JPS6215052B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel liquid crystal compounds useful as electro-optic display materials. Nematic liquid crystals are currently widely used as display elements. These display methods can be roughly divided into the TN type (Nujire Nematic Type),
Typical examples include DS type (dynamic scattering type), DAP type (field-controlled birefringence type), PC type (cholesteric-nematic phase transition type), and GH type (guest-host type) using dichroic dyes. It is something. Until now, smectic liquid crystals have not been widely used in practice, but depending on their compatibility with nematic liquid crystals, they can be added to nematic liquid crystals to improve their properties. Capacity information can now be displayed, and there is an urgent need to put it into practical use, and there is also active development of display methods that have faster response performance than the TN type. At present, there is no single compound of liquid crystal materials used in these display elements that can withstand practical use due to its various properties, such as liquid crystal temperature range, operating voltage, response performance, etc.; Currently, liquid crystal compounds that are suitable for practical use are obtained by mixing about 20 types of liquid crystal compounds. Particularly recently, liquid crystal display elements have come to be used in automobiles and the like, and there is a demand for devices that can be used in a wider temperature range and that have a faster response speed at low temperatures. In order to constitute such a liquid crystal composition, a high temperature liquid crystal compound (one with a high upper limit of the liquid crystal temperature range) and a low viscosity liquid crystal compound are essential as its components. Usually, the former high temperature liquid crystal compound has an inherently high viscosity, and the latter low viscosity liquid crystal compound, e.g.

【Formula】Ya

[Production of trans, trans-4-propyl-4'-methyloxymethylbicyclohexane]

First step: Put 68.2 g (0.270 mol) of trans-4-(trans-4'-propylcyclohexyl)cyclohexanecarboxylic acid, 200 ml of methyl alcohol, and 14 ml of concentrated sulfuric acid into a 500 ml three-necked flask, heat with a mantle heater, and reflux for 4 hours. do. After cooling, 200ml of water
Add 100ml of heptane, transfer to a separatory funnel, and wash the organic layer with water. Heptane is distilled off under reduced pressure, and the crude product is dissolved in 50 ml of ethyl alcohol and recrystallized.
After separating and drying the crystals, 65 g of trans-4-(trans-4'-propylcyclohexyl)cyclohexanecarboxylic acid methyl ester () was obtained. The melting point (C-N point) of this product is 34.2℃ and the clearing point (N-
Point I) was 62.8°C. Second stage: 7.0 g (0.183 mol) of lithium aluminum hydride in 440 ml of dried tetrahydrofuran (THF)
ml and stirred vigorously, then added 65 g (0.244 mol) of the compound () obtained in the first stage to 65 ml of THF.
Add the solution dissolved in the solution dropwise while keeping the reaction temperature below 20℃. After the dropwise addition is completed, the mixture is heated to 55°C, reacted for 2 hours, and then cooled. Next, 13ml of ethyl acetate and water
After adding 100ml, add 400ml of 18% sulfuric acid water to separate into an organic layer and an aqueous layer. heptane 200ml
Transfer to a separatory funnel, wash with 500 ml of water, then wash with 500 ml of 2% aqueous sodium carbonate solution, and further wash until the aqueous layer becomes neutral. heptane,
THF, etc. are distilled off under reduced pressure, and the product remaining in the pot is recrystallized from 100 ml of ethyl alcohol, and the crystals are separated and dried to obtain 49.3 g of compound (). The melting point of this product was 125.8-126.9°C. 3rd step: 49.2 g (0.268 mol) of compound () was dissolved in 100 ml of dry pyridine and 240 ml of dry toluene, cooled to below 5°C, and 42 g (0.216 mol) of p-toluenesulfonic acid chloride was added to 70 ml of dry toluene.
Add the solution dissolved in the mixture dropwise little by little from the dropping funnel so that the reaction temperature does not exceed 10°C. When the addition is complete, remove the cold bath and stir at room temperature for 4 hours, then add 100 ml of water and 300 ml of toluene and stir. Transfer to a separatory funnel and add 100ml of 6N-HCl water to the toluene layer.
Wash twice, then once with 200ml of water, then 2N-
Wash twice with 100 ml of NaOH water and then four times with 200 ml of water. Toluene was distilled off under reduced pressure, and the resulting crystals were recrystallized from 200 ml of ethyl alcohol. The crystals were separated and dried to obtain 54 g of compound (). The melting point was 94.8-95.8°C. Step 4 Stir 50ml of methyl alcohol at room temperature,
Cut 1.8 g (0.080 mol) of metallic sodium into small pieces and add them little by little to make sodium methoxide. After the metallic sodium pieces are gone, a solution of 24 g (0.061 mol) of the compound () obtained in the third stage dissolved in 50 ml of dry toluene is gradually added to the dropping funnel while keeping the internal temperature within the range of 50 to 60°C. Add to. After the dropwise addition was completed, the mixture was refluxed for 4 hours, cooled, and 20 ml of water was added, transferred to a separatory funnel, and the toluene layer was washed with water until the aqueous layer became neutral. After toluene is distilled off under reduced pressure, the boiling point is 113-117℃/1.5mm.
Collect the Hg fraction. The crystals of this fraction are recrystallized from 15 ml of ethyl alcohol, and the crystals are separated and dried to produce the desired compound, namely trans, trans-4.
12 g of -propyl-4'-methyloxymethylbicyclohexane () was obtained. This substance shows a smectic phase and a nematic phase, and its melting point (CS point) is 44.8℃ and S-N point is
The clearing point (NI point) was 52.0°C.
Moreover, the elemental analysis values agreed well with the calculated values as shown below. Actual value (%) Calculated value (%) (as C ₁₇ H ₃₂ O) C 80.86 80.88 H 12.75 12.78 Examples 2 to 9 Trans-4- (trans-
Trans-4-(trans-4'-methylcyclohexyl)cyclohexanecarboxylic acid, trans-4-(trans-4'-ethylcyclohexyl)cyclohexanecarboxylic acid, trans-4- (trans-4'-butylcyclohexyl)cyclohexanecarboxylic acid, trans-4-(trans-4'-pentylcyclohexyl)cyclohexanecarboxylic acid, trans-4-(trans-4'-hexylcyclohexyl)cyclohexanecarboxylic acid or trans-4 -(trans-4'-heptylcyclohexyl)cyclohexanecarboxylic acid, and by reacting with ethyl alcohol, propyl alcohol, etc. instead of methyl alcohol in the fourth step. Table 1 shows the results of Example 1. Table 2 shows the melting points of the intermediate compounds obtained in the second and third stages.

