JPH10114693A - Alkenylbiphenyl derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject new compound having low viscosity, large dielectric anisotropy and small lowering degree of the upper limit temperature of nematic phase caused by the addition of the compound and, accordingly, giving a liquid crystal composition having low viscosity and broad liquid crystal temperature range and drivable at a low voltage. SOLUTION: This compound is expressed by the formula I (R is H or a 1-10C alkyl; (m) is 2-6; Z is F, trifluoromethyl, etc.; X and Y are each H or F), e.g. 3,4,5-trifluoro-4'-(3-butenyl)biphenyl. The compound can be produced e.g. by reacting an alkenylbenzene derivative of the formula II (W is Br or I) with an organometallic compound of the formula III (M is MgBr, MgI, etc.) in the presence of a transition metal catalyst. The transition metal catalyst is preferably a palladium (0) complex such as tetrakistriphenylphosphine palladium (0) or a palladium (II) complex such as dicyclobistriphenylphosphine palladium (II).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an alkenyl biphenyl derivative which is a novel liquid crystal compound and a liquid crystal composition containing the same. These are useful for electro-optical liquid crystal displays, especially as nematic liquid crystal materials capable of low-voltage driving and high-speed response.

[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

According to these display systems and drive systems, various characteristics are required also as a liquid crystal material. Among them, a high-speed response and a decrease in drive voltage have been particularly emphasized recently.

The physical properties required of a liquid crystal material to increase the response speed are directly (i) reducing the viscosity or (ii) increasing the elastic constant. However, when the elastic constant is increased, the threshold voltage often rises. Therefore, when low voltage driving is required, it is important to reduce the viscosity without increasing the elastic constant too much. On the other hand, in order to enable low-voltage driving by lowering the threshold voltage, it is necessary to (i) increase the dielectric anisotropy or (ii) reduce the elastic constant. However, when the elastic constant is reduced, the response becomes slower this time, so it is necessary to increase the dielectric anisotropy.

Therefore, in order to achieve both high-speed response and low-voltage driving, a so-called P-type liquid crystal having low viscosity and large dielectric anisotropy is required. However, such low-viscosity P-type compounds generally have low liquid crystallinity. For this reason, a sufficient amount cannot be added to the composition, or it is necessary to simultaneously use a high-temperature liquid crystal having large viscosity for temperature compensation,
In many cases, the effect cannot be sufficiently exhibited. Therefore, even if it is not necessary to exhibit liquid crystallinity, it is desired that the addition lowers the degree of reduction in the maximum temperature of the nematic phase (T _NI ).

[0006] From the above, a liquid crystal compound which is a P-type compound having a small viscosity and a large dielectric anisotropy and having a minimum decrease in the maximum nematic phase temperature (T _NI ) due to its addition is desired. It is rare.

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

[0008]

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A fluorine-containing biphenyl derivative represented by
General formula (III)

[0010]

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The fluorine-containing cyclohexylbenzene derivative represented by the following formula: In the above formula, R ^a represents a linear alkyl group, U and V, respectively, represent a fluorine atom or a hydrogen atom.

However, even with the use of these compounds, it is actually difficult to simultaneously meet the demands such as lowering the viscosity of the liquid crystal material, lowering the driving voltage, and securing a wider temperature range. Liquid crystalline compounds have been desired.

[0013]

An object of the present invention [0005] to solve is to meet the above object, a viscosity less large biphenyl derivative of the dielectric anisotropy, and by the addition of T _NI It is an object of the present invention to provide a liquid crystal compound having a small degree of reduction, and to provide a liquid crystal composition having a low viscosity, a wide liquid crystal temperature range, a low threshold voltage, and a low voltage drive using the compound.

[0014]

The present invention has been made in order to solve the above problems. General formula (I)

[0015]

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(Wherein R is a hydrogen atom or a group having 1 to carbon atoms)
Represents an alkyl group of 10, m represents an integer of 2 to 6,
Is a fluorine atom, a chlorine atom, a trifluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group or 2,
Represents a 2,2-trifluoroethoxy group, and X and Y each independently represent a hydrogen atom or a fluorine atom. ). 2. 2. The compound according to the above 1, wherein in the general formula (I), Z is a fluorine atom or a trifluoromethoxy group. 3. 3. The compound according to the above 1 or 2, wherein m = 2 in the general formula (I). 4. 4. The compound according to the above 1, 2, or 3, wherein R is a hydrogen atom in the general formula (I). 5. 2. A liquid crystal composition comprising the compound represented by the general formula (I) as described in 1 above. As the above-mentioned solution.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the present invention will be described below. In the general formula (I) of the present invention, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably a hydrogen atom or a linear alkyl group having 1 to 3 carbon atoms,
In order to obtain a low viscosity, a hydrogen atom is particularly preferable. When R represents an alkyl group, the double bond is preferably in a trans configuration. m represents an integer of 2 to 6, preferably 2 to 4, and particularly preferably 2. Therefore, the entire side chain is preferably a 3-alkenyl group or a terminal alkenyl group, and most preferably a 3-butenyl group. X and Y each independently represent a hydrogen atom or a fluorine atom, but at least one of them is preferably a fluorine atom in order to enhance the effect of reducing the threshold voltage. Z represents a fluorine atom, a chlorine atom, a trifluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group or a trifluoroethoxy group, and a fluorine atom and a trifluoromethoxy group are preferred. The compound of the general formula (I) can be produced based on the following steps.

That is, the general formula (IVa)

[0019]

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An alkenylbenzene derivative represented by the general formula (Vb)

[0021]

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The compound can be easily produced by reacting the compound with the organometallic compound represented by the formula (1) in the presence of a transition metal catalyst. In the above formula, W represents a bromine atom or an iodine atom, preferably an iodine atom, and M represents MgBr, MgCl,
It represents MgI or Li, preferably MgBr or MgI. Further, R, m, X, Y and Z represent the same meaning as in the general formula (I).

The transition metal catalyst is preferably a palladium-based or nickel-based catalyst, particularly a palladium (0) complex such as tetrakistriphenylphosphinepalladium (0) and a palladium (II) complex such as dichlorobistriphenylphosphinepalladium (II). Is preferred.

Alternatively, the general formula (Va)

[0025]

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A halogenated benzene derivative represented by the general formula (IVb)

[0027]

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Can also be produced by reacting the same with the organometallic compound represented by the formula (1). In the above formula,
W represents a bromine atom or an iodine atom, preferably an iodine atom, and M represents MgBr, MgCl, MgI or Li, preferably MgBr or MgI. Also, R, m,
X, Y and Z have the same meaning as in formula (I).

The selection of this step is not particularly limited, and may be determined based on the availability of starting materials, the yield of the final compound, the ease of purification, and the like. In addition, the compound in which W is an iodine atom in the general formula (IVa) used here is a compound that the present inventors have previously reported elsewhere.

Representative compounds of the present invention thus prepared are shown in Table 1 together with their phase transition temperatures.

[0031]

[Table 1]

(In the table, Cr represents a crystal phase, I represents an isotropic liquid phase, and the phase transition temperature is “° C.”.) As can be seen from Table 1, the general formula (I) of the present invention is used. The compound of (1) alone does not show a liquid crystal phase. However, as described later, the maximum temperature of the nematic phase (T _NI ) when added to a general-purpose liquid crystal composition is lower than that of the compound of the general formula (II) or the general formula (III). Is relatively small, which means that it has improved liquid crystallinity.

The excellent effects obtained by adding the compound of the general formula (I) to the liquid crystal composition are as follows. Among the compounds represented by the general formula (I), it is a typical compound where m = 2. (I
-1)

[0034]

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20% by weight of the compound (A) and the host liquid crystal composition (H)

[0036]

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Liquid crystal composition (M-1) consisting of 80% by weight
Was prepared. The characteristic values of the host liquid crystal (H) used here are as follows. T _NI : 116.7 ° C. Threshold voltage (V _th ): 1.88 V Viscosity (20 ° C.): 19.8 cp Dielectric anisotropy (Δε): 4.8 Refractive index anisotropy (Δn): 0.090 Here, the threshold voltage (V _th ) is a value measured at 20 ° C. by enclosing in a TN cell having a thickness of 4.5 μm, and the viscosity, dielectric anisotropy and refractive index anisotropy are all at 20 ° C. It is a measured value.

On the other hand, the characteristic values of (M-1) were as follows. T _NI : 72.5 ° C. Threshold voltage (V _th ): 1.35 V Viscosity (20 ° C.): 15.2 cp Dielectric anisotropy (Δε): 5.7 Refractive index anisotropy (Δn): 0.088 On the other hand, on the other hand, the conventionally used general formula (II)
Typical formula (A) represented by

[0039]

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20% by weight of the compound (A) and a host liquid crystal (H)
A liquid crystal composition (MA) consisting of 80% by weight was prepared, and the measured characteristic values were as follows. T _NI : 69.0 ° C. Threshold voltage (V _th ): 1.33 V Viscosity (20 ° C.): 16.0 cp Dielectric anisotropy (Δε): 5.7 Refractive index anisotropy (Δn): 0.086 Furthermore, a typical formula (B) represented by a general formula (III) conventionally used

[0041]

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20% by weight of the compound (A) and a host liquid crystal (H)
A liquid crystal composition (MB) consisting of 80% by weight was prepared, and the measured characteristic values were as follows. T _NI : 70.5 ° C. Threshold voltage (V _th ): 1.46 V Viscosity (20 ° C.): 15.5 cp Dielectric anisotropy (Δε): 5.8 Refractive index anisotropy (Δn): 0.082 As described above, the liquid crystal composition (MI) of the present invention comprises (M
-Exhibits a low threshold voltage comparable to (A) and a low viscosity comparable to (MB), plus a higher T than any of the compositions
_It can be seen that it has _NI .

Accordingly, in order to obtain a liquid crystal composition having a wide temperature range, a low viscosity and a low driving voltage, No. 1 of the general formula (I) is used. The compound of the formula (I-1) is represented by the general formula (II)
It can be seen that the compound has more excellent properties than the compound of the formula (A) represented by the formula (A) or the compound of the formula (B) represented by the formula (III).

Next, No. 1 shown in Table 1 was used. (I-
4)

[0045]

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20% by weight of the compound (A) and a host liquid crystal (H)
A liquid crystal composition (M-4) consisting of 80% by weight was prepared.
The characteristic values of this composition were as follows. T _NI : 80.5 ° C. Threshold voltage (V _th ): 1.71 V Viscosity (20 ° C.): 14.0 cp Dielectric anisotropy (Δε): 5.0 Refractive index anisotropy (Δn): 0.097 Accordingly, although the threshold voltage was slightly higher than that of (M-1), its viscosity could be further reduced, and T
_NI could also get higher.

As described above, the compound of the general formula (I) of the present invention has a low viscosity, excellent responsiveness, a wide nematic phase temperature range, and a conventional liquid crystal composition having a low threshold voltage. It is evident that it shows an effect superior to the compound.

Therefore, the compound of the general formula (I) of the present invention has a T
It can be suitably used as a material for an N-type or STN-type field effect display cell, particularly as a low-viscosity high-speed responsive material that can be driven at a low voltage. Further, since the compound of the general formula (I) of the present invention 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 as a component of a liquid crystal material for driving an active matrix. It is also possible to use. The present invention also provides a liquid crystal composition containing at least one compound represented by the general formula (I) as a component thereof. Preferred representative examples of the nematic liquid crystal compound which can be used as a mixture with the compound of 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- (4-substituted cyclohexanecarbonyloxy) benzoate 4-substituted phenyl,
4- (4-substituted cyclohexyl) benzoic acid 4-substituted phenyl, 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, 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)
Examples include benzene, 2- (4-substituted phenyl) -5-substituted pyrimidine, 2- (4′-substituted biphenylyl) -5-substituted pyrimidine, and compounds in which the benzene ring has a lateral substituent in each of the above compounds. it can.

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.

[0050]

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 the composition
Represents "% by weight". Reference Example 1 Synthesis of 4-iodo-1- (3-butenyl) benzene 16.4 g of magnesium was suspended in 20 mL of dry THF. To this 4-bromo-1- (3-butenyl)
A solution of 150 g of benzene in 600 mL of THF was added dropwise at a rate at which the solvent continued to gently reflux. After completion of the dropwise addition, the mixture was stirred for 2 hours and allowed to cool to room temperature. 162 g of iodine in THF4
It was dissolved in 80 mL and added dropwise at 10 ° C. for 1 hour. After completion of the dropwise addition, the mixture was stirred 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 give 4-
171 g of iodo-1- (3-butenyl) benzene was obtained. (Example 1) 3,4,5-trifluoro-4 '-(3
Synthesis of -butenyl) biphenyl

[0052]

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1.84 g of magnesium was dried in THF
Suspended in 2 mL. 4-bromo-3,4,5
-A solution of 15.9 g of trifluorobenzene in 60 mL of THF was added dropwise at such a rate that the solvent continued to gently reflux. After the addition, the mixture was further stirred for 2 hours, and then allowed to cool to room temperature to prepare a Grignard reagent. Next, 15 g of 4-iodo-1- (3-butenyl) benzene obtained in Reference Example 1 was added to THF60.
The solution was dissolved in mL, and 670 mg of tetrakistriphenylphosphine palladium (0) was added. The Grignard reagent prepared above was added dropwise thereto at 30 ° C. or lower over 2 hours. After further stirring for 2 hours, water and a small amount of diluted hydrochloric acid were added, and the mixture was extracted with ethyl acetate. After washing with water and then with a saturated saline solution, it was dehydrated and dried with anhydrous sodium sulfate. The solvent was distilled off, and 18.7 g of a crude product obtained was purified by silica gel column chromatography (hexane) to give a colorless oily 3,4,5-trifluoro-4 ′-(3-butenyl) biphenyl. 15.2 g were obtained.

The following compounds were obtained in the same manner. 3,4-difluoro-4 '-(3-butenyl) biphenyl 4-fluoro-4'-(3-butenyl) biphenyl 4-trifluoromethoxy-4 '-(3-butenyl) biphenyl 3-fluoro-4-tri Fluoromethoxy-4 '-(3
-Butenyl) biphenyl 3,5-difluoro-4-trifluoromethoxy-4 ′
-(3-butenyl) biphenyl 4-difluoromethoxy-4 '-(3-butenyl) biphenyl 3-fluoro-4-difluoromethoxy-4'-(3-
(Butenyl) biphenyl 3,5-difluoro-4-difluoromethoxy-4 ′-(3-butenyl) biphenyl 4-trifluoromethyl-4 ′-(3-butenyl) biphenyl 3-fluoro-4-trifluoromethyl-4 ′ -(3-
Butenyl) biphenyl 3,5-difluoro-4-trifluoromethyl-4'-
(3-butenyl) biphenyl 4-chloro-4 '-(3-butenyl) biphenyl 3-fluoro-4-chloro-4'-(3-butenyl) biphenyl 3,5-difluoro-4-chloro-4 '-( 3-butenyl) biphenyl 4- (2,2,2-trifluoroethoxy) -4'-
(3-butenyl) biphenyl 3-fluoro-4- (2,2,2-trifluoroethoxy) -4 ′-(3-butenyl) biphenyl 3,5-difluoro-4- (2,2,2-trifluoro Ethoxy) -4 '-(3-butenyl) biphenyl 3,4,5-trifluoro-4'-(5-hexenyl)
Biphenyl 3,4-difluoro-4 '-(5-hexenyl) biphenyl 4-fluoro-4'-(5-hexenyl) biphenyl 4-trifluoromethoxy-4 '-(5-hexenyl)
Biphenyl