JPH10182609A - 5-(2-fluoroalkoxy)pyridine derivative, liquid crystal composition containing the same, and liquid crystalline display element by using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new compound suitable for constituting a ferromagnetic liquid crystalline composition having low temperature dependence of an response velocity and rapid in response velocity even at a low temperature. SOLUTION: This new compound is a compound of formula I (R1 is a 1-16C alkyl or an alkoxyl; R2 is a 1-12C alkyl), e.g. 2-(4-butylphenyl)-5-(2- fluoropropyloxy)pyridine. The compound of formula I is obtained, for example, by a method for reacting a tosylate of formula III (Ts is toluenesulfonyl) obtained by reacting an optically active 2-fluoroalkan-1-ol of formula II with p-toluenesulfonyl chloride, etc., with 5-pyridinol of formula IV in the presence of an alkali, or a method for reacting the optically active 2-fluoroalkan-1-ol of formula II with the 5-pyridinol of formula IV in the presence of an azodicarbonic diester and triphenylphosphine, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel optically active liquid crystal compound which can be very suitably used for a liquid crystal display device, especially a ferroelectric liquid crystal display device, a liquid crystal composition using the liquid crystal compound, and the liquid crystal composition. The present invention relates to a liquid crystal display device using an object.

[0002]

2. Description of the Related Art Liquid crystal display devices are widely used, and most of them use liquid crystals exhibiting a nematic phase. As a relatively new display method using a nematic liquid crystal, a thin film transistor (TF) is used as a switching element for each pixel.
T) or the like, or the twist angle of the twisted nematic method (TN method) is set to 20.
There is a super twisted nematic system (STN system) having an angle of 0 ° or more. With the progress of these display methods, display quality has been improved compared to the TN method, but the response speed is slower than that of a display device using a cathode ray tube (CRT), and improvement is desired.

On the other hand, display devices using ferroelectric liquid crystals or antiferroelectric liquid crystals have been actively researched and developed. Surface-stabilized ferroelectric liquid crystal display using ferroelectric liquid crystal (SS
FLC) method was introduced in 1980 by NA Clark and S.M.
Suggested by T. Ragawall. The antiferroelectric liquid crystal phase was first discovered by Furukawa et al. In 1987 and was tentatively named the chiral smectic Y (SY ^* ) phase (see Ferroelectronics, Vol. 85, p. 451, 1988). Later, Chandani et al. Showed that the phase was an antiferroelectric liquid crystal phase. (Japanese Journal
Of Applied Physics, 28 turns, 1265
1989). Both of these are display methods for eliminating viewing angle dependence of display colors, including inversion of color tone, which is an essential defect of TN display. Further, even during high-time-division driving, display can be performed with a simple matrix type cell structure, so that reduction in element fabrication cost is expected. So far, compounds having optically active sites of various structures have been proposed as ferroelectric liquid crystal compounds. Among them, a liquid crystal compound having fluorine in an optically active site has features of low viscosity and high-speed response, and thus attracts attention, and many patent applications have been filed. The present inventors also filed a patent application for a liquid crystal compound containing fluorine, and proposed a compound represented by the general formula (I) in Patent No. 2538578. In Example 10, the following compound is described.

[0004]

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[0005]

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[0006] Liquid crystal display devices have been used in various fields, and stable driving in a wide temperature range such as outdoor use is required. In general, the response speed of ferroelectric liquid crystals remarkably depends on a change in temperature in many cases, and there are problems such as consideration of setting of driving conditions according to a change in temperature. The compound described in the above-mentioned prior patent and the ferroelectric liquid crystal composition formed using the compound still have a problem that the response speed has a large temperature dependence. The compound represented by the general formula (1) of the present invention is described in the above Patent No.
It is formally included in the general formula (I) proposed in US Pat. However, in the specification of Patent No. 2538578, there is no specific description of the compound represented by the general formula (1) of the present invention, such as the compound name and physical properties, and the description suggests the present invention. Nor.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optically active liquid crystal compound suitable for forming a ferroelectric liquid crystal composition having a low response speed and a high response speed even at a low temperature. An object of the present invention is to provide a liquid crystal composition using a liquid crystal compound and a liquid crystal display device using the liquid crystal composition.

[0008]

That is, the present invention provides a compound represented by the following general formula (1):

[0009]

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Wherein R 1 represents an alkyl group or an alkoxy group having 1 to 16 carbon atoms, and R 2 represents an alkyl group having 1 to 12 carbon atoms. A derivative, a liquid crystal composition containing the derivative, particularly a ferroelectric liquid crystal composition, and a liquid crystal display device using the liquid crystal composition. In the general formula (1), R1 has 1 to 16 carbon atoms, preferably 4 to 1 carbon atoms.
And particularly preferably an alkyl or alkoxy group having 6 to 10 carbon atoms. These groups may include not only straight chains but also branches, and may be optically active groups. Preferred specific examples of R1 include the following groups. Butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, 2-
Methylbutyl, 3-methylpentyl, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, 2-methylbutyloxy, 1-methylheptyloxy. In the general formula (1), R2 is an alkyl group having 1 to 12 carbon atoms, preferably 4 to 12 carbon atoms, particularly preferably 6 to 10 carbon atoms. The alkyl group may be not only a straight chain but also one containing a branch, and may be an optically active group. Specific examples of preferred R2 include the following groups. Butyl, pentyl,
Hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, 2-methylpropyl, 2-methylbutyl.

In general, a method for obtaining a ferroelectric liquid crystal composition includes a method of forming a composition using only a ferroelectric liquid crystal compound, and a method of forming a non-chiral smectic C, F,
A compound or composition exhibiting an inclined smectic phase such as G, H, I (hereinafter abbreviated as a phase such as Sc) is used as a basic substance, and one or more ferroelectric liquid crystal compounds or non-liquid crystal optical There is a method in which an active compound is mixed to form a composition exhibiting a ferroelectric liquid crystal phase as a whole. The 5- (2-fluoroalkoxy) pyridine derivative of the present invention is an optically active liquid crystal compound, and can be added to a compound exhibiting a phase such as Sc to obtain a ferroelectric liquid crystal composition.
Examples of the skeleton structure of a basic substance suitable for constituting a ferroelectric liquid crystal composition by mixing with the optically active liquid crystal compound of the present invention are as follows (wherein Ra and Rb each independently represent a carbon number) 1-16 alkyl groups or alkoxy groups.).

[0012]

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[0013]

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Method for Preparing Compound The compound of the present invention represented by the general formula (1) can be suitably prepared by the following synthetic route. That is, an optically active 2-fluoroalkane-1-ol (2) is reacted with p-toluenesulfonyl chloride or the like to form a tosylate (3), which is reacted with 5-pyridinol (4) in the presence of an alkali. By doing so, the desired compound of formula (1) can be obtained.

[0015]

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Further, in the presence of diethyl azodicarboxylate and triphenylphosphine, an optically active 2-fluoroalkane-1-ol (2) is reacted with 5-pyridinol (4) to obtain the desired compound represented by the following formula: The compound of 1) can be obtained. This reaction is a reaction generally called the Mitsunobu (Mitsunobu: person's name) reaction.

[0017]

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5-pyridinol (4), one of the starting materials for the above reaction, can be produced by the following method. Using 4-substituted bromobenzene (5) as Grignard reagent, and reacting with 2,5-dibromopyridine (6) in the presence of a catalyst,
Produce 2- (4-substituted phenyl) -5-bromopyridine (7). This is lithiated, trimethoxyboron is reacted to form boric acid, and this is oxidized to produce 5-pyridinol (4).

[0019]

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In the production of the compound of the formula (1) wherein R 1 is an alkoxy group, a protecting group can be used.
That is, 4-benzyloxybromobenzene (8) is used as a starting material, which is converted into a Grignard reagent, and reacted with 2,5-dibromopyridine (6) in the presence of a catalyst to give 2
-(4-Benzyloxyphenyl) -5-bromopyridine (9) can be produced. This is subjected to a hydrogenolysis reaction to remove the protecting group to give phenol (10), which is subjected to alkylation to give the above-mentioned 2- (4-substituted phenyl)-.
5-bromopyridine (7 ') can be prepared. After (7 ′), 5-pyridinol (4) can be produced according to the aforementioned route.

