JPH04235935A - New ether compound - Google Patents

Abstract

PURPOSE:To provide a new ether-type liquid crystal compound having excellent viscosity-reducing effect for host liquid crystal, low vapor pressure and excellent compatibility with host liquid crystal. CONSTITUTION:The liquid crystal compound of formula I (R<1> is 1-7C straight- chain alkyl; R<2> is 1-7C straight-chain alkyl or alkoxy; n is 1-7; X is H or F; the configuration of the cyclohexane ring is trans). The compound can be produced by reacting a compound of formula II (psi is phenyl) with triphenylphosphine in toluene, treating the obtained compound of formula III with a strong base in THF to obtain a Wittig reagent, reacting the reagent with a compound of formula IV and catalytically reducing the obtained product in ethyl acetate in the presence of Raney-nickel catalyst.

Description

Description: FIELD OF INDUSTRIAL APPLICATION This invention relates to a novel ether-based liquid crystal compound useful as an electro-optical display material. [Prior Art] Typical liquid crystal display cells include M. Schadt and others [APPLIE
D PHYSICS LETTERS 18,127~
128 (1971)] or the field effect mode cell proposed by G.H.
eier ) etc. [ PROCEEDING OF TH
E I. E. E. E. 56 1162 ~ 1171
(1968)], a dynamic light scattering cell (
dynamic scattering mode cell) or G.H. Heilmeyer
ier ) etc. [ APPLIEDPHYSICS LE
TTERS 13, 91 (1968)] or D.L. White, etc.
JOURNAL OF APPLIED PHYSICS
S 45, 4718 (1974)], there is a guest-host type cell. These liquid crystal display cells are required to have various characteristics, including being able to be driven in a wide temperature range;
High-speed response is a particularly important required characteristic. A compound that increases the nematic phase-isotropic liquid phase transition temperature (hereinafter referred to as the N-I 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, the response time (τ) has a proportional relationship with the viscosity (η) of the liquid crystal material as shown in the following equation: [Equation 1] A liquid crystal display cell with excellent properties can be manufactured. [0006]Problems to be Solved by the Invention [0006]Excellent viscosity reducing agents currently used for this purpose include the formula (a)
A compound represented by the following formula is known. However, although the compound of formula (a) above can reduce the viscosity of the liquid crystal composition, at the same time, this compound itself has a high vapor pressure, and even when mixed with other liquid crystal compounds, it does not evaporate from the liquid crystal composition. However, there was a problem in that the composition was easily changed when it was sealed in a liquid crystal display cell. [0009] The problem to be solved by the present invention is currently:
The object of the present invention is to provide a compound which, when added to a parent liquid crystal commonly used as a nematic liquid crystal material, can effectively reduce the viscosity of the resulting mixed liquid crystal and has a low vapor pressure. [Means for Solving the Problems] In order to solve the above problems, the present invention provides the general formula (I): 7 represents a linear alkyl group, R2 represents a linear alkyl group or a linear alkoxyl group having 1 to 7 carbon atoms, and n represents 1
represents an integer of ~7, X represents H or F, and the cyclohexane ring is in the trans configuration. ) is provided. The compound represented by the general formula (I) according to the present invention can be produced according to the following production method. [0014] [0015] (wherein R1, R2, n and X represent the general formula (
Each has the same meaning as in case I), and φ represents a phenyl group. ) Step 1 - A compound of formula (II) in toluene,
Reaction with triphenylphosphine produces a compound of formula (III). Step 2 - The compound of formula (III) is treated with a strong base such as potassium-t-butoxide in tetrahydrofuran to give a Wittig reagent, followed by the formula (
IV) to produce a compound of formula (V). Third step - catalytic reduction of the compound of formula (V) in ethyl acetate with Raney nickel as a catalyst to form the compound of formula (I) according to the invention.
Manufacture the compound. Table 1 lists the melting points of representative compounds of general formula (I) thus produced. [0017] The compound represented by the general formula (I) according to the present invention can be used, for example, in the form of a mixture with another nematic liquid crystal compound having positive or negative dielectric constant anisotropy. It can be used as a material for field effect display cells. As described above, representative examples of preferable compounds that can be used in combination with the compound represented by the general formula (I) include 4-substituted benzoic acid 4'-substituted phenyl ester, 4-substituted cyclohexane, etc. carboxylic 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 phenyl 4'-substituted cyclohexane, 4-substituted 4'' -substituted terphenyl, 4-substituted biphenyl, 4'-substituted cyclohexane, 2-(4'-substituted phenyl)5-substituted pyrimidine, etc. Base liquid crystal (A) currently widely used as a nematic liquid crystal material
90% by weight of the compound N of the general formula (I) shown in Table 1
o. 1 or No. The viscosity (unit: centipoise) at 20°C measured for each mixed liquid crystal consisting of 10% by weight of 2 and 10% by weight of The graph shows the viscosity measured for a mixed liquid crystal consisting of 90% by weight of a compound of formula (a) below and 10% by weight of a compound of formula (a) commonly used as a viscosity reducing agent. Note that the base liquid crystal (A) consists of the following formula: It is a compound. [Table 2] From Table 2 above, the compound represented by the general formula (I) has a higher concentration of the parent liquid crystal (A) than the compound of the formula (a).
) can be understood to effectively reduce the viscosity of FIG. 1 shows compound No. of the general formula (I) of the present invention. 1, N
o. 2 is a chart showing the relationship between temperature and vapor pressure of compounds of formula (a) and (a). It can be seen from FIG. 1 that the compound of general formula (I) of the present invention has a lower vapor pressure than the compound of formula (a). [Example] The present invention will be further explained by showing examples of the present invention below. However, the present invention is not limited to these examples. (Example 1) 18.5 g (0.1 mol) of the compound of the formula [Image Omitted] was dissolved in 200 ml of toluene, and 26.3 g (0.1 mol) of triphenylphosphine was added to this solution. The mixture was added and heated under reflux for 3 hours. After cooling, the precipitated crystals were collected by filtration and dried under vacuum to obtain 40.0 g (0.089 mol) of the following compound. ##STR8## (In the formula, φ represents a phenyl group.) 40.0 g (0.089 mol) of the above compound was added to 200 ml of tetrahydrofuran, cooled to -5.degree. C., and potassium-t
After treatment with 13.5 g (0.12 mol) of -butoxide, the mixture was reacted at room temperature for 1 hour. Next, this reaction mixture was cooled to -5°C, and 80 ml of a solution of 12.9 g (0.07 mol) of the compound of the formula: The reaction was allowed to proceed for 2 hours. After the reaction is complete, add 250ml of water and add 150ml of ethyl acetate.
The extract was washed with water and dried, and then the solvent was distilled off under reduced pressure. The residue was added to 100 ml of toluene and dissolved by heating, and then the same amount of hexane was added to precipitate triphenylphosphine oxide. The precipitate was filtered off, and the filtrate was concentrated under reduced pressure. The obtained residue was purified using silica gel chromatography, and this eluate was further concentrated under reduced pressure to obtain the following compound 1.
5.8 g (0.058 mol) was obtained. ##STR10## 15.8 g (0.058 mol) of the above compound
was dissolved in 180 ml of ethyl acetate, and 2 g of Raney nickel was added.
Catalytic reduction was carried out at 60° C. and under a hydrogen pressure of 5 kg/cm 2 for 5 hours using as a catalyst. After the reaction was completed, the catalyst was filtered off, the filtrate was concentrated under reduced pressure, and purified by recrystallization from ethanol to obtain 14.9 g (0.054 mol) of the following compound. (Example 2) In Example 1, the formula 004
1] The following procedure was carried out in the same manner as in Example 1, except that 20.3 g (0.1 mol) of the compound of the formula [Chemical 13] was used instead of the compound of the formula [Chemical 12] [0042] The compound was obtained. [Effects of the Invention] The compound represented by the general formula (I) according to the present invention has excellent compatibility with the matrix liquid crystal that is currently widely used as a nematic liquid crystal composition. The viscosity of liquid crystal can be effectively reduced. In particular, the compound of general formula (I) has an excellent viscosity-reducing effect and low vapor pressure compared to the compound of formula (a), which is a typical viscosity-lowering agent. The composition of the liquid crystal composition does not change when it is sealed in a liquid crystal display cell.

[Brief explanation of the drawing]

FIG. 1 shows compound No. 1 of general formula (I) according to the present invention. 1.No. 2 is a chart showing the relationship between temperature and vapor pressure of compounds of formula (a) and (a).

Claims (1)

[Claims] Claim 1: General formula [Formula 1] (wherein, R1 represents a linear alkyl group having 1 to 7 carbon atoms, and R2 represents a linear alkyl group or alkoxyl group having 1 to 7 carbon atoms; , n represents an integer of 1 to 7, X represents H or F, and the cyclohexane ring has a trans configuration.