JPS642113B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel organic compounds, and more particularly to metadioxane compounds useful as components of liquid crystal materials. Nematic liquid crystals having positive dielectric anisotropy can be used in twisted nematic mode display devices and liquid crystal color display devices that utilize the guest-host effect. The liquid crystal used for these is stable against moisture, air, light, heat, etc., and is preferably in a liquid crystal state not only at room temperature but also in a wide range from low to high temperatures. However, there is currently no single compound that satisfies all of these properties, and the current goal is to be achieved by liquid crystal compositions that are a combination of several types of compounds. The purpose of the present invention is to provide a system with excellent practical performance.
The object of the present invention is to provide a compound useful as a component constituting a stable liquid crystal composition. Compound general formula of the present invention (However, in the above formula, R ₁ represents H or an alkyl group having 1 to 10 carbon atoms, or an alkyloxy group, and R ₂ represents H or an alkyl group having 1 to 10 carbon atoms.) A metadioxane compound and a liquid crystal composition containing the same. Although the compound of formula () of the present invention cannot be used alone in display elements, it generally has good compatibility and stability, and is therefore suitable for use in combination with other liquid crystal substances. In other words, many of these compounds have a good and wide liquid crystal temperature range, so the N-I of the liquid crystal composition
It is useful as a so-called high-temperature liquid crystal component that raises the point and S-I point, and the dielectric anisotropy Δε is positive but almost 0, so the temperature dependence of the threshold voltage is small. Useful for adjusting high temperature liquid crystals that can be dynamically driven. The compound of the present invention can be synthesized by the following steps. (However, X is

[expression]) That is, first, a carboxylic acid R ₁ -X-COOH is reacted with a halogenating agent such as SOC1 ₂ by a conventional method to form a carboxylic acid chloride, which is then hydrogenated using a catalyst to exchange chlorine and hydrogen to form an aldehyde. shall be. As this catalyst, it is preferable to use a 5% palladium catalyst using barium sulfate as a carrier, whose activity is weakened by adding a suitable catalyst poison. The reaction is carried out in an inert solvent at normal pressure and at room temperature to reflux temperature. After isolating the aldehyde, the 2-alkyl-
Propanediol-1,3 is reacted in the presence of a catalyst in an inert organic solvent. As this catalyst
Lewis acids such as A1C1 ₃ or acids such as toluenesulfonic acid are used. The reaction proceeds at normal pressure and at the reflux temperature of the reaction system. The rest can be separated and purified using conventional methods, but the cis-isomer, which is produced simultaneously with the trans-isomer of compound (), can be removed during the recrystallization process. The production method and usage examples of the compound of the present invention will be explained in more detail with reference to Examples below. Example 1 [Synthesis of 2-(4-n-pentyl-4'-biphenylyl)-5-n-propyl-1,3-dioxane) 4-n-pentyl-4'-diphenylcarboxylic acid
50g (0.186 mol) to 44.0g (0.372 mol) of thionyl chloride
mol) and reacted under heating under reflux for 1 hour, and then excess thionyl chloride was distilled off under reduced pressure. The acid chloride thus obtained was dissolved in 200 ml of dry xylene, 5 g of 5% palladium catalyst with barium sulfate as a carrier and 0.5 ml of quinoline-sulfur solution (1 g of sulfur) as a catalyst poison.
After refluxing 6 g of quinoline and quinoline for 5 hours, add 70 ml of xylene.
(diluted). After replacing the air in the flask with hydrogen, heat it to 140-150℃ on an oil bath.
The reaction is completed by blowing hydrogen into the mixture for about 3 hours while stirring. After the reaction is complete, cool and add 10% NaOH solution.
Add 100 ml to remove unreacted acid chloride, then wash the xylene layer with water, dry it over anhydrous sodium sulfate, and then distill off the xylene under reduced pressure. Distill the residue under reduced pressure to 165-166℃/mmHg
29.8g of fraction was obtained. This is 4-n-pentylbiphenyl-4'-aldehyde. Next, 2.524 g (0.01 mol) of this aldehyde, 1.19 g (0.01 mol) of 2-n-propylpropanediol-1,3, and 100 mg of p-toluenesulfonic acid were dissolved in 50 ml of well-dried toluene, and the mixture was heated under reflux. below
The reaction was allowed to take place for 30 minutes. After the reaction is completed, the reaction solution is cooled and washed twice with a 5% aqueous solution of NaHCO ₃ and then with water. The toluene solution portion is dried over anhydrous sodium sulfate, and the toluene is distilled off. The remaining oil was recrystallized with 20 ml of ethyl alcohol to obtain 2.186 g of needle-like crystals of the target product, 2-(4-n-pentyl-4'-biphenylyl)-5-n-propyl-1,3-dioxane ( 0.0062 mol) was obtained. Yield 62%. This compound has a C-N point of 85℃, N
-The nematic temperature range is high and wide at I point 160℃.
Moreover, the elemental analysis values were in good agreement with the theoretical values as shown below. Analytical value (%) Calculated value (%) (as C ₂₄ H ₃₂ O ₂ ) C 81.98 81.77 H 9.10 9.15 Examples 2 to 14 4-n-pentyl-4'-diphenylcarboxylic acid in Example 1, and 5-n-propyl-1,
In place of 3-dioxane, R ₁ , shown in Table 1, respectively
Compounds shown in Examples 2 to 14 in Table 1 were obtained in the same manner as in Example ₁ using the raw materials corresponding to R2.
The phase transition points, including those of Example 1, are shown in Table 1.

[Table] Example 3 (Application example) The nematic liquid crystal temperature range of a liquid crystal composition containing three types of compounds of the present invention having a composition of -20°C or lower
The viscosity at 84°C and 20°C was 30 cp. This liquid crystal composition was sealed in a TN cell (twisted nematic cell) with a cell gap of 10 μm that had been surface treated by rubbing, and its operating threshold voltage was measured at 25°C. It was 1.78V and the saturation voltage was 2.40V. It was hot. In addition, the liquid crystal temperature range of the liquid crystal composition containing only the remaining four components after removing the three components of the compound of the present invention from the above composition is below -20°C to 72.5°C, and the viscosity at 20°C is
30cp, the operating threshold voltage under the same conditions as above is
The voltage was 1.80V, and the saturation voltage was 2.45V.

Claims (1)

[Claims] 1. General formula (However, in the above formula, R ₁ is H or has 1 to 10 carbon atoms.
an alkyl group or an alkyloxy group, R ₂ is H
or an alkyl group having 1 to 10 carbon atoms). 2 General formula (However, in the above formula, R ₁ is H or has 1 to 10 carbon atoms.
an alkyl group or an alkyloxy group, R ₂ is H
or an alkyl group having 1 to 10 carbon atoms) A liquid crystal composition containing at least one 2,5-substituted metadioxane compound represented by: