JP2696963B2 - Pyrimidine derivatives - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pyrimidine derivative which is a novel liquid crystal compound used as an electro-optical display material.

[Summary of the Invention] The present invention has a general formula (Wherein, R is a linear alkyl group having 1 to 12 carbon atoms,
X represents fluorine, chlorine or hydrogen, and the cyclohexane ring has a trans configuration. Is a novel liquid crystal compound having a nematic phase.
Further, the compound (1) of the present invention is characterized by having a high nematic phase-isotropic liquid transition temperature (hereinafter, referred to as NI point) and a large positive and anisotropic dielectric constant (hereinafter, referred to as Δε). 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 high practical temperature range and a low threshold voltage can be provided.

[Prior Art] A liquid crystal display device uses an electro-optic effect of a liquid crystal, and a display method using a nematic liquid crystal phase has a twisted nematic type, a voltage controlled birefringence type, a guest-host type, and a dynamic scattering. The mold has been put to practical use. Recently, as an improvement of the twisted nematic type, the twist angle has been increased from 90 ° to 18 °.
The supersted nematic type, which has been expanded to around 0-250 °, is in the stage of practical use, and a super twisted birefringence controlled type using a transition between bistable states with a twist angle of 270 ° was proposed. It has not been converted. By the way, liquid crystal display devices have the advantages of being small and thin, can be driven with low voltage and low power consumption, and have the advantage that they are light-receiving elements so that their eyes are not tired even when used for a long time. It is widely applied to car dashboards and audio equipment. In particular, recently, it has been attracting attention as a display device that is applied to displays of personal computers and word processors, and further to pocket color televisions and replaces CRTs.

As described above, various characteristics are required for a liquid crystal material used in a liquid crystal display device applied to various fields depending on a display method, a use, and the like.Taking a twisted nematic, which is currently most widely used, as an example, 1. No heat, light, electrical and chemical stability without coloring.

2. Wide operating temperature range.

3. Fast electro-optical response speed.

4. Low drive voltage.

5. The rise of the voltage-light transmittance characteristics should be sharp and the temperature dependency should be small.

6. Wide viewing angle range.

And other characteristics.

[Problems to be Solved by the Invention] Among these various characteristics, low drive voltage and wide practical temperature range are one of important characteristics. In the case of the twisted nematic type, the following relationship exists between the threshold voltage Vth and the dielectric anisotropy Δε. here, K11, K22 and K33 are elastic constants for spray, twist and bend, respectively, and k is a proportional constant. Therefore, to lower the threshold voltage, Δε needs to be positive and large. However, conventionally used liquid crystal compounds having large Δε, 4-alkylbenzoic acid 4-cyanophenyl ester, 4-alkyl-4′-cyanobiphenyl In such cases, the NI point is low and the nematic temperature range is narrowed. 4-alkyl-4 ″ -cyanoterphenyl, 4- (trans-4′-alkylcyclohexyl)-having a high NI point and a large Δε
4 ″ -cyanobiphenyl and the like have a large elastic constant, so that the threshold voltage increases.

Accordingly, the present invention meets the demands in such a situation, and its purpose is to increase the upper limit of the nematic temperature range and lower the threshold voltage by mixing with one or more other nematic liquid crystal compounds. An object of the present invention is to provide a novel liquid crystal compound capable of obtaining a liquid crystal composition.

[Means for Solving the Problems] The present invention has a general formula (Wherein, R is a linear alkyl group having 1 to 12 carbon atoms,
X represents fluorine, chlorine or hydrogen, and the cyclohexane ring has a trans configuration. ).

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

Step 1 Compound (3) is obtained by reacting compound (2) with diethyl malonate in ethanol in the presence of sodium ethoxide.

Step 2 Compound (5) is obtained by reacting compound (4) with ethanol using sulfuric acid as a catalyst.

(Wherein, R is a linear alkyl group having 1 to 12 carbon atoms,
X represents fluorine, chlorine or hydrogen, and the cyclohexane ring has a trans configuration. Step 3) Compound (5) is reacted with anhydrous ethanol and hydrogen chloride gas dried in benzene, and after about half of the solvent is distilled off, it is recrystallized. The obtained crystals are reacted with ammonia gas dried in anhydrous ethanol to obtain a compound (6).

Step 4 Compound (3) and compound (6) are reacted in anhydrous methanol in the presence of sodium methoxide to obtain compound (7).

Step 5 Compound (7) is reacted with phosphorus oxychloride in the presence of N, N-diethylaniline to obtain compound (8).

Step 6 Compound (8) is reacted with hydrogen gas in the presence of potassium acetate using 5% palladium-carbon as a catalyst in ethanol to obtain compound (9).

Step 7 Compound (9) is hydrolyzed in ethanol in the presence of sodium hydroxide and water to obtain compound (10).

Step 8 Compound (10) is reacted with thionyl chloride to obtain compound (11).

Step 9 The compound (11) and the compound (12) are reacted in anhydrous pyridine to obtain a novel liquid crystal compound (1) of the present invention.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Application Examples.

Example 1 5- [2 ′-(trans-4 ″ -pentylcyclohexyl) ethyl] -2- [4- (4′-cyano-3)
'- the production of fluoro-phenoxyethanol carbonyl) phenyl] pyrimidine (Compound (1) in R is C ₅ H ₁₁ as X is fluorine).

Step 1 Dissolve 3.2 g of metallic sodium in 70 cm ³ of absolute ethanol, and stir with 22.4 g of diethyl malonate, followed by 2- (trans-4'-pentylcyclohexyl) -1
- bromoethane (Compound (2) in which R is a C ₅ H ₁₁₎ 41.
After adding 5 g, the mixture was refluxed for 10 hours. After cooling, ethanol was distilled off, 200 cm ³ of water was added to the residue, and the mixture was extracted three times with 50 cm ³ of chloroform. After washing with water, chloroform was distilled off. The residue was distilled under reduced pressure (bp 156 ° C / 0.3 mmHg) to give 2- (trans-
There were obtained 36.8 g of diethyl 4'-pentylcyclohexyl) ethylmalonate.

Step 2 P- cyanobenzoic acid (Compound (4)) in concentrated sulfuric acid 4 cm ³ the presence of 73.6g of ethanol 400 cm ³ was refluxed for 20 hours. After the ethanol was distilled off, chloroform (250 cm ³⁾ was added to the residue, and the mixture was washed with water, a 5% Na ₂ CO ₃ aqueous solution and water in this order, and then chloroform was distilled off. The residue was recrystallized from 150 cm ³ of ethanol to obtain 71 g of ethyl 4-cyanobenzoate.

Step 3 71 g of ethyl 4-cyanobenzoate was dissolved in anhydrous ethanol and anhydrous benzene, and hydrogen chloride gas dried with concentrated sulfuric acid was stirred under cooling with ice water until saturated (about 2 hours). It was left below 3 ° C. for 3 days. Next, the solvent was distilled off under reduced pressure of an aspirator, and 400 cm ³ of anhydrous ethanol saturated with dried ammonia gas was added to the residue, followed by stirring overnight. About 2/3 of the ethanol was distilled off, and the precipitated crystals were filtered to obtain 65.1 g of 4-ethoxycarbonylbenzamidine hydrochloride.

Step 4 Dissolve 5.9 g of metallic sodium in 128 cm ³ of anhydrous methanol and, with stirring, 21.7 g of diethyl 2- (trans-4′-pentylcyclohexyl) ethylmalonate
Add 14.6 g of ethoxycarbonylbenzamidine hydrochloride and add 1
Refluxed for 5 hours. After cooling, the reaction solution is concentrated hydrochloric acid 600 cm ³ and ice 120 g
Yellow crystals precipitated by pouring into the mixture were passed through and washed with water. Next, the crystals were stirred in 600 cm ³ of hot methanol for 1 hour and then sufficiently washed with hot methanol. The crystals were dried at 80 ° C. for 5 hours and 4,6-dihydroxy-5- [2 ′-(trans-
4 "-pentylcyclohexyl) ethyl] -2- (4
-Ethoxycarbonylphenyl) -pyrimidine (24.8 g) was obtained.

Step 5 4,6-Dihydroxy-5- [2 '-(trans-4 "-pentylcyclohexyl) ethyl] -2- (4
-Ethoxycarbonylphenyl) pyrimidine 24.8 g, phosphorus oxychloride 112 cm ³ and N, N-diethylaniline 17 cm ³
Refluxed for 70 hours. Excess phosphorus oxychloride is distilled off, 250 g of ice and 120 cm ^{3 of a} 20% aqueous NaOH solution are added to the residue, and the mixture is sufficiently stirred, and extracted three times with 60 cm ³ of chloroform.
Washing was performed in the order of H aqueous solution, water, 10% hydrochloric acid, and water. After the chloroform was distilled off, the residue was recrystallized from a mixed solvent of chloroform and acetone to give 4,6-dichloro-5- [2 '-(trans-4 "-pentylcyclohexyl) ethyl] -2-.
(4-ethoxycarbonylphenyl) pyrimidine 13.8
g was obtained.

Step 6 4,6-Dichloro-5- [2 '-(trans-
4 "-pentylcyclohexyl) ethyl] -2- (4
—Ethoxycarbonylphenyl) pyrimidine (13.8 g), potassium acetate (8.5 g), 5% palladium-carbon (1.4 g) and ethanol (1200 cm ³⁾ were heated to 65-70 ° C., and hydrogen gas was introduced for 5 hours while stirring vigorously. After cooling, palladium-carbon was passed through and thoroughly washed with ethanol, and then ethanol in the liquid was distilled off. The residue was recrystallized from a mixed solvent of chloroform and acetone to obtain 7.4 g of 5- [2 ′-(trans-4 ″ -pentylcyclohexyl) ethyl] -2- (4-ethoxycarbonylphenyl) pyrimidine.

Step 7 7.4 g of 5- [2 '-(trans-4 "-pentylcyclohexyl) ethyl] -2- (4-ethoxycarbonylphenyl) pyrimidine, 7.2 g of sodium hydroxide, water
It was refluxed for 13cm ³ of ethanol 1000 cm ³ 7 hours. After cooling, ethanol was distilled off, and 100 cm ³ of water was added to the residue, and the mixture was stirred and passed. Crystalline concentrated hydrochloric acid 20 cm ^3, water 100 cm ^3, and stirred for 20 h at room temperature provided the ethanol 1000 cm ^3. After distilling off the ethanol, add 100 cm ³ of water to the residue, stir,
The crystals were dried under vacuum to obtain 7.1 g of 5- [2 '-(trans-4 "-pentylcyclohexyl) ethyl] -2- (4-carboxyphenyl) pyrimidine.

Step 8 7.1 g of 5- [2 ′-(trans-4 ″ -pentylcyclohexyl) ethyl] -2- (4-carboxyphenyl) pyrimidine and 22 g of thionyl chloride were refluxed for 5 hours. And 30 cm ³ of toluene were added to dissolve the crystals, and the toluene was distilled off to give 5- [2′-
(Trans-4 ″ -pentylcyclohexyl) ethyl]
-2- (4-chloroformylphenyl) pyrimidine 7.
4 g were obtained.

Step 9 0.4 g of 5- [2 '-(trans-4 "-pentylcyclohexyl) ethyl] -2- (4-chloroformylphenyl) pyrimidine and 2-fluoro-4-hydroxybenzonitrile (compound (12), Is fluorine)
0.14 g was left in anhydrous pyridine overnight. The reaction solution was poured into 20 cm ³ of concentrated hydrochloric acid and 50 g of ice, and the precipitated crystals were washed with water.
The crystals were recrystallized from a mixed solvent of chloroform and acetone to give 5- [2 '-(trans-4 "-pentylcyclohexyl) ethyl] -2- [4- (4'-cyano-3).
'-Fluorophenoxycarbonyl) phenyl] pyrimidine (0.2 g) was obtained. The purity of this compound analyzed by gas chromatography was 99.8%. The phase transition temperature of this compound was as follows.

(Here, C1 and C2 are solids, N is a nematic phase, and I is an isotropic liquid.) (Example 2) 5- [2 ′-(trans-4 ″ -pentylcyclohexyl) ethyl] -2- [4- (4'-cyano-3
'- the production of chloro-phenoxyethanol carbonyl) phenyl] pyrimidine (Compound (1) in R is C ₅ H ₁₁ as X is chlorine).

5- [2 ′-(trans-4 ″ -pentylcyclohexyl) ethyl] -2- (4) obtained in Step 8 of Example 1
-Chloroformylphenyl) pyrimidine (0.4 g) and 1.53 g of 2-chloro-4-hydroxybenzonitrile (compound (12) wherein X is chlorine) were prepared in the same manner as in Step 9 of Example 1 to give 5- [2'- (Trans-4 "-pentylcyclohexyl) ethyl] -2- [4- (4'-cyano-3
'-Chloropheninoxycarbonyl) phenyl] pyrimidine (0.22 g) was obtained. The purity of this compound by gas chromatography was 99.5%, and the phase transition temperature was as follows.

(C1, C2, N, and I are the same as those in Example 1.) (Example 3) 5- [2 '-(trans-4 "-pentylcyclohexyl) ethyl] -2- [4- (4'-cyanophenoxy) Cycarbonyl) phenyl] pyrimidine (compound (1)
Where R is C ₅ H ₁₁ and X is hydrogen).

5- [2 ′-(trans-4 ″ -pentylcyclohexyl) ethyl] -2- (4) obtained in Step 8 of Example 1
5-chloroformylphenyl) pyrimidine and 1.19 g of 4-hydroxybenzonitrile (compound (12) wherein X is hydrogen) were prepared in the same manner as in Step 9 of Example 1 to give 5-
[2 ′-(trans-4 ″ -pentylcyclohexyl)
0.18 g of ethyl] -2- [4- (4'-cyanophenoxycarbonyl) phenyl] pyrimidine was obtained. The gas chromatographic purity of this compound was 99.8%, and the phase transition temperature was as follows.

(Here, C, N, and I represent a solid, a nematic phase, and an isotropic liquid, respectively.) Application Example 1 A liquid crystal compound of Example 1 of the present invention was added to a commercially available liquid crystal composition ZLI-1565 (manufactured by Merck). 5- [2 '-(trans-4 "
-Pentylcyclohexyl) ethyl] -2- [4-
(4'-cyano-3'-fluorophenoxycarbonyl) phenyl] pyrimidine (A) mixed with 10% by weight and ZLI-1565 and 4-cyano-4 ″-for comparison.
Composition [B] containing 10% by weight of pentyl terphenyl
Was prepared, and the CN point and the NI point were measured. Next, each of the compositions [A] and [B] was sealed in a TN type cell having a thickness of 8 μm, and voltage-luminance characteristics were measured at 25 ° C. by an AC static driving method. Degree is defined as the voltage value at 10%). The results are shown in Table 1.

[Effects of the Invention] As described above, it has been found that the liquid crystal compound of the present invention has a wide nematic liquid crystal temperature range. Further, it was confirmed that by mixing the liquid crystal compound of the present invention with a conventional liquid crystal composition, the practical temperature range was wide and the threshold voltage was low. Therefore, the liquid crystal compound of the present invention is very useful as a mixed component of a nematic liquid crystal composition.

Claims (1)

(57) [Claims] (1) General formula (Wherein, R is a linear alkyl group having 1 to 12 carbon atoms,
X represents fluorine, chlorine or hydrogen, and the cyclohexane ring has a trans configuration. A pyrimidine derivative represented by the formula: