the desired 4-(trans-
4'-Alkylcyclohexyl)benzyl ethyl ether is obtained. Hereinafter, the compounds of the present invention will be explained in more detail based on Examples. Example 1 [Production of 4-(4′-transpentylcyclohexyl)benzyl ethyl ether] 30 g (0.11 mol) of 4-(trans-4′-pentylcyclohexyl)benzoic acid and thionyl chloride
32.8 g (0.28 mol) was reacted under heating under reflux for 1 hour, and after the reaction was completed, excess thionyl chloride was distilled off under reduced pressure to obtain 29.5 g (0.1 mol) of acid chloride. After gradually adding 23 g (0.50 mol) of ethyl alcohol and heating at 60° C. for 2 hours, the reaction mixture is cooled and the product is extracted with 50 ml of toluene. The extract was washed with 20% hydrochloric acid, then with a 10% aqueous sodium hydroxide solution, and then with water to make it neutral, and the toluene was distilled off from the extract to give 29 g.
(0.10 mol) of 4-(trans-4'-pentylcyclohexyl)benzoic acid ethyl ester was obtained. Dissolve this in 50 ml of dry tetrahydrofuran, then 2.3 g (0.06 mol) of lithium aluminum hydride in 40 ml of dry tetrahydrofuran.
was suspended and added dropwise to the vigorously stirred solution.
After the addition was complete, the mixture was heated under reflux for 2 hours. After cooling, water was carefully added to decompose the excess lithium aluminum hydride, and then the mixture was gradually added to 200 ml of 20% sulfuric acid water.
Stir until the inorganics are dissolved. 100ml of product
After washing the extract with water and drying with anhydrous magnesium sulfate, the toluene was distilled off from the extract, and the residue was recrystallized with 30 ml of n-hexane to obtain 20.2 g (0.08 mol) of 4- (Trance-
4′-pentylcyclohexyl)benzyl alcohol was obtained. The melting point of this product was 48.2°C. Next, 27 g of hydrobromic acid (47%) was gradually added to 9 g of concentrated sulfuric acid to prepare a mixture, to which the previously obtained benzyl alcohol was added and stirred at about 100° C. for 4 hours.
After cooling the mixture, 50 ml of toluene was added to extract the product, and the extract was washed with a 10% aqueous sodium bicarbonate solution and then with water. The toluene was distilled off from the extract, and the residue was distilled under reduced pressure. 18.1g
(0.06 mol) of 4-(trans-4'-pentylcyclohexyl)benzyl bromide was obtained. The boiling point of this product was 165°C/1 mmHg. Next, add 1.4 g (0.06 mol) of sodium metal to 50
ml of anhydrous ethyl alcohol, and add 30 ml of the above 18.1 g (0.06 mol) of 4-(trans-4'-pentylcyclohexyl)benzyl bromide.
Gradually drop a solution dissolved in dry toluene,
After completion of the dropwise addition, the reaction mixture was heated under reflux for 2 hours. After the reaction was completed, the mixture was allowed to cool, water was added, the toluene extract was washed with water, and dried over anhydrous magnesium sulfate.
Toluene was distilled off from the extract, and the residue was distilled under reduced pressure to obtain the target product, 4-(trans-4'-pentylcyclohexyl)benzyl ethyl ether.
12.4g (0.04mol) was obtained. The boiling point of this thing is 164
The temperature was ~166°C/1mmHg. The physical properties of this compound are shown in Table 1. Furthermore, the calculated values of the elemental analysis of the compound and the measured values are in good agreement as shown below. Calculated value Actual value (as C ₂₀ H ₃₂ O) C 83.27% 83.4% H 11.18% 11.4% Examples 2 to 5 Similar to Example 1, other R ₁ , R ₂ in formula ()
A compound having the combination of was obtained, and its physical properties are shown in Table 1 together with those of the compound of Example 1.

[Table] Example 10 (Application example 1) The liquid crystal composition having the above composition had an NI point of 57°C and a viscosity η ₂₀ of 38 cps at 20°C.
10μm thick with horizontal alignment treatment by rubbing
When it was sealed in a twisted nematic cell, its threshold voltage was 1.4V, and the response speed when a 3V, 32Hz square wave (blinking 500msec each) was applied was a rise time of 70msec and a fall time of 70msec. of the present invention

The composition without [Formula] has an N-I point of 63℃ and η ₂₀ 48cps. The operating characteristics under the same conditions were a threshold voltage of 1.4 V, a rise time of 90 msec, and a fall time of 100 msec. Example 11 (Application example 2) EN-30 (manufactured by Chitsuso Co., Ltd. Dielectric constant anisotropy △ε is -5.4
of the present invention (Example 4) to 90 parts of N-type liquid crystal composition)

The liquid crystal composition to which 10 parts of [Formula] was added had a CI point of 53°C and η ₂₀ =45 cps. When this product was sealed in a 10 μm thick cell that had been vertically aligned using octadecyltriethoxysilane, a 6V32Hz square wave (blinking
500msec), the response speed is a rise time of 30
msec, fall time was 170 msec. The CI point of EN-30 only is 62℃, η ₂₀ = 57cps.The response speed measured in the same way is a rise time of 50msec,
The fall time was 200msec.

Claims (1)

[Claims] 1. General formula (However, R ₁ and R ₂ each represent an alkyl group having 1 to 10 carbon atoms.) 4-(trans-4'-alkylcyclohexyl)benzyl alkyl ether. 2 General formula (However, R ₁ and R ₂ each represent an alkyl group having 1 to 10 carbon atoms.) A liquid crystal composition containing at least one compound represented by the following.