JPH0567144B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to fluoroalkylpyrimidine derivatives useful as electro-optic display materials. [Prior art] Typical liquid crystal display cells include M.Sehadt [APPLIED PHYSICS]
LETTERS 18 , 127-128 (1971)] or the field-effect mode cell proposed by GH Heilmeier et al.
OF THE IEEE 56 , 1162-1171 (1968)].
scattering mode cell) or GH Heilmeier et al. [APPLIED PHYSICS LETTERS 13 , 91
(1968)] or DL White (DL
White) etc.〔JOURNAL OF APPLIED
Examples include the guest-host cell proposed by [Physics 45 , 4718 (1974)]. These liquid crystal display cells are required to have various characteristics, but high-speed response and low threshold voltage (V _th ) are particularly important required characteristics. A liquid crystal display cell having a low threshold voltage can be driven at a low voltage. Since the response time (τ) is proportional to the viscosity (η) of the liquid crystal material (τ∝η), a liquid crystal display cell with high-speed response can be manufactured by using a liquid crystal material with low viscosity. Currently, excellent viscosity reducing agents used for this purpose include

[Means for solving problems]

The present invention general formula

[Formula] [In the formula, R represents a linear alkyl group or alkoxy group having 1 to 20 carbon atoms, and n represents an integer of 1 to 10. ] The present invention provides a compound represented by the following. The compound of formula () of the present invention can be produced by a three-step reaction described below. In each formula below, n represents an integer from 1 to 10.

[ka]

[ka]

[ka]

[Chemical formula] Step 1 - A compound of formula () is dissolved in anhydrous ether;
React with absolute ethanol in the presence of hydrochloric acid gas,
A compound of formula () is produced. Second Step - A compound of formula () is prepared by treating the compound of formula () prepared in the first step with ammonia-saturated absolute ethanol. Third step - The compound of formula () produced in the second step and the compound of formula () are reacted in alcohol under basic conditions. The reaction is carried out at normal pressure and at a temperature ranging from room temperature to the reflux temperature of the reaction mixture. The desired compound of formula () can be isolated by subjecting the reaction product to a series of purification treatments such as solvent extraction, water washing, drying, and recrystallization. The transition temperatures of representative compounds of formula () thus produced are shown in Table 1. In Table 1, C represents a crystalline phase, N represents a nematic phase, and N represents an isotropic liquid phase.

[Table] Although the compound of formula () according to the present invention does not exhibit a nematic phase, for example, it can be used in a dynamic light scattering display cell in a mixture with other nematic liquid crystal compounds having negative dielectric constant anisotropy. It can also be used as a material for field-effect display cells in a mixture with other nematic liquid crystal compounds having positive or negative dielectric anisotropy. Thus, preferred representative examples which can be used in admixture with the compound of formula () include, for example, 4-substituted benzoic acid-4'-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid-4'-substituted phenyl ester, 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-
Examples include 4'-substituted cyclohexane, 4-substituted-4'-substituted terphenyl, 4-substituted biphenyl-4'-substituted cyclohexane, and 2-(4-substituted phenyl)-5-substituted pyrimidine. Table 2 shows 90 base liquid crystals (A) that are currently widely used as nematic liquid crystal materials with excellent time-division drive characteristics.
Weight % and Compound No. 1 of formula () shown in Table 1
The viscosity and threshold voltage (V _th ) measured for each mixed liquid crystal consisting of 10% by weight and 90% by weight of the base liquid crystal (A) and the base liquid crystal (A) with an excellent viscosity reducing agent are posted for comparison. A mixed liquid crystal consisting of 10% by weight of the following compound (a) commonly used as a base liquid crystal (A) and 90% by weight of the base liquid crystal (A) and the following compound having a similar structure to the compound of formula () according to the present invention. The viscosity measured for a mixed liquid crystal consisting of 10% by weight of known compound (b) and
V _th is posted. The base liquid crystal (A) contains 40% by weight.

【formula】 30% by weight

【formula】 as well as, 30% by weight

[Formula] Compound (a) and compound (b) are
It is expressed by the following formula.

[ka]

[ka]

[Table] It can be seen from Table 2 that the compound of formula () lowers the viscosity of the base liquid crystal (A) and significantly lowers the threshold voltage (V _th ). This superiority is especially true compared to compound (a) and compound (b).
It is clearly superior in the effect of lowering V _th . Example 1 Formula

26 g (0.16 mol) of the compound of the formula was dissolved in a mixed solvent of 8.3 g (0.18 mol) of anhydrous ethanol and 15 ml of anhydrous ether, and dry hydrogen chloride gas was introduced while cooling to below 10°C. After saturation with dry hydrogen chloride gas, the reaction was allowed to proceed at room temperature for 2 days. After the reaction was completed, the precipitated crystals were collected by filtration and dried to obtain 23 g (0.10 mol) of the following compound.

[Formula] This compound is converted into ammonia-saturated anhydrous ethanol.
The mixture was added to 100 ml and reacted at room temperature for 2 days. After the reaction was completed, the ammonia chloride produced as a by-product was filtered off, the filtrate was concentrated, and the precipitated crystals were collected by filtration and dried to obtain 16 g (0.074 mol) of the following compound.

[Formula] 12g (0.06mol) of this compound was added to methanol
Add to a solution of 17 g (0.4 mol) of sodium hydroxide dissolved in 140 ml, cool to below 15°C, and form the formula

The compound of [Formula] was added dropwise, and the mixture was reacted under reflux for 10 hours. After the reaction was completed, 300 ml of water was added to the reaction solution, extracted with ethyl acetate, the extract was washed with water, dried, and ethyl acetate was distilled off under reduced pressure. The obtained reaction product was purified by silica gel column chromatography, and then purified by recrystallization with methanol to obtain 5.2 g (0.018 mol) of the following compound.

〔Effect of the invention〕

The compound of formula () according to the present invention has a viscosity-lowering effect and is a compound that effectively lowers the threshold voltage, and this viscosity-lowering effect has been known as an excellent viscosity-lowering agent. This compound has the same or lower viscosity-reducing properties as other viscosity-reducing agents, and, unlike conventional viscosity-reducing agents, it has the excellent property of significantly lowering the threshold voltage.
Furthermore, compared to known compounds with similar structures,
The effect of lowering the threshold voltage is significantly large. When a liquid crystal material with a low threshold voltage using the compound of the present invention is driven with the same voltage as a conventional liquid crystal material with a higher threshold voltage, the response at the time of voltage application (on time) The speed will inevitably increase.

Claims (1)

[Scope of Claims] 1 General Formula [Formula] [In the formula, R represents a linear alkyl group or an alkoxy group having 1 to 20 carbon atoms, and n represents an integer of 1 to 10. ] A compound represented by