JPS5998038A - 2,4,5-trifluorobenzoic acid phenyl ester - Google Patents

Abstract

NEW MATERIAL:2,4,5-Trifluorobenzoic acid 4-trans-4-(trans-4-alkylcyclohexyl)- cyclohexylphenyl ester of formula I (R is H or 1-10C alkyl). USE:A component of liquid crystal composition. It has small positive dielectric anisotropy, and low threshold voltage, saturation voltage, driving voltage and power consumption. A composition especially having high N-I point can be obtained. PROCESS:The compound of formula I can be prepared by reacting 2,4,5-trifluorobenzoic acid chloride of formula II with 4-[trans-4-(trans-4-alkylcyclohexyl) cyclohexyl]phenol in the pesence of pyridine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel fluorine-containing organic compound having weak positive dielectric anisotropy useful as a component of a liquid crystal composition, and a liquid crystal composition containing the same.

Display elements using liquid crystals have come to be widely used in watches, trains, etc. These liquid crystal display elements are divided into TN type (twisted nematic type), DB type (dynamic scattering type), guest-host type, DAP type, dual frequency method type, etc. depending on the liquid crystal display method, and are used depending on each type. Although the properties of the liquid crystals used are different, there is a demand for liquid crystals with a large absolute value of dielectric anisotropy. This is because by using a liquid crystal composition with a large absolute value of dielectric anisotropy, the driving voltage of the display element can generally be lowered and the response characteristics can be improved. However, if there is a liquid crystal that can be driven at low voltage even if the absolute value of dielectric anisotropy is not large, the power consumption of the display element can be further reduced.
This makes it even more desirable.

The present inventor has extensively searched for compounds having such characteristics, and as a result, has discovered that certain fluorine-containing compounds satisfy such requirements, and has arrived at the present invention.

That is, the present invention provides 2, 4. represented by the general formula (in the above formula, R represents an alkyl group having 1 to 10 carbon atoms). A liquid crystal composition containing 5-1-lifluorobenzoic acid-4-[trans-4-(trans-4-alkylcyclohexyl)cyclohexyl] phenyl ester and a small amount (at least one type thereof).

The compounds of the present invention exhibit a nematic phase over a wide temperature range,
It has low viscosity, and the dielectric anisotropy value Δε is about +1. Although the liquid crystal composition containing the compound of the present invention has a small dielectric anisotropy, the threshold voltage and saturation voltage are low, and it is possible to obtain a liquid crystal display element with a low driving voltage and therefore low power consumption. enable. The liquid crystal compound to be mixed with the present compound may be appropriately selected depending on the type of display device, usage, etc. (It is particularly suitable for producing a composition with a high N (nematic)-I (transparent) point.

Furthermore, the compound of the present invention can handle the heat, light, humidity, and
It also has stability against electricity and tends to have a low viscosity when mixed with other liquid crystals.

Next, the method for producing the compound of the present invention is shown by reacting 4-[trans-4-(trans-4-alkylcyclohexyl)cyclohexacyl]phenol with 2,4,5-trifluorobenzoic acid chloride in the presence of pyridine. By doing so, the desired 2,4°5-trifluorobenzoic acid-4-[trans-4-(trans-4-alkylcyclohexyl)cyclohexyl]phenyl ester can be obtained.

This is represented by a chemical formula (R is the same as above).The present invention will be explained in more detail by showing production examples and usage examples of the compounds of the present invention as Examples.

Example 1 (Preparation of 2,4', 5''l-lifluorobenzoic acid-4-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]phenyl ester) 2.4..5-1-lifluorobenzoic acid Chloride 1, O
g, 4-trans-4-(trans-4-propylcyclohexyl)cyclohexyl]phenol 1.5#
(0,005 mol) dissolved in pyridine 50-. After the reaction, add 50 g of toluene and leave it overnight, then pour into 100 g of water. Separate the toluene layer and 5N-EC
After extracting three times with t and three times with a 2N-NaOH aqueous solution, the toluene layer is washed with water until it becomes completely neutral, and then the toluene layer is reduced in pressure and the toluene is distilled off, leaving crystals. Recrystallize it with ethanol to obtain the desired product (2, 4.5-)
Lifluorobenzoic acid-4-[trans-4-(trans-47-propylcyclohexyl)cyclohexyl]phenyl ester was obtained. Yield: 0.9 g, yield: 39. The C-8m point is 104'Q, and the Sm-N point is 144
'[, N-1 point was 260C.

Example 2 4-[trans-4-(trans-4) in Example 1
-Propylcyclohexy)L/)cyclohexyl]Phenol was replaced with 4-Ctrans-4-():l>Nsu4-alkylcyclohexyl)cyclohexyl]Phenol (0.005 mol). A compound was prepared.

2.4.5-1 Lifluorobenzoic acid-4-[trans-
(trans-4-butylcyclohexyl)cyclohexyl]phenyl ester. C-8m point 101C, 8m-N
Point 141'r::, am-N point 204C0 Example 3 (Usage example) 4-pentel-4'-cyanobiphenyl 51%
(Weight, the same below) 4-hephthyl-4'-cyanobiphenyl 32-4-octyloxy-47-cyanobiphenyl The N-I point of the liquid crystal mixture with the composition 17 is 44.3r, the viscosity is 400p at 2Or, and the dielectric The anisotropy value is +12.4.

When it is made into a TN cell, the threshold voltage is 1.65
V, the saturation voltage is 2.31V. 3. 2.4 of Example 1 of the present invention was added to 95 parts of this liquid crystal mixture. ．． 5
-Trifluorobenzoic acid-4-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]
The N-I point of the liquid crystal mixture to which 5 parts of phenyl ester was added was 54. Ot? The dielectric anisotropy value increased to +11.0. The viscosity was 20c and 400p. Also, when using a TN cell, the threshold voltage is 1.60V and the saturation voltage is 23. It became a little lower in OV.

that's all

Claims (2)

[Claims] (1) 2,4,5-trifluorobenzoic acid-4- represented by the general formula (in the above formula, R represents a hydrogen atom or an alkyl group having 1 to 1 o carbon atoms)
[trans-4-(trans-4-alkylcyclohexyl)cyclohexyl]phenyl ester. (2) 2,4,5-trifluorobenzoic acid-4- represented by the general formula (in the above formula, R represents a hydrogen atom or an alkyl group having 1 to 1 o carbon atoms)
A liquid crystal composition containing at least one type of [trans-4-(trans-4-alkylcyclohexyl)cyclohexyl]phenyl ester.