JPS6220179B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to liquid crystalline ester compounds. There are various types of display elements using liquid crystals, such as FE type, DSM type, and guest-host type, but in order for these front elements to be used, the liquid crystal composition must be stable and the operating temperature of the element must be within the liquid crystal temperature range. It is necessary to cover the Such a liquid crystal composition can be obtained by combining and mixing several types of liquid crystal compounds having appropriate chemical structures. An object of the present invention is to provide a novel compound useful as a material for such a liquid crystal composition. The compounds of the present invention have the general formula (In the formula, R represents a straight-chain alkyl group having 1 to 6 carbon atoms.) trans-4-n-alkylcyclohexane-1-carboxylic acid-2'-chloro-
4'-(4-n-octylphenyl)-phenyl ester, this compound is trans-4-n-
Alkylcyclohexanone-1-carboxylic acid is converted into an acid chloride with thionyl chloride, and this and 2-chloro-
It can be obtained by reacting with 4-(4'-n-octylphenyl)-phenol. This reaction can be expressed as a chemical equation as follows. (However, in the formula, R represents a straight-chain alkyl group having 1 to 8 carbon atoms.) The carboxylic acid as a raw material used in the above reaction can be obtained by reducing the corresponding 4-n-alkylbenzoic acid. was completed (Tokuko Showa 53-
22882) and 2-chloro-4-(4'-n-octylphenyl)-phenol can be synthesized by the method disclosed in Japanese Patent Publication No. 52-142683. Next, the compound of the present invention 4-n-alkylcyclohexane-1-carboxylic acid-2'-chloro-4'-(4
The method for producing -n-octylphenyl)-phenyl ester will be explained in detail. Commercially available trans-4-n-alkylcyclohexane-1-carboxylic acid (these compounds are
They can be synthesized by methods such as No. 53-22882, and the properties of these compounds are shown in Table 1. ) and an excess amount of thionyl chloride are heated to reflux in a flask, and after refluxing, excess thionyl chloride is distilled off and the residue is distilled under reduced pressure to obtain trans-4-n-alkylcyclohexane-1-carboxylic acid chloride. Then an equimolar amount of 2-chloro-4-(4-n-
octylphenyl)-phenol (This compound can be synthesized by the method described in Japanese Patent Publication No. 142683/1983.)
The desired product can be obtained by placing 4-n-alkylcyclohexane-1-carboxylic acid chloride in a flask and allowing it to stand at 80°C for 2 hours, and then recrystallizing the reaction product from ethanol. EXAMPLES Below, in order to demonstrate the embodiments of the present invention in more detail, examples of its production and application examples showing its usefulness will be described. Example 1 10 g of commercially available trans-4-n-hexylcyclomexane-1-carboxylic acid and 20 ml of thionyl chloride were added.
Place in a 100ml flask and heat under reflux for 1 hour.
After refluxing, excess thionyl chloride was distilled off under reduced pressure. Trans-4-n-hexylcyclohexane-1 was obtained by distilling the residue after thionyl chloride was distilled off under reduced pressure.
-Carboxylic acid chloride was obtained. Boiling point 103-106℃/mmHg Yield 85% Next, 2-chloro-4-(4-n-octylphenyl)- was synthesized by the method of Japanese Patent Publication No. 142683/1983.
1.5 g of phenol (melting point 42°C) (the infrared absorption spectrum of this compound is shown in Figure 1) and 1.1 g of trans-4-n-hexylcyclohexane-1-carboxylic acid chloride were placed in a flask and left at 80°C for 2 hours. . After standing, the reaction product was repeatedly recrystallized with ethanol until the melting point became constant, and 1.2 g (yield: 50%) of white crystals were obtained. This compound, namely trans-4-n-hexylcyclohexane-1-carboxylic acid-2'-chloro-4'-
The melting point of (4-n-octylphenyl)-phenyl ester was 36°C and the clearing point was 87°C. The infrared absorption spectrum of this compound is shown in FIG. Examples 2 to 6 In the same manner as in Example 1, trans-4-methylcyclohexane-1-carboxylic acid and trans-4-ethylcyclohexane-1-carboxylic acid were used instead of trans-4-n-hexylcyclohexane-1-carboxylic acid. Carboxylic acid, trans-4-n-propylcyclohexane-1-carboxylic acid, trans-4
-n-butylcyclohexane-1-carboxylic acid,
trans-4-n-pentylcyclohexane-1
- Trans-4-n-alkylcyclohexane-1-carboxylic acid-2'-chloro-4'-(4-n
-octylphenyl)-phenyl ester was obtained. The infrared absorption spectra of these synthesized compounds are shown in FIGS. 3 to 7. Further, the progress and results of the synthesis are shown in Tables 2 and 3.

