JPH0615507B2 - Liquid crystalline substance, method for producing the same and liquid crystal composition containing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid crystal compound having a 1,2-dialenenylethane skeleton, a method for producing the same, and a chiral smectic liquid crystal composition containing the same.

INDUSTRIAL APPLICABILITY The liquid crystal compound of the present invention and the liquid crystal compound containing the same are useful as a display device having excellent image display responsiveness.

At present, a display element made of a liquid crystal material is a light-receiving type display system, and has features such as low power consumption and the ability to create a thin display device, and is widely put to practical use. On the other hand, EL (electroluminescence) and plasma displays, which are light-emitting display systems and feature high-speed response, are also being actively developed.

[Conventional technology]

Most of the liquid crystals that have been used for display devices so far are nematic liquid crystals, and the mainstream of them is TN (Twisted Nematic (Tw
isted Nematic)] type. This TN type display system
Although it has advantages such as small size and low power consumption, it also has a drawback that the response speed of image display is slow. Various attempts have been made to improve this point, but Molecular Crystals and Liquid Crystals (Molecular Cry
stals and Liquid Crystals) Vol. 94, pp. 155-165, only the results of demonstrating the theoretical limit values seem to be reached, and the development of materials for TN type displays is almost at the limit.

Therefore, in order to overcome the above drawbacks, in recent years, interest has been shifted to the development of chiral liquid crystals in place of nematic liquid crystals, and considerable progress has been made especially in ferroelectric liquid crystals.

The first developed ferroelectric liquid crystal was A compound represented by (wherein * represents an asymmetric carbon atom) (hereinafter abbreviated as DOBAMBC), and its liquid crystal phase sequence and phase transition temperature (° C) are as follows.

(In the formula, C represents a liquid crystal phase, S _A represents a smectic A phase, S _C ^* represents a chiral smectic C phase, S _H ^* represents a chiral smectic H phase, and I represents an isotropic liquid).

Ferroelectricity is found in a chiral smectic C phase (hereinafter abbreviated as S _C ^* ) or a chiral smectic H phase (hereinafter abbreviated as S _H ^* ) which is classified and named according to the molecular arrangement. The possibility of obtaining a display element that can be used is due to RB Meyer, et al., Journal of Physics France (Journal of P
hysics France) 36, 69 (1975).

Since then, various analogues of DOBAMBC have been synthesized, but since the lower limit of the temperature range belonging to S _C ^* or S _H ^* is higher than room temperature, and the compound itself is unstable to moisture and light,
The focus of research has shifted to the ferroelectric liquid crystal compounds of ester yarns shown in Table 1 below.

(Note) The symbols in the table indicate the following.

[Problems to be Solved by the Invention] As a result, although chemically stable compounds were obtained, as shown in Table 1, these liquid crystal compounds alone have a melting point higher than room temperature and are not practical. In addition, when the compounds shown in Table 1 are mixed with each other, a large melting point drop is not found because the molecular structures are similar.

[Means for solving problems]

The present inventor found a liquid crystalline substance suitable for use in a display device as a result of searching for a basic skeleton that essentially influences the physical properties of the liquid crystalline substance from the above viewpoint, and arrived at the present invention.

That is, the present invention has the general formula [I] (Wherein R is an alkyl group having 1 to 20 carbon atoms, R ^* is an optically active alkyl group having 4 to 13 carbon atoms having an asymmetric carbon atom, and n is 0 or 1). , 2
-A liquid crystalline compound having a diallenylethane skeleton, a method for producing the same, and a liquid crystal composition containing the same.

In the general formula [I], the 1,2-diphenylethane skeleton part is named as follows.

Therefore, the compound represented by the above general formula [I] is
1- (4'-alkyloxycarbonylphenyl) -2- (4 "-alkoxyphenyl) ethane for n = 0, 1- [4 '-(p-alkoxycarbonylphenyl) for n = 1 Oxycarbonylphenyl] -2-
They can be named as (4 ″ -alkoxyphenyl) ethane, respectively.

The production method of the compound represented by the general formula [I] will be described in detail below, but an optically active alcohol is used as one of the production raw materials. The optically active alcohol can be obtained at low cost in consideration of industrial versatility, for example, 1-methylbutanol, 2-methylbutanol, 3-methylpentanol, 4-methylhexanol, 5-methylheptanol, 6- Methyloctanol, 1-methylheptanol, 1-methylpropanol, etc. are often used.

The outline of the method for producing the compound of the present invention is represented by the following formula.

[Wherein R ^* is , R is an alkyl group having 1 to 20 carbon atoms, and n is 0 or 1
, And Pd / C represents palladium / carbon, respectively.].

In the production method of the present invention, palladium / carbon is used as a catalyst. In addition to this, Ni-based such as Raney nickel, Pt-based and Ph-based such as platinic oxide can be used, but Pd / C-based is cheap and easy to handle. preferable.

The solvent used in the production method of the present invention may be any solvent as long as it dissolves the substrate and does not react with the substrate, but ethyl acetate is preferred because it is common and easy to handle.

[Action]

Many of the compounds of the present invention showed an S _C ^* phase suitable for a display device utilizing ferroelectricity. Further, a compound having a larger spontaneous polarization magnitude P _S value in the S _C ^* phase than a conventional compound is expected.

This is due to the structure in which the chiral carbon atom is located closer to the dipole as shown in the following formula [Group A] (Katsumi Yoshino et al., Jpn. J. Appl. Phys., 23 (3), L175
(1984)).

(In the formula, * represents a chiral carbon atom, and ↑ represents the dipole polarization direction.) Therefore, in the present invention, as shown in the following formulas [group B] and [group C], a fluorine atom or a triatomic atom is used. By introducing a methyl fluoride group, it is possible to synthesize a compound having a similarly large P _S value.

(In the formula, R is an alkyl group, and * and ↑ have the same meanings as above.) From the formula [IV], it is important that the magnitude P _{S of the} spontaneous polarization is important for obtaining a switch element having a fast response. Easy to judge.

(In the formula, τ is the response time, η is the viscosity, P _S is the spontaneous polarization, and E is the strength of the electric field.) As described above, in the present invention, a liquid crystal compound having a large spontaneous polarization is expected. The compounds of the invention have the characteristic of exhibiting a melting point close to or below room temperature. This property is considered to be based on the flexible ethylene group (—CH ₂ CH ₂ —) in the basic skeleton of the compound of the present invention.

〔Example〕

Next, the present invention will be described with reference to examples, but% in the examples means% by weight.

Production Example 1 Synthesis of 4-alkoxycarbonylbromobenzene and 4- (4'-alkoxycarbonylphenyl) oxycarbonylbrombenzene In a 100 cc three-necked flask equipped with a stirrer, thermometer and reflux condenser, 4-bromobenzoic acid was added. After charging 3 g (15 mmol) and 10 ml of thionyl chloride and reacting at 70 ° C. for 2 hours with stirring, excess thionyl chloride was distilled off under reduced pressure.
The corresponding acid chloride was obtained. In another reaction vessel similar to the above, 15 mmol of optically active alcohol or optically active alkoxycarbonylphenol and 10 ml of pyridine were placed and dissolved.
To this pyridine solution, the above acid chloride dissolved in 20 ml of tetrahydrofuran was added under ice cooling, and the temperature was raised to room temperature.
It was stirred for 24 hours. Tetrahydrofuran and pyridine were distilled off under reduced pressure, and the residue was dissolved in 100 ml of ether, 10% NaO.
It was washed with an aqueous solution of H and dried over anhydrous sodium sulfate. After that, the ether was distilled off, and the residue was subjected to silica gel column chromatography (200 mesh silica gel 100 g, developing solvent hexane: benzene = 1: 1) to give 4- in Table 2.
Alkoxycarbonyl brombenzene or 4- (4'-
Alkoxycarbonylphenyl) oxycarbonylbromobenzene was obtained in a yield of 74-97%. Its structure is IR,
Confirmed by NMR spectrum and Weilstein test.

The results are shown in Table 2.

Production Example 2 Synthesis of 4-alkoxyphenylacetylene [A] In a 500 cc three-necked flask equipped with a stirrer, thermometer and reflux condenser, 4-alkoxybromobenzene 0.234 mol, 3-methyl-1- Butyn-3-ol 29.5
7 g (0.352 mol), triphenylphosphine 1.00 g, dichlorobis (triphenylphosphine) palladium catalyst
0.52 g (0.73 mmol) and 200 ml of triethylamine were charged, dissolved with stirring, and 160 mg of copper iodide was added. After stirring at room temperature for 3 hours, the mixture was gradually heated, and the internal temperature was brought to 90 ° C in 30 minutes. The reaction was carried out at this temperature for 20 hours. After the reaction, the temperature was returned to room temperature, triethylamine was distilled off under reduced pressure, 300 ml of ether was added to the residue, washed with water, and dried over anhydrous sodium sulfate. After that, ether was distilled off, and the residue was subjected to silica gel column chromatography (200 mesh silica gel 400
g, developing solvent: benzene) to obtain a compound [B] of the following formula as an intermediate compound.

