JPH05255194A - Ester derivative - Google Patents

Abstract

PURPOSE:To provide the subject derivative consisting of a carboxylic acid allyl ester derivative containing cyclohexylene group, capable of controlling birefringence to an arbitrary level and lowering its viscosity to increase the response speed and useful e.g. as a liquid crystal material having low threshold voltage and drivable at a low voltage. CONSTITUTION:The objective ester derivative of formula II [e.g. 4-(trans-4'- propylcyclohexyl)benzoic acid allyl ester] can be produced by reacting a cyclohexylbenzoic acid of formula I (R<1> is 1-10C alkyl; A is 1,4-phenylene or 1,4-cyclohexylene) [e.g. 4-trans-4'-propylcyclohexyl)benzoic acid] with thionyl chloride for 2hr under refluxing, distilling out thionyl chloride under reduced pressure, extracting the product with toluene, distilling out the solvent, recrystallizing the residue with methanol to obtain an acid chloride, dissolving the acid chloride in pyridine, adding allyl alcohol to the solution, reacting at 40 deg.C for 3hr, adding water to the reaction product, separating the organic layer, distilling out the solvent under reduced pressure and recrystallizing the product with hexane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ester derivative and a liquid crystal composition containing the ester derivative.

[0002]

A twisted nematic type (TN type) liquid crystal display device utilizes optical anisotropy and dielectric anisotropy of a liquid crystal material and is widely used in watches, calculators, televisions and the like.

[0003]

The characteristics required of the conventional TN type liquid crystal display device include high-speed response, low voltage driving, high contrast and wide viewing angle. In response to such demands, liquid crystal materials are required to have optimized birefringence Δn for high contrast, reduced viscosity for high-speed response, and reduced threshold voltage Vth for low voltage driving. Has been done.

However, at present, no liquid crystal compound satisfying all such requirements has been obtained. Therefore, at present, several kinds of liquid crystal compounds are mixed or additives are mixed for practical use.

Therefore, the object of the present invention is to provide an ester derivative which can be added to a liquid crystal composition to bring its birefringence Δn to a desired value and to reduce the viscosity.

[0006]

The ester derivative of the present invention is represented by the following general formula (I), and the liquid crystal composition contains at least one ester derivative.

[0007]

[Chemical 2]

(However, R ¹ represents an alkyl group having 1 to 10 carbon atoms, and A represents 1,4-phenylene or 1,4-cyclohexylene.)

The ester derivative (I) of the present invention can be produced, for example, by the production method shown in Chemical formula 3.

[0010]

[Chemical 3]

First, a halogenating agent is allowed to act on 4- (trans-4'-alkylcyclohexyl) benzoic acid or 4- (trans-4'-alkylcyclohexyl) cyclohexylcarboxylic acid (a) to give an acid chloride (b). obtain. As the halogenating agent, thionyl chloride, phosphorus pentoxide or the like can be used.

Next, after reacting the acid chloride (b) with allyl alcohol in an inert solvent such as pyridine, the reaction product is subjected to purification operations such as washing with water, drying, recrystallization, etc. The ester derivative (I) can be produced.

The ester derivative (I) of the present invention has a high solubility in other liquid crystal materials, and can be easily dissolved in other liquid crystal materials to prepare a liquid crystal composition. Ester-based, cyclohexylphenyl-based, biphenyl-based, dioxane-based, tolan-based, and the like can be given as examples of liquid crystal materials that can be mixed.

[0014]

EXAMPLES The present invention will be described in detail below based on examples.

EXAMPLE 1 24.6 g of 4- (trans-4'-propylcyclohexyl) benzoic acid and 35.7 g of thionyl chloride were reacted under reflux for 2 hours, and after completion of the reaction, thionyl chloride was distilled off under reduced pressure. Next, the reaction product was extracted with toluene, washed, dried and filtered. The obtained filtrate was distilled off under reduced pressure, and the residue was recrystallized from methanol to obtain 18 g of 4- (trans-4′-propylcyclohexyl) benzoic acid chloride.

After dissolving this acid chloride in 90 ml of pyridine, 4.7 g of allyl alcohol and 8 g of pyridine were further added.
Was added and reacted at 40 ° C. for 3 hours. 100 water after reaction
ml was added and the organic layer was separated, washed, dried and filtered.
The solvent was distilled off under reduced pressure from the liquid behind. The obtained reaction product was recrystallized from hexane to obtain 12 g of 4- (trans-4′-propylcyclohexyl) benzoic acid allyl ester represented by Chemical formula 4. The melting point of this compound was 0 ° C.
The infrared absorption spectrum of this compound is shown in FIG.

[0017]

[Chemical 4]

Example 2 The procedure of Example 1 was repeated except that 26 g of 4- (trans-4′-butylcyclohexyl) benzoic acid was used instead of 4- (trans-4′-propylcyclohexyl) benzoic acid. 13 g of 4- (trans-4′-butylcyclohexyl) benzoic acid allyl ester represented by 5 was obtained. The melting point of this compound was -2 ° C. The infrared absorption spectrum of this compound is shown in FIG.

[0019]

[Chemical 5]

Example 3 The same as Example 1 except that 25.2 g of 4- (trans-4′-propylcyclohexyl) cyclohexanecarboxylic acid was used instead of 4- (trans-4′-propylcyclohexyl) benzoic acid. And represented by the formula 6 4-
14 g of (trans-4′-propylcyclohexyl) cyclohexanecarboxylic acid allyl ester was obtained. This compound was a liquid crystal and had a C-S point of 7 ° C and an SI point of 43 ° C. The infrared absorption spectrum of this compound is shown in FIG.

[0021]

[Chemical 6]

Example 4 Example 4 was repeated except that 4- (trans-4′-pentylcyclohexyl) cyclohexanecarboxylic acid g was used in place of 4- (trans-4′-propylcyclohexyl) benzoic acid. 14 g of 4- (trans-4′-pentylcyclohexyl) cyclohexanecarboxylic acid allyl ester represented by Chemical formula 7 was obtained. This compound was a liquid crystal and had a C-S point of 32 ° C and an SI point of 70 ° C. The infrared absorption spectrum of this compound is shown in FIG.

[0023]

[Chemical 7]

Example 5 A liquid crystal composition was prepared by adding 10 parts by weight of the compound represented by the chemical formula 4 to 90 parts by weight of the liquid crystal composition consisting of the compound represented by the chemical formula 8 and measuring its characteristics ( Table 1). Further, this liquid crystal composition was mounted in a TN type liquid crystal cell having a cell thickness of 9 μm, and the threshold voltage Vth thereof was measured.

[0025]

[Chemical 8]

[0026]

[Table 1]

Comparative Example The characteristics of the liquid crystal composition consisting only of the compound represented by the chemical formula 8 are: NI point 63 ° C., Δn 0.1070, viscosity 37.2.
cps, threshold voltage Vth 49V.

Examples 6 to 8 To 90 parts by weight of a liquid crystal composition consisting only of the compound represented by the chemical formula 8, the compounds represented by the chemical formulas 5, 6, and 7 are added.
A liquid crystal composition containing 0 part by weight was prepared, and its characteristics were measured in the same manner as in Example 5, and the results are shown in Table 1.

[0029]

As described above, when the ester derivative of the present invention is added to the liquid crystal composition, its birefringence Δ
The viscosity can be reduced by setting n to a desired value. Further, as is clear from the examples, it is a very excellent liquid crystal material because it does not lower the NI point and does not raise the threshold voltage Vth. Furthermore, the ester derivative of the present invention has high mutual solubility with various compounds,
It can be used in combination with many liquid crystal materials as a constituent component of the liquid crystal composition, and is useful for improving the characteristics of the liquid crystal composition.

[Brief description of drawings]

FIG. 1 is a diagram showing an infrared absorption spectrum of an ester derivative of the present invention.

FIG. 2 is a diagram showing an infrared absorption spectrum of the ester derivative of the present invention.

FIG. 3 is a diagram showing an infrared absorption spectrum of the ester derivative of the present invention.

FIG. 4 is a diagram showing an infrared absorption spectrum of the ester derivative of the present invention.

Claims (2)

[Claims] 1. An ester derivative represented by the following general formula (I). [Chemical 1] (However, R ¹ represents an alkyl group having 1 to 10 carbon atoms,
A represents 1,4-phenylene or 1,4-cyclohexylene. ) 2. A liquid crystal composition containing at least one ester derivative according to claim 1.