JPH1017500A - Dialkenyltolan derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new compound comprising a specific liquid crystalline compound, hardly having the lowering degree of upper limit temperature of nematic phase, excellent in improving effect on viscosity-reducing effect and responsiveness and extremely useful for liquid crystal displays, especially requiring high speed response. SOLUTION: This compound is represented by formula I [R and R' are each independently H or a 1-5C alkyl; (m) and (n) are each independently an integer of 2-6], especially preferably a compound of formula II. The compound of formula I is obtained by reacting an alkenylbenzene derivative of formula III (X is Br, I, Cl, p-toluenesulfonyl, etc.) with a (4-alkenylphenyl)acetylene derivative of formula IV in the presence of a transition metal catalyst. Thereby, effects such as lowering of viscosity, increase of refractive index anisotropy and raising of nematic phase upper limit temperature (TN-1 ) can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dialkenyl tolane derivative which is a novel liquid crystal compound and a liquid crystal composition containing the same. These are useful as materials for electro-optical liquid crystal display, particularly as materials for nematic liquid crystal display.

[0002]

2. Description of the Related Art Liquid crystal display elements have been used in various measuring instruments, such as watches and calculators, automobile panels, word processors, electronic organizers, printers, computers, televisions, and the like. Typical liquid crystal display methods are TN (twisted nematic) type and S type.
TN (super twisted nematic) type, DS (dynamic light scattering) type,
There are GH (guest / host) type or FLC (ferroelectric liquid crystal), etc., and the driving method is generally multiplex driving instead of conventional static driving, and moreover, simple matrix method, recently active matrix method is practical. Has been

[0003] In accordance with these display methods and drive methods, various characteristics are required as liquid crystal materials. Above all, high-speed response is very important in most cases. The physical properties required of the liquid crystal material in order to increase the response speed are directly (i) decreasing the viscosity or (i)
i) To increase the elastic constant. However,
When the elastic constant is increased, the threshold voltage often increases. Therefore, when low voltage driving is required, it is necessary to reduce the viscosity without increasing the elastic constant too much.

Further, as a means for increasing the response of the liquid crystal element, it is very effective to reduce the cell thickness. However, in a liquid crystal element, the product (Δnd) of the cell thickness (d) and the refractive index anisotropy (Δn) is set to a certain value (0.
5, 1.0, 1.6, 2.2, usually the former two are often used). Therefore, to reduce the cell thickness, a liquid crystal material having a large refractive index anisotropy (Δn) is required.

In general, compounds having low viscosity often have low liquid crystallinity. Therefore, in many cases, the effect cannot be sufficiently exhibited, for example, it is not possible to add a sufficient amount to the composition, or it is necessary to simultaneously use a high-viscosity high-temperature liquid crystal for temperature compensation. Therefore, even if it is not necessary to exhibit liquid crystallinity, it is desired that the addition lowers the degree of decrease in the maximum nematic phase temperature (T _NI ).

In view of the above, there is a demand for a liquid crystal compound having a small viscosity, a large refractive index anisotropy (Δn), and a minimum nematic phase maximum temperature (T _NI ) due to its addition.

At present, as a low-viscosity liquid crystal which satisfies such conditions relatively well, for example, the general formula (II)

[0008]

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(Wherein R ^a and R ^b each represent a straight-chain alkyl group), but the properties thereof are no longer satisfactory.

In the liquid crystal compound, as a side chain group,
It is known that the above effects (decrease in viscosity, increase in refractive index anisotropy, increase in T _NI ) may be obtained by using an alkenyl group having a double bond introduced in place of an alkyl group. I have. Based on this finding, the present inventors have found that a compound of the general formula (III) having an alkenyl group in its side chain

[0011]

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(Wherein R ^c is an alkyl group, R ^d is a hydrogen atom or an alkyl group, and l is an integer of 2 to 6). It has been reported that it has better properties than the tolan derivative of (II). However, even with this,
It has become difficult to sufficiently meet the demand for lowering the viscosity of liquid crystal materials with the improvement in display quality, and there is a need for a more excellent viscosity reducing agent.

[0013]

An object of the present invention is to provide a liquid crystal display having excellent effects such as a decrease in viscosity, an increase in refractive index anisotropy and an increase in _TNI . An object of the present invention is to provide an alkenyl tolan derivative as a compound and a method for producing the same, and to provide a liquid crystal composition having a low viscosity, a large refractive index anisotropy (Δn) and a wide liquid crystal temperature range using the compound.

[0014]

According to the present invention, there is provided a compound represented by the following general formula (I):

[0015]

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(Wherein, R and R ′ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and m and n each independently represent an integer of 2 to 6). A dialkenyl tolan derivative.

In the above formula, R and R 'are each independently preferably a hydrogen atom or a methyl group, and more preferably R and R' both represent a hydrogen atom. When R and / or R ′ represent an alkyl group, the configuration of the double bond is preferably trans (E). m and n are each independently preferably an even number of 2, 4 or 6, and both m and n are 2
Is more preferable.

In the general formula (I), R, R ', m
And n can include more compounds, among which Formulas (Ia)-(Ic)

[0019]

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The compound of formula (Ia) is most preferred. The compound of the general formula (I) can be produced as follows. That is, the general formula (IV)

[0021]

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An alkenylbenzene derivative represented by the general formula (V):

[0023]

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(4-alkenylphenyl)
Acetylene derivative (wherein X is a bromine atom, iodine atom,
It represents a leaving group such as a chlorine atom, a p-toluenesulfonyl group, a methanesulfonyl group or a trifluoromethanesulfonyl group, preferably a bromine atom or an iodine atom, particularly preferably an iodine atom. Further, R, m, R ′ and n have the same meaning as in the general formula (I). ) In the presence of a transition metal catalyst.

As the transition metal catalyst, a palladium catalyst is preferable, and it is effective and preferable to use a copper (I) compound, particularly copper (I) iodide in combination. The reaction is carried out in a solvent. As the solvent, a so-called polar solvent such as dimethylformamide (DMF), dimethylacetamide (DMA) or dimethylsulfoxide (DMSO) is preferable, and usually an amine solvent such as triethylamine is used in combination.

The thus prepared general formula (I) of the present invention
In the dialkenyl tolan derivatives represented by the following formula (Ia):

[0027]

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The _TNI was 43 ° C. The dialkyltran derivative represented by the general formula (II) shown above and the general formula (II) having relatively similar side chain carbon atoms.
Compared to the alkyl alkenyl tolan derivatives of I),
For example, the formula (IIa) represented by the general formula (II)

[0029]

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The dialkyltolan derivative of the formula (I)
Formula (IIIa) represented by II)

[0031]

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The compounds of the general formula (I) according to the present invention have the general formula (II) or the general formula (III) since both of the alkylalkenyl tolan derivatives of the present invention do not exhibit liquid crystallinity when used alone.
It can be seen that the compound has significantly improved liquid crystallinity as compared with the compound of

The excellent effects obtained by adding the compound of the formula (Ia) represented by the general formula (I) of the present invention to a general-purpose liquid crystal composition are as follows. General-purpose host liquid crystal composition (H)

[0034]

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(In the formula, “%” represents “% by weight”.) A liquid crystal composition (M-1) comprising 70% by weight and 30% by weight of the compound of the formula (Ia) was prepared. Here, the physical properties and electro-optical properties of the host liquid crystal (H) were as follows.

T _NI : 116.7 ° C. Threshold voltage (V _th ): 1.88 V Viscosity (20 ° C.): 19.8 cp Response time (τr = τd): 21.5 ms Refractive index anisotropy (Δn): 0.090 Here, the threshold voltage (V _th ) is a value measured by enclosing in a TN cell having a thickness of 4.5 μm, the viscosity is a measured value at 20 ° C., and the response time is a rise time (τr) and a fall time. This is a measured value at the time of applying a voltage at which the time (τd) becomes equal.

On the other hand, the physical properties and electro-optical properties of (M-1) were as follows. T _NI : 92.0 ° C. Threshold voltage (V _th ): 2.45 V Viscosity (20 ° C.): 17.4 cp Response time (τr = τd): 11.5 ms Refractive index anisotropy (Δn): 0.146 Thus, it can be seen that the viscosity has been considerably reduced and the response time has been greatly improved to less than half. The refractive index anisotropy also increased about 1.5 times. Although T _NI is decreased by about 25 ° C., so as compound a nematic liquid crystallinity alone of formula (Ia) as described above, T _NI by the addition
Is small as compared with the case of the dialkyl tran derivative and the alkyl alkenyl tran derivative as described later.

On the other hand, 30% by weight of the above-mentioned dialkyltolan derivative of the formula (IIa) and the host liquid crystal (H) 7
A comparative composition (MR-1) consisting of 0% by weight was prepared.
The physical properties and electro-optical properties were as follows.

T _NI : 81.7 ° C. Threshold voltage (V _th ): 2.41 V Viscosity (20 ° C.): 16.3 cp Response time (τr = τd): 10.5 ms Refractive index anisotropy (Δn): 0.143 When this is compared with (M-1), especially _TNI is about 10
° C is also high, and it turns out that it has improved significantly.

Next, 30% by weight of the above-mentioned alkylalkenyl tolan derivative of the formula (IIIa) and the host liquid crystal (H)
A comparative composition (MR-2) consisting of 70% by weight was prepared. The physical properties and electro-optical properties were as follows.

T _NI : 86.0 ° C. Threshold voltage (V _th ): 2.42 V Viscosity (20 ° C.): 15.0 cp Response time (τr = τd): 9.5 ms Refractive index anisotropy (Δn): 0.146 Thus, although (MR-1) and compared to the that T _NI is improved, it can be seen that not reach the (M-1).

As described above, the compound of the formula (Ia) represented by the general formula (I) of the present invention is a liquid crystal composition having a low viscosity, excellent responsiveness, a large refractive index anisotropy and a wide nematic phase temperature range. It is clear that the compound of the formula (IIa) or (IIIa) has a superior effect in obtaining a product.

The dialkenyl tolan derivative of the general formula (I) can be converted into a mixture with another nematic liquid crystal compound by T
It can be suitably used for an N-type or STN-type field effect type display cell, particularly as a material having low viscosity and high response speed. In addition, since the general formula (I) does not have a strong polar group in the molecule, it is easy to obtain a large specific resistance and a high voltage holding ratio, and can be used as a component of a liquid crystal material for driving an active matrix. is there. The present invention also provides a liquid crystal composition containing at least one of the dialkenyl tolan derivatives represented by the general formula (I) as a component thereof.

Preferred representative examples of the nematic liquid crystal compound which can be used by mixing with the general formula (I) in this composition include, for example, 4-substituted benzoic acid 4-
Substituted phenyl, 4-substituted cyclohexanecarboxylic acid 4-
Substituted phenyl, 4-substituted cyclohexanecarboxylic acid 4 '
-Substituted biphenylyl, 4-substituted phenyl 4- (4-substituted cyclohexanecarbonyloxy) benzoate, 4- (4
-Substituted cyclohexyl) benzoic acid 4-substituted phenyl, 4
4- (4-substituted cyclohexyl) benzoic acid 4-substituted cyclohexyl, 4,4′-substituted biphenyl, 1- (4-substituted cyclohexyl) -4-substituted benzene, 4,4′-substituted bicyclohexane, 1- [2- (4-Substituted cyclohexyl) ethyl] -4-substituted benzene, 1- (4-substituted cyclohexyl) -2- (4-substituted cyclohexyl) ethane, 4,4 "-substituted terphenyl, 4- (4-substituted cyclohexyl) -4'-substituted biphenyl, 4- [2- (4
-Substituted cyclohexyl) ethyl] -4'-substituted biphenyl, 4- (4-substituted phenyl) -4'-substituted bicyclohexane, 4- [2- (4-substituted cyclohexyl) ethyl] -4'-substituted biphenyl, -[2- (4-substituted cyclohexyl) ethyl] cyclohexyl-4'-substituted benzene, 4- [2- (4-substituted phenyl) ethyl]-
4'-substituted bicyclohexane, 1- (4-substituted phenylethynyl) -4-substituted benzene, 1- (4-substituted phenylethynyl) -4- (4-substituted cyclohexyl) benzene, 2- (4-substituted phenyl) -5-substituted pyrimidines,
Examples thereof include 2- (4′-substituted biphenylyl) -5-substituted pyrimidine and compounds in which the benzene ring in each of the above compounds has a lateral substituent.

Among them, 4,4'-substituted biphenyl, 1- (4-substituted cyclohexyl) -4-substituted benzene, 4,4'-substituted bicyclohexane, 1- [2- (4- Substituted cyclohexyl)
Ethyl] -4-substituted benzene, 1- (4-substituted cyclohexyl) -2- (4-substituted cyclohexyl) ethane,
4,4 "-substituted terphenyl, 4- (4-substituted cyclohexyl) -4'-substituted biphenyl, 4- [2- (4-substituted cyclohexyl) ethyl] -4'-substituted biphenyl,
4- (4-substituted phenyl) -4'-substituted bicyclohexane, 4- [2- (4-substituted cyclohexyl) ethyl]-
4'-substituted biphenyl, 4- [2- (4-substituted cyclohexyl) ethyl] cyclohexyl-4'-substituted benzene, 4- [2- (4-substituted phenyl) ethyl] -4'-
Substituted bicyclohexane, 1- (4-substituted phenylethynyl) -4-substituted benzene, 1- (4-substituted phenylethynyl) -4- (4-substituted cyclohexyl) benzene and compounds in which the benzene ring is fluorine-substituted Is suitable.

[0046]

EXAMPLES Examples of the present invention are shown below to further explain the present invention. However, the invention is not limited to these examples.

The structure of the compound was confirmed by a nuclear magnetic resonance spectrum (NMR), a mass spectrum (MS) and an infrared absorption spectrum (IR). In addition, "%" of the composition
Represents "% by weight". Reference Example 1 Synthesis of 4-iodo-1- (3-butenyl) benzene

[0048]

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16.4 g of magnesium was dried in THF
The suspension was suspended in 20 mL, and 150 g of 4-bromo-1- (3-butenyl) benzene obtained in Reference Example was added to THF.
The 600 mL solution was added dropwise at a rate at which the solvent continued to reflux gently. After completion of the dropwise addition, the mixture was stirred for 2 hours and allowed to cool to room temperature. Dissolve 162 g of iodine in 480 mL of THF and
For 1 hour. After dropping, after stirring for 1 hour,
Water and then an aqueous solution of sodium hydrogen sulfite were added, and the mixture was extracted with toluene. The organic layer was washed with water and then with a saturated saline solution and dried over anhydrous sodium sulfate. The crude product obtained by evaporating the solvent was purified by silica gel column chromatography (hexane) to obtain 171 g of 4-iodo-1- (3-butenyl) benzene. Reference Example 2 Synthesis of 4-ethynyl-1- (3-butenyl) benzene

[0050]

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86.4 g of 4-iodo-1- (3-butenyl) benzene obtained in Reference Example 1, 2.35 g of dichlorobis (triphenylphosphine) palladium (II) and 637 mg of copper (I) iodide were added to 120 mL of DMF and triethylamine. Dissolved in 90 mL. At 30 ° C. or lower, 42.2 g of 2-methyl-3-butyn-2-ol in DMF60m
The L solution was added dropwise, and the mixture was further stirred at room temperature for 2 hours.

Dilute hydrochloric acid and toluene were added, the aqueous layer was extracted with toluene, and the organic layers were combined and washed with water and then with saturated saline. After dehydration and drying with anhydrous sodium hydrogen sulfate, the solvent was distilled off under reduced pressure to obtain 73.7 g of a crude product of 4- [4- (3-butenyl) phenyl] -2-methyl-3-butyn-2-ol. Obtained.

670 mg of sodium hydroxide was added to the whole amount, and the mixture was stirred at 80 ° C. for 2 hours while distilling off generated acetone. Distillation under reduced pressure (165 ° C./15 mmHg) gave 4-ethynyl-1- (3-butenyl) benzene 39.3.
g was obtained. (Example 1) Bis [4- (3-butenyl) phenyl]
Synthesis of ethyne (compound of formula (Ia))

[0054]

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8.76 g of 1- (3-butenyl) -4-iodobenzene was added to 15 ml of DMF and triethylamine 5
The mixture was dissolved in ml, and 370 mg of dichlorobistriphenylphosphine palladium (II) and 55 mg of copper (I) iodide were added. A solution of 5.0 g of 4-ethynyl-1- (3-butenyl) benzene in 15 ml of DMF was added dropwise at an internal temperature of 30 ° C. or lower, and the mixture was further stirred at room temperature for 3 hours. Water and 10% hydrochloric acid were added, the aqueous layer was separated, extracted with hexane, and the organic layers were combined and washed with 10% hydrochloric acid, water and then saturated saline. After dehydration drying with anhydrous sodium sulfate, the solvent was distilled off to obtain 9 g of crude crystals of bis [4- (3-butenyl) phenyl] ethyne. This was purified using silica gel column chromatography (hexane), and further recrystallized from ethanol to obtain 2.1 g of a purified product. This compound showed a nematic phase at a temperature of 43 ° C. or less when cooled from an isotropic liquid phase, and its melting point was 45 ° C.

Instead of 4-ethynyl-1- (3-butenyl) benzene or 1- (3-butenyl) -4-iodobenzene, another 1-alkenyl-4-ethynylbenzene or 1-alkenyl-4-halogeno is used. The following compounds were obtained in the same manner by using benzene.

Bis [4- (4-pentenyl) phenyl]
Ethyne bis [4- (5-hexenyl) phenyl] ethyne (compound of formula (Ic)) bis [4- (6-heptenyl) phenyl] ethyne bis [4- (7-octenyl) phenyl] ethyne bis [4- ( 3-pentenyl) phenyl] ethyne bis [4- (3-hexenyl) phenyl] ethyne bis [4- (3-heptenyl) phenyl] ethyne bis [4- (3-octenyl) phenyl] ethyne 1- [4- (3 -Pentenyl) phenyl] -2- [4-
(3-butenyl) phenyl] ethyne 1- [4- (4-pentenyl) phenyl] -2- [4-
(3-butenyl) phenyl] ethyne 1- [4- (3-hexenyl) phenyl] -2- [4-
(3-butenyl) phenyl] ethyne 1- [4- (4-hexenyl) phenyl] -2- [4-
(3-butenyl) phenyl] ethyne 1- [4- (5-hexenyl) phenyl] -2- [4-
(3-Butenyl) phenyl] ethin (compound of formula (Ib)) 1- [4- (3-Heptenyl) phenyl] -2- [4-
(3-butenyl) phenyl] ethyne 1- [4- (4-heptenyl) phenyl] -2- [4-
(3-butenyl) phenyl] ethyne 1- [4- (5-heptenyl) phenyl] -2- [4-
(3-butenyl) phenyl] ethyne 1- [4- (6-heptenyl) phenyl] -2- [4-
(3-butenyl) phenyl] ethyne 1- [4- (3-octenyl) phenyl] -2- [4-
(3-butenyl) phenyl] ethyne 1- [4- (7-octenyl) phenyl] -2- [4-
(3-Butenyl) phenyl] ethin (Example 2) Preparation of liquid crystal composition General-purpose host liquid crystal (H)

[0058]

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Was prepared. This host liquid crystal (H) is 11
Shows a nematic phase at 6.7 ° C or less, and its melting point is 11 ° C.
Met. The viscosity of this composition at 20 ° C., the threshold voltage (V _th ) of a TN cell having a cell thickness of 4.5 μm formed using the composition, the response time at that time, and the refractive index anisotropy (Δ)
n) was as follows.

Threshold voltage (V _th ): 1.88 V Viscosity (20 ° C.): 19.8 cp Response time (τr = τd): 21.5 ms Refractive index anisotropy (Δn): 0.090 The time is a measured value when a voltage is applied so that the rise time (τr) and the fall time (τd) are equal.

Next, 70% by weight of the host liquid crystal (H) and the compound of the present invention represented by the formula (Ia)

[0062]

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A liquid crystal composition (M-1) consisting of 30% by weight of the compound (1) was prepared. The physical properties and electro-optical properties of this composition were as follows. T _NI : 92.0 ° C. Threshold voltage (V _th ): 2.45 V Viscosity (20 ° C.): 17.4 cp Response time (τr = τd): 11.5 ms Refractive index anisotropy (Δn): 0.146 Thus, it can be seen that the viscosity is considerably reduced and the response time is greatly improved to less than half. The refractive index anisotropy also increased about 1.5 times. Although T _NI is lowered by about 25 ° C., the compound of formula (Ia) alone exhibits nematic liquid crystallinity as described above,
_As will be described later, the decrease in _NI is small as compared with the case of dialkyltran derivatives and alkylalkenyltran derivatives. (Comparative Example 1) On the other hand, in the same manner as in the general formula (Ia), the compound of the formula (IIa) having a tolan skeleton but having both side chains of a linear alkyl group

[0064]

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30% by weight of the compound (A) and the host liquid crystal (H)
A comparative composition (MR-1) consisting of 70% by weight was prepared. Physical properties of this composition measured in the same manner were as follows.

T _NI : 81.7 ° C. Threshold voltage (V _th ): 2.41 V Viscosity (20 ° C.): 16.3 cp Response time (τr = τd): 10.5 ms Refractive index anisotropy (Δn): 0.143 Thus, the maximum temperature of the nematic phase of (MR-1) is (M
-1) is about 10 ° lower. Therefore, the compound of the formula (Ia) represented by the general formula (I) of the present invention is a liquid crystal composition having a low viscosity, a large refractive index anisotropy and an excellent high-speed response, and a high _TNI and a high temperature. It can be seen that the compound of formula (IIa) is considerably superior in preparing a liquid crystal material having a wide range. Comparative Example 2 Next, as in the general formula (Ia), the compound represented by the formula (II)
Ia)

[0067]

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30% by weight of the compound (A) and the host liquid crystal (H)
A comparative composition (MR-2) consisting of 70% by weight was prepared. Physical properties of this composition measured in the same manner were as follows.

T _NI : 86.0 ° C. Threshold voltage (V _th ): 2.42 V Viscosity (20 ° C.): 15.0 cp Response time (τr = τd): 9.5 ms Refractive index anisotropy (Δn): 0.146 Thus, although its T _NI is improved when compared to (MR-1), it is clear that it does not reach (M-1).

As described above, the compound of the formula (Ia) represented by the general formula (I) of the present invention is a liquid crystal composition having low viscosity, high refractive index anisotropy and excellent high-speed response. In preparing a liquid crystal material having a high T _{N- I} and a wide temperature range, the compound of the formula (IIa) having a structure similar to that of the compound of the present invention.
Alternatively, it can be seen that it is considerably better than the compound of the formula (IIIa).

[0071]

As described in the examples, the dialkenyl tolan derivatives provided by the present invention can be easily produced industrially. The obtained dialkenyl tolan derivative has a lower degree of decrease in the maximum temperature of the nematic phase than the conventionally used thinning liquid crystalline compound having the same or similar skeleton, and thus has the effect of improving the viscosity reducing effect and the response. Therefore, the liquid crystal composition containing the same is extremely useful as a practical liquid crystal, particularly for a liquid crystal display requiring a high-speed response.

Claims (4)

[Claims] 1. A compound of the general formula (I) (Wherein, R and R ′ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and m and n each independently represent an integer of 2 to 6). 2. The compound represented by the general formula (I) according to claim 1, wherein R and R ′ are both hydrogen atoms. 3. The compound represented by the general formula (I) according to claim 1, wherein m and n are both 2. 4. A liquid crystal composition comprising the compound of the formula (I) according to claim 1.