JPH0261471B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel organic compound, and more particularly to a novel compound having positive dielectric anisotropy. Liquid crystal materials with positive dielectric anisotropy can be used in liquid crystal display devices that use nematic liquid crystals with twisted alignment, so-called TN cells, and they can also be used in liquid crystal display devices that use nematic liquid crystals with twisted alignment, and in addition, by adding appropriate dye materials, the guest-host effect can be applied. It is also used in color liquid crystal display devices. When these liquid crystal materials are used as single compounds, there are few that can withstand practical use in terms of their performance, such as liquid crystal temperature range, operating voltage, response performance, etc., and for practical purposes, it is necessary to mix several types of liquid crystal mixtures or non-liquid crystal compounds. At present, we have obtained products that can withstand some use. An object of the present invention is to provide a compound useful as a component of such a stable liquid crystal composition with excellent practical performance.

That is, the present invention provides 4-(trans-5-alkyl-1,
3-diox-2-yl)benzoic acid 3-chloro-
4-cyanophenyl ester.

The compound of formula () of the present invention has a large positive dielectric anisotropy, a wide liquid crystal temperature range, and especially a clearing point (N-
It is a liquid crystal compound with excellent stability at point I). However, since this compound has a relatively high melting point (CN point), this compound alone cannot be used for ordinary display devices. However, it has excellent compatibility with other liquid crystal compounds, such as Schiff base type, azoxy type, benzoic acid phenyl ester type, cyclohexane carboxylic acid phenyl ester type, cyclohexane carboxylic acid cyclohexane ester type, biphenyl type, etc. It is useful as a so-called high-temperature liquid crystal component that increases the clearing point by mixing it with one type of liquid crystal such as phenylcyclohexane, phenylpyrimidine, and phenylmetadioxane, or a mixture of several types. Furthermore, compared to liquid crystal materials such as cyanoterphenyl and cyanobiphenylcyclohexane, which have been widely used for similar purposes, the anisotropy of the dielectric constant, that is, △ε, is large, so it has the effect of lowering the driving voltage. are doing.

Next, a method for producing the compound of the present invention will be shown. First, the outline of the chemical formula is shown below: K0627 K0628 K0629 K0630 That is, first, diethyl malonate is reacted with an alkyl bromide in the presence of sodium ethoxide in an anhydrous ethyl alcohol solvent, and then diethyl malonate (2-alkyl diethyl malonate) ).

This is reduced using lithium aluminum hydride in a tetrahydrofuran solvent to give 2-alkyl-1,3-propanediol (2).
Other known reducing agents (for example, borane methyl sulfide) and reduction methods can be used to reduce the malonic acid ester, if necessary. This 2-
Reacting alkyl-1,3-propanediol () and terephthalaldehydic acid using an appropriate catalyst such as p-toluenesulfonic acid, aluminum chloride, hydrochloric acid, or sulfuric acid in an inert organic solvent such as benzene or toluene. 4-(5-alkyl-1,3-diox-2-yl)benzoic acid is obtained. This carboxylic acid is obtained as a mixture of two types: trans form and cis form. The target compound is the trans form, and the cis form can be removed by recrystallization. Next, this 4-(trans-5-
Alkyl-1,3-diox-2-yl)benzoic acid is converted to the corresponding acid chloride () with a chlorinating agent such as thionyl chloride or phosphorus pentachloride, and 3-chloro-4-cyanophenol is added to this with pyridine or triethylamine. The desired compound 4-(trans-5-alkyl-1,3-diox-2-yl)benzoic acid 3-chloro-4-cyanophenyl ester () is obtained by reacting in a basic solvent such as .

Hereinafter, synthesis examples and usage examples of the compounds of the present invention will be shown as Examples, and will be explained in more detail.

Example 1 [4-(trans-5-pentyl-1,3-diox-2-yl)benzoic acid 3-chloro-4-
Production of cyanophenyl ester] Dissolve 41.3 g (0.61 mol) of sodium ethoxide in 200 ml of absolute ethyl alcohol. Next, 96 g (0.60 mol) of malonic acid diethyl ester is added, and the mixture is heated and stirred. There, 90.6g of normal amyl bromide
(0.6 mol) was gradually added dropwise, and after the addition was completed, the mixture was heated under reflux for 4 hours. Thereafter, the ethyl alcohol was distilled off at normal pressure, and 200 ml of cold water was added to the remaining reaction mixture to dissolve the sodium bromide. Next, the aqueous layer and organic layer were separated, the aqueous layer was extracted with 200 ml of n-hexane, the extract was combined with the upper organic layer, washed with water, the n-hexane was distilled off under reduced pressure, and diethylbentylmalonate was extracted. ester()
95.3g (0.41 mol) was obtained. Its boiling point is 98-101
The temperature was ℃/3mmHg.

69.1 g (0.3 mol) of pentylmalonic acid diethyl ester () obtained in this way was dried in tetrahydrofuran using calcium hydride.
Dissolve in 150cc and add this to tetrahydrofuran.
Lithium aluminum hydride 15g (0.4
mol) in a solution that is suspended and stirred vigorously.
It was added dropwise at 25°C. After the addition was complete, the mixture was heated under reflux for 2 hours. After heating, the reaction mixture was cooled in an ice bath, and 10 ml of ethyl acetate was added thereto to decompose excess lithium aluminum hydride. Then, 200 ml of 20% sulfuric acid was added to this mixture and stirred vigorously until the inorganic matter was dissolved. The product was extracted with 100 ml of ether, and the extract was washed twice with a 5% aqueous sodium bicarbonate solution, then washed with water, and then dried over anhydrous sodium sulfate. After that, ether was distilled off from the extract,
The residue was distilled to obtain 31 g (0.21 mol) of 2-pentyl-1,3-propanediol (2). Its boiling point was 125-126°C/2.5mmHg.

Next, add the above 2-pentyl-
1,3-propanediol () 21.9g (0.15mol), terephthalaldehydic acid 22.5g (0.15mol)
and 0.1 g of p-toluenesulfonic acid, and the reaction is carried out under heating and reflux until no water produced by the reaction is distilled out. After the reaction was completed, it was allowed to cool, and the precipitated crystals were recrystallized from 150 ml of p-dioxane.
4-(trans-5-pentyl-1,3-diox-2-yl)benzoic acid () was obtained. This substance shows a liquid crystal phase, C-N point: 207℃, N-I point: 211
It was warm at ℃. Yield: 25.5g (0.09mol).

Next, 5 g (0.018 mol) of the compound () obtained above was dissolved in 4.3 g of thionyl chloride, and after reacting for 1 hour under reflux, excess thionyl chloride was distilled off under reduced pressure and the acid I got something (). Separately, 2.8 g (0.019 mol) of 3-chloro-4-cyanophenol was dissolved in 5 ml of pyridine, and the above acid chloride was added thereto at room temperature, followed by further heating and stirring at 70°C for 2 hours. After the reaction was completed, the reaction product was allowed to cool to room temperature, extracted with 50 ml of benzene, the extract was washed with dilute hydrochloric acid, dilute aqueous alkaline solution, and water, and the extract was dried over anhydrous magnesium sulfate, and then extracted with benzene. was removed. The residue was recrystallized from 10 ml of ethyl acetate to obtain the desired product, 4-(trans-
5-pentyl-1,3-diox-2-yl)benzoic acid 3-chloro-4-cyanophenyl ester
4.2g (0.01 mol) was obtained.

This substance shows a liquid crystal phase, and the C-N point: 116.9~
117.0°C, N-I point: 142.0-143.0°C.
Moreover, the elemental analysis values of this compound were in good agreement with the calculated values as shown below.

Analytical value (%) Calculated value (%) (as C ₁₃ H ₂₄ NO ₂ Cl) C 66.8 66.7 H 5.7 5.8 Examples 2 to 4 The following compounds were synthesized in the same manner as in Example 1.

4-(trans-5-ethyl-1,3-diox-2-yl)benzoic acid 3-chloro-4-cyanophenyl ester (Example 2) C-I point: 150.2-150.8°C 4-(trans- 5-propyl-1,3-diox-2-yl)benzoic acid 3-chloro-4-cyanophenyl ester (Example 3) C-N point: 125.4-125.8°C, N-I point: 145.6-146.5°C 4-(trans-5-butyl-1,3-diox-2-yl)benzoic acid 3-chloro-4-cyanophenyl ester (Example 4) C-N point: 116.9-117.5°C N-I point: 141.9 to 142.5°C Example 5 (Usage Example 1) The N-I point of the liquid crystal composition having the composition K0631 K0632 K0633 K0634 is 57.8°C. The cell thickness is obtained by forming a SiO film on a glass substrate using this liquid crystal composition and subjecting it to surface alignment treatment by rubbing.
When sealed in a 10 μm TN type liquid crystal cell, the dielectric constant anisotropy Δε = 13.8, the threshold voltage at room temperature measured using a 32 Hz square wave was 1.31 V, and the saturation voltage was 1.79 V. Among the above components, the N-I point of the product without the fourth compound of the present invention is 52.4
℃, Δε=11.1, threshold voltage was 1.50V, and saturation voltage was 2.10V. In addition, in the above composition, in place of the compound of the present invention, a compound which is conventionally well known as a high temperature liquid crystal component may be used. If the same method is used except that the same amount of
The operating voltage is extremely high, with a saturation voltage of 2.41V and a saturation voltage of 1.72V.

Claims (1)

[Claims] 1 4-(trans-5-alkyl-1,
3-diox-2-yl)benzoic acid 3-chloro-
4-cyanophenyl ester. 2 4-(trans-5-alkyl-1,
3-diox-2-yl)benzoic acid 3-chloro-
A liquid crystal composition containing at least one 4-cyanophenyl ester.