JPS6058218B2 - liquid crystalline ester compound - Google Patents

Description

Detailed Description of the Invention The present invention has a wide liquid crystal temperature range and has a refractive index anisotropy (Δ
The present invention relates to a liquid crystalline ester compound in which n) is relatively small.

Conventionally, various display principles have been applied to electro-optical display elements using liquid crystals, and these have been put into practical use.

Nowadays, color displays are especially desired, and dichroic dyes or pleochroic dyes are added to liquid crystal compositions with positive or negative dielectric anisotropy, and cholesteric liquid crystals or optically active substances are also added. BACKGROUND ART A phase change type guest-host display that displays images by controlling the orientation of a liquid crystal composition using an electric field is attracting attention. The conditions required for liquid crystal materials used in phase change type guest-host displays are (
b) Wide liquid crystal temperature range.

(Note) The refractive index anisotropy (Δn) must be small to ensure the contrast of the display. 11 → Must have low viscosity.

and so on. Based on these conditions, there are compounds represented by the general formulas R R' and R N as known compounds that are advantageous for forming a matrix of a liquid crystal composition for a phase change type guest-host display. All of them have a small Δn and are excellent in low viscosity, but have the drawbacks of a low clearing point and a narrow liquid crystal temperature range.

On the other hand, as a compounding technology that improves the liquid crystal temperature range compared to conventional methods,
Addition of compounds with a wide liquid crystal temperature range and particularly high clearing point,
For example, compounds of the general formula R(',)be([〉1<[DX) are used, but all of these have the disadvantage of large Δn.Therefore, what is particularly required here is , Δn are small, and the liquid crystal temperature range is wide.An object of the present invention is to provide a liquid crystal compound that can be effectively used as a liquid crystal material for a phase change type guest host display as described above. There is.

That is, the compound of the present invention has the general formula (wherein R1 represents a straight chain alkyl group having 3 or 4 carbon atoms, and R2 represents a straight chain alkyl group having 4 or 5 carbon atoms.

) is P-(4″-n-alkylcyclohexyl)phenyl 4-n-alkylcyclohexyl carbonate.
″-alkylcyclohexyl)bendonitrile according to the literature (MOl.CrySt.Liq.CrySt.l979
4 according to the method of vOl56reTte5pp5l~56)
-(4''-Alkylcyclohexyl)aniline, 4-(4'-alkylcyclohexyl)phenol by a conventional method, and then esterified with commercially available 4-alkylcyclohexylcarbonyl chloride.
The reaction steps will be shown and outlined below. [Reaction process] Step Commercially available 4-(4-n-alkylcyclohexyl)benzonitrile "R. , 4-
(4'-n-alkylcyclohexyl)benzate.

SteP2 The above benzamide is placed in dry methanol in which sodium metal has been dissolved, and bromine is added while stirring vigorously.

Heat with stirring for 4 hours, then methanol is distilled off.
Water was added to the residue to precipitate methyl-4-(4″-n-
alkylcyclohexyl) phenyl carbamate
″7)′＞−NHCOOCH[R1→H＞7・−
5.3i pass.

Step 3 The above phenyl carbamate is dissolved in 80% ethanol, potassium hydroxide is added, and the mixture is refluxed for 24 hours under a nitrogen stream.

After refluxing, ethanol was distilled off, the residue was poured into water, and extracted with ether.

SteP4 After mixing the above aniline with 70% sulfuric acid, a sodium nitrite aqueous solution is gradually added while cooling to prepare a diazosulfate solution.

This diazosulfate solution is poured into a 50% sulfuric acid solution heated to about 100° C. for hydrolysis. The cooled and solidified crystals were filtered, washed with water, dried, and sublimated under reduced pressure to give 4-(4″-n-alkylcyclohexyl)phenol
)-0H] is prepared.

Step 5 The above phenol and commercially available 4-n-alkylcyclohexylcarbonyl chloride [R to H>-COI
] in pyridine to obtain the related P-(4
″-n-alkylcyclohexyl carbonate is produced.

Hereinafter, production examples and application examples will be described as examples, and aspects of the present invention will be explained in more detail.

Example 1 [Production Example 1] Stepl Commercially available 4-(4''-n-propylcyclohexyl)benzonitrile 23y and 36 g of potassium hydroxide were dissolved in 750 ml of 70% ethanol and heated under reflux for 16 hours.

After refluxing, the precipitated crystals were filtered, washed with water, and dried. The infrared absorption spectrum of the compound is shown in FIG. Step 2 80f of sodium metal was dissolved in 3900ml of dry methanol, and 13.5y of acid amide obtained by StePl was dissolved in this solution that was cooled to room temperature.

An additional 40.5 ml of bromine was added while stirring vigorously, and the mixture was gently heated for 4 hours. After the reaction, methanol was distilled off, 3000J1L of water was added to the residue, and the resulting precipitate was filtered. The infrared absorption spectrum of the compound is
As shown in the figure. Step 3 7.8y of crude carbamate obtained in stepP2 was added to 860ml of 80% ethanol in which 215y of potassium hydroxide was dissolved.
In addition to the solution, a rubber balloon sealed with nitrogen was placed above the condenser and heated under reflux for 2 hours.

After refluxing, ethanol was distilled off, and the residue was poured into 1000 mL of water. This aqueous solution was placed in a separator and extracted three times with 200 mL of ether. The ether solutions were combined and dehydrated over anhydrous sodium sulfate, and then the ether was distilled off. Further, the residue was distilled under reduced pressure. The infrared absorption spectrum of the compound is shown in FIG. SteP4 The aniline 5y obtained in steP3 was mixed with 12 ml of concentrated flowing acid, and further 12 ml of 40% sulfuric acid was added, stirred thoroughly to form a homogeneous mixture, and then cooled on ice.

Meanwhile, dissolve 2.7y of sodium nitrite in 6ml of water,
While cooling, the mixture was gradually added dropwise to the aniline and sulfuric acid mixture to prepare a diazosulfate solution. This was left to cool for about 1 hour. While diazotization is in progress, a 50% sulfuric acid solution is heated at 90°C on a water bath.
The diazo sulfate solution was added to this hot solution and stirred. Stir for 30 minutes, then cool and wash the solidified crystals with water.
After drying, sublimation was performed under reduced pressure (2 mHg).

FIG. 4 shows the infrared absorption x vector of the compound. St
Phenol 1y obtained in ep5-SteP4 was added to pyridine 10rf.
The mixture was dissolved in Lt, 0.93y of 4-n-butylcyclohexylcarbonyl chloride was added thereto, mixed well, and then left at room temperature for 15A.

After the reaction, an appropriate amount of ice chips was poured into hydrochloric acid, and the precipitated crystals were filtered 7 and recrystallized with ethanol. The infrared absorption spectrum of the compound is shown in FIG. In this way, the related P-(4″-n-propylcyclohexyl)phenyl 4-n-butylcyclohexyl carbonate was produced. The transition point of the compound is shown in Table 1. Example 2 [Production Example 2] Example 1 The 4-(4″-n-propylcyclohexyl)phenol obtained in (Step 4) and commercially available 4-n-pentylcyclohexylcarbonyl chloride were esterified in the same manner, and the resulting P-(4″-n-propylcyclohexyl)phenyl 4 -n-pentylcyclohexyl carbonate was produced.

The infrared absorption spectrum of the compound is shown in FIG. 6, and the transition point is shown in Table 1. Example 3 [Production Example 3] In the same manner as in Example 1, 4-(4″-n-butylcyclohexyl)benzonitrile manufactured by Merck & Co., Ltd. was converted into 4-(4″-n-butylcyclohexyl)benzonitrile.
Butylcyclohexyl)phenol was esterified with 4-n-butylcyclohexylcarbonyl chloride to produce P-(4''-n-butylcyclohexyl)phenyl 4-n-butylcyclohexyl carbonate.

The infrared absorption spectrum of the compound is shown in FIG. 7, and the transition point is shown in Table 1. Example 4 [Production Example 4] 4-(4″-butylcyclohexyl)phenol obtained in Example 3 and 4-n-pentylcyclohexylcarbonyl chloride were esterified to produce the related P-(4′-n-
Butylcyclohexyl) phenyl 4-n-pentylcyclohexyl carbonate was prepared.

The infrared absorption spectrum of the compound is shown in FIG. 8, and the transition point is shown in Table 1. Example 5 (Evaluation) A liquid crystal composition shown in Table 2 was prepared, and the compound P-(4-n-propylcyclohexyl)phenyl 4-
Changes in Δn and clearing point depending on the amount of n-butylcyclohexyl carbonate mixed were investigated.

As a result, Δn hardly changed, and its value was small at around 0.1. In addition, the change in clearing point had a remarkable increasing effect. These properties are excellent in terms of the conditions required of the liquid crystal material for the phase change type guest-host display described above.
As described above, the liquid crystalline ester compound provided by the present invention has a relatively small Δn, a wide liquid crystal temperature range, and has very excellent properties as a phase change type guest-host liquid crystal material. It has great practical value.

Furthermore, the compound provided by the present invention is not limited to the liquid crystal composition formed in Example 5, but can also be mixed with various existing liquid crystal substances to form liquid crystal compositions with excellent properties. , the liquid crystal composition is used in various field effect liquid crystal displays.

[Brief explanation of the drawing]

Figures 1 to 8 are infrared absorption spectra of the compounds shown below.

Claims (1)

[Claims] 1 The general formula is ▲ Numerical formula, chemical formula, table, etc. 1. A liquid crystalline ester compound represented by (representing a straight-chain alkyl group).