JPH0733354B2 - Optically active biphenyl ester derivative - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel optically active biphenyl ester derivative useful as an electro-optical display material.

[Conventional technology]

Currently, in order to prevent the occurrence of reverse domains in TN (Twisted Nematic) liquid crystal display devices, a method of adding about 0.1% cholesteric liquid crystal or about 0.1 to 1% optically active compound to a nematic liquid crystal composition is usually used. It is taken.

Recently, TJ Scheffer et al. [APPLIED PHYSICS LETTERS, 45 , 1021-1023 (1984)]
SBE (Supertwisted Birefringence) proposed by
Effect) The display element is particularly excellent in high time division performance and is suitable for flat panels. The nematic liquid crystal in this SBE display device is
~ 270 ℃ twisted. Therefore, there is a need for an optically active compound that can achieve a short helical pitch by adding as little as possible.

[Problems to be solved by the invention]

The problem to be solved by the present invention is to provide a novel optically active compound capable of preparing a chiral nematic liquid crystal composition having a short helical pitch by adding a small amount to the nematic liquid crystal composition.

[Means for solving problems]

In order to solve the above problems, the present invention provides a general formula (In the formula, R represents a linear alkenyl group having 4 to 20 carbon atoms and having one trans double bond, and R'represents a linear alkyl group having 2 to 8 carbon atoms or a phenyl group. And a compound represented by the formula C ^* represents an asymmetric carbon atom.

The compound of formula (I) according to the present invention can be produced according to the following production method.

(R, R'and C ^* in the above formulas (II), (III), (IV), and (V) have the same meanings as those in the formula (I), and X represents a halogen atom.) First step-The compound of formula (II) is reacted with an alkyl halide in the presence of potassium hydroxide in aqueous ethanol. The compound of formula (III) can be isolated by subjecting the reaction product to purification treatment such as solvent extraction, washing with water, drying and recrystallization.

2nd step-To the compound of formula (III) prepared in the 1st step,
A halogenating agent is reacted to produce a compound of formula (IV). In the compound of formula (IV), preferred X is a chlorine atom, and thionyl chloride may be used as the halogenating agent. The reaction is carried out at normal pressure and the reflux temperature of the reaction mixture.
It is not necessary to isolate the compound of formula (IV) from the mixture formed by the reaction, only the excess halogenating agent need be removed.

Step 3—The crude compound of formula (IV) prepared in step 2 and the optically active alcohol of formula (V) are reacted in a basic solvent such as pyridine. The target compound of formula (I) can be isolated by subjecting the reaction product to purification treatment such as solvent extraction, washing with water, drying and recrystallization.

The transition temperature and the specific optical rotation of the representative compound of formula (I) thus produced are as shown in Table 1.

(In Table 1, C represents a crystalline phase, S represents a smectic phase, and I represents an isotropic liquid phase.) The compound of formula (I) according to the present invention is a nematic liquid crystal usually used as an electro-optical display material. It can be used by being mixed with the composition. Representative examples of preferred liquid crystal compounds that can be used by mixing with the compound of formula (I) are, for example, 4-substituted benzoic acid 4′-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4′-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4 '
-Substituted biphenyl ester, 4 (4-substituted cyclohexanecarbonyloxy) benzoic acid 4'-substituted phenyl ester, 4 (4-substituted cyclohexyl) benzoic acid 4'-substituted phenyl ester, 4 (4-substituted cyclohexyl) benzoic acid 4 ' -Substituted cyclohexyl ester, 4-substituted 4'-substituted biphenyl, 4-substituted 4'-substituted phenylcyclohexane, 4-substituted 4'-substituted terphenyl, 4-
Substituted 4'-biphenylcyclohexane, 2 (4'-substituted phenyl) -5-substituted pyrimidine and the like can be mentioned.

FIG. 1 shows various compounds of formula (I) shown in Table 1 (compounds No. 1 and No. 2 shown in Table 1) in the matrix liquid crystal (A) which is widely used as a nematic liquid crystal material. The reciprocal of the spiral pitch P in the liquid crystal composition obtained by adding in a ratio (1 /
3 shows the relationship between P) and the amount of the compound of formula (I) added.

The base liquid crystal (A) is 24% by weight. 36% by weight 25% by weight And 15% by weight It consists of

FIG. 1 shows a nematic liquid crystal composition in which the value of 1 / P is rapidly increased by adding a small amount of the compound of formula (I) to the host nematic liquid crystal, that is, a chiral nematic liquid crystal composition having a short spiral pitch. It indicates that the product can be prepared.

Example 1 4- (4'-hydroxy) biphenylcarboxylic acid 8.6 g
(0.04 mol) is added to hydrous ethanol in which 5.3 g (0.08 mol) of potassium hydroxide is dissolved, and the mixture is stirred at room temperature for 30 minutes. 5.5 g (0.06 mol) of crotyl chloride under reflux.
Was added dropwise, and the mixture was heated under reflux for 2 hours. After completion of the reaction, ethanol was distilled off under reduced pressure, 50 ml of 18% HCl was added to the residue, and the precipitated crystals were collected by filtration, washed with water and dried under reduced pressure, and the following compound 5.
3 g (0.02 mol) was obtained.

Next, excess thionyl chloride was added, and the mixture was heated under reflux for 2 hours.
After completion of the reaction, excess thionyl chloride was distilled off under reduced pressure, 30 ml of pyridine and 2.6 g (0.02 mol) of (S)-(+)-2-octanol were added to the obtained crude product, and the mixture was reacted at 50 ° C for 1 hour. It was After completion of the reaction, the reaction product was extracted with toluene under acidic hydrochloric acid, washed with water and dried, and the solvent was distilled off under reduced pressure, followed by recrystallization purification with methanol to obtain 5.1 g (0.014 mol) of the following compound.
Got

Yield 70% Transition temperature 60 ° C. (SI) ▲ [α] ²⁵ _D ▼ = + 30.4 Example 2 In the same manner as in Example 1, the following compound was obtained.

Yield 63% Transition temperature 82 ° C. (C → I) ▲ [α] ²⁵ _D ▼ ＝ + 87.4 [Effect of the invention] The optically active compound according to the present invention is added in a small amount to a nematic liquid crystal composition which is currently widely used. By doing so, it is possible to prepare a chiral nematic liquid crystal composition having a short helical pitch.

[Brief description of drawings]

FIG. 1 shows various compounds (No. 1 to No. 2 shown in Table 1) of the formula (I) shown in Table 1 in the matrix liquid crystal (A) which is currently widely used as a nematic liquid crystal material. 2 is a chart showing the relationship between the reciprocal number (1 / P) of the helical pitch P and the addition amount of the compound of formula (I) in the liquid crystal composition obtained by adding the compound of the formula (I).

Claims (1)

[Claims] 1. A general formula (In the formula, R represents a linear alkenyl group having 4 to 20 carbon atoms and having one trans double bond, and R'represents a linear alkyl group having 2 to 8 carbon atoms or a phenyl group. And C ^* represents an asymmetric carbon atom.).