JPH0759566B2 - Fluoroalkane derivative and liquid crystal composition containing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel liquid crystal compound, a liquid crystal composition containing the same, and a liquid crystal device using the liquid crystal composition. More specifically, the present invention relates to an optically active fluoroalkane derivative. The present invention relates to a liquid crystal compound, a liquid crystal composition containing the liquid crystal compound, and a liquid crystal device using the liquid crystal composition.

BACKGROUND ART Conventional liquid crystal elements include, for example, M.Sc
hadt) and W. Helfrich, “Applied Physics Letters” (“Applied
Physics Letters ") Volume 18, Issue 4 (Published February 15, 1971), pages 127-128," Voltage Dependant Optical Activity of a Twisted Nematic Liquid Crystal ". (“Volt
age Dependent Optical Activity of a Twisted Nemati
c Liquid Crystal ") is known to use a twisted nematic liquid crystal. This TN liquid crystal is a cross-type liquid crystal that is driven by a time division drive using a matrix electrode structure with high pixel density. The number of pixels is limited because of the problem of generating talk.

Further, the use as a display has been limited because the electric field response is slow and the viewing angle characteristics are poor.

In addition, a display element of a type in which a switching element using a thin film transistor is connected to each pixel and switching is performed for each pixel is known, but a step of forming a thin film transistor on a substrate is extremely complicated, and a large area display element is used. There are problems that are difficult to create.

The use of bistability-type liquid crystal elements is known as Clark (Cl
ark) and Lagerwall (JP-A-56-107216, US Pat. No. 4,367,924, etc.). A liquid crystal having bistability is generally a chiral smectic C phase (SmC ^* ) or H phase (SmH ^* ).
A ferroelectric liquid crystal having is used.

This ferroelectric liquid crystal has a very fast response speed due to its spontaneous polarization, and can express a bistable state with a memory property. Moreover, it has a large viewing angle characteristic and thus has a large capacity and a large capacity. Suitable as a display material for screens.

Further, since the material used as the ferroelectric liquid crystal has asymmetry, it can be used not only as the ferroelectric liquid crystal utilizing the chiral smectic phase but also as the following optical element. .

1) Utilizing the cholesteric / nematic phase transition effect in the liquid crystal state (JJWysoki, A. Adams and
W.Haas; Phys.Rev.Lett., 20,1024 (1968)), 2) White Taylor type guest in the liquid crystal state
Using host effect (DLWhite and GNTaylo
r; J.Appl., Phy., 45 4718 (1974)), etc. are known. Although detailed description of each method is omitted, it is important as a display element or a modulation element.

In such a method using the electric field response optical effect of liquid crystal, it is said that it is preferable to introduce a polar group in order to enhance the response of the liquid crystal. Especially in ferroelectric liquid crystals, it is known that the response speed is proportional to the spontaneous polarization,
It is desired to increase the spontaneous polarization for speeding up. From this point of view, P. Keller et al. Showed that by introducing a chlorine group directly into the asymmetric carbon, the spontaneous polarization can be increased and the response speed can be increased (CRAcad.Sc.Paris,
282 C, 639 (1976)). However, the chlorine group introduced into the asymmetric carbon is chemically unstable and has a drawback that the stability of the liquid crystal phase is deteriorated due to its large atomic radius, and improvement thereof is desired. There is.

On the other hand, a functional material required for an optical element characterized by having optical activity is often synthesized through an optically active intermediate itself, but as an optically active intermediate used conventionally, 2 -Methyl butanol, secondary octyl alcohol, secondary butyl alcohol, p- (2-methylbutyl) benzoic acid chloride, secondary phenethyl alcohol, amino acid derivatives, camphor derivatives, cholesterol derivatives, etc. Almost no polar group was introduced into. For this reason, the method of increasing spontaneous polarization by directly introducing a polar group into an asymmetric carbon atom has not been effectively used.

Effect of the Invention The present invention has been made in view of the above points. That is, the present invention contains a liquid crystalline compound in which a polar group is enhanced by directly introducing a stable and large dipole moment fluorine group into an asymmetric carbon atom, and at least one kind of the liquid crystalline compound is improved. It is an object to provide a liquid crystal composition.

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and has the general formula (I) (Here, R ₁ is an alkyl group having 4 to 16 carbon atoms having an asymmetric carbon atom, R ₂ is an alkyl group having 1 to 16 carbon atoms, and C ^* is an asymmetric carbon atom.) Fluoroalkane derivatives represented are provided.

The present invention also provides a liquid crystal composition containing the fluoroalkane derivative as at least one compounding ingredient.

DETAILED DESCRIPTION OF THE INVENTION The fluoroalkane derivative represented by the general formula (I) is preferably synthesized from an optically active intermediate such as 2-fluoro-1-alkanol described in the specification of Japanese Patent Application No. 60-232886. To be done.

For example, the fluoroalkane derivative represented by the general formula (I) can be obtained from these optically active intermediates by the following synthetic route.

(Here, R ₁ , R ₂ and C ^* are as defined above.) The liquid crystal composition of the present invention contains at least one fluoroalkane derivative represented by the general formula (I) as a blending component. To do. For example, when this fluoroalkane derivative is combined with a ferroelectric liquid crystal represented by the following formulas (1) to (13), spontaneous polarization is increased and the response speed can be improved.

In such a case, it is preferable to use the fluoroalkane derivative of the present invention represented by the general formula (I) in an amount of 0.1 to 99% by weight, particularly 1 to 90% by weight of the obtained liquid crystal composition. .

Further, by compounding with a smectic liquid crystal which is not chiral itself as shown in the following formulas 1) to 5), a composition usable as a ferroelectric liquid crystal can be obtained.

In this case, it is preferable to use the fluoroalkane derivative of the present invention represented by the general formula (I) in an amount of 0.1 to 99% by weight, particularly 1 to 90% by weight of the obtained liquid crystal composition.

Such a composition can obtain a large spontaneous polarization due to the content of the fluoroalkane derivative of the present invention.

Here, the symbols indicate the following phases, respectively.

Cryst .: crystalline phase, SmA: smectic A phase, SmB: smectic B phase, SmC: smectic C phase, N: nematic phase, Iso .: isotropic phase.

Further, the fluoroalkane derivative represented by the general formula (I) is effective in preventing the generation of the reverse domain in the TN type cell by adding it to the nematic liquid crystal. In this case, 0.01 to 50% by weight of the obtained liquid crystal composition
It is preferable to use the fluoroalkane derivative of the formula (I) such that

Also, by adding to nematic liquid crystal or chiral nematic liquid crystal, as chiral nematic liquid crystal,
It can be used as a liquid crystal composition in a phase transition type liquid crystal device or a white Taylor type guest-host liquid crystal device. In this case, it is preferable to use the fluoroalkane derivative of the formula (I) in an amount of 0.01 to 80% by weight of the obtained liquid crystal composition.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 5- (4-methylhexyl) -2 represented by the above formula
-[4- (2-Fluorooctyloxy) phenyl] pyrimidine was prepared by the following steps.

(1) Synthesis of 2-fluorooctyl-p-toluenesulfonic acid ester.

2-Fluoro-n-octanol (10 g, 67.6 mmol) was dissolved in pyridine (20 ml), and a solution of p-toluenesulfonic acid chloride (15.5 g, 81.1 mmol) in pyridine was added dropwise under cooling to 0 ° C. at 0 ° C. to 5 ° C. The reaction was carried out for 1 hour and further at 15 ° C to 20 ° C for 7 hours. Then, the reaction solution was poured into 200 ml of ice water, then acidified with 2N HCl aqueous solution, and further extracted with methylene chloride.The extracted layer was washed with water, and after confirming that the aqueous layer was neutral, sulfuric acid was added. It was dried using magnesium and the solvent was distilled off. Further, purification was carried out using silica gel column chromatography to obtain 13.0 g of 2-fluorooctyl-p-toluenesulfonic acid ester.

(2) Synthesis of p- (2-fluorooctyloxy) cyanobenzene.

p-Toluenesulfonic acid (2-fluorooctyl) 2.85
g (9.44mmol) and p-cyanophenol 1.15g (9.44mmo
l) is dissolved in 4 ml of n-butanol and sodium hydroxide is added.
0.477 g (11.3 mmol) was added and the mixture was refluxed at 120 ° C. for 5 hours. After the reaction was completed, the reaction mixture was extracted with ether and subjected to p- (2) by column chromatography (dichloromethane: benzene = 4: 1).
-Fluorooctyloxy) cyanobenzene 2.22 g (8.92 m
mol) was obtained. Yield 94%.

▲ [α] ^26.8 _D ▼ -2.40 ° (C = 0.916, benzene) ▲ [α] ^26.8 ₄₃₅ ▼ -8.52 ° (C = 0.916, benzene) (3) p- (2-fluorooctyloxy) benzamidine hydrochloride Synthetic.

Blow hydrogen chloride into a solution prepared by adding 2.66 g (10.7 mmol) of p- (2-fluorooctyloxy) cyanobenzene to 13 ml of dry ethanol in a freezing agent, and let it stand at room temperature for 24 hours.
Stir for hours. After the reaction, the solvent was distilled off, the residue was dried over phosphorus pentoxide and potassium hydroxide, and then 10 ml of dry ethanol was added.
Was added. The obtained solution is preliminarily dried with ethanol.
Ammonia was blown into 20 ml to be saturated, and the solution thus prepared was immediately poured into the solution and stirred at room temperature for 2 nights. After that, the solvent was distilled off, the residue was filtered with ether, and then 6N hydrochloric acid 23
Recrystallization was performed with ml to obtain 2.57 g (8.50 mmol) of p- (2-fluorooctyloxy) benzamidine hydrochloride.
Yield 79%. mp 150 ℃ -182 ℃.

(4) Synthesis of 4,6-dihydroxy-5- (4-methylhexyl) -2- [4- (2-fluorooctyloxy) phenyl] pyrimidine.

To 7 ml of dry methanol, 0.29 g (12.6 ml) of sodium was added and completely dissolved. Then, 1.29 g (4.2 mmol) of p- (2-fluorooctyloxy) benzamidine hydrochloride and 2-
(Diethyl 4-methylhexylmalonate 1.08 g (4.2 mmo
l) was added, the mixture was refluxed at 80 ° C. for 8 hours, and further stirred at room temperature for 14 hours. After completion of the reaction, 2N-hydrochloric acid was added, and the mixture was filtered, washed with water and ethanol, and dried at 120 ° C for 1 hour. After that, recrystallization with 5 ml of DMF was performed to 4,6-dihydroxy-5-
(4-methylhexyl) -2- [4- (2-fluorooctyloxy) phenyl] pyrimidine 1.21 g (2.93 mmo
l) got. Yield 70%.

(5) 4,6-dichloro-5- (4-methylhexyl)
Synthesis of 2- [4- (2-fluorooctyloxy) phenyl] pyrimidine.

4,6-dihydroxy-5- (4-methylhexyl) -2
-[4- (2-Fluorooctyloxy) phenyl] pyrimidine 1.20 g (2.9 mmol) was added with N, N-diethylaniline 1
ml and phosphoryl chloride 6 ml were added, and the mixture was refluxed at 110 ° C. for 47 hours. After completion of the reaction, excess phosphoryl chloride was distilled off, sodium hydroxide solution was added, and the mixture was extracted with ether. The extract was washed successively with 1N-hydrochloric acid and water and then subjected to column chromatography (benzene: hexane = 1: 2) to give 4,6-dichloro-5- (4-methylhexyl) -2- [4- (2
-Fluorooctyloxy) phenyl] pyrimidine 1.08
g (2.4 mmol) was obtained. Yield 83%.

▲ [α] ^25.6 _D ▼ -1.09 ° (C = 0.920, benzene) ▲ [α] ^26.4 ₄₃₅ ▼ -5.00 ° (C = 0.920, benzene) (6) 5- (4-methylhexyl) 2- [4- (2-
Synthesis of fluorooctyloxy) phenyl] pyrimidine.

To 10 ml of ethanol and 0.6 ml of water, 4,6-dichloro-5- (4
-Methylhexyl) -2- [4- (2-fluorooctyloxy) phenyl] pyrimidine 0.95 g (2.1 mmol),
5% -Palladium activated carbon 200mg, magnesium oxide 0.32g
(8.0 mmol) was added, and hydrogen substitution was carried out using an atmospheric pressure hydrogenation device. After the reaction, by column chromatography (benzene), 5- (4-methylhexyl) -2- [4-
(2-Fluorooctyloxy) phenyl] pyrimidine
0.41 g (1.08 mmol) was obtained. Yield 51%.

▲ [α] ^26.8 _D ▼ + 5.83 ° (C = 0.824, Et ₂ O) ▲ [α] ^26.8 ₄₃₅ ▼ + 18.0 ° (C = 0.824, Et ₂ O) Examples 2 to 3 Used in Example 1. 2-fluorooctanol,
In place of diethyl 4-methylhexylmalonate, ₂ -fluoro-1-alkanol which gives R ₁ and R ₂ shown in Table 1 and a diethyl malonate derivative were used in the same manner as in Example 1 except that Table 1 was used. A fluoroalkane derivative as shown was obtained.

The specific optical rotation and the phase transition temperature of the product are shown in Table 1 together with that of Example 1.

Example 4 The following liquid crystal composition containing the fluoroalkane derivative produced in Example 1 and Example 3 as a blending component was prepared.

This liquid crystal composition has a SmC ^* phase at 5.4 to 44.3 ° C and is at 25 ° C.
It was found to have a large spontaneous polarization of 8.0 nC / cm ² . Then, the above liquid crystal composition was sandwiched between a pair of electrode substrates obtained by subjecting the polyimide coating covering the electrodes to a rubbing treatment to prepare an element having a liquid crystal layer thickness of 2 μm. When driven at 25 ° C with a drive voltage of ± 15 V and a pulse width of 300 μsec,
A good switching state was obtained with a contrast of 17.

Example 5 A polyimide resin precursor [SP manufactured by Toray Industries, Inc.] was formed on a glass substrate on which an ITO (Indium Tin Oxide) film was formed as a transparent electrode.
-510] and spin-coating to form a film, then 300 ℃
And baked for 60 minutes to form a polyimide film. Next, this coating was subjected to orientation treatment by rubbing to make cells so that the rubbing treatment axes were orthogonal to each other (cell spacing 8 μm).
A nematic liquid crystal composition [Rixon GR-63: biphenyl liquid crystal mixture manufactured by Chisso Corp.] was injected into the above cell to form a TN (twisted nematic) type cell, which was observed with a polarization microscope to find that the reverse domain (stripe pattern ) Has occurred.

Using a liquid crystal mixture obtained by adding the fluoroalkane derivative (1 part by weight) of Example 2 of the present invention to Rixon GR-63 (99 parts by weight), and observing a TN cell in the same manner as above, a reverse No domain was observed and the nematic phase had good uniformity. From this, it was found that the fluoroalkane derivative of the present invention is effective in preventing the reverse domain.

Front Page Continuation (72) Inventor Goji Kadano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kazuharu Katagiri 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. In the company

Claims (2)

[Claims] 1. The following general formula (I): (Here, R ₁ is an alkyl group having 4 to 16 carbon atoms having an asymmetric carbon atom, R ₂ is an alkyl group having 1 to 16 carbon atoms, and C ^* is an asymmetric carbon atom.) A represented fluoroalkane derivative. 2. The following general formula (I) (Here, R ₁ is an alkyl group having 4 to 16 carbon atoms having an asymmetric carbon atom, R ₂ is an alkyl group having 1 to 16 carbon atoms, and C ^* is an asymmetric carbon atom.) A liquid crystal composition comprising at least one kind of the represented fluoroalkane derivative.