JPH03153673A - Pyrimidine derivative - Google Patents

Abstract

NEW MATERIAL:A compound expressed by formula I (R is 1-8C straight-chain alkyl; cyclohexane ring is trans configuration). EXAMPLE:2-(4'-Fluorophenyl)-5-[2'-(trans-4''-propylcyclohexyl)ethyl]py rimidine. USE:Useful as a component of nematic liquid crystal compositions used in liquid crystal display devices and capable of providing liquid crystal compositions having a low n and threshold voltage by mixing thereof with other liquid crystal compositions. PREPARATION:A compound expressed by formula II is catalytically reduced with hydrogen in the presence of potassium acetate in ethanol solvent using 5% Pd-carbon as a catalyst to afford the compound expressed by formula I.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to pyrimidine derivatives useful as components of nematic liquid crystal compositions used in liquid crystal display devices.

[Summary of the invention]

The present invention is a novel pyrimidine derivative represented by the general formula % ((in the above formula, R represents a straight-chain alkyl group having 1 to 8 carbon atoms, and the cyclohexane ring is in a trans configuration), It has a nematic liquid crystal phase.Furthermore, the compound of the present invention is characterized by a large dielectric constant anisotropy (Δε).

Therefore, by mixing the compound of the present invention with other nematic liquid crystal compounds or similar compounds thereof, a nematic liquid crystal composition with a low driving voltage can be obtained.

[Conventional technology]

Display methods of liquid crystal display devices that utilize the electro-optical effect of the nematic liquid crystal phase include dynamic scattering type, guest-host type, twisted nematic type (TN type), and super twisted nematic type (STN type).
type), etc., and the drive methods used to operate these include a static drive method, a dynamic drive method (or time-division drive method), a two-frequency drive force method, and an active matrix drive method.

Compared to other display systems, liquid crystal display devices have the following advantages: 1) They can be easily made smaller and thinner.

2) The driving voltage is low.

3) Very low power consumption.

4) Since it is a light-receiving element, your eyes won't get tired even if you use it for a long time.

It has the following characteristics. Taking advantage of these features, time-division drive type TN type liquid crystal display devices are used in watches, calculators, etc.
It has been widely applied to audio equipment, automobile dashboards, and various measuring instruments. Furthermore, in recent years, active matrix drive type TN type liquid crystal display devices (TFT type and MIM type have been put into practical use) have been used for liquid crystal color televisions, and STN type liquid crystal display devices have been used for personal computer and word processor displays, and the number of display pixels has increased significantly. It is being applied to many large-capacity display devices, and is attracting attention as a display device that will replace CRT in the future. In this way, the fields of application are expected to continue to expand in the future, and the characteristics required of the liquid crystal materials used will also change, but the characteristics listed below are the basic ones. It is something.

1) No coloration and thermal, optical, electrical and chemical stability.

2) The practical temperature range should be as wide as possible around room temperature.

3) Low driving voltage.

4) The rise of the voltage-luminance characteristic is steep, and the temperature dependence of the threshold voltage (Vlh) is small.

5) Fast electro-optical response speed.

6) Wide viewing angle range.

There is no known liquid crystal material that satisfies all of these characteristics, and liquid crystal compositions are produced with emphasis on several items depending on the field of use.

[Problem to be solved by the invention]

Many liquid crystal compounds are known that satisfy 1) of the above properties, but no liquid crystal compound that satisfies the following properties (2) with a 111-component is known.

Therefore, the required characteristics are obtained by using a liquid crystal composition in which a plurality of liquid crystal compounds or similar compounds thereof are mixed. However, as mentioned earlier, no matter what liquid crystal composition is used, it is not possible to obtain a liquid crystal composition that satisfies all of the characteristics 2) to 6). The field is very wide, including liquid crystal display devices using lithium batteries and liquid crystal display devices using solar cells, and is expected to expand further in the future. A method for lowering the driving voltage of a liquid crystal display device is to lower the VI of the liquid crystal composition used therein. Vlh of the liquid crystal composition is expressed by the following formula.

Here, K represents an elastic constant. Therefore, it can be seen that a liquid crystal composition containing a liquid crystal compound having a large Δε may be used. By the way, the conventional △ε(V()(N, or C
qH+r'Cj■pe! Although CN has a high nematic-isotropic liquid phase transition temperature (N-1 point), it has a large K value and has the disadvantage that Vl increases when mixed.

Therefore, an object of the present invention is to provide a pyrimidine derivative with a large Δε that can be mixed with other liquid crystal compounds or similar compounds thereof to obtain a liquid crystal composition with a low driving voltage.

[Means to solve the problem]

The pyrimidine derivative of the present invention is characterized by being represented by the general formula (in the above formula, R represents a straight-chain alkyl group having 1 to 8 carbon atoms, and the cyclohexane ring has a trans configuration). Compound (1) of the present invention
can be obtained, for example, by the following synthesis method. That is,
Diethyl 2-(trans-4-alkylcyclohexyl)ethylmalonate (2) and 4-fluorobenzamidine hydrochloride (3) were reacted with sodium methoxide in methanol to produce 2-(4'-fluorophenyl)-5. −[
2'(trans-41-alkylcyclohexyl)ethyl]-4,6-cyhydroxypyrimidine (4) is obtained (
Step 1). Compound (4) was chlorinated with phosphorus oxychloride in the presence of diethyl+1211 aniline to give 2-(4
'-Fluorophenyl)-5-[2'(trans-4'
-alkylcyclohexyl)ethyl]-4,6-dichloropyrimidine (5) is obtained (Step 2). Compound (5
) was catalytically reduced with hydrogen in the presence of potassium acetate in an ethanol solvent using 5% palladium-carbon as a catalyst to obtain the 2-(4'-fluorophenyl)-5-[2'
-(trans-4'-alkylcyclohexyl)ethyl]pyrimidine (1) (Step 3).

Next, compound (2) was obtained by the following synthesis method.
OON (B) Steerable J, N
aAJIjz(0(41140CIly)z/ Toluene R combination C1120i1 (7) Steab 2 ↓ 5OC12, (Big cut R()CII□C4(8
) Stairb3 ↓ NaCN/ DMSOR%CIl□C
N (9) Step 4 ↓ Na0II
, 11 2 0 /BtO1+R%C112CO
O1[(10) Step 5 ↓ NaAj 112(0(41140C
I11) 2/) Ruen R (VClI2 Clh O
il (It) Steab 6 ↓5o (Jz
, (j,≠8N(2). That is, trans-4-alkylcyclohexanecarboxylic acid (6) is reduced using sodium bis(methoxyethoxy)aluminum hydride to form trans-4-alkyl-1-hydroxymethylcyclohexane. (7) is obtained (Step 1). Compound (7) is chlorinated with thionyl chloride in the presence of pyridine to obtain trans-4-alkyl-1-
Obtain chloromethylcyclohexane (8) (Step 2
).

Compound (8) is cyanated with sodium cyanide in dimethyl sulfoxide (DMSO) to give trans-4-alkyl-1-cyanomethylcyclohexane (9) (
Step 3). Compound (9) is hydrolyzed in ethanol using water and sodium hydroxide to obtain trans-4-alkylcyclohexyl acetic acid (10) (Step 4)
. Compound (]O) is reacted in the same manner as when compound (6) is reduced to obtain trans-4-alkyl-1,-(2-hydroxyethyl)cyclohexane (11) (Step 5). Compound (11) was reacted in the same manner as when compound (7) was chlorinated to form trans-4-alkyl-1-(
2-chloroethyl)cyclohexane (12) is obtained (Step 6). Compound (12) and diethyl malonate (13)
) is reacted with sodium ethoxide in ethanol to obtain compound (2) (Step 7). Moreover, compound (3) can be obtained by the following synthesis method. That is, commercially available 4-
Fluorobenzonitrile (14) is dissolved in ethanol(3)-ol and hydrogen chloride gas is blown into it to obtain 4-fluorobenzamidine hydrochloride (15) (Step 1).

Compound (15) is reacted with an ethanol solution that has absorbed ammonia gas to obtain 4-fluorobenzamidine hydrochloride (3) (Step 2).

〔Example〕

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

Example 1 Method for producing diethyl 2-(trans-4'-propylcyclohexyl)ethylmalonate.

trans-4-propylcyclohexanecarboxylic acid 34
0 g (2,0 mol) in 600 cm3 of toluene and 1400 cm' (5,0 mol) of a 70% toluene solution of sodium bis(methoxyethoxy)aluminum hydride.
mol) was added dropwise with stirring, and the mixture was stirred at 80-90°C for 3 hours. 10% hydrochloric acid was added dropwise to the reaction solution while stirring, and the separated oil layer was washed in the order of 1096 hydrochloric acid and water, and toluene was distilled off. The remaining liquid was distilled under reduced pressure (b, p, 85°C
/2mmHg) and trans-4-propyl-1-hydroxymethylcyclohexane 300g (1°9 mol)
was obtained (Step 1). 160g of dehydrated pyridine
Thionyl chloride 2
74 g (2.3 mol) was added dropwise to 105 g with stirring.
Heated to -110°C for 5 hours. The reaction product was added with 300 c of concentrated hydrochloric acid.
Pour into m3 and 200 g of ice, extract with chloroform, and add 1
It was washed with 0% hydrochloric acid and water in that order, and chloroform was distilled off. The remaining liquid was distilled under reduced pressure (98°C/3.0mmHg) to obtain 313g (1.8 mol) of trans-4-propyl-1-chloromethylcyclohexane (Step 2).
. Dissolve this in 360 cm' of dimethyl sulfoxide,
Add 92 g (1.9 mol) of sodium cyanide to 14
Heated to 0°C.

The reaction mixture was cooled, added with 500 cm' of water, extracted with hexane, and washed with water. The residue was distilled under reduced pressure (115°C/3.
5 mmHg) to obtain 291 g (1.8 mol) of trans-4-propyl-1-cyanomethylcyclohexane (Step 3). This was dissolved in 1200 cm3 of ethanol, 126 cm3 of water and 464 g of potassium hydroxide were added, and the mixture was refluxed for 10 hours. Distill the ethanol in the reaction product,
Dissolve the residue in 1200cm3 of water and add 1000cm3 of concentrated hydrochloric acid.
3 was added, extracted with chloroform, and washed with water. Chloroform was distilled off to obtain 325 g (1.8 mol) of trans-4-propylcyclohexyl acetic acid (Step 4).
). Dissolve this in 500 cm3 of toluene and dissolve 70% of sodium bis(methoxyethoxy)aluminum hydride.
1230 cm3 (4.4 mol) of toluene solution was added dropwise with stirring, and the mixture was stirred at 80-90°C for 3 hours. 10% hydrochloric acid was added dropwise to the reaction solution while stirring, and the separated oil layer was
It was washed with 0% hydrochloric acid and water in that order, and toluene was distilled off. The remaining liquid was distilled under reduced pressure (105°C/3 mmHg) to obtain 277 g (1.6 mol) of trans-4-propyl-1-(2'-hydroxyethyl)cyclohexane (
Step 5). 65 g (0.38 mol) of this alcohol was dissolved in 32 g (0.4 Q mol) of dehydrated pyridine.
Then, 55 g of thionyl chloride was added dropwise while stirring under water cooling, and 105 g of thionyl chloride was added dropwise while stirring.
Stirred at -110°C for 5 hours. Pour the reaction product into 60 cm of concentrated hydrochloric acid.
' and poured into 40g of ice, extracted with chloroform, and 10%
It was washed with hydrochloric acid and water in that order, and chloroform was distilled off. The remaining liquid was distilled under reduced pressure (90°C, 73 mm Hg) to obtain 63.5 g (0°34 mol) of trans-4-propyl-1-(2'-aloethyl)cyclohexane (Step 6). Sodium 7 in 340 cm' of ethanol,
Dissolve 8 g (0.34 mol) of diethyl malonate 6
5.6 g (0.41 mol) and the chloride obtained in the previous step were added and refluxed for 10 hours. Ethanol in the reaction product was distilled off, 300 cm' of water was added to the residue, extracted with chloroform, washed with water, and chloroform was distilled off. The remaining liquid was distilled under reduced pressure (151°C/3.0mmHg) to obtain 65g (0.21 mol) of diethyl 2-(trans-4'-propylcyclohexyl)ethylmalonate (Step 7).
.

The following compound was obtained by a similar synthetic method.

Diethyl 2-(trans-41-ethylcyclohexyl)ethylmalonate b,p,i3g℃/3*m11g2
-(trans-4'-butylcyclohexyl)ethyl diethyl malonate b, ρ, 165℃/3asl1g2
-(trans-41-pentylcyclohexyl)ethyl diethyl malonate b, p, 180℃/3gml1g2-
Diethyl (trans-4'-hexylunechlorohexyl)ethylmalonate b, p, 197℃/3mm11g2
-(trans-4'-hebutylcyclohexyl)ethyl diethyl malonate b, p, 200℃/1mm11g2
-(trans-4'-octylcyclohexyl)ethyl diethyl malonate b, ρ, 213°C/lIl*IIg
Example 2 Method for producing 4-fluorobenzamidine hydrochloride.

50 g (0.41 mol) of commercially available (manufactured by Aldrich) 4-fluorobenzonitrile was dissolved in 80 cm of ethanol and 100 cm of benzene, absorbed dry hydrogen chloride gas until saturated, and left at 5°C or below for 2 days. .

The solvent in the reaction mixture was distilled off under reduced pressure, and the residue was dissolved in ethanol 2
00 cm' to obtain 80 g (0.39 mol) of 4-fluorobenzamidine hydrochloride (Step 1)
.

This imidate hydrochloride was added to 300 cm3 of ethanol saturated with ammonia gas, and the mixture was stirred overnight at room temperature. Approximately half of the ethanol in the reaction solution was distilled off and recrystallized to obtain 54 g (0.31 mol) of 4-fluorobenzamidine hydrochloride.
was obtained (Step 2).

Example 3 Method for producing 2-(4'-fluorophenyl)-5-[2'-(trans-41-propylcyclohexyl)ethyl]pyrimidine.

1.9 g of sodium (0.08 cm) in 80 cm' of methanol
2-(trans-mol) synthesized in Example 1.
6.3 g (0.02 mol) of diethyl 4'-propylcyclohexyl)ethylmalonate and 4.2 g (0.02 mol) of 4-fluorobenzamidine hydrochloride synthesized in Example 2.
24 mol) was added and refluxed for 7 hours. The reaction product was mixed with concentrated hydrochloric acid 2
The mixture was poured into 50 g of ice, and the precipitated yellow crystals were filtered and washed with water. The crystals were heated and stirred with 200 cm3 of ethanol, filtered, washed with ethanol, and dried to give 2-(4'-fluorophenyl)-5-[2'-
(trans-4'-propylcyclohexyl)ethyl]
-3,6-cyhydroxypyrimidine 6.1g (0,0
17 mol) was obtained (Step 1). This was dissolved in 51 cm3 of phosphorus oxychloride, and 7.
7 cm' was added and refluxed for 100 hours. Phosphorous soxychloride in the reaction product was distilled off under reduced pressure, the residue was dissolved in chloroform, and mixed with 70 cm of a 20% aqueous sodium hydroxide solution and ice]
The chloroform layer was separated and washed in the following order: 10% aqueous sodium hydroxide solution, water, 10% hydrochloric acid, and water. The chloroform was distilled off and the residue was recrystallized from a mixed solvent of acetone and methanol to give 2-(4'-fluorophenyl)-5-[2'-(trans-4'-propylcyclohexyl)ethyl]-3,6- Dichloropyrimidine 5
3 g (0,013 mol) were obtained (Step 2).

Dissolve this in 450 cm3 of ethanol, add 0.7 g of 5% palladium to carbon and 5.5 g of potassium acetate (0,
06 mol) was added and hydrogen gas was absorbed while stirring. The reaction product was filtered to remove palladium-carbon, the ethanol in the filtrate was distilled off, the residue was dissolved in chloroform, and washed in the order of 10% hydrochloric acid and water. Chloroform was distilled off, and the residue was recrystallized from a mixed solvent of acetone and methanol to obtain 3.3 g of 2-(4-fluorophenyl)-5-[2'(trans-4'-propylcyclohexyl)ethyl]pyrimidine (0 ,01 mol) was obtained (Step 3
). The phase transition temperature of this compound was measured by DSC and the results were as follows.

The following compound was synthesized by the same synthesis method as in Example 3.

2-(4'-fluorophenyl)-5-[2'-(trans-41-ethylcyclohexyl)ethyl]pyrimidine 2-(4'-fluorophenyl)-5-[2'-(trans-41-butylcyclohexyl) )ethyl]pyrimidine 2-(4'-fluorophenyl)-5-[2'-(trans-4'-pentylcyclohexyl)ethyl]pyrimidine 2-(4'-fluorophenyl)-5-[2'-(trans -41-hexylcyclohexyl)ethyl]pyrimidine 2-(4'-fluorophenyl)-5-[2'-(trans-4'-hebutylcyclohexyl)ethyl]pyrimidinyl]pyrimidine liquid crystal composition mixed with 10% by weight [A]
, or as a comparative example, C=, H+ ++ΣX◇\CN
Δn
was measured. These liquid crystal compositions were sealed in a TN type cell (cell thickness 9 μm), and the voltage-luminance characteristics V,
The results of measuring h (voltage at which the brightness becomes 10%) are shown in Table 1.

Table 1 2-(4'-fluorophenyl)-5-[2'-(
Application example of trans-41-octylcyclohexyl)ethyl]pyrimidine The compound of the present invention 2-(4'-fluorophenyl)-5-[ 2'(trans-41-butylcyclohexyl)ethyl [Effects of the Invention] As described above, by mixing the pyrimidine derivative of the present invention with other liquid crystal compositions, a liquid crystal composition with a small Δn and a low vl2 can be obtained. I was able to confirm that it was obtained.

that's all

Claims (1)

[Claims] General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (1) (In the above formula, R represents a straight-chain alkyl group having 1 to 8 carbon atoms, and the cyclohexane ring is in the trans configuration. .) A pyrimidine derivative characterized by being represented by: