JPS6346740B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel organic compound, and more particularly to a liquid crystal compound useful as a component of a liquid crystal composition.

Nematic liquid crystals with positive dielectric anisotropy are used in twisted nematic mode liquid crystal display elements, display elements that utilize the guest-host effect, and DS type display elements that utilize the dynamic scattering effect.
It is also used in DAP-type display elements that utilize the electric field-controlled birefringence effect. The liquid crystal used in these devices must exhibit a liquid crystal state over as wide a temperature range as possible from low temperatures to high temperatures, including room temperature, and must be stable against moisture, air, light, heat, and the like. However, there is currently no single compound that satisfies all of these conditions, and the objective has been achieved to some extent by using a liquid crystal composition that is a mixture of several types of liquid crystal compounds or non-liquid crystal compounds. ing. The present invention provides a liquid crystal compound useful as a component constituting such a stable liquid crystal composition with excellent practical performance. That is, the compound of the present invention has the general formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms) 4-trans(trans-4'-alkylcyclohexyl)cyclohexylmethyl 4-
A liquid crystal composition containing cyanophenyl ether and at least one thereof.

Although the compound of the present invention has a wide nematic temperature range but has a high melting point, it cannot be used practically as a display element alone, but it has excellent compatibility with other liquid crystal compounds, and has a clearing point (NI).
point), other liquid crystal substances such as Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, benzoic acid phenyl ester liquid crystal, cyclohexanecarboxylic acid phenyl ester liquid crystal, cyclohexanecarboxylic acid cyclohexyl ester liquid crystal,
By mixing it with one or more of phenylcyclohexane-based liquid crystals, phenylpyrimidine-based liquid crystals, phenylmetadioxane-based liquid crystals, etc., its clearing point can be raised, making it useful as a so-called high-temperature liquid crystal component. .

The compound of the present invention can be produced by the following steps.

That is, first, 4-trans(trans-4'-alkylcyclohexyl)cyclohexanecarboxylic acid is reacted with a halogenating agent to form its acid chloride,
It is reacted with ethanol to obtain its ethyl ester. In this case, it is also possible to directly esterify carboxylic acid and ethanol using a mineral acid or the like as a catalyst. Lithium aluminum hydride (LiAlH ₄ ) is then reacted and reduced at low temperature in a solvent such as tetrahydrofuran to give 4-trans (trans-4'-alkylcyclohexyl)cyclohexylmethyl alcohol, which is then treated with hydrogen bromide under acidic sulfuric acid. Reaction with acid yields its bromide. By reacting this with p-cyanophenol in alcohol in the presence of an alkali, the target compound of formula (), namely 4-trans(trans-4'-alkylcyclohexyl)cyclohexylmethyl 4-cyanophenyl ether, is obtained. It will be done.

The 4-trans(trans-4'-alkylcyclohexyl)cyclohexanecarboxylic acid used as a raw material was prepared by heating 4-alkyldiphenyl-4'-carboxylic acid with acetic acid as a solvent at 150°C over a Pt catalyst.
The product obtained by carrying out the hydrogenation reaction at 50 atm was purified by recrystallization and used.

Hereinafter, the method for producing the compound of the present invention and examples of its use will be explained in more detail with reference to Examples.

Example 1 [Production of 4-trans(trans-4'-propylcyclohexyl)cyclohexylmethyl 4-cyanophenyl ether] 30.3 g of 4-trans(trans-4'-propylcyclohexyl)cyclohexanecarboxylic acid
(0.12 mol) and 32.8 g (0.28 mol) of thionyl chloride are reacted under heating under reflux for 1 hour, and excess thionyl chloride is distilled off under reduced pressure to obtain 29.8 g (0.11 mol) of the acid chloride. 23 g (0.5 mol) of ethyl alcohol is gradually added to this, and the mixture is heated and stirred at about 60° C. for 2 hours. After the reaction, cool down and add 50ml of n-
Extract with hexane, extract the extract with 20% hydrochloric acid, then 10%
Washed with NaOH aqueous solution, further washed with water until neutral, and then distilled off n-hexane to give 33.6g
(0.102 mol) of 4-trans(trans-4'-propylcyclohexyl)cyclohexanecarboxylic acid ethyl ester is obtained. This is dissolved in 50 ml of well-dried tetrahydrofuran, and the solution is added dropwise to a suspension of 2.3 g (0.06 mol) of lithium aluminum hydride in 60 ml of dry tetrahydrofuran, which is being vigorously stirred. After the addition was completed, the mixture was heated under reflux for 2 hours, and after cooling, 20 ml of water was carefully added to decompose the excess lithium aluminum hydride, and the mixture was then diluted with 20% sulfuric acid.
Gradually add to 100ml and stir until all the inorganic substances are dissolved. It was extracted with 100 ml of tetrahydrofuran, washed with water, dried over anhydrous magnesium sulfate, and then the tetrahydrofuran was distilled off. The residue was recrystallized with 20 ml of n-hexane to yield 19.9 g.
(0.084 mol) of 4-trans(trans-4'-propylcyclohexyl)cyclohexylmethyl alcohol was obtained. The melting point of this product was 123°C.

Next, add 28.8 g of hydrobromic acid (47%) to 9.3 g of concentrated sulfuric acid.
The entire amount of alcohol was added to the liquid obtained by gradually adding the alcohol, and the mixture was heated and stirred at about 100°C for 4 hours. After cooling, 20 ml of toluene was added for extraction, and the extract was washed with a 10% aqueous sodium carbonate solution and then with water, the toluene was distilled off, and the residue was recrystallized with 50 ml of ethanol to yield 13.3 g (0.044 mol). 4-trans(trans-4'-propylcyclohexyl)cyclohexylmethyl bromide was obtained. The melting point of this thing is
It was 43.5℃. On the other hand, 4-cyanophenol 5.48
g (0.046 mol) was dissolved in 40 ml of ethyl alcohol, and 1.84 g of sodium hydroxide was further added to the solution.
A solution of the bromide in 50 ml of ethyl alcohol is added dropwise to the solution of the bromide obtained earlier (13.3 g). After the dropwise addition, the reaction was heated under reflux for 4 hours, and after the reaction was completed, the mixture was allowed to cool, and 50 ml of toluene was added to extract it, which was first washed with a 10% aqueous sodium hydroxide solution and then with water, and then washed with anhydrous magnesium sulfate. After drying, the toluene was further distilled off, and the residue was recrystallized twice using ethyl alcohol to obtain the target product, 4-trans(trans-4'-propylcyclohexyl)cyclohexylmethyl 4-
10.18 g (0.03 mol) of cyanophenyl ether was obtained. This material is a nematic liquid crystal material, with a melting point (C-N point) of 94℃ and a clearing point (N-I point) of 185.3.
It was warm at ℃. Moreover, the elemental analysis values of this product were as shown below, and were in good agreement with the theoretical values.

Analytical value (%) Theoretical value (%) (as C ₂₃ H ₃₃ ON) C 81.2 81.36 H 9.9 9.80 Examples 2 and 3 Completely the same as Example 1 except that starting materials with different alkyl groups were used. 4-trans (trans-4'-pentylcyclohexyl)
Cyclohexylmethyl 4-cyanophenyl ether (Example 2) and 4-trans (trans-
4'-heptylcyclohexyl)cyclohexylmethyl 4-cyanophenyl ether was obtained. The former C-N point is 116℃, the N-I point is 181.8℃, and the latter also shows a smectic liquid crystal phase (Sm), the C-Sm point is 94.6℃, the Sm-N point is 105℃, and the N-I point. is 172.8
It was warm at ℃.

Example 4 (Usage example 1) When a liquid crystal composition with the above formulation containing 15 parts of the compound of formula () of the present invention was prepared, its NI point was the NI point of the liquid crystal composition not containing 15 parts of the compound of formula ().
The temperature rose from 53.5℃ to 71℃. When this liquid crystal composition was sealed in a twisted nematic cell with a cell thickness of 10 μm and its operating characteristics were measured, the threshold voltage was
It showed excellent practicality with a saturation voltage of 1.80V and 2.50V. The Δε of this composition was 10.3.

Claims (1)

[Claims] 1. General formula (However, in the above formula, R represents an alkyl group having 1 to 10 carbon atoms.) 4-trans(trans-4'-alkylcyclohexyl)cyclohexylmethyl 4-
Cyanophenyl ether. 2 General formula (However, in the above formula, R represents an alkyl group having 1 to 10 carbon atoms.) 4-trans(trans-4'-alkylcyclohexyl)cyclohexylmethyl 4-
A liquid crystal composition containing at least one cyanophenyl ether.