JPH02243675A - Phenylpyrimidine derivative - Google Patents

Abstract

NEW MATERIAL:A compound expressed by formula I (R<1> and R<2> each are independently 1-18C straight-chain or branched alkyl; formula II is 1,4- cyclohexylene ring of trans configuration). EXAMPLE:2-[4-(trans-4-Heptylcyclohexyl)methoxy]phenyl-5-octylpyr-imidine. USE:A liquid crystal compound useful as an electrooptical display material, especially exhibiting a smectic C phase. PREPARATION:For example, a 2-(4-hydroxyphenyl)-5-alkylpyrimidine expressed by formula III is reacted with a compound expressed by formula IV (X is leaving group, such as Cl, I or p-toluenesulfonyloxy) in the presence of a base to afford the compound expressed by formula I.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel liquid crystalline compound useful as an electro-optical display material, and particularly to a liquid crystalline compound exhibiting a smectic C phase.

In particular, the present invention provides compounds that are useful materials for obtaining liquid crystal materials having ferroelectric properties.

[Prior art]

Liquid crystal display elements are currently widely used due to their excellent features (low voltage operation, low power consumption, thin display capability, and can be used in bright places without straining the eyes). However, in the most common TN type display system, CR
Compared to light-emitting display systems such as T, the response is extremely slow, and there is no memorization of the display (memory effect) when the applied electric field is turned off. There are many restrictions on the application to the necessary video screens of televisions, etc., and it cannot be said that it is suitable.

Recently, Mayer et al. reported a display method using ferroelectric liquid crystal, which is expected to be a next-generation liquid crystal display element that can achieve a high-speed response and memory effect that is 100 to 1000 times faster than the TN type. Research and development is actively underway.

The liquid crystal phase of the strong VlIE liquid crystal belongs to the tilt xyl smectic phase, but in practical terms, xyl smectic C (hereinafter referred to as SC*) has the lowest viscosity.
It is abbreviated as ) phase is the most desirable.

Many liquid crystal compounds exhibiting the SC* phase have already been synthesized and studied, but the conditions for using them as strongly conductive display elements are: (a) SC* phase in a wide temperature range including room temperature;
(b) In order to obtain good orientation, SC”
It has an appropriate phase series on the high temperature side of the phase, and its helical pitch is large; (c) it has an appropriate tilt angle;
2) It is preferable that the viscosity is low, and (e) that the spontaneous polarization is large to some extent, but there is no known material that satisfies these requirements alone.

Therefore, at present, liquid crystal compositions (hereinafter referred to as
It is called SC* liquid crystal composition. ) is used for study purposes.

sc" liquid crystal composition, a liquid crystal compound or composition (hereinafter referred to as a base liquid crystal) that does not exhibit ferroelectricity and exhibits a non-xyl smectic C (hereinafter abbreviated as SC) phase, compound (hereinafter referred to as chiraldono f
It is called nt. ) is a common method, and it is easier to obtain a high-speed response than when only xyl compounds are mixed.

The host liquid crystal is preferably one that exhibits an SC phase up to around room temperature. Therefore, what has been used as the main component of the host liquid crystal so far is a two-ring type compound such as a 7-functional nylpyrimidine compound of the following general formula (1) or a 7-functional nylbe/shade compound of general formula (II) ( In the formula, R1 and R5
(represents an alkyl group or an alkoxyl group) However, in the parent liquid crystal composed of these bicyclic compounds, the upper limit temperature of the SC phase (hereinafter abbreviated as Tc) is reached.

) is low, and in order to expand the temperature range it has become necessary to add compounds with high c.

However, compounds with high T also have high viscosity and sc
``When used in liquid crystal compositions, K often had an adverse effect on its responsiveness.

The present inventors have already discovered a compound represented by the following general formula (III) as a compound that increases the Tc point and does not increase its viscosity by mixing (
(Japanese Patent Application No. 62-236934).

represents. ) However, the compound represented by the above general formula (III) cannot be said to have sufficient compatibility with other liquid crystal compounds such as the compounds represented by general formulas (1) and (n), and may cause precipitation. It has the disadvantage that it easily occurs, and it has been quite difficult to lower the melting point sufficiently during the preparation of the parent liquid crystal.

[Problem to be solved by the invention]

The problem to be solved by the present invention is to have low viscosity, exhibit an SC phase up to high temperatures, have good compatibility with other host liquid crystal compounds, and, when mixed, have a low melting point and exhibit an SC phase up to a high temperature range. The object of the present invention is to provide a compound from which a liquid crystal composition can be obtained, to provide such a liquid crystal composition, and further to provide a liquid crystal display element having such a liquid crystal composition as a constituent element.

[Means to solve the problem]

In order to solve the above problems, the present invention provides the following general formula (A
) is provided.

In the above formula, R1 and R2 each independently have 1 to 2 carbon atoms.
0 straight-chain or branched alkyl group, preferably an alkyl group having 4 to 10 carbon atoms, particularly preferably a straight-chain alkyl group, and 1,4-cyclohexylene group is alkyl group in trans configuration.

The present invention also provides a liquid crystal composition containing at least one compound represented by the above formula. In particular, the liquid crystal composition according to the invention is suitable for use in chiral smectic liquid crystals for ferroelectric liquid crystal displays or for preparing chiral smectic liquid crystals.
If it is preferable to use it as a C matrix liquid crystal, the proportion of the compound represented by a single pattern in the liquid crystal composition is preferably in the range of 2 to 80% by weight, particularly preferably in the range of 5 to 50% by weight.

Furthermore, the present invention provides a liquid crystal display element comprising the above-mentioned composition as a constituent element, and particularly provides a strongly conductive liquid crystal display element capable of high-speed response in a wide temperature range from low to high temperatures.

The compound of formula (4) according to the present invention can be produced, for example, according to the following molding method.

(In the above reaction formula, R1 and R2 represent the same meanings as R1 and R2 in -Momonana (A), respectively, and X is ! element, -
Ml represents a leaving group such as io+7, p-) luenesulfonyloxy group. ) That is, 2-(4-hydroxyphenyl)-5-furkylpyrimidine represented by the symbol (B)! :, - Monana (
It can be produced by reacting the compound represented by C) in the presence of a basic substance.

The compound represented by general formula (B) is a known compound, and the compound represented by -Momonena (C) is trans-4-
Alkylcyclohexanecarboxylic acid or its acid chloride or its ester is reduced to give tra/su-4-alkylcyclohexylmethanol, which is converted into phosphorus oxychloride,
It can be obtained by halogenating with a phosphorus tribromide or other oxidizing agent, or by converting i4radluenesulfonyl chloride into a cytosylate ester. Trans-4-alkylcyclohexanecarboxylic acid is a known compound, and some of it is commercially available.

The phase transition temperatures of typical compounds of formula (A) thus produced are shown below.

Compound Black Structural Formula Here, Cr represents a crystalline phase, SC represents a smectic C phase, N represents a nematic phase, and ■ represents an isotropic liquid phase.

In this way, the compound of formula (A) of the present invention has a high upper limit temperature of the SC phase, and no other liquid crystal phase is observed in the low temperature range of the SC phase. It can be used extremely effectively for the purpose of expanding the temperature range by adding it to the temperature range.

In general, in order to lower the viscosity of a liquid crystal compound, (1) at least one side chain should be an alkyl group, (11) polar groups such as ester bonds should be removed from the molecule, (Ili) Means such as substituting part or all of the aromatic ring with cyclohexane are known.

SC phase or SC phase, such as the compound of formula (A) of the present invention.
*Compounds used for the purpose of expanding the temperature range of the phase and satisfying the above (1) and (II) include:
For example, the above-mentioned 3-ring pyrimidine compound represented by fluorine-substituted 3-ring pyrimidine/ ( R
, R4, R5, and R6 all represent an alkyl group or an alkoxy group).

However, all of these compounds have a rigid structure in which three aromatic rings are directly connected, and there are problems in terms of compatibility with other liquid crystal compounds.

In the compound of formula (A) of the present invention, one of the rings is a cyclohexane ring, and by introducing an oxymethylene bond (-CH20-) between it and the phenylpyrimidine skeleton, other liquid crystalline compounds can be formed. It has excellent compatibility with

As a compound having an oxymethylene group in its skeleton, a pyrimidine compound represented by the formula (R7 and R8 represent an alkyl group) is known.

This compound shows an SC phase up to a high temperature range, so it can be used for similar purposes, but for example, the phase transition temperature of a substance is SF (SF is smectic F Smetek phase), and when compared with the compound of formula (A) of the present invention, S
The upper limit temperature of the C phase is also low, and there are other drawbacks such as the presence of other smectic phases in the low temperature range.

In the compound of formula (A) of the present invention, the temperature range of the SC phase can be expanded by replacing one of the aromatic rings with a cyclohexane ring.

In general, introducing a hecyclohexane ring into a liquid crystal molecule often significantly reduces SC properties (or SCI properties), so this effect of introducing a cyclohexyl ring can be said to be surprising. The thus obtained compound of formula (A) of the present invention is the above-mentioned (1).

(ii) (It satisfies all the conditions of liD and has a very low viscosity for a liquid crystal compound used for such purposes.

〔Example〕

The present invention will be specifically explained with reference to Examples below.
Of course, the gist and scope of the present invention are not limited by these examples. In addition, in the examples, [%]
represents "outside the weight".

Example 1. Synthesis of 2-(4-(trans-4-hebutylcyclohexyl)methoxy)phenyl-5-octylpyrimidi/(compound of formula (A-1)) Synthesis of 1-&-trans-1-bromomethyl-4-octylcyclohexane 1, 60 p of aluminum hydride in 100 d of ether
suspended in it. This suspension is cooled with water,
-Octylcyclohexa/cal? acid ethyl ester (
This compound was synthesized by esterifying commercially available trans-4-octylcyclohexanecarboxylic acid in ethanol in the presence of a sulfuric acid catalyst. ) 10.05 L of a 20m+7 solution of tetrahydrofuran (hereinafter referred to as THF) was added dropwise over 30 minutes. After the dropwise addition was completed, the mixture was stirred at room temperature for 30 minutes. Saturated brine was added to the reaction mixture to decompose excess hydride, and the formed precipitate was removed by decanting. The precipitate was washed with ether. The organic layers were combined, washed with saturated brine, and then diluted with anhydrous sulfuric acid. ) Dehydrated and dried with IJum.

The crude product obtained by distilling off the solvent was purified using silica gel column chromatography to obtain an oily product of trans-4-octylcyclohexylmethanol, 7.609-. (Yield 91%) This compound 6.7554 was dissolved in dichloromethane 201%. Add 2.90% phosphorus tribromide to this solution under water cooling. was added dropwise over 30 minutes. After stirring for an additional 8 hours at room temperature, water was added slowly to destroy excess tribromide/. The organic layer was washed with an aqueous sodium bicarbonate solution, water, and saturated brine, then dehydrated and dried over anhydrous sodium sulfate. The crude product obtained by distilling off the solvent was subjected to silica gel column chromatography (distillation solvent:
1-bromomethyl-4-octylcyclohexane 3.715'
I got it. (Yield 42%)! -b0 Synthesis of compound 2-(4-hydroxyphenyl]-5-octylpyrimidine 1.01 d in dimethylformamide (DMF)
Dissolved in t-butoxypotassium 0.416? was added and stirred. To this, 0.6 bromide obtained in (1-b)
55' was dissolved in DMF 101+7 and added dropwise over 10 minutes while cooling with water. After stirring at room temperature for 6 hours, ether 100
Add 1j, add water, then add 10% until the water layer becomes slightly acidic.
Hydrochloric acid was added. The ether layer was separated, washed with water until the washing solution became neutral, further washed with saturated saline, and dehydrated by adding anhydrous sulfuric acid.

The crude product obtained by distilling off the solvent was subjected to silica gel column chromatography (distillation solvent: hexane-ethyl acetate).
and further recrystallized from ethanol,
White crystals of the listed compound 0.652? I got it. (Yield 37
%) The structure was confirmed by infrared absorption spectrum (IR) and nuclear magnetic resonance spectrum (NMR).

IR: 1605, 1585, 1520, 143
0, 1255, 1170, 1040.

CH2, CH) 0.88 (t, 6H, CH,) The melting point of this compound is 96°C, shows an SC phase below 110°C, an N phase below 140.5°C, and at higher temperatures in! It became a phase.

Note that the phase transition temperature is determined using a temperature control stage (METTLER FP).
82) Observation of the optical structure using a polarizing microscope equipped with
A differential scanning calorimeter (DSC) was also used.

Example 2 (Preparation of sc" liquid crystal composition) An SC* liquid crystal composition having the following composition was prepared.

Koshikisu This SC* liquid crystal composition exhibits an SC* phase up to 62°C65
It showed an SA phase up to 70.5°C, an N* phase up to 70.5°C, and an isotropic liquid (I) phase at higher temperatures.

(For reference, the compound of formula (A-1) was not used, and the compound of formula (B-
28% of the compound of formula (B-2), 24% of the compound of formula (B-3), 14.6% of the compound of formula (C-1), and the compound of formula (C-2) 5.1). When we prepared a 5CI11 liquid crystal composition consisting of
C” phase was shown at 57° C. or lower.) Example 3 (Creation of display element) Two transparent glass FjA! electrodes subjected to alignment treatment (priimide coating/rapi/g) were coated with a thickness of approximately 2 μm. The SC* liquid crystal composition obtained in Example 2 was then filled into this with a spacer interposed therebetween to create a cell.

By slowly cooling the phase (2) to room temperature, uniformly oriented monodomains of the SC* phase were obtained.

This cell has an electric field strength of 10 Vp-pi Am, 50
When a Hz square wave was applied and the electro-optical response speed was measured, it was 43 μsec at 25°C.

The spontaneous polarization at this time was 19.5 n07 m'', the tilt angle was 25.2°, and the contrast was very good.

〔Effect of the invention〕

The compound of the general formula (, A) of the present invention exhibits an SC phase in a wide temperature range up to a high temperature range, and when mixed and added, the temperature range is expanded to a particularly high temperature range. A liquid crystal composition can be obtained.

In addition, the compound of -Momona (A) has a low viscosity since it does not have a highly polar alkoxy group or ester bond in its molecule, and is capable of high-speed response even in the above-mentioned SC* liquid crystal composition.

Further, as shown in the Examples, the compound of general formula (A) of the present invention can be easily produced industrially, and the compound itself is colorless and chemically very stable.

Therefore, the compound of general formula (A) of the present invention has excellent high-speed response and is useful as a ferroelectric liquid crystal material.

Agent Patent Attorney Katsutoshi Takahashi

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
~18 linear or branched alkyl groups. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is 1,4 in trans configuration
-Represents a cyclohexylene group. ) A compound represented by 2. A liquid crystal composition containing the compound according to claim 1. 3. The liquid crystal composition according to claim 2, which exhibits a ferroelectric chiral smectic phase. 4. A liquid crystal display element comprising the liquid crystal composition according to claim 3 as a constituent element.