JPS634817B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel fluorine-containing organic compound having positive dielectric anisotropy and useful as a component of a liquid crystal composition. Liquid crystal displays utilize optical anisotropy and dielectric anisotropy, which are the characteristics of liquid crystal materials, and display methods include TN type (twisted nematic type), DS type (dynamic scattering type), guest There are various types such as host type and DAP type, and each type requires different characteristics of the liquid crystal material used. However, in any case, the liquid crystal materials used in these display elements are required to exhibit a liquid crystal phase over as wide a temperature range as possible, and to be stable against moisture, heat, air, light, and the like. However, at present, there is no single compound that satisfies 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 be put to practical use. In particular, recently there has been a demand for liquid crystal display elements with a wide operating range, and the liquid crystal used therein has become required to exhibit a liquid crystal phase even in a higher temperature range than before. The object of the present invention is to provide a compound useful as a component constituting a liquid crystal having such a wide liquid crystal temperature range. That is, the present invention is based on the general formula (In the above formula, X is R, RO,

[Synthesis of 4-ethylbenzoic acid 4′-fluoro-4″-biphenylyl ester]

2.3 g of 4-ethylbenzoic acid and 6 g of thionyl chloride
Add and heat on a hot water bath at 70-80℃ for 2 hours. Since the whole mixture becomes homogeneous, the mixture is left to stand for an additional hour, and then the pressure is reduced to completely distill off excess thionyl chloride. The remaining oil is 4-ethylbenzoic acid chloride.
Add 2 g of 4-fluoro-4'-hydroxybiphenyl dissolved in 2 g of pyridine and 30 ml of toluene while shaking vigorously, leave it overnight, pour into 50 ml of water, and add 50 ml of toluene for extraction. . The toluene layer is washed with 6N hydrochloric acid, then with a 2N aqueous sodium hydroxide solution, and then further washed with water until neutral, filtered, and the toluene is distilled off under reduced pressure. The remaining solid was recrystallized from ethanol to obtain 2.4 g of the desired product, 4'-fluoro-4''-biphenyl 4-ethylbenzoate.
The yield is 70.7% based on 4-fluoro-4'-hydroxybiphenyl. This is a smectic liquid crystal with a C-Sm point (solid phase-smectic phase transition point) of 136.3 to 136.4°C and an Sm-I point (clearing point).
The temperature was 178.4-178.7℃. Moreover, the elemental analysis values are in good agreement with the theoretical values as shown in Table 1. Examples 2 to 8 Table 1 was carried out in exactly the same manner as in Example 1, except that 4-substituted benzoic acid having another alkyl group, an alkoxy group, or an alkylcyclohexyl group was used in place of 4-ethylbenzoic acid. A compound of formula () as shown in was obtained. The yield, physical properties, etc. are shown in Table 1 together with the results of Example 1.

[Table] Example 9 (Application example 1) Trans-4-propyl-(4'-cyanophenyl)
Cyclohexane 28% trans-4-pentyl-(4'-cyanophenyl)
Cyclohexane 43% trans-4-heptyl-(4'-cyanophenyl)
Nematic temperature range of liquid crystal composition A with a composition of 29% cyclohexane
3 to 52℃, dielectric anisotropy value is +10.5, threshold voltage value when TN cell is 1.53V, saturation voltage is
It is 2.12V. 85 parts of this liquid crystal composition was added with 4-heptylbenzoic acid 4-fluoro-4-heptylbenzoate of Example 5, which is a compound of the present invention.
The nematic temperature range of the liquid crystal mixture with 15 parts of 4'-biphenyl ester expanded from -5 to 58.4°C;
Although the dielectric anisotropy value decreased to +10.2, the threshold voltage of the TN cell decreased to 1.50V and the saturation voltage to 2.10V. Example 10 (Application Example 2) 4″-Fluoro-4-biphenylyl 4-(trans-4′-heptylcyclohexyl)benzoate of Example 8 of the present invention was added to 85 parts of the liquid crystal composition A in Application Example 1. The nematic temperature range of the liquid crystal composition containing 15 parts of ester expanded significantly from -10 to 68°C.The dielectric anisotropy value decreased to +10.3, and accordingly the threshold voltage was 1.60V and the saturation voltage was Although the voltage rose slightly to 2.30V, in this case the nematic temperature range expanded significantly, so it was found that the purpose was sufficiently achieved and it was useful.

Claims (1)

[Claims] 1. General formula (In the above formula, X is R, RO, or [Formula], and R represents an alkyl group having 1 to 10 carbon atoms.) Benzoate derivative of 4-fluoro-4'-hydroxybiphenyl represented by . 2 General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms.) 4-alkylbenzoic acid 4''-fluoro-4'-biphenyl ester according to claim 1, represented by the following formula: 3 General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms.)
(trans-4′-alkylcyclohexyl)benzoic acid 4″-fluoro-4-biphenyl ester. 4 General formula (In the above formula, X is R, RO, or [Formula], and R represents an alkyl group having 1 to 10 carbon atoms.) Benzoate derivative of 4-fluoro-4'-hydroxybiphenyl represented by A liquid crystal composition comprising at least one component.