JPH0247985B2 - PENTAFURUOROANSOKUKOSANNOTAKANSHIKUROHEKISHIRUESUTERU - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel liquid crystal material exhibiting a liquid crystal phase over a wide temperature range and having weak positive dielectric anisotropy, and a liquid crystal composition containing the same. Display elements using liquid crystals have come to be widely used in watches, calculators, etc. This liquid crystal display element utilizes the properties of optical anisotropy and dielectric anisotropy of the liquid crystal material, and the liquid crystal phases include a nematic liquid crystal phase, a smectic liquid crystal phase, and a cholesteric liquid crystal phase. The one used is the one most widely put into practical use. That is, they include TN (twisted nematic) type, DS (dynamic scattering type), guest-host type, DAP type, etc., and the properties required of the liquid crystal materials used for each type are different. However, in any case, it is desirable that the liquid crystal substances used in these display elements exhibit a liquid crystal phase over as wide a range as possible in nature, but there is currently no single substance that satisfies such conditions. Currently, materials that can be put to practical use are obtained by mixing several types of liquid crystal substances or non-liquid crystal substances. In addition, these materials must of course be stable against moisture, light, heat, air, etc., and the threshold voltage and saturation voltage necessary to drive the display element must be as low as possible, and the response speed must be as low as possible. In order to speed up the process, it is desirable that the viscosity be as low as possible. By the way, in order to widen the liquid crystal temperature range toward higher temperatures, it is necessary to use a liquid crystal substance with a high melting point as a component, but liquid crystal substances with a high melting point generally have a high viscosity, and therefore the liquid crystal composition containing it also has a high viscosity. As a result, the response speed of liquid crystal display elements that can be used at high temperatures, for example, up to about 80° C., particularly at low temperatures, has tended to become significantly slower. However, the present inventors have found a liquid crystal material that exhibits a liquid crystal phase over a wide temperature range, has a high clearing point, and has a low viscosity, and has thus arrived at the present invention. 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) trans-4-alkyl-trans-4″-(4-pentafluorobenzoyloxy)-
Octadecahydro-trans-p-terphenyl and a liquid crystal composition containing the same. The compounds of the present invention have a high clearing point, for example trans-4-propyl-trans-4''-(pentafluorobenzoyloxy)-octadecahydro-trans-p-terphenyl, which is one of the compounds of the present invention. C-S point is 107℃, S-N point is 215.4
C., N-I point is 280.3 DEG C., and exhibits a liquid crystal phase over a wide temperature range, and by adding it as a component of the composition, the clearing point can be raised without increasing the viscosity of the liquid crystal composition. Further, although the dielectric anisotropy value of the compound of the present invention is about +1, it does not change the threshold voltage and saturation voltage of the composition so much. Also moisture,
It also has good stability against heat, light, etc. Next, the method for producing the compound of the present invention will be described. First, 4-methoxy-[trans-
4′-(trans-4″-alkylcyclohexyl)
cyclohexyl]benzene is demethylated with hydrobromic acid to obtain 4-[trans-4'-(trans-4''-alkylcyclohexyl)cyclohexyl]phenol. This is heated at 180°C using a ruthenium catalyst in an ethanol solvent. , catalytic reduction under the conditions of 50Kg/cm ² to obtain trans-4-alkyl-4-hydroxy-trans-octadecahydro-p-terphenyl.This product was recrystallized from acetone to give trans-4-alkyl. -trans-4-hydroxy-trans-octadecahydro-p-terphenyl was separated.This was reacted with pentafluorobenzoic acid chloride in the presence of pyridine to obtain the desired trans-4-alkyl-trans-4''-(pentafluoro Benzoyloxy)-octadecahydro-trans-p-terphenyl was prepared. If the above is expressed as a chemical formula, Hereinafter, the production method and usage examples of the compound of the present invention will be explained in more detail with reference to Examples. Example 1 [trans-4-propyl-trans-4″-
Production of (pentafluorobenzoyloxy)-octadecahydro-trans-p-terphenyl] 4-Methoxy-[trans-4'-(trans-
4″-propylcyclohexyl)cyclohexyl]
Mix 15g of benzene with 200ml of hydrobromic acid (47%) and acetic acid.
Reflux with 200 ml for 20 hours. After the reaction is complete, add 500 ml of water and filter out the precipitated crystals. After thoroughly washing with water, it was recrystallized from an acetone-ethanol mixed solvent. This is 4-[trans-4′-(trans-
4″-propylcyclohexyl)cyclohexyl]
It is phenol. Yield 11g, yield 77%. 8 g of 4-[trans-4′-(trans-4″-propylcyclohexyl)cyclohexyl]phenol produced in this way was dissolved in 400 ml of ethanol, 1.0 g of ruthenium/carbon catalyst was added,
Catalytic hydrogen reduction was carried out at 50 Kg/cm ² at ℃ for 5 hours. After the reaction is completed, the catalyst is separated and the solvent is distilled off under reduced pressure. The remaining crystalline material is recrystallized with 1 acetone. This is trans-4'-propyl-trans-
4″-Hydroxy-octadecahydro-trans-
It is p-terphenyl. Yield 3.8g, yield 47%,
Melting point 232-237℃. Next, 1 g of pentafluorobenzoic acid chloride is added to a solution of 1 g dissolved in 50 ml of pyridine, and the mixture is left overnight. Add 200 ml of toluene and wash the toluene layer in a separatory funnel first with 6N hydrochloric acid, then with 2N caustic soda solution, and finally with water until neutral. After drying it over anhydrous sodium sulfate, the toluene layer was distilled off under reduced pressure. When the precipitated crystals are recrystallized with acetone, the desired trans-4-propyl-trans-4″-(pentafluorobenzoyloxy)-octadecahydro-
Trans-p-terphenyl was obtained. Yield 0.6g,
Yield 33%. The C-S point of this product is 107.0℃, S-
The N point was 215.4°C and the N-I point was 280.3°C. Examples 2 and 3 4-methoxy[trans-
4′-(trans-4″-propylcyclohexyl)
4-Methoxy-[trans-4′-(trans-4″-alkylcyclohexyl)cyclohexyl]benzene with another alkyl group is used instead of cyclohexyl]benzene to create other trans-4-alkyl-trans-4″- (4-pentafluorobenzoyloxy)-octadecahydro-trans-
p-terphenyl was produced. Their physical property values are shown in Table 1.

[Table] Example 4 (Usage example) Trans-4-propyl-(4'-cyanophenyl)cyclohexane 28% Trans-4-pentyl-(4'-cyanophenyl)cyclohexane 42% Trans-4-heptyl-(4'- The N-I point of a liquid crystal composition having a composition of 30% cyanophenyl cyclohexane is 52°C.
When this liquid crystal composition was sealed in a TN cell (twisted nematic cell) with a cell thickness of 10 μm, the operating threshold voltage was 1.53V and the saturation voltage was 2.12V. The viscosity was 23 cp at 20°C. Trans-4-propyl-trans-4''-(pentafluorobenzoyloxy)-octadecahydro- prepared in Example 1 was added to 97 parts of this liquid crystal composition.
The N-I point of a liquid crystal composition containing 3 parts of trans-p-terphenyl reaches 58°C, and when this is made into a TN cell similar to the above, the threshold voltage is 1.56V,
The saturation voltage was 2.15V. The viscosity was 26 cp at 20°C.

Claims (1)

[Claims] 1. General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms) trans-4-alkyl-trans-4″-(pentafluorobenzoyloxy)-octadecahydro-trans-p-terphenyl. 2 General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms.) A liquid crystal composition characterized by containing one type of liquid crystal composition.