JPS5982347A - Pentafluorobenzoic acid polycyclic cyclohexyl ester - Google Patents

Abstract

NEW MATERIAL:The compound of formula I (R is H or 1-10C alkyl). EXAMPLE:trans-4-Propyl-trans-4''-( pentafluorobenzoyloxy )-octadecahydrotrans-p- terphenyl. USE:A liquid crystal composition. A liquid crystal substance exhibiting liquid crystal phase over wide temperature range, and having high clear point and nevertheless low viscosity. PROCESS:The compound of formula I can be prepared by (1) demethylating the compound of formula II with hydrobromic acid to obtain the compound of formula III, (2) reducing the compound catalytically in ethanol solvent using ruthenium catalyst at 180 deg.C and 50kg/cm<2>, (3) separating the resultant compound of formula IV by recrystallizing with acetone, and (4) reacting the compound with pentafluorobenzoyl chloride of formula V in the presence of pyridine.

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 di 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 liquid crystal materials, and liquid crystal phases include nematic liquid crystal phase, smectic liquid crystal phase, and cholesteric liquid crystal phase, among which nematic liquid crystal is used. The one that has been put into practical use is the most widely used. 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 high 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, so the liquid crystal composition containing it also has a high viscosity. As a result, the response speed 1 of a liquid crystal display element that can be used at high temperatures, for example, up to about 80° C., especially at low temperatures, tends to become significantly slower. However, the present inventors have discovered 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, leading to the present invention.

That is, the present invention provides trans-4-alkyl-trans-4" represented by the general formula:
-(4-pentafluorobenzoyloxy)-octadecahydro-trans-p-terphenyl and a liquid crystal composition containing the same.

The compounds of the invention cure high clearing points, e.g. trans-4-propyl-trans-
The C-S point of 4"-(pentafluorobenzoyloxy)-octadecahydro-trans-p-terphenyl is 1
07℃, S-N point is 215.4℃, N-I point is 280.
It exhibits a liquid crystal phase in a wide temperature range of 3°C, and this
By adding it as a component, 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 approximately +1, the threshold voltage and saturation voltage of the composition are not increased to that extent. It also has good stability against moisture, 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)cycloheginyl J benzene produced by a known method is treated with hydrobromic acid. Demebulization yields 4-[trans-4'-()trans-4''-alkylcyclohexyl)duclohexyl]phenol. This was prepared using a rudenium catalyst in an ethanol solvent at 180°C for 50 minutes.
Contact collapse under the condition of 0N/C11t and transformer-4
-Alkyl-4"-hydroquine-transsuit hydrop-terphenyl was obtained.

This product was recrystallized from acetone to separate trans-4-alkyl-trans-4"'-hydroquine-trans-octadecahydro-p-terphenyl. This was reacted with pentafluorobenzoic acid chloride in the presence of pyridine. The desired trans-4-alkyl-trans-4”-(pentafluorobenzoyloxy)-octadecahydro-
Trans-p-terphenyl was produced. [1 is represented by the chemical formula: (+1 Hereinafter, the manufacturing 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 trans-4-propyl-trans-4''-(pentafluorobenzoyloxy)-octadecahydro-trans-p-terphenyl] 4-methquine-[trans-4' produced by a known method
-()Lannou 4"-propylcyclohexyl)cyclohexyl]Hensen 15f to hydrobromic acid (47%) 20
Reflux with 0 ml V and 200 ml acetic acid for 20 hours. After the reaction is completed, 500 g of water is added and the precipitated crystals are filtered off. After thoroughly washing with water, it was recrystallized from an acetone-ethanol mixed solvent. This is 4-[trans-4'-()trans-4''-furopyrunchlohequinl)nchlohexyl]phenol. Yield: 1dllF, yield: 77cm.

4-[trans-4'-(trans-4''-propylene clohequine) produced in this manner]
Phenol 81 was dissolved in ethanol 400 - and ruthenium/carbon catalyst 1. Add Of, 180℃, 50Kq/
7 for 5 hours of catalytic hydrogen reduction. After the reaction is completed, the catalyst is separated and the solvent is distilled off under reduced pressure. l of the remaining crystals
I! Recrystallize with acetone. This is trans-4'-
Propyl-trans-4"-hydroxy-octadecahydro-trans-p-terphenyl. Yield 3-8
t1 yield: 47゜, melting point: 232-237°C. Next, part 12
12 of pentafluorobenzoic acid chloride was added to a solution of 50 ml of pyridine, and the mixture was allowed to stand overnight. Add 200 g 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. The precipitated crystals were recrystallized from acetone to obtain the desired trans-4-propyl-trans-4"-(pentafluorobenzoyloxy)-octadecahydro-trans-p-terphenyl. Yield: 0.69. 33 Chi. This thing's C-
8 points are 10'7.0℃, S-N points are 215.4℃, N
-I point was 280.3°C.

Example 2.3 4-methoxy-[trans-4'-(
Trans-4'-(trans-4'-(trans-4'-alkylcyclohexyl)ncroheginyl) having an alkyl group instead of benzene can be used to create other trans -4-alkyl-trans-4"-(4-
Pentafluorobenzoyloxy)-octadecahydro-trans-p-terphenyl t Manufacture L ta.

Their physical property values are shown in Table 1.

Table 1 Example 4 (Usage example) Trans-4-propyl-(4'-anophenyl)cyclohexane 28 Thitrans-4-benzene(4'-anophenyl)cyclohexane 42 Thitrans-4-hebutyl-(4'-anophenyl) The N-I point of the liquid crystal composition having the composition of cyclohexane 30q6 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 1.53.
V, the saturation voltage was 2.12 V. Also, the viscosity is 2
It was 23 Cp at 0°C.

To 97 parts of this liquid crystal composition was added the trans-transformer produced in Example 1.
4-Propyl-trans-4"-(pentafluorobenzoyloxy)-ophtadehydrotran-p-terphenyl 3 parts k The N-I point of the liquid crystal composition added is 5
When the temperature rises to 8℃ and this is made into a TN cell similar to the above, the threshold voltage is 1.56 V and the saturation voltage is 2.15.
It was V. The viscosity was 26 Cp at 20°C.

Claims (2)

[Claims] (1) Trans-4-alkyl-trans-4'' represented by the general formula (indicates hydrogen or an alkyl group having 1 to 10 carbon atoms)
-(Pentafluorobenzoyloxy)-octadecahydro-trans-p-terphenyl. (2) trans-4-alkyl-trans-4'' represented by the general formula (in the above formula, R represents hydrogen or an alkyl group having 1 to 10 carbon atoms)
A liquid crystal composition comprising at least one type of -(pentafluorobenzoyloxy)-octadecahydro-trans-p-terphenyl.