JPH0131499B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to liquid crystal substances having a wide liquid crystal temperature range and positive dielectric anisotropy, and liquid crystal compositions containing them. Liquid crystal display elements utilize optical anisotropy and dielectric anisotropy, which are characteristics of liquid crystal materials. There are various types of liquid crystal display elements, such as TV (twisted nematic) type, DS (dynamic scattering) type, guest-host type, and DAP type, and the characteristics required of the liquid crystal material used for each type are different. is different. However, in either method, the liquid crystal material is exposed to moisture, heat,
It is necessary to be stable in air, light, etc., and it is desirable to use a substance that exhibits a liquid crystal phase over as wide a temperature range as possible. However, at present, there is no single compound that satisfies these conditions, and the current situation is to use a mixture of several types of liquid crystal materials. Recently, there has been a demand for display devices that operate from low temperatures (approximately -20°C) to high temperatures (80 to 90°C), but conventional combinations of compounds alone cannot meet this demand. It was difficult to meet such demands. The compounds of the present invention were designed to meet these demands. That is, the present invention is based on the general formula (In the above formula, R represents a linear or branched alkyl group having 1 to 10 carbon atoms.) Trans-4-(4'-substituted phenyl)-cyclohexanecarboxylic acid 4-cyanobiphenyl ester. The compound of the present invention has a wide liquid crystal temperature range in the high temperature region. For example, 4-cyanobiphenyl trans-4-(4'-bentylphenyl)-cyclohexanecarboxylate exhibits a wide and high smectic temperature range from 117.5°C to over 290°C, so small amounts of this compound can be added to other liquid crystal systems. Just N-I
You can raise your points. Next, a method for producing the compound of the present invention will be described. First, trans-4-(4'-substituted phenyl)-
Cyclohexanecarboxylic acid and thionyl chloride are reacted to form an acid chloride, and then 4'-cyano-4-hydroxybiphenyl is reacted in pyridine to obtain the desired trans-4-(4'-substituted phenyl)-cyclohexanecarboxylic acid. 4-cyanobiphenyl ester is obtained. If the above is expressed as a chemical formula, The present invention will be explained in more detail with reference to Examples below. Example 1 [trans-4-(4'-propylphenyl)-
Production of 4-cyanobiphenyl cyclohexanecarboxylic acid ester] Add 10 ml of thionyl chloride to 0.02 mol (4.9 g) of trans-4-(4'-propylphenyl)-cyclohexanecarboxylic acid and heat. It becomes homogeneous in about 1 hour, and after heating for about 1 hour, excess thionyl chloride is distilled off under reduced pressure, and the remaining oil is converted into trans-4-(4'-propylphenyl)-cyclohexanecarboxylic acid acid It is a thing. On the other hand 4-
3.9g of 4′-cyanophenylphenol in pyridine
Dissolve in 10 ml, add the acid chloride from above, stir well, and leave overnight. Toluene there
Add 200ml of the toluene layer to 6NHCl.
Then, wash with 2N NaOH aqueous solution and finally with water until it becomes neutral. After drying over anhydrous sodium sulfate, the toluene is completely distilled off under reduced pressure, and the remaining crystals are recrystallized from acetone to obtain the desired trans-4-(4'-propylphenyl)-
4.5 g of crystals of cyclohexanecarboxylic acid 4-cyanobiphenyl ester were obtained. The yield was 53%. The physical property values are shown in Table 1.

[Table] Examples 2 to 4 In place of 0.02 mol (4.9 g) of trans-4-(4'-propylphenyl)-cyclohexanecarboxylic acid in Example 1, trans-4-(4' -Substituted phenyl)-cyclohexanecarboxylic acid 0.02 mol was used, but the corresponding trans-4-
(4'-Substituted phenyl)-cyclohexanecarboxylic acid 4-cyanobiphenyl ester was produced.
Their yields, physical properties, etc. are shown in Table 1 together with the results of Example 1. Example 5 (Application example) 4-pentyl-4'-cyanobiphenyl 46 parts 4-heptyl-4'-cyanobiphenyl 28 parts 4-octyloxy-4'-cyanobiphenyl
15 parts 4-pentyl-4'-cyanophenyl ester
The liquid crystal composition consisting of 11 parts has a nematic temperature range of -5 to 63°C, a viscosity of 48 cp at 20°C, and an operating threshold voltage of 1.60 when it is sealed in a TN cell with a cell thickness of 10 μm. V, the saturation voltage is 2.20V. Trans-4 of Example 4 was added to 90 parts of this liquid crystal mixture.
A liquid crystal composition containing 10 parts of 4-cyanobiphenyl ester of -(4'-heptylphenyl)-cyclohexanecarboxylic acid had a nematic temperature range of -6 to 90°C and a viscosity of 50 cp at 20°C. .
When this was sealed in the same cell as in the previous case and the characteristics of the liquid crystal cell were measured under the same conditions, the threshold voltage was 1.65V and the saturation voltage was 2.25V.

Claims (1)

[Claims] 1. General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms) trans-4-(4'-substituted phenyl)-cyclohexanecarboxylic acid 4-cyanobiphenyl ester. 2 General formula Contains at least one component of trans-4-(4'-substituted phenyl)-cyclohexanecarboxylic acid 4-cyanobiphenyl ester represented by (in the above formula, R represents a linear or branched alkyl group having 1 to 10 carbon atoms) A liquid crystal composition characterized by: