JPH0629261B2 - Pyrimidine derivative - Google Patents

Description

The present invention relates to a novel pyrimidine derivative used as an electro-optical display material.

[Outline of Invention]

The present invention has the general formula (In the above formula, R represents a linear alkyl group having 1 to 10 carbon atoms, and the cyclohexane ring has a trans configuration.), And has a nematic liquid crystal phase. Further, the compound of the present invention has the following characteristics.

1. The nematic-isotropic liquid transition point (hereinafter referred to as NI point) is high.

2. The dielectric anisotropy (hereinafter referred to as Δε) is positive and very large.

Therefore, by using a liquid crystal composition in which the compound (1) of the present invention is mixed with another liquid crystal compound, a liquid crystal display device having a wide operating temperature range and a low driving voltage can be provided.

[Conventional technology]

The liquid crystal display device utilizes the electro-optical effect of liquid crystal, and the liquid crystal phase used for the liquid crystal display device has a nematic phase, a cholesteric phase, and a smectic phase. The currently most widely used display method is a twisted nematic (hereinafter referred to as TN) type that utilizes a nematic phase.

The liquid crystal display device is 1. It is small and can be made thin.

2. Low drive voltage and low power consumption.

3. Since it is a light-receiving element, it will not tire your eyes even if you use it for a long time.

Since it has advantages such as, it has been applied to watches, calculators, audio devices, various measuring instruments, automobile dashboards, etc. In particular, recently, it has been applied to a display of a personal computer or a word processor, and also to a display with a very large number of pixels such as a black and white or color pocket TV, and has been attracting attention as a display device replacing the CRT. As described above, the liquid crystal display device is applied in various fields, and its application field is expected to further expand in the future. The characteristics required for liquid crystal materials are expected to change along with this, but the characteristics shown below are basic and indispensable.

1. It has no color and is stable to heat, light, electricity, and chemicals.

2. Wide operating temperature range.

3. High electro-optical response speed.

4. Low drive voltage.

5. The voltage-light transmittance characteristic has a steep rise, and its threshold voltage (hereinafter referred to as V _th ) has little temperature dependence.

6. Wide viewing angle range.

[Problems to be Solved by the Invention]

Many liquid crystals satisfying one of these characteristics are known, but no liquid crystal compound satisfying the characteristics of 2 or less with a single component is known. Therefore, in order to obtain these characteristics, a liquid crystal composition in which several kinds of nematic liquid crystal compounds or non-liquid crystal compounds are mixed is used. And, in order to satisfy the characteristic of 2, in general, a crystal with a relatively low molecular weight is used.
A nematic transition point (hereinafter referred to as C-N point) or a liquid crystal compound having a melting point near room temperature and a high molecular weight N-I point of 200.
A composition in which a liquid crystal compound having a temperature of not less than 0 ° C. is combined is used. To satisfy the characteristic of No. 4, the threshold voltage must be lowered, but V _th and the elastic constant (hereinafter K
And Δε have the following relationship, and in order to reduce V _th , a liquid crystal compound having a large Δε of V _th ∝ (K / Δε) ^{1/2 and a} small K is required.

However, there are almost no liquid crystal compounds satisfying the characteristics 2 and 4 at the same time, specifically, liquid crystal compounds having a high NI point and a large Δε.
At present, a composition in which a liquid crystal compound having a large ε is combined is used.

Therefore, the present invention responds to the demand in such an actual situation, and an object thereof is to widen the practical temperature range by mixing with one or more kinds of nematic liquid crystal compounds or non-liquid crystal compounds, and to improve the threshold voltage. A novel liquid crystal compound capable of obtaining a low liquid crystal composition is provided.

[Means for Solving the Problems]

The present invention has the general formula (In the above formula, R represents a linear alkyl group having 1 to 10 carbon atoms, and the cyclohexane ring has a trans configuration).

The compound (1) of the present invention can be obtained by the following production method.

Step 1) Compound (2) is reacted with bromine in chloroform to obtain compound (3).

Step 2) Compound (3) is reacted with cuprous cyanide in N-methylpyrrolidone to obtain compound (4).

Step 3) Compound (4) is reacted with sodium nitrite and sulfuric acid in acetic acid to form a diazonium salt, and then reacted with cuprous bromide in hydrobromic acid to obtain compound (5).

Step 4) Compound (5) is reacted with dry hydrogen chloride gas in a mixed solvent of ethanol and benzene. Evaporate the solvent,
The obtained crystals are reacted with dry ammonia gas in ethanol to obtain the compound (6).

Step 5) Compound (6) and compound (7) are reacted with metallic sodium in ethanol to obtain compound (8).

Step 6) Compound (8) is reacted with cuprous cyanide in N-methylpyrrolidone to obtain compound (1).

[Examples] Hereinafter, the present invention will be described in more detail with reference to examples and application examples.

Example 1 Preparation of 2- (3 ', 5'-difluoro-4'-cyanophenyl) -5- (trans-4 "-propylcyclohexyl) pyrimidine Step 1) 231 g of 2,6-difluoroaniline was added to 400 m of chloroform. After dissolution, 300 g of bromine was added dropwise, and after refluxing for 1 hour, the reaction solution was poured into 10% potassium hydroxide solution, which was extracted with chloroform, and the organic layer was washed with 10% potassium hydroxide solution and water. After the chloroform was distilled off, vacuum distillation was carried out (bp 70-80 ° C /
4mmHg) Recrystallized from hexane to give 4-bromo-2,6
-292 g of difluoroaniline were obtained.

Step 2) 4-Bromo-2,6-difluoroaniline 13
2 g, cuprous cyanide 70 g, N-methylpyrrolidone 4
44 m was placed in a flask and refluxed for 3 hours. afterwards,
The reaction solution was poured into a solution of 266 g of ferric chloride, 85 m of concentrated hydrochloric acid, and 315 m of water. The solution was extracted with chloroform, washed with water and a 10% potassium hydroxide solution, and then chloroform was distilled off. The residue is distilled under reduced pressure (bp90-
It was recrystallized from a mixed solvent of 110 ° C./4 mmHg) hexane and chloroform to obtain 56 g of 4-cyano-2,6 difluoroaniline.

Step 3) 24 g of sodium nitrite was added into 180 m of concentrated sulfuric acid, and after cooling to 10 ° C or lower, 38 m of acetic acid was added. Then 4-cyano-2, so as to keep the solution at 20 to 25 ° C,
53 g of 6-difluoroaniline were gradually added. 1 hour 2
After stirring at 0 to 25 ° C, 60 g of cuprous bromide was dissolved in 180 m of 48% hydrobromic acid solution, and the reaction solution was added dropwise thereto. After completion of dropping, the mixture was stirred at room temperature for 15 hours. Water was added to the reaction solution, followed by extraction with chloroform and washing with water. Chloroform of the organic layer was distilled off, and the residue was recrystallized from a mixed solvent of methanol and acetone to obtain 25 g of 2-bromo-5-cyano-1,3-difluorobenzene.

Step 4) 25 g of 2-bromo-5-cyano-1,3-difluorobenzene was added to 48 m of ethanol and benzene 165.
It was dissolved in a mixed solvent of m and cooled to 0 ° C. or lower, and dry hydrogen chloride gas was absorbed for 1 hour. Then, the solvent of the reaction solution was distilled off, and the residue was washed with crystalline ether. The obtained crystals were added to 48 m of ethanol, stirred, and cooled to 0 ° C or lower. 16% Ammonia-absorbed ethanol was added thereto, and the mixture was stirred for 1 hour. The solvent of the reaction solution was distilled off, and the crystals of the residue were washed with ether to obtain 27 g of 4-bromo-3,5-difluorobenzamidine hydrochloride.

Step 5) Sodium metal into 290 m of ethanol 3.
Dissolve 7 g and adjust the sodium ethylate solution.
4-Bromo-3,5-difluorobenzamidine hydrochloride 4 g, 3-ethoxy-2- (trans-4-propylcyclohexyl) acrolein (synthesis method: A.Vi
lliger, Z. Natur-forsch. 34b.1535 (1979)). Then, the mixture was stirred at room temperature overnight and then refluxed for 1 hour. After cooling the reaction solution, water was added and the precipitated crystals were filtered.
The obtained crystals are recrystallized from a mixed solvent of acetone and methanol to give 2- (3 ′, 5′-difluoro-4 ′).
1.5 g of -bromophenyl) -5- (trans-4 "-propylcyclohexyl) pyrimidine was obtained.

(Step 6) 1.5 g of 2- (3 ′, 5′-difluoro-4′-bromophenyl) -5- (trans-4 ″ -propylcyclohexyl) pyrimidine 0.8 cuprous cyanide
g, N-methylpyrrolidone 10m was placed in a flask,
Refluxed for 5 hours. Then, the reaction solution was poured into a solution of ferric chloride 2.2 g, concentrated hydrochloric acid 0.5 m, and water 2.2 m.
The solution was extracted with chloroform, washed with water and a 10% potassium hydroxide solution, and then chloroform was distilled off. The residue was purified by silica gel-chloroform column chromatography and then recrystallized from a mixed solvent of acetone and methanol to give 2- (3 ', 5'-difluoro-4'-
0.4 g of cyanophenyl) -5- (trans-4 ″ -propylcyclohexyl) pyrimidine was obtained. This compound has a nematic liquid crystal phase and is 114.9 at C-N point.
The C and NI points were 156.7 ° C.

Application Example 1 Commercially available mixed liquid crystal ZLI-1565 (product of Merck & Co., N-
I point 89.3 ° C) is used as a base liquid crystal, and is generally N-
4-pentyl-used to increase the I point
A comparison of the characteristics of 4 "-cyanoterphenyl and 2- (3 ', 5'-difluoro-4'-cyanophenyl) -5- (trans-4" -propylcyclohexyl) pyrimidine of Example 1 which is a compound of the present invention. I did.

[Composition A]

[Composition B] Compositions A and B made of the above were prepared, and each was enclosed in a TN cell having a thickness of 7 μm, and the voltage-luminance characteristics (see FIG. 2) were measured at 20 ° C. under AC static drive. The results are shown in Table 1.

In the table, V ₁₀ is a voltage value when the transmittance is 10% and is a measured value from the TN cell measuring direction θ = 90 °. And α and β
Are factors representing the viewing angle characteristic and the threshold characteristic, respectively, and are defined as follows.

_{α = θ90 ° V 50 / θ50} ° V 50 as described (see FIG. 2) (Figure 2 _{reference) β = θ90 ° V 10 /} θ90 ° V 90 [ Effect of the Invention] above, compounds of the present invention Electro-optical characteristics (α value / β value) by mixing with general liquid crystal composition
The effect is to raise the NI point and significantly lower the threshold voltage without deteriorating the threshold voltage.

From these points, the present invention is extremely useful as a basic component of a liquid crystal composition of super twisted nematic type display, which is currently the mainstream of liquid crystal display devices.

[Brief description of drawings]

1 is an infrared absorption diagram of the compound 2- (3 ′, 5′-difluoro-4′-cyanophenyl) -5- (trans-4 ″ -propylcyclohexyl) pyrimidine of the present invention. (a) (b) is a figure which shows the voltage-luminance characteristic of a general TN cell, and its measuring direction (theta).
° indicates the voltage-luminance characteristic from the measurement direction θ = 90 °. Further, the respective V ₁₀ , V ₅₀ , and V ₉₀ are the voltages when the light transmittance is 10%, 50%, and 90%, respectively.

Claims (1)

[Claims] 1. A general formula (In the above formula, R represents a linear alkyl group having 1 to 10 carbon atoms, and the cyclohexane ring has a trans configuration).