[0021]

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Further, it can be suitably manufactured by the following route. That is, 2- (4-substituted phenyl) -5-lithiopyridine can be produced by using 4-substituted bromobenzene (5) as a lithium reagent and reacting it with pyridine. Hydrolysis of this can also produce 5-pyridinol (4).

[0023]

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Optically active 2-fluoroalkane-1-ol (2), which is another starting material of the compound of the formula (1), can be suitably produced by the following route. That is,
Amino acid (11) can be diazotized and further substituted with fluorine to produce α-fluoroalkanoic acid (12). The compound of the formula (2) can be produced by lower esterifying this and then reducing the ester.

[0025]

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Separately, the amino acid (11) is diazotized, the amino group is converted to a hydroxyl group to obtain (13), which is lower-esterified to obtain (14), and the hydroxyl group is subjected to p-toluenesulfonylation (15). This is fluorinated to give (16), and the ester is further reduced to produce (2). Instead of p-toluenesulfonylation, methanesulfonylation or benzenesulfonylation may be performed.

[0027]

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The compound of the formula (2) can also be obtained by a ring opening reaction of the compound of the formula (17) in HF / pyridine.

[0029]

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Alternatively, the compound of the formula (1) can be produced as follows. That is, the hydroxyl group of the compound (14) is exemplified by a suitable protecting group (here, a 2-tetrahydropyranyl group is exemplified. In addition, a methoxymethyl group, an ethoxyethyl group, an ethoxy-1-ethyl group, and the like are exemplified. To give compound (18), which is reduced to (19). The generated hydroxyl group is converted to a reactive sulfonyl group (here, Ts: p-toluenesulfonyl group is taken as an example. In addition, a methanesulfonyl group,
A benzenesulfonyl group etc.) to give compound (20), which is etherified with pyridinol (4) under alkaline conditions to give (21). This is deprotected to give compound (22), which is fluorinated with a fluorinating reagent to produce the desired compound (1).

[0031]

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The 2-fluoroalkanes already mentioned
Epoxyalkane (17) which is a raw material of 1-ol
Can be purchased commercially, but it can also be produced as follows. The compound (20) is deprotected and the hydroxyl group regenerated (23) is intramolecularly etherified under alkalinity to produce an epoxy alkane (17). Also,
The optically active (14) serving as these raw materials can be suitably obtained by optically resolving the racemate (14-racemi) with a catalyst such as lipase.

[0033]

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The 5- (2-fluoroalkoxy) pyridine derivatives thus produced are exemplified below. 2- (4-butylphenyl) -5- (2-fluoropropyloxy)
Pyridine 2- (4-pentylphenyl) -5- (2-fluoropropyloxy) pyridine 2- (4-hexylphenyl) -5- (2-fluoropropyloxy) pyridine 2- (4-heptylphenyl) -5- (2-fluoropropyloxy) pyridine 2- (4-octylphenyl) -5- (2-fluoropropyloxy) pyridine 2- (4-nonylphenyl) -5- (2-fluoropropyloxy)
Pyridine 2- (4-decylphenyl) -5- (2-fluoropropyloxy)
Pyridine 2- (4-undecylphenyl) -5- (2-fluoropropyloxy) pyridine 2- (4-dodecylphenyl) -5- (2-fluoropropyloxy) pyridine 2- (4-butyloxyphenyl)- 5- (2-fluoropropyloxy) pyridine 2- (4-pentyloxyphenyl) -5- (2-fluoropropyloxy) pyridine 2- (4-hexyloxyphenyl) -5- (2-fluoropropyloxy) pyridine 2- (4-heptyloxyphenyl) -5- (2-fluoropropyloxy) pyridine 2- (4-octyloxyphenyl) -5- (2-fluoropropyloxy) pyridine 2- (4-nonyloxyphenyl)- 5- (2-fluoropropyloxy) pyridine 2- (4-decyloxyphenyl) -5- (2-fluoropropyloxy) pyridine 2- (4-undecyloxyphenyl) -5- (2-fluoropropyloxy) Pyridine 2- (4-dodecyloxyphenyl) -5- (2-fluoropropyloxy) pyridi N

2- (4-butylphenyl) -5- (2-fluoro-4-
Methylpentyloxy) pyridine 2- (4-pentylphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- (4-hexylphenyl) -5- (2-fluoro-4-methylpentyloxy) Pyridine 2- (4-heptylphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- (4-octylphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- ( 4- (nonylphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- (4-decylphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- (4-undecyl Phenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- (4-dodecylphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- (4-butyloxyphenyl)- 5- (2-fluoro-4-methylpentyloxy) pyridine 2- (4-pentyloxyphenyl) -5- (2-fluoro-4-methylpentyloxy) pyri 2- (4-hexyloxyphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- (4-heptyloxyphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2 -(4-octyloxyphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- (4-nonyloxyphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- ( 4- (decyloxyphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- (4-undecyloxyphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine 2- (4 -Dodecyloxyphenyl) -5- (2-fluoro-4-methylpentyloxy) pyridine

2- (4-butylphenyl) -5- (2-fluorohexyloxy) pyridine 2- (4-pentylphenyl) -5- (2-fluorohexyloxy) pyridine 2- (4-hexylphenyl)- 5- (2-fluorohexyloxy) pyridine 2- (4-heptylphenyl) -5- (2-fluorohexyloxy) pyridine 2- (4-octylphenyl) -5- (2-fluorohexyloxy) pyridine 2- (4-nonylphenyl) -5- (2-fluorohexyloxy)
Pyridine 2- (4-decylphenyl) -5- (2-fluorohexyloxy)
Pyridine 2- (4-undecylphenyl) -5- (2-fluorohexyloxy) pyridine 2- (4-dodecylphenyl) -5- (2-fluorohexyloxy) pyridine 2- (4-butyloxyphenyl)- 5- (2-fluorohexyloxy) pyridine 2- (4-pentyloxyphenyl) -5- (2-fluorohexyloxy) pyridine 2- (4-hexyloxyphenyl) -5- (2-fluorohexyloxy) pyridine 2- (4-heptyloxyphenyl) -5- (2-fluorohexyloxy) pyridine 2- (4-octyloxyphenyl) -5- (2-fluorohexyloxy) pyridine 2- (4-nonyloxyphenyl)- 5- (2-fluorohexyloxy) pyridine 2- (4-decyloxyphenyl) -5- (2-fluorohexyloxy) pyridine 2- (4-undecyloxyphenyl) -5- (2-fluorohexyloxy) Pyridine 2- (4-dodecyloxyphenyl) -5- (2-fluorohexyloxy) pyridi N

2- (4-butylphenyl) -5- (2-fluoroheptyloxy) pyridine 2- (4-pentylphenyl) -5- (2-fluoroheptyloxy) pyridine 2- (4-hexylphenyl)- 5- (2-fluoroheptyloxy) pyridine 2- (4-heptylphenyl) -5- (2-fluoroheptyloxy) pyridine 2- (4-octylphenyl) -5- (2-fluoroheptyloxy) pyridine 2- (4-nonylphenyl) -5- (2-fluoroheptyloxy)
Pyridine 2- (4-decylphenyl) -5- (2-fluoroheptyloxy)
Pyridine 2- (4-undecylphenyl) -5- (2-fluoroheptyloxy) pyridine 2- (4-dodecylphenyl) -5- (2-fluoroheptyloxy) pyridine 2- (4-butyloxyphenyl)- 5- (2-fluoroheptyloxy) pyridine 2- (4-pentyloxyphenyl) -5- (2-fluoroheptyloxy) pyridine 2- (4-hexyloxyphenyl) -5- (2-fluoroheptyloxy) pyridine 2- (4-heptyloxyphenyl) -5- (2-fluoroheptyloxy) pyridine 2- (4-octyloxyphenyl) -5- (2-fluoroheptyloxy) pyridine 2- (4-nonyloxyphenyl)- 5- (2-fluoroheptyloxy) pyridine 2- (4-decyloxyphenyl) -5- (2-fluoroheptyloxy) pyridine 2- (4-undecyloxyphenyl) -5- (2-fluoroheptyloxy) Pyridine 2- (4-dodecyloxyphenyl) -5- (2-fluoroheptyloxy) pyridi N

2- (4-butylphenyl) -5- (2-fluorooctyloxy) pyridine 2- (4-pentylphenyl) -5- (2-fluorooctyloxy) pyridine 2- (4-hexylphenyl)- 5- (2-fluorooctyloxy) pyridine 2- (4-heptylphenyl) -5- (2-fluorooctyloxy) pyridine 2- (4-octylphenyl) -5- (2-fluorooctyloxy) pyridine 2- (4-nonylphenyl) -5- (2-fluorooctyloxy)
Pyridine 2- (4-decylphenyl) -5- (2-fluorooctyloxy)
Pyridine 2- (4-undecylphenyl) -5- (2-fluorooctyloxy) pyridine 2- (4-dodecylphenyl) -5- (2-fluorooctyloxy) pyridine 2- (4-butyloxyphenyl)- 5- (2-fluorooctyloxy) pyridine 2- (4-pentyloxyphenyl) -5- (2-fluorooctyloxy) pyridine 2- (4-hexyloxyphenyl) -5- (2-fluorooctyloxy) pyridine 2- (4-heptyloxyphenyl) -5- (2-fluorooctyloxy) pyridine 2- (4-octyloxyphenyl) -5- (2-fluorooctyloxy) pyridine 2- (4-nonyloxyphenyl)- 5- (2-fluorooctyloxy) pyridine 2- (4-decyloxyphenyl) -5- (2-fluorooctyloxy) pyridine 2- (4-undecyloxyphenyl) -5- (2-fluorooctyloxy) Pyridine 2- (4-dodecyloxyphenyl) -5- (2-fluorooctyloxy) pyridi N

2- (4-butylphenyl) -5- (2-fluorononyloxy) pyridine 2- (4-pentylphenyl) -5- (2-fluorononyloxy)
Pyridine 2- (4-hexylphenyl) -5- (2-fluorononyloxy)
Pyridine 2- (4-heptylphenyl) -5- (2-fluorononyloxy)
Pyridine 2- (4-octylphenyl) -5- (2-fluorononyloxy)
Pyridine 2- (4-nonylphenyl) -5- (2-fluorononyloxy) pyridine 2- (4-decylphenyl) -5- (2-fluorononyloxy) pyridine 2- (4-undecylphenyl) -5 -(2-fluorononyloxy) pyridine 2- (4-dodecylphenyl) -5- (2-fluorononyloxy)
Pyridine 2- (4-butyloxyphenyl) -5- (2-fluorononyloxy) pyridine 2- (4-pentyloxyphenyl) -5- (2-fluorononyloxy) pyridine 2- (4-hexyloxyphenyl) -5- (2-fluorononyloxy) pyridine 2- (4-heptyloxyphenyl) -5- (2-fluorononyloxy) pyridine 2- (4-octyloxyphenyl) -5- (2-fluorononyloxy) Pyridine 2- (4-nonyloxyphenyl) -5- (2-fluorononyloxy) pyridine 2- (4-decyloxyphenyl) -5- (2-fluorononyloxy) pyridine 2- (4-undecyloxyphenyl ) -5- (2-Fluorononyloxy) pyridine 2- (4-dodecyloxyphenyl) -5- (2-fluorononyloxy) pyridine

2- (4-butylphenyl) -5- (2-fluorodecyloxy) pyridine 2- (4-pentylphenyl) -5- (2-fluorodecyloxy)
Pyridine 2- (4-hexylphenyl) -5- (2-fluorodecyloxy)
Pyridine 2- (4-heptylphenyl) -5- (2-fluorodecyloxy)
Pyridine 2- (4-octylphenyl) -5- (2-fluorodecyloxy)
Pyridine 2- (4-nonylphenyl) -5- (2-fluorodecyloxy) pyridine 2- (4-decylphenyl) -5- (2-fluorodecyloxy) pyridine 2- (4-undecylphenyl) -5 -(2-fluorodecyloxy) pyridine 2- (4-dodecylphenyl) -5- (2-fluorodecyloxy)
Pyridine 2- (4-butyloxyphenyl) -5- (2-fluorodecyloxy) pyridine 2- (4-pentyloxyphenyl) -5- (2-fluorodecyloxy) pyridine 2- (4-hexyloxyphenyl) -5- (2-fluorodecyloxy) pyridine 2- (4-heptyloxyphenyl) -5- (2-fluorodecyloxy) pyridine 2- (4-octyloxyphenyl) -5- (2-fluorodecyloxy) Pyridine 2- (4-nonyloxyphenyl) -5- (2-fluorodecyloxy) pyridine 2- (4-decyloxyphenyl) -5- (2-fluorodecyloxy) pyridine 2- (4-undecyloxyphenyl ) -5- (2-Fluorodecyloxy) pyridine 2- (4-dodecyloxyphenyl) -5- (2-fluorodecyloxy) pyridine

[0041]

The compounds of the present invention will be described in more detail with reference to the following examples. Example 1 Production of S-2- (4-octylphenyl) -5- (2-fluorooctyloxy) pyridine (1st step) Production of S-2-fluorooctan-1-ol Cool, and here R-1,
2-epoxyoctane (manufactured by Japan Energy) 8.5
g ether solution (20 ml) was added dropwise. 2 at the same temperature
After stirring for an hour, the temperature was returned to room temperature. 100 ml of water was added, and the mixture was extracted twice with 50 ml of ether. The organic layer was washed with alkali, washed with water, added with crystalline calcium chloride, stirred for 1 hour, and dried over MgSO4. After filtering off the desiccant, the mixture was distilled under reduced pressure to give 126 ° C-129 ° C /
4.9 g of a 80 mmHg fraction were obtained. This is heptane 4
Recrystallization using 0 ml gave 3.7 g of S-2-fluorooctan-1-ol. [Α] _D ²⁶ -13.1 (C 1.7, benzene) m. p. 33.1 ° C. to 34.8 ° C. (2nd stage) Production of S-2-fluoro-1-p-toluenesulfonyloxyoctane 3.0 g of S-2-fluorooctan-1-ol, p-
4.5 g of toluenesulfonyl chloride and pyridine 5
0 ml were mixed and stirred at room temperature. 100 ml of water,
200 ml of toluene was added and liquid separation was performed. Pickling the organic layer,
After alkali washing and water washing, the resultant was dried with anhydrous magnesium sulfate. After the desiccant was filtered off, the filtrate was concentrated to obtain 6.0 g of S-2-fluoro-1-p-toluenesulfonyloxyoctane.

(Third stage) 2.3 g of metallic magnesium,
A Grignard reagent was prepared from 25 g of 4-octylbromobenzene dissolved in 200 ml of dry tetrahydrofuran, and 23 g of 2,5-dibromopyridine and tetrakistriphenylphosphine palladium (0) were prepared.
0.57 g (hereinafter abbreviated as Pd (TPP) 4) was added, and the mixture was heated under reflux for 2 hours. After cooling, extract with ether,
Washed with aqueous ammonium chloride and water. After drying over anhydrous magnesium sulfate, the solvent was distilled off, and the residue was purified by silica gel chromatography to give 5-bromo-
35 g of 2- (4-octylphenyl) pyridine were obtained. It had the following phase transition temperature (° C.): Cr 45 Sm 66.4 ISO (where Cr indicates a crystal phase, Sm indicates a smectic phase, and ISO indicates an isotropic liquid phase.) (Fourth stage) 5-bromo-2 obtained in the third stage − (4-
Octylphenyl) pyridine 10 g THF 100 ml
The solution was cooled to -60 ° C and n-butyllithium (1.6
18 ml of a 3 mol / l hexane solution) was added dropwise, and the mixture was stirred for 1 hour while maintaining the same temperature. Then, 6 g of trimethyl borate was added dropwise, and further stirred for 1 hour. The internal temperature is gradually returned to room temperature, and a saturated aqueous ammonium chloride solution (80 ml) is added.
Extraction was performed using 200 ml of diethyl ether. The organic layer was washed with water, dried over magnesium sulfate, and concentrated to obtain 10 g of 2- (4-octylphenyl) pyridine-5-boronic acid. (Fifth stage) 10 g of 2- (octylphenyl) -pyridine-5-boronic acid obtained in the fourth stage, 20 ml of aqueous hydrogen peroxide (36%), 80 ml of MeOH, and THF
80 ml were mixed and stirred at room temperature for 24 hours. The mixture was extracted with 200 ml of diethyl ether, and the organic layer was washed with a saturated aqueous solution of sodium hydrogen sulfite, water, and subsequently with an aqueous solution of ammonium chloride. Dried over magnesium sulfate and concentrated. The obtained solid was recrystallized using a mixed solution of heptane-ethyl acetate to obtain 5.8 g of 5-hydroxy-2- (4-octylphenyl) -pyridine. Its melting point was 134 to 135.5 ° C.

(Sixth Step) Production of S-2- (4-octylphenyl) -5- (2-fluorooctyloxy) pyridine 80% sodium hydride (50% oily) was added to THF10.
Then, 300 mg of 5-hydroxy-2- (4-octylphenyl) pyridine was added thereto, and S-2-
Fluoro-1-p-toluenesulfonyloxy-octane (320 mg) was added, and DMF (50 ml) was added.
The mixture was heated and stirred at 8 ° C. for 8 hours. Toluene (50 ml) was added, and the mixture was separated. The organic layer was washed with alkali and water, concentrated, and purified by column chromatography packed with activated alumina. After concentration again, the residue was recrystallized from ethanol to give the title S-2- (4-octylphenyl) -5-
200 mg of (2-fluorooctyloxy) pyridine were obtained. This exhibited the following phase transition temperature (° C.). Cr 59 SX ^* 73.5 Sc ^* 81.8 SA
87.1 ISO (where Cr is a crystal phase, SX ^* is an unidentified ferroelectric chiral smectic phase, Sc ^* is a ferroelectric chiral smectic C phase, SA is a smectic A phase, and ISO is an isotropic liquid phase. Shown respectively.)

Example 2 Preparation of S-2- (4-hexylphenyl) -5- (2-fluorooctyloxy) pyridine 5-Hydroxy-2- used in the sixth stage of Example 1
In the same manner as in the sixth column of Example 1 except that 5-hydroxy-2- (4-hexylphenyl) pyridine (melting point: 149-151 ° C.) was used instead of (4-octylphenyl) pyridine, the title S-2- (4-hexylphenyl) -5- (2-fluorooctyloxy) pyridine was obtained. It exhibited the following phase transition temperatures: Cr 56.0 S3 72.4 S2 79.7 Sc
* 84.9 ISO (where S3 and S2 represent unidentified smectic phases)

Example 3 S-2- (4-octylphenyl) -5- (2-fluorooctyloxy) obtained in Example 1 as a liquid crystal material
A liquid crystal display device was constructed using only pyridine, and its ferroelectric liquid crystal physical properties were measured. The measurement temperature was 76.8 ° C (S
c * 5 ° C lower than the upper limit). Spontaneous polarization Ps (nC / cm ² ): 145.6 Tilt angle θ (°): 20.9 Response time τ (μsec): 6.5 Viscosity (Nsec / m ² ): 2.04 × 10 ^-2 Physical properties were measured according to the following methods. Spontaneous polarization value (Ps): Sawyer-Tauer method. Tilt angle (θ): A helical structure is extinguished by applying a sufficiently high electric field higher than the critical electric field to the homogeneously oriented cell,
Next, the polarity was reversed, and the extinction position was obtained from the moving angle (corresponding to 2θ) under the orthogonal Nicols. Response time: The change time of the transmitted light intensity when a liquid crystal was injected into an alignment-treated cell having an electrode spacing of 2 μm and a rectangular shape of ± 10 V / μm and 100 Hz was applied was adopted. Thus, the 5- (2-fluoroalkoxy) of the present invention
Even if the pyridine derivative is used alone, a ferroelectric liquid crystal display device having a very fast response can be produced.

Example 4 An Sc composition (composition A) comprising the following compounds was prepared. This composition A exhibited the following phase transition temperature (° C.). Cr 4 Sc 65 SA 79 N 90 Iso

[0047]

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The respective concentrations were 30, 20, 10, 1
0, 20, and 10 wt%. A ferroelectric liquid crystal composition (composition B) composed of 80% by weight of the above composition and 20% by weight of the compound obtained in Example 1 was prepared. This composition B exhibited the following phase transition temperature. Room temperature Sc ^* 70.8 SA 80.9 N ^* 84.
7 Iso The spontaneous polarization, the tilt angle, and the response time at each temperature of the composition B were measured and are shown in Table 1.

[0049]

[Table 1]

Comparative Example 1 The ferroelectric liquid crystal properties of the following compound (Compound A) described in Example 2 of the aforementioned Japanese Patent No. 2,538,578 were measured.

[0051]

Embedded image

This compound A exhibited the following phase transition temperature. Cr 62.8 SI ^* 73.7 Sc ^* 81.0
Iso A ferroelectric liquid crystal composition (composition C) comprising the above composition A 80% by weight and this compound A 20% by weight was prepared.
This composition C exhibited the following phase transition temperature. Room temperature SC ^* 67.8 SA 79.5 N ^* 83.
9 Iso The spontaneous polarization, the tilt angle, and the response time at each temperature of the composition C were measured and are shown in Table 2 and FIG.

[0053]

[Table 2]

Example 5 A nematic liquid crystal composition (ZLI-113, manufactured by Merck & Co., Ltd.)
To 2), 1% by weight of S-2- (4-octylphenyl) -5- (2-fluorooctyloxy) pyridine obtained in Example 1 was added to obtain a chiral nematic liquid crystal composition. The helical pitch at each temperature of the chiral nematic liquid crystal composition was as follows. Measurement temperature (° C.) Pitch (μm) 60 50.0 50 51.3 40 53.5 30 57.6 25 60.8 20 60.8

[0055]

The 5- (2-fluoroalkoxy) pyridine derivative of the present invention has a large spontaneous polarization and a large temperature dependence of the spontaneous polarization. Accordingly, it is possible to manufacture a liquid crystal display element having a high response speed, particularly, a quick response at a low temperature and a small temperature dependence of the response speed. This will be described in more detail. The response time of a ferroelectric liquid crystal is
In principle, it is expressed by the following equation. τ = η / (Ps × E) (where τ is response time, η is viscosity, Ps is spontaneous polarization, E
Indicates an applied voltage. In general, both viscosity and spontaneous polarization increase at low temperatures. However, since the temperature dependence of the viscosity is significantly greater than the temperature dependence of the spontaneous polarization, the response speed of the ferroelectric liquid crystal becomes slow at low temperatures. The ferroelectric liquid crystal composition using the compound of the present invention (Example 4) is more spontaneous in a high temperature region than the ferroelectric liquid crystal composition using the compound described in the prior art (Comparative Example 1). The magnitude of the polarization is not much different. However, in the low temperature region, the magnitude of the spontaneous polarization of the composition of Example 4 was about 1.2 to 1.4 that of the composition of Comparative Example 1.
It is twice as large (Fig. 1). This difference appears as a clear difference in the temperature dependence of the response times of the two (FIG. 2). In the high-temperature region, both have almost the same response speed, but in the low-temperature region, the difference in the response speed is greatly increased. When the liquid crystal having a flat temperature characteristic is used for a liquid crystal display element, an element which is less affected by a temperature change of an external environment can be manufactured.

[Brief description of the drawings]

FIG. 1 shows the temperature dependence of spontaneous polarization.

FIG. 2 is a diagram showing the temperature dependence of response time.

Claims (3)

[Claims] 1. A compound of the general formula (1) (Wherein, R 1 represents an alkyl group or an alkoxy group having 1 to 16 carbon atoms, and R 2 represents an alkyl group having 1 to 12 carbon atoms). 2. A compound of the general formula (1) (Wherein R 1 represents an alkyl group or an alkoxy group having 1 to 16 carbon atoms, and R 2 represents an alkyl group having 1 to 12 carbon atoms). A liquid crystal composition containing one type. 3. General formula (1) (Wherein R 1 represents an alkyl group or an alkoxy group having 1 to 16 carbon atoms, and R 2 represents an alkyl group having 1 to 12 carbon atoms). A liquid crystal display device characterized by using a liquid crystal composition containing at least one of them.