【table】

【table】

【table】

[Table] Example 7 Application Example When the liquid crystal composition shown in Table 4 was prepared, the clearing point was 75.5°C. When this liquid crystal composition was filled into a liquid crystal cell with a thickness of 8.5 .mu.m and the contrast characteristics were measured at 40.degree. C., a graph as shown in FIG. 8 was obtained. From now on, the compounds of the present invention are
It can be seen that it can be used as a component of a liquid crystal composition used in an FE type liquid crystal display.

[Table] In the present invention, it was confirmed by actually synthesizing that a compound consisting of a biphenyl ring and a cyclohexane ring can secure liquid crystallinity.In addition, as another effect, by adding a cyclohexane ring, the viscosity (η) and refractive index (△
This has the advantage that n) can be greatly improved. Needless to say, small η and Δn are advantageous in terms of high-speed response and wide viewing angle characteristics when actually used in a display. Furthermore, the liquid crystal compound of the present invention has a dipole moment in a direction substantially perpendicular to the molecular axis, so that the dielectric anisotropy becomes negative, and its absolute value |△ε| exhibits a large value of approximately 2. It is a promising liquid crystal compound that also has the ability to lower driving voltage. Therefore, by appropriately combining the liquid crystal compounds of the present invention, they can also be combined with a wide range of other liquid crystals, such as biphenyl liquid crystals, ester liquid crystals, azoxy liquid crystals, and phenylcyclohexane liquid crystals. , it is possible to improve responsiveness, viewing angle characteristics, drive voltage, etc., and to expand the high temperature range of liquid crystal temperature characteristics, without adversely affecting other characteristics of the liquid crystal, even in small amounts. 60°C) can be obtained. Furthermore, by using cyclohexanecarboxylic acid, the manufacturing method is simple and can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is an infrared absorption spectrum diagram of 2-chloro-4-(4-n'-octylphenyl)-phenol. Figure 2 shows trans-4-n-hexylcyclohexane-1-carboxylic acid-2'-chloro-
FIG. 2 is an infrared absorption spectrum diagram of 4'-(4-n-octylphenyl)-phenyl ester. Figure 3,
Figures 4, 5, 6, and 7 show trans-4-methylcyclohexane-1-carboxylic acid-2'-chloro-4'-(4-n-octylphenyl)-phenyl ester, respectively. , trans-4-ethylcyclohexane-1-carboxylic acid-2'-chloro-
4'-(4-n-octylphenyl)-phenyl ester, trans-4-n-propylcyclohexane-1-carboxylic acid-2'-chloro-4'-(4-n
-octylphenyl)-phenyl ester, trans-4-n-butylcyclohexane-1-carboxylic acid-2'-chloro-4'-(4-n-octylphenyl)-phenyl ester, trans-4- n
-Pentylcyclohexane-1-carboxylic acid-
2'-chloro-4'-(4-n-octylphenyl)-
It is an infrared absorption spectrum diagram of phenyl ester. FIG. 8 shows the contrast characteristics of a liquid crystal display filled with the liquid crystal composition described in Example 7.

Claims (1)

[Claims] 1 General formula having a biphenyl ring and a cyclohexane ring (However, R represents a straight-chain alkyl group having 1 to 6 carbon atoms.) An ester compound represented by: