JPS6136256A - Liquid crystal compound and liquid crystal composition - Google Patents

Abstract

NEW MATERIAL:A compound expressed by the formula (R is 1-10C alkyl). USE:A liquid crystal composition for electrooptical display elements, having a wide liquid crystal temperature range and improved compatibility with another liquid crystal compound, and stable to light, heat, moisture, etc. PREPARATION:A p-alkylbiphenyl is sulfonated and reacted with thionyl chloride to give a sulfonyl chloride, which is then reduced and converted into a thiophenol. The resultant thiophenol is then reacted with p-cyanobenzoyl chloride to afford the aimed compound expressed by the formula.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to liquid crystal compounds used as a component of liquid crystal material mixtures used in electro-optic display elements.

A- Conventional configuration and problems thereof In recent years, liquid crystal display elements have come to be used in a wide range of applications such as watches, calculators, automobile instrument panels, office automation equipment, and televisions.

Display methods using liquid crystals include the TN method, which displays by twisting nematic liquid crystal molecules between upper and lower substrates and applying an electric field, and the TN method, which displays by adding a dichroic dye to the liquid crystal and applying an electric field to the liquid crystal mixture. There is a GH method for displaying images, EC'B method, DS method, etc., but in all cases, the liquid crystal materials used are stable against heat, light, moisture, etc., and have a wide liquid crystal temperature range including near room temperature. It is required to have

However, until now, no single compound has been known that has such a wide liquid crystal range, including near room temperature, and that satisfies all other requirements. At present, the necessary physical properties have been obtained.

OBJECTS OF THE INVENTION The object of the present invention is to provide a new compound that can be used as a component of a liquid crystal composition, particularly for the purpose of widening the liquid crystal temperature range of a liquid crystal composition containing the compound of the present invention. It is.

Constitution of the Invention The compound of the present invention is a p~cyanothiobenzoic acid ester compound represented by the general formula (R in the formula represents an alkyl group having 1 to 10 carbon atoms).

Description of Examples The compound represented by the general formula (1) can be synthesized from commercially available p-alkylbiphenyl and p-cyanobenzoic acid according to the reaction route shown below.

1 space below Page 7 The compound represented by the general formula (1) of the present invention has a wide liquid crystal temperature range, is excellent in stability, and has good compatibility with other liquid crystal compounds, so it can be used in liquid crystal compositions. When used as a component, it is effective in expanding the liquid crystal temperature range of the liquid crystal composition.

The details of the present invention will be explained below with reference to specific examples.

Example 1 Step 1: Add 41 ml of concentrated sulfuric acid to a mixture of 134f p-n-pentylbiphenyl and 67 ml of acetic anhydride with stirring.
1 was added dropwise. After that, incubate (3) 1 at 100°C for 3 hours.
Got 5oy.

Stelaph 2: 100f of sodium sulfonate (3) to 1tsoml of dimethylformamide! 40 ml of thionyl chloride was added dropwise, stirred at room temperature for 10 minutes, poured into ice water in which sodium chloride was dissolved, and the precipitate was filtered out, washed with cold water and dried to obtain sulfonyl 905'. .

Step 3: Sulfonyl chloride (4) 901i1.
Zinc powder 972 was added little by little to a mixture of 580 f of ice and 106 ml of concentrated sulfuric acid at O'C with stirring. After adding everything, return to room temperature, then heat to 100'C for 6 hours.
Heating and stirring were continued for an hour. A reduction product of 697 ether was obtained.

Step 4: p-cyanobenzoic acid 52 and thionyl chloride 1
After heating the oml under reflux on a water bath for 1 hour, excess thionyl chloride was completely distilled off under reduced pressure.

The residue was dissolved in dry benzene and n-hexane was added to give 5.12 g of white crystals of p-dianobenzoic acid chloride.

Step 5: Thiophenol (5) 2.5f (H pyridine 7) was dissolved in 10ml of vane, and while stirring, a solution of 1°8y of the acid chloride obtained in step 4 dissolved in 10ml of pyridine was added dropwise for about 1 hour. After continued stirring at room temperature, 4 N −
Hydrochloric acid poured into HCj2 and filtered out the precipitate,
The mixture was washed with water, dried, and recrystallized from ethanol-chloroform to obtain 2.52 cm of white crystals of the desired thioester compound (2).

The compound of formula (2) melted at 108°C to become a smectic liquid crystal state, transitioned to a nematic liquid crystal state at 159°C, and became an isotropic liquid at 243°C.

The IR spectrum of this compound is shown in FIG.

Example 2 Example 1 was prepared from p-n-hexylvinenyl in the same manner as in steps 1 to 3 of Example 1, from thiophenolphenol (7) and p-cyanobenzoic acid chloride obtained in step 4 of Example 1. The desired thioester compound (6) was obtained in the same manner as Step 5.

The compound of formula (6) melted into a smectic liquid crystal state at 108°C, became a nematic liquid crystal state at 152°C, and became an isotropic liquid at 230'C. The IR spectrum of this compound is shown in FIG.

Example 3 When the compound of formula (6) obtained in Example 2 is mixed in a liquid crystal composition ZLI=1557 manufactured by Merck in an amount of 10Ji, the result is a case where the compound of formula (6) is not mixed. The clearing point (CP) of 61°C increased to 78°C. Well, when we sealed this liquid crystal mixture in a TN cell and measured the threshold voltage Vth, ■th was 2.
．． At 1v, there was no change from that in which the compound of formula (6) was not mixed.

Effects of the Invention As shown above, the liquid crystal compound of the present invention has a very wide liquid crystal temperature range, and when used as a component of a liquid crystal composition, it can expand the liquid crystal temperature range of the liquid crystal composition, especially its upper limit. It is effective in raising the temperature9. In addition, it has good stability against light, heat, moisture, etc., making it highly practical as a liquid crystal compound.

[Brief explanation of the drawing]

FIG. 1 shows the infrared absorption spectrum of the thioester compound of the present invention, and FIG. 2 shows the infrared absorption spectrum of the thioester compound.

Claims (2)

[Claims] (1) A liquid crystal compound represented by the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (R in the formula represents an alkyl group having 1 to 10 carbon atoms). (2) It is characterized by containing at least one liquid crystal compound represented by the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (R in the formula represents an alkyl group having 1 to 10 carbon atoms) liquid crystal composition.