【table】

[Table] Example 10 The nematic liquid crystal temperature range (MR) of the liquid crystal composition consisting of is -3 to 52.5℃, and the viscosity η ₂₀ at 20℃ is
23cp, dielectric anisotropy △ε is 11.3 (ε=16.2, ε
⊥=4.9), and when this was sealed in a TN cell with a cell thickness of 10 μm, the threshold voltage was 1.5V and the saturation voltage was 2.2V. The MR of the liquid crystal composition obtained by adding 20 parts of the compound of Example 1 and 10 parts of the compound of Example 7, which are one of the compounds of the present invention, to this composition is -10°C or less - 52.2
°C, η ₂₀ is 17 cp, △ε is 7.6 (ε = 11.8, ε⊥ =
4.2), and when sealed in the same cell as above, the threshold voltage was 1.61V and the saturation voltage was 2.33V. Example 11 A liquid crystal composition containing the compound of Example 2 as a compound of formula () was prepared. N of this composition
- Although the I point is as high as 85.4℃, the viscosity is
A nematic liquid crystal composition with extremely low response speed of 15.4 cps (at 20°C) and fast response speed was obtained. When driven in a cell similar to Example 10, the threshold voltage was 2.7V and the saturation voltage was 3.8V.

Claims (1)

[Claims] 1. General formula (However, in the above formula, R ₁ and R ₂ represent an alkyl group having 1 to 8 carbon atoms.) trans, trans-4-alkyl-4'-alkyloxymethylbicyclohexane. 2 General formula (However, in the above formula, R ₁ and R ₂ represent an alkyl group having 1 to 8 carbon atoms.) Contains at least one type of trans, trans-4-alkyl-4'-alkyloxymethylbicyclohexanes A liquid crystal composition characterized by: