JPH0212211B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel liquid crystal materials exhibiting positive dielectric anisotropy. Liquid crystal display elements utilize the optical anisotropy and dielectric anisotropy of liquid crystal materials, and their display methods include TN type, DS type, guest-host type,
There are various types such as DAP type and White-Taylor type, and each type requires different properties of the liquid crystal material used. For example, depending on the type of display element, a liquid crystal material with a positive dielectric anisotropy Δε may be required, a material with a negative dielectric anisotropy may be required, or a material with an intermediate value may be suitable.
However, in any case, the liquid crystal materials used exhibit a liquid crystal phase over a wide temperature range, and also contain moisture and
It must be stable against heat, air, light, etc. At present, there is no single compound that satisfies all of these conditions, and the current state of affairs is to mix several types of liquid crystal compounds and non-liquid crystal compounds to obtain compounds that can withstand practical use. In general, liquid crystal compounds with arbitrary Δε values can be obtained by appropriately mixing those with positive Δε values and those with negative Δε values, but in this case, compounds with large absolute values of Δε values are difficult to mix together and crystals form. Because it is easy to appear,
A compound having a small absolute value of Δε value, low viscosity, and good compatibility is desired as a component constituting a practical liquid crystal composition. The present inventors have discovered the compound of the present invention which satisfies such demands to some extent. That is, the present invention is based on the general formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms,
X and Y are H or CH ₃ , one of which is CH ₃
It is a methyl-substituted 4-chlorophenyl ester of trans-4-(trans-4'-alkylcyclohexyl)cyclohexanecarboxylic acid represented by The compound of the present invention has a Δε of approximately +1.3, exhibits a liquid crystal phase (smectic liquid crystal phase and/or nematic liquid crystal phase) over a wide strength range up to high temperatures, has low viscosity, and has good compatibility with other liquid crystals. It is useful to obtain a liquid crystal composition for a liquid crystal display element that can be used in a wide strength range, particularly at high temperatures. Next, the method for producing the compound of the present invention will be described. First, trans-4-(trans-4'-alkylcyclohexyl)cyclohexanecarboxylic acid is converted into an acid chloride using thionyl chloride, and then, in the presence of pyridine, methyl-substituted-4- Reaction with chlorophenol yields the desired compound. Showing it as a chemical formula (In the above formula, R, X, and Y are the same as above.) Hereinafter, the manufacturing method and usage examples of the compound of the present invention will be explained in more detail with reference to Examples. Example 1 [Production of trans-4-(trans-4'-ethylcyclohexyl)cyclohexanecarboxylic acid 3-methyl-4-chlorophenyl ester] 2.4 g of trans-4-(trans-4'-ethylcyclohexyl)cyclohexanecarboxylic acid
(0.01 mol) and 10 ml of thionyl chloride are placed in a flask and heated at 70°C for 3 hours until it becomes homogeneous. Excess thionyl chloride is distilled off under reduced pressure, leaving an oily acid chloride. On the other hand, 3-methyl-4-chlorophenol 1.6
Dissolve g (0.011 mol) in 10 ml of pyridine,
The above acid chloride is added to this, reacted, and left overnight. Add 200ml of toluene to it and pour into water. The toluene layer is separated, washed with 6N hydrochloric acid and 2N aqueous sodium chloride solution, then washed with water until neutral, and then dried over anhydrous sodium sulfate. When toluene is distilled off under reduced pressure, a crystalline substance remains, which is recrystallized from ethanol to obtain crystals of the desired trans-4-(trans-4'-ethylcyclohexyl)cyclohexanecarboxylic acid 3-methyl-4-chlorophenyl ester. 1.7 g was obtained (yield 49%). The C-Sm point of this product was 88.5°C, and the Sm-N point was 92.4°C. Examples 2 to 8 Trans-4-(trans-
trans-4-(trans-4'-alkylcyclohexyl) with another alkyl group instead of cyclohexanecarboxylic acid (4'-ethylcyclohexyl)
The first step was carried out in the same manner as in Example 1, using 0.01 mol of cyclohexanecarboxylic acid, and using 2-methyl-4-chlorophenol instead of 3-methyl-4-chlorophenol in Examples 6 to 10. A compound of formula () shown in the table was produced. The physical property values and the like are shown in Table 1 together with the results of Example 1.

【table】

[Table] Example 9 (Usage example) Nematic liquid crystal of a liquid crystal composition having the following composition: 4-pentyl-4'-cyanobiphenyl 50% 4-heptyl-4'-cyanobiphenyl 33% 4-octyloxy-4'-cyanobiphenyl 17% The temperature range is -2 to 44.3℃, the viscosity at 20℃ is 39.9cp,
The threshold voltage of a TN cell using this is 1.40
, the saturation voltage is 1.90. This liquid crystal composition 85
Trans-4- (Trans-4'-
Propylcyclohexyl)cyclohexanecarboxylic acid 3-methyl-4-fluorophenyl ester
7.5 parts and Example 4 trans-4-(trans-
The nematic temperature range of the liquid crystal composition to which 7.5 parts of 4'-propylcyclohexyl)cyclohexanecarboxylic acid 3-methyl-4-fluorophenyl ester was added was -5 to 56.5°C, mainly widening on the high temperature side.
The viscosity at 20°C was 380°C, the threshold voltage of the TN cell using this was 1.55, and the saturation voltage was 2.02.

Claims (1)

[Claims] 1. General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms,
X and Y are H or CH ₃ , one of which is CH ₃
A methyl-substituted 4-chlorophenyl ester of trans-4-(trans-4'-alkylcyclohexyl)cyclohexanecarboxylic acid represented by