In a 300 cc. Three-necked flask equipped with a stirrer, a thermometer and a distillation device, the above compound [B] 58.4 mmol, in a nitrogen stream,
120 ml of anhydrous toluene and sodium hydride (60%
Nudur dispersant) (310 mg) was added, and the mixture was stirred at room temperature for 30 minutes. It was heated gradually and the internal temperature was brought to 70 ° C after 30 minutes. Acetone (by-product) started to reflux and started to distill with toluene, but it was further heated and the reaction was continued until the distillation temperature reached the boiling point of toluene. During this period, 2 hours were required, and the amount of the solvent distilled off was 60 ml. After completion of the reaction, the temperature was returned to room temperature, 100 ml of benzene was added, washed with water, and dried with anhydrous sodium sulfate. After that, the organic solvent was distilled off, and the residue was subjected to silica gel column chromatography (200 mesh silica gel 150
g, developing solvent: hexane) to give 4-alkoxyphenylacetylene of Table 3 in a yield of 70 to 82%. Its structure was confirmed by IR and NMR spectra.

The results are shown in Table 3.

Similarly, in the group -OR, a compound in which R is a methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, nonyl, undecyl, tridecyl or tetradecyl group can be prepared.

Production Example 3 Production of 4-alkoxycarbonyl-4′-alkoxytran [III] (n = 0) In a 100 cc. Three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, in Production Example 1 in a nitrogen stream. The obtained 4-optically active alkoxycarbonyl brombenzene 23.3 mmol,
4-alkoxyphenylacetylene obtained in Production Example 2
Charge 23.3m mol, triphenylphosphine 100mg, dichlorobis (triphenylphosphine) palladium catalyst 60mg and triethylamine 50ml, dissolve with stirring, copper iodide
20 mg was added. After stirring at room temperature for 2 hours, gradually heat to 30
The internal temperature was set to 70 ° C. by taking necessary time. The reaction was carried out at this temperature for 8 hours. After the reaction, the temperature was returned to room temperature, triethylamine was distilled off under reduced pressure, 100 ml of ether was added to the residue, washed with water, and dried over anhydrous sodium sulfate. After that, ether was distilled off, and the residue was subjected to silica gel column chromatography (200 g of silica gel 100 g, developing solvent benzene: hexane = gradient of 2: 8 to 4: 6) for isolation and purification. Recrystallized from petroleum ether to give 4-alkoxycarbonyl-
4'-Alkoxytran [I] (n = 0) was obtained in a yield of 85-91%. The structure of each compound was confirmed by IR and NMR spectral data.

Example [Compound No. 5] Yield 87% The results are shown in Table 4 together with the melting points of the obtained compounds.

Production Example 4 4- (4 ″ -alkyloxycarbonylphenyl) oxycarbonyl-4′-alkoxytran [II
I] (n = 1) Production of 4- (4 ″ -optically active alkoxycarbonylphenyl) oxycarbonyl obtained in Production Example 1 in a nitrogen stream in a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser. Brombenzene (5 mmol), 4-alkoxyphenylacetylene (5 mmol) obtained in Preparation Example 2, triphenylphosphine (100 mmol), dichlorobis (triphenylphosphine) palladium catalyst (60 mg) and triethylamine (60 ml) were charged and dissolved with stirring to obtain 6 mg of copper iodide. After stirring at room temperature for 2 hours, the mixture was gradually heated and required 30 minutes to bring the internal temperature to 70 ° C. The reaction was carried out at this temperature for 8 hours, after which the temperature was returned to room temperature and the triethylamine was distilled off under reduced pressure. And ether to the residue
100 ml was added, washed with water, and dried over anhydrous sodium sulfate.
After that, the ether was distilled off, and the residue was subjected to silica gel column chromatography (200 mesh silica gel 100 g,
It was isolated and purified by applying a developing solvent of benzene: hexane = 1: 1). Recrystallized from hexane to give 4- (4 "-alkyloxycarbonylphenyl) oxycarbonyl-4 '.
-Alkoxytran [I] (n = 1) was obtained in a yield of 86-92%. The structure of each compound was confirmed by IR and NMR spectrum data.

Example. [Compound No. 21] Yield 86% The results are shown in Table 5 together with the melting points of the obtained compounds.

Example 1 Preparation of 1- (4′-alkyloxycarbonylphenyl) -2- (4 ″ -alkoxyphenyl) ethane [I] (n = 0) Stirrer, thermometer, reflux condenser and hydrogen gas were collected. 4-alkoxycarbonyl-4'-alkoxytran obtained in Preparation Example 3 4.4 mmol, 5
% Palladium-carbon catalyst 500 mg and ethyl acetate 10 ml were charged. After replacing with hydrogen gas, the reaction was carried out at room temperature. The degree of progress of the reaction was examined by a thin layer chromatography chip. The reaction is about 6
It was almost complete in time, but stirring was continued in a hydrogen atmosphere for another 14 hours. After the reaction, the catalyst was removed with a glass filter lined with Dicalite, and ethyl acetate was distilled off under reduced pressure. The reaction crude product was purified by silica gel column chromatography (200 mesh silica gel 50 g, developing solvent; benzene / hexane = 1/1). Yield is 84 ~
It was 93%. The structure of each compound was confirmed by IR and NMR spectra.

Example. [Compound No. 24] Yield 92% The results are shown in Table 6 together with the phase transition temperatures of the obtained compounds.

(Note) The symbols in Table 6 indicate the following.

C: Crystal phase, S _A : Smectic A phase, S _C ^* : Chiral smectic C phase, I: Isotropic liquid phase, S _X : Smectic phase with undecided origin.

Example 2 1- [4 '-(p-alkyloxycarbonylphenyl) oxycarbonylphenyl] -2- (4 "
Preparation of -alkoxyphenyl) ethane [I] (n = 1) Starting from 4- (4 "-alkyloxycarbonylphenyl) oxycarbonyl-4'-alkoxytran [III] (n = 1) obtained in Preparation Example 4 The starting material was reacted with hydrogen gas under the same reaction procedure and reaction conditions as in Example 1. The target product was purified by recrystallization from ethanol, and the yield was 82 to 95%.

The structure of each compound was confirmed by IR and NMR spectra.

Example. [Compound No. 40] Yield 95% The results are shown in Table 7 together with the phase transition temperatures of the obtained compounds.

(Note) The symbols in Table 7 indicate the following.

C: Crystal phase, S _A : Smectic A phase, S _C ^* : Chiral smectic C phase, I: Isotropic liquid phase, S _y : Smectic phase with undecided origin, P _S : Value of spontaneous polarization (nc / cm ² ).

Example 3 Liquid crystal compositions of the following Table 8 were prepared using the liquid crystal compounds of the present invention of compounds No. 32, No. 33 and No. 39 of Table 7, and the phase transition temperatures thereof were measured. It was as shown in Table 8.

The liquid crystal composition, a polyimide film is applied, by rubbing the surface subjected to a parallel alignment process, was injected cell membrane cell having a transparent electrode which was controlled to 2 [mu] m, the cell of uniform alignment in S _C ^* Was obtained. When a square wave voltage of ± 10 V is applied at a temperature of 30 ° C, the response time is 1.4 ms and the contrast is 1
0 display elements were obtained.

Example 4 90% of the liquid crystal composition of Example 3 and the following structural formula A liquid crystal composition consisting of 10% of the compound represented by and the phase transition temperature thereof was measured.

When this liquid crystal composition was injected into the same cell as that used in Example 3, a cell with uniform alignment of S _C ^* could be obtained. The cell had a response time of 1.3 ms at 25 ° C and a contrast of 13. It was possible to lower the melting point and extend the temperature range of S _C ^* by mixing with a biphenyl-based or pyrimidine-based liquid crystal compound in addition to the ester-based material.

〔The invention's effect〕

As shown in Examples 1 and 2, the compound of the present invention is a compound exhibiting the S _C ^* phase near room temperature and having ferroelectricity, and the results of Examples 3 and 4 show that the compound has a wide range including room temperature. It is clear that it is an effective component in obtaining a chiral smectic liquid crystal composition in the temperature range. Such an effect is first achieved by the present invention.

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Claims (4)

[Claims] 1. A general formula [I] (Wherein R represents an alkyl group having 1 to 20 carbon atoms, R ^* represents an optically active alkyl group having 4 to 13 carbon atoms having an asymmetric carbon atom, and n represents 0 or 1). ，
A liquid crystalline compound having a 2-diarenylethane skeleton. 2. In the general formula [I], R ^* is the general formula [I
I] The optically active alkyl group represented by the formula (wherein m is an integer of 0 to 5, 1 is an integer of 1 to 5, and * is an asymmetric carbon atom). Liquid crystalline compound. 3. In the presence of a palladium-carbon catalyst and a solvent,
General formula (III) (Wherein R is an alkyl group having 1 to 20 carbon atoms, R ^* is an optically active alkyl group having 4 to 13 carbon atoms having an asymmetric carbon atom, and n is 0 or 1). General formula [I] characterized by reacting hydrogen with an acetylene compound (Wherein R, R ^* and n have the same meanings as described above) and a method for producing a liquid crystal compound having a 1,2-dialenenylethane skeleton. 4. A general formula [I] (Wherein R represents an alkyl group having 1 to 20 carbon atoms, R ^* represents an optically active alkyl group having 4 to 13 carbon atoms having an asymmetric carbon atom, and n represents 0 or 1). ，
A liquid crystal composition comprising at least one liquid crystalline compound having a 2-diarenylethane skeleton.