JPH03220145A - Viscosity-reducing ether liquid crystal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel ether-based thinning liquid crystal useful as an electro-optical display material.

[Conventional technology]

M-Shut (M,
5chadt) etc. [APPLIED PHYSICS
LETTER31B, 127-128 (197
1)') or the field effect mode cell proposed by G.H. Beilmeier (G.

Hl) leilmeier) etc. (PROCEEDING
OF THE 1. E, E, E.

Dynamic light scattering mode cell proposed by G. H. Heilmeier et al. (APPLI).
ED PHYSICSLETTERS [, 91 (19
68)] or] Dale White (D, L,
White ) etc. (JO[IRNAL 0FAPPL
IED PHYSICS, 4718 (1974)
), such as the guest-host cell proposed by

These liquid crystal display cells are required to have various characteristics, and particularly important characteristics are the ability to drive in a wide temperature range and high-speed response.

A compound that increases the nematic phase-isotropic liquid phase transition temperature (hereinafter referred to as the N-1 point) of a liquid crystal composition and simultaneously lowers the viscosity is a liquid crystal material useful for automotive liquid crystal display cells and liquid crystal televisions. be. In particular, since the response time (τ) is proportional to the viscosity (η) of the liquid crystal material (τ■η), it is possible to create a liquid crystal display cell with excellent high-speed response by using a liquid crystal material with low viscosity. I can do it.

[Problem to be solved by the invention]

Currently, there are excellent viscosity reducing agents used for this purpose.

[Means to solve the problem]

In order to solve the above problems, the present invention provides the general formula (wherein,
There are compounds in which R1 and R2 each independently represent a linear alkyl group having 1 to 7 carbon atoms, and n is 3 to 5.

However, although the above compound (a) can lower the viscosity of the liquid crystal composition, it also has the problem of lowering the N-1 point at the same time.

The problem to be solved by the present invention is that when added to a parent liquid crystal that is currently widely used as a nematic liquid crystal material,
We present a new compound that increases the N-1 point of the parent liquid crystal and effectively lowers the viscosity. ) is provided.

The compound of formula (1) according to the present invention can be produced according to the following production method.

... <I[[] Represents. ) Step 1 - Preparing a compound of formula (IV) by reacting a compound of formula (II) with a ylide obtained by treating a compound of formula (III) with a strong base in t-butyl methyl ether.

Second step - Compound (1) is produced by subjecting the compound of formula (IV) to catalytic reduction in ethyl acetate using Raney nickel as a catalyst.

Table 1 lists the phase transition temperatures of representative compounds of formula (1) thus produced.

Table 1 (wherein R' and Rt each independently have a carbon atom number of 1 to 7
represents a linear alkyl group, n is 3-5 al-equatorial) (In the table, C represents a crystalline phase, S represents a smectic phase, and ■ represents an isotropic liquid phase.) The compound of formula (I) according to the invention can be used as a material for a field-effect display cell, for example, in a mixture with other nematic liquid crystal compounds having positive or negative dielectric anisotropy.

Thus, preferred representative examples that can be used in combination with the compound of formula (1,) include 4-substituted benzoic acid 4'-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4'-substituted phenyl ester, etc. ester, 4-substituted cyclohexanecarboxylic acid 4'-W-substituted biphenyl ester, 4-(4-substituted cyclohexanecarbonyloxy)benzoic acid 4'-substituted phenyl ester, 4-(4-substituted cyclohexanecarbonyloxy)benzoic acid 4'-substituted phenyl ester,
-11cyclohexyl)benzoic acid 4'-substituted phenyl ester, 4-(4-substituted cyclohexyl)benzoic acid 4
'-Km cyclohexyl ester, 4-fi1m4'-
Substituted biphenyl, 4-substituted phenyl-4'-substituted cyclohexane, 4-substituted 4''-substituted terphenyl, 4-substituted biphenyl-4'-substituted cyclohexane, 2-(4'-substituted phenyl)-5-substituted pyrimidine, etc. be able to.

Table 2 shows each mixture consisting of 75% by weight of the base liquid crystal (A), which is currently widely used as a nematic liquid crystal material with excellent time-division driving characteristics, and 1025% by weight of the compound of formula (I) shown in Table 1. The N-I point and viscosity measured for the liquid crystal are posted, and for comparison, 75% by weight of the parent liquid crystal (A) and 25% by weight of the following compound (a), which is commonly used as an excellent viscosity reducing agent. The N-1 point and viscosity measured for a mixed liquid crystal consisting of . The base liquid crystal (A) is composed of and, and the compound (a) is represented by the following formula.

After the second surface treatment, the mixture was stirred at room temperature for 1 hour. Then, after cooling the reaction mixture to 0°C, the compound of formula (I) was compared with compound (a) from Table 2.
It can be seen that the N-I point of the base liquid crystal (A) is raised and the viscosity is effectively lowered. A solution of 25I111 in tetrahydrofuran (Example 1 mol) was added dropwise and reacted for 2 hours.

After the reaction was completed, 80 ml of water was added to the reaction mixture, and the reaction product was extracted twice with 80 ml and 11 ml of ethyl acetate.

After washing the extract with water and drying, the solvent was distilled off under reduced pressure, and the resulting residue was purified using column chromatography to obtain 8.4 g (0.03 mol) of the following compound.

19.5 g (0,054 mol) of t-butyl methyl ether 80 mj! In addition, 8.4 g (0.03 mol) of the above compound was treated with 7.8 g (0.07 mol) of potassium t-butoxide under stirring at -5°C in 200 ml of ethyl acetate.
111, and 1 g of Raney nickel was added to this solution, followed by catalytic reduction under a hydrogen pressure of 5 atm.

After completion of the reduction, the catalyst was filtered off, the solvent was distilled off under reduced pressure, and the resulting residue was purified by recrystallization from ethanol to obtain 4 g (0,014 mol) of the following compound.

Transition temperature: 29°C (C-+5) 88°C (S!I) [Effects of the invention] The compound of formula (1) according to the present invention can be mixed into a base liquid crystal that is currently widely used as a nematic liquid crystal composition. Accordingly, the nematic phase-isotropic liquid phase transition temperature of the host liquid crystal can be raised and the viscosity can be effectively lowered.

In particular, the compound of formula (1) exhibits excellent characteristics in improving the nematic phase-isotropic liquid phase transition temperature of the host liquid crystal, compared to the known representative compound (a) used as a viscosity reducing agent.

It also has excellent compatibility with nematic liquid crystal compositions that are currently in widespread use.

Therefore, the compound of formula (I) of the present invention is useful as a material for liquid crystal display cells for automobiles, televisions, word processors, etc., which can be driven in a wide temperature range and require high-speed response.

teenager Reason Man

Claims (1)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R^1 and R^2 each independently represent the number of carbon atoms of 1
It represents a linear alkyl group of ~7, n represents an integer of 3 to 5, and ▲ includes numerical formulas, chemical formulas, tables, etc. ▼ represents a cyclohexane ring in trans (equatorial-equatorial) configuration. ) A compound represented by