JPH0229055B2 - JISHIKUROHEKISHIRUBENZENJUDOTAI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel liquid crystal material and a liquid crystal composition containing the same.

Liquid crystal display elements utilize the optical anisotropy and dielectric anisotropy of liquid crystal materials, and depending on the display format, there are TN type (twisted nematic type), DS type (dynamic scattering type), and guest type. There are various types such as host type and DAP type, and the properties of the liquid crystal materials suitable for each type of use are different. However, all liquid crystal materials have in common that they need to be stable against moisture, air, heat, light, etc., and they are also required to exhibit a liquid crystal phase over as wide a temperature range as possible, centered around room temperature. ing. However, at present, there is no single compound that satisfies these conditions, and the current situation is to use liquid crystal compositions obtained by mixing several types of liquid crystal compounds and non-liquid crystal compounds. Especially recently-
Liquid crystal display elements that operate over a wide temperature range of 20°C to 80°C have come to be required. In order to satisfy such requirements, an effective means is to lower the viscosity, especially the viscosity at low temperatures. However, in general, those with a high clearing point (NI point) have a high viscosity, and those with a low viscosity, such as alkylphenylcyclohexane derivatives, have a low clearing point.

An object of the present invention is to provide a liquid crystal compound that has low viscosity and a high clearing point and can be driven at low voltage to meet the above requirements.

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) 4-[trans-4'-(trans-
4″-substituted cyclohexyl)cyclohexal]benzotrifluoromethane.

The compound of the present invention is smectic at about 130°C.
Because it has a clearing point (SI point) and low viscosity,
By appropriately mixing this material with other liquid crystal substances, a liquid crystal composition having low viscosity and a high clearing point can be constructed.

Next, a method for producing the compound of the present invention will be described.

First, 4-trifluoromethylbromobenzene is reacted with metallic magnesium to form 4-trilifluoromethylbenzene magnesium bromide, which is then reacted with 4-(trans-4'-alkylcyclohexyl)cyclohexane to produce 4-[4'-(trans -4″-alkylcyclohexyl)cyclohexane-1′-ol]benzotrifluoromethane.Next, this is dehydrated with potassium hydrogen sulfate to give 4
-[4'-(trans-4''-alkylcyclohexyl)cyclohexen-1'-yl]benzotrifluoromethane is obtained. This is dissolved in toluene and subjected to catalytic reduction under a Raney-nickel catalyst at room temperature and pressure to obtain the desired 4-[ Transformer-4'- (Trans-
4″-alkylcyclohexyl)cyclohexyl]
Obtain benzotrifluoromethane. 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 [Production of 4-[trans-4′-(trans-4″-propylcyclohexyl)cyclohexyl]benzotrifluoromethane] 1.2 g (0.049 mol) of magnesium turnings was placed in a three-necked flask and 4-trifluoromethane was added. 25 ml of a solution of 11.0 g (0.049 mol) of methylbromobenzene dissolved in _{tetrahydrofuran} was heated to a reaction temperature of 30 ~
While keeping the temperature at 35°C, the magnesium is slowly added dropwise, and the reaction dissolves in 3 hours to form a homogeneous liquid, producing 4-trifluoromethylbenzenemagnesium bromide, which is followed by 4-(trans-
8.7 g (0.039 mol) of cyclohexanone (4'-propylcyclohexyl) dissolved in tetrahydrofuran to make 50 ml is added dropwise as quickly as possible while maintaining the reaction temperature at 5 to 110°C. After the dropwise addition, the mixture was heated to room temperature, stirred for 1 hour, and then 100 ml of 3N hydrochloric acid was added. Transfer 100ml of the reaction solution to a separating funnel.
After extraction three times with toluene, the combined toluene layers were washed with saturated brine until the washings became neutral, and then the toluene was distilled off under reduced pressure. The remaining oil is 4
-[4′-(trans-4″-propylcyclohexyl)cyclohexane-1′-ol]benzotrifluoromethane, and potassium hydrogen sulfate is added to it.
Add 4.0g and dehydrate at 150℃ for 1 hour in a nitrogen stream.
After cooling, add 200 ml of toluene, separate the potassium hydrogen sulfate, and wash the toluene layer with water until the washing solution becomes neutral. Then, toluene was distilled off under reduced pressure,
The remaining oil was recrystallized with ethanol to give 4-[4'-
Obtain (trans-4″-propylcyclohexyl)cyclohexen-1′-yl]benzotrifluoromethane. Dissolve 3.2g of this in 100ml of toluene.
Add 1 g of Ranenitsuketsuketu and perform catalytic reduction at room temperature and pressure. The reaction was followed by gas chromatography, and the reaction was terminated when the raw materials disappeared. After separating the catalyst, the solvent was distilled off under reduced pressure, and recrystallization was performed with n-heptane to obtain 0.4 g of the desired 4-[trans-4-(trans-4″-propylcyclohexyl)cyclohexyl]benzotrifluoromethane.Crystals. Smectic point (C-S point) below room temperature, S-I
The temperature at the point was 131.7℃.

Example 2 (Usage example) Trans-4-propyl-(4'-cyanophenyl)cyclohexane 28% Trans-4-pentyl-(4'-cyanophenyl)cyclohexane 42% Trans-4-heptyl-(4'-cyanophenyl)cyclohexane The nematic liquid crystallinity range of the liquid crystal composition having a composition of 30% is -3 to 52°C. This liquid crystal composition has a cell thickness of
When sealed in a 10 μm TN cell (twisted nematic cell), the operating threshold voltage was 1.53V and the saturation voltage was 2.12V. The viscosity was 23 cp at 20°C, and the refractive index anisotropy Δn was 0.120.

A nematic liquid crystal composition prepared by adding 10 parts of 4-[trans-4'-(trans-4''-propylcyclohexyl)cyclohexyl]benzotrifluoromethane shown in Example 1 of the present invention to 90 parts of the above liquid crystal composition. The clearing point rose to 56.3℃, and although it was sealed in the above cell, the operating threshold voltage remained unchanged at 1.5V and the saturation voltage remained at 2.0V, and the viscosity at 20℃ did not increase much at 25.1cp.As described above, The compounds of this invention are useful in making compositions with low viscosity and a wide nematic temperature range.

Claims (1)

[Claims] 1. General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms) 4-[trans-4'-(trans-
4″-substituted cyclohexyl)cyclohexyl]benzotrifluoromethane. 2 General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms.)
A liquid crystal composition containing at least one type of 4″-substituted cyclohexyl)cyclohexyl]benzotrifluoromethane.