JPH04975B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to 2-cyano-4-halogenophenol esters, and relates to a novel liquid crystal compound having negative dielectric anisotropy and a liquid crystal composition containing the same. Liquid crystal display elements utilize the optical anisotropy and dielectric anisotropy of liquid crystal materials, and can be divided into TN type (twisted nematic type), DS type (dynamic scattering type), and guest-host type depending on the display format. There are various types such as , DAP type, etc., and the properties of the liquid crystal materials suitable for each use are different. Both liquid crystal materials are free from moisture, air,
It is common that these materials must be stable to heat, light, etc., and there is also a demand for materials that exhibit a liquid crystal phase over as wide a temperature range as possible, centering on room temperature. At present, there is no single compound that satisfies these conditions, and liquid crystal compositions obtained by mixing several types of liquid crystal compounds and non-liquid crystal compounds are used. Recently, guest-host type liquid crystal display devices, which are one type of color liquid crystal display method, have been attracting attention. This uses a mixture of liquid crystal and dye, and a liquid crystal with negative dielectric anisotropy is used in the positive guest-host display element. There is a need for liquid crystal compounds with negative properties. An object of the present invention is to provide a novel liquid crystal compound suitable for such uses. That is, the present invention is based on the general formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms,

【formula】

[Formula] is each

[Formula] or

[Formula], and X represents either F or Cl. ) An ester derivative of 2-cyano-4-halogenophenol and a liquid crystal composition containing the same. The compounds of the present invention have high clearing points, such as 4-(trans-4-
The crystalline nematic point (hereinafter abbreviated as C-N point) of pentylcyclohexyl)biphenylyl-4'-carboxylic acid-2-cyano-4-fluorophenyl ester is 93.8°C, and the nematic clearing point (hereinafter referred to as N Point -I) exhibits a liquid crystal phase over a wide temperature range of 266.0°C, and by adding it as a component of a liquid crystal composition, the clearing point of the liquid crystal composition can be raised. Furthermore, since the dielectric anisotropy value (hereinafter abbreviated as Δε) of the compound of the present invention is about -3, it can be mixed with other nematic liquid crystals to create a negative anisotropy value that can be used for guest-host type display devices. A liquid crystal composition having dielectric anisotropy can be obtained. In addition, by combining it with one having positive dielectric anisotropy, it can be used in a dual frequency method type display element. Next, a method for producing the compound of the present invention will be described. 4-alkylterphenyl-4″-carboxylic acid (compound ()) is reacted with thionyl chloride to form acid chloride (compound ()), which is then reacted with 2-cyano-4-halogenophenol in the presence of pyridine. , the desired 4-alkylterphenyl-4''-carboxylic acid-2-cyano-4-halogenophenyl ester (compound ()) can be produced. Method for producing trans-4 by reducing the above-mentioned compound () with metallic sodium in isoamyl alcohol.
-(4-Alkylbiphenylyl-4')-cyclohexanecarboxylic acid (compound ()) was obtained, and then the compound () was reacted with thionyl chloride to form the acid chloride (compound ()), and the 2- React with cyano-4-halogenophenol to obtain the desired trans-4-(4-alkylbiphenyl-4')
-Cyclohexanecarboxylic acid-2-cyano-4-
Halogenophenyl ester (compound ()) can be produced. Production method of 4-(trans-4-alkylcyclohexyl)
Biphenylyl-4'-carboxylic acid (compound ())
was reacted with thionyl chloride to form acetic acid chloride (compound ()), and in the presence of pyridine, 2-cyano-4
- By reacting with halogenophenol, the desired 4-
(trans-4-alkylcyclohexyl)biphenylyl-4'-carboxylic acid-2-cyano-4-halogenophenyl ester (compound ()) can be produced. Method for producing trans-4 by reducing the above-mentioned compound () with metallic sodium in isoamyl alcohol.
-[4-(trans-4-alkylcyclohexyl)phenyl]cyclohexanecarboxylic acid (compound ()) is obtained, and then the compound () is reacted with thionyl chloride to form an acid chloride (compound (XI)),
React with 2-cyano-4-halogenophenol in the presence of pyridine to obtain the desired trans-4-
-(trans-4-alkylcyclohexyl)phenyl]cyclohexanecarboxylic acid-2-cyano-4-halogenophenyl ester (compound (XII))
can be manufactured. If the above is expressed as a chemical formula, (R and X are the same as above.) 2-Cyano-4-halogenophenol used in the above reaction formula is obtained by dehydrating 5-halogenosalicylaldehyde oxime using acetic anhydride and then alkali metal hydroxide. It can be produced by hydrolyzing the product. This can be expressed as a chemical formula: (X is the same as above.) The compounds of the present invention will be explained in more detail below with reference to Examples. Example 1 4-pentylterphenyl-4″-carboxylic acid-
2-cyano-4-fluorophenyl (compound () in which R is n-C ₅ H ₁₁ and X is F)
Production (1) Production of 2-cyano-4-fluorophenol 5-fluorosalicylaldehyde oxime
20.2g was dissolved in 100ml of acetic anhydride and refluxed for 5 hours. After the reaction, acetic anhydride was distilled off under reduced pressure.
Add 20g of potassium hydroxide to the remaining oil and 100ml of water.
Add the solution dissolved in and 100ml of ethanol at 80°C.
The mixture was heated for 2 hours. Leave to cool to room temperature, then 6N
Separate the crystals precipitated by adding 50 ml of hydrochloric acid and 200 ml of water, and recrystallize with 30 ml of methanol to obtain 15.6 g of needle-shaped crystals (melting point 121-122°C).
I got it. (2) Esterification 1.49 g of 4-pentylterphenyl-4″-carboxylic acid (compound ()) was heated to 80°C with 10 ml of thionyl chloride. The reaction solution became homogeneous in 2 hours, and the reaction was continued for another 1 hour. Then, excess thionyl chloride was distilled off under reduced pressure to leave a crystalline acid chloride (compound ()).Separately, 2-cyano-4-fluorophenol produced in the above (1)
0.62 g was dissolved in 5 ml of pyridine, and the above acid chloride (compound ()) dissolved in 10 ml of toluene was added thereto while shaking. After the reaction, 50 ml of toluene was added and the mixture was poured into water. The separated toluene layer was mixed with 6N hydrochloric acid and 2N
It was washed with a sodium hydroxide solution and then with water, and finally dried using anhydrous sodium sulfate. Next, toluene was distilled off under reduced pressure to obtain a crystalline product, which was recrystallized from ethyl acetate to obtain the desired product, 4-pentylterphenyl-4″-carboxylic acid-2-cyano-4-fluorophenyl ester ( 1.05 g (yield: 52.4%) of compound () was obtained.The crystal-smectic point (hereinafter abbreviated as C-Sm point) of this product was 167.0°C, and the smectic-nematic point (hereinafter abbreviated as Sm-N point). ) is 173.4
℃, and the N-I point was 274.5℃. Example 2 4-pentylterphenyl-4″-carboxylic acid-
Production of 2-cyano-4-chlorophenyl ester (compound () in which R is n-C ₅ H ₁₁ and X is Cl) (1) Production of 2-cyano-4-chlorophenol 5-chlorosalicylaldehyde oxime 20g
was dissolved in 100 ml of acetic anhydride and refluxed for 10 hours.
After the reaction, acetic anhydride was distilled off under reduced pressure, and a solution of 20 g of potassium hydroxide dissolved in 100 ml of water and 100 ml of ethanol were added to the remaining oil, and the mixture was heated at 80° C. for 5 hours. After cooling to room temperature, the mixture was completely acidified with 6N hydrochloric acid, and the precipitated crystals were separated and dried. The melting point was 164-168°C, and the yield was 14g.
This was used as it was in the next reaction. (2) Esterification In a method similar to Example 1, 4-pentylterphenyl-4″-carboxylic acid (compound ())
From 1.49g and 0.70g of 2-cyano-4-chlorophenol, 4-pentylterphenyl-
4″-carboxylic acid-2-cyano-4-chlorophenyl ester (compound ()) 1.13g (yield
54.5%). The C-Sm point of this item is 157.6
℃, Sm-N point is 159.2℃, N-I point is 284.1℃
It was hot. Example 3 4-(trans-4-pentylcyclohexyl)
Biphenylyl-4'-carboxylic acid-2-cyano-
4-fluorophenyl ester (compound ()
_Production of 4-(trans-4) in accordance with Example ₁
-pentylcyclohexyl)biphenylyl-4'-
From 2.00 g of carboxylic acid (compound (XII)) and 0.75 g of 2-cyano-4-fluorophenol, 4-(trans-4-pentylcyclohexyl)biphenylyl-4'-carboxylic acid-2-cyano-4-fluorophenyl 1.58 g (yield 60.0%) of ester (compound ()) was obtained. The C-N point of this is 93.8
℃, and the N-I point was 266.0℃. Example 4 4-(trans-4-pentylcyclohexyl)
Biphenylyl-4'-carboxylic acid-2-cyano-
Production of 4-chlorophenyl ester (compound () in which R is n-C ₅ H ₁₁ and X is Cl) 4-(trans-4
-pentylcyclohexyl)biphenylyl-4'-
From 1.17 g of carboxylic acid (compound ()) and 0.56 g of 2-cyano-4-chlorophenol, 4-(trans-4-pentylcyclohexyl)biphenylyl-4'-carboxylic acid-2-cyano-4-chlorophenyl ester ( Compound ()) 0.98g (yield
60.7%). The C-N point of this product is 105.2℃,
The N-I point was 274.5°C. Example 5 Trans-4-[4-(trans-4-pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid-2-cyano-4-fluorophenyl ester (compound (XII) where R is n-C ₅ H ₁₁ , X
is F) (1) Production of trans-4-[4-(trans-4-pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid (compound ()) 4-(trans-4-pentylcyclohexyl)biphenylyl- 10 g of 4'-carboxylic acid (compound ()) was stirred with 2500 ml of isoamyl alcohol and heated to 90°C. Next, 30 g of metallic sodium was added to cause a vigorous reaction. While continuing to reflux, an additional 120 g of metallic sodium was added over the course of 3 hours, and the reaction solution gradually became homogeneous. After the reaction was completed, it was allowed to cool to 100°C. Next, while adding water, the isoamyl alcohol was distilled off, and then 2000 ml of water was added. then
Add two doses of 6N hydrochloric acid to make it completely acidic, separate the precipitate, wash with water, and recrystallize with acetic acid to obtain trans-4-[4-trans-4-pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid (compound ( )) 4.5g was obtained. This carboxylic acid also exhibits liquid crystallinity, and its C-S point is
239.1℃, Smekchitsk-clearing point (hereinafter referred to as S-
It is abbreviated as point I. ) was 274.3℃ (accompanied by decomposition).
showed that. (2) Esterification In a method similar to Example 1, 0.80 g of trans-4-[4-(trans-4-pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid (compound ()) produced in (1) above was added. From 0.32 g of 2-cyano-4-fluorophenol, 0.77 g of trans-4-[4-(trans-4-pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid-2-cyano-4-fluorophenyl ester (yield 75.4%) ) was obtained. The C-N point of this product was 118.0°C, and the N-I point was 231.6°C. Example 6 trans-4-[4-(trans-4-pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid-2-cyano-4-chlorophenyl ester (compound (XII) where R is n-C ₅ H ₁₁ and X is
Production of trans-4-[4-
(trans-4-pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid (compound ())
1.02g and 2-cyano-4-chlorophenol 0.46
0.95 g (yield: 67.5%) of trans-4-[4-(trans-4-pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid-2-cyano-4-chlorophenyl ester was obtained. The C-N point of this product was 106.8°C, and the N-I point was 214.0°C. Example 7 (Usage example) Ester-based nematic liquid crystal composition (Chitsuso Co., Ltd.)
The N-I point of Rixon FN-45) is 63.4℃,
Δε is -0.9, and the viscosity at 20°C is 18.5 cp.
A commercially available dye (G-
A guest-host cell was created by adding 1% by weight of 224) into a cell with a spacing of 10 μm between opposing transparent electrodes, and the threshold voltage was measured.
It was 3.80V. Next, the compound of the present invention, 4-(trans-4
-pentylcyclohexyl)biphenylyl-4'-
5% by weight of carboxylic acid-2-cyano-4-fluorophenyl ester (obtained in Example 3),
5% by weight of trans-4-[4-(trans-4-pentylcyclohexyl)phenyl]cyclohexanecarboxylic acid-2-cyano-4-fluorophenyl ester (obtained in Example 5) and trans-4-[ 5% by weight of 4-(trans-4-pentylcyclohexyl)phenyl cyclohexanecarboxylic acid-2-cyano-4-chlorophenyl ester (obtained in Example 6) was added to 85% by weight of the liquid crystal composition (FN-45). A liquid crystal composition was prepared by mixing %. The N-I point of the composition was 83.4°C, Δε was -1.2, and the viscosity at 20°C was 30.3 cp, to which 1% by weight of dye G-224 was added as before.
I made a guest-host type liquid crystal cell sealed in the same cell as above and measured its threshold voltage.
It dropped significantly to 3.26V.

Claims (1)

[Claims] 1. General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms, [Formula] and [Formula] are either [Formula] or [Formula], respectively, and X is either F or Cl. 2-cyano-4-halogenophenol esters represented by 2 General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms, [Formula] and [Formula] are either [Formula] or [Formula], respectively, and X is either F or Cl. A liquid crystal composition containing an ester of 2-cyano-4-halogenophenol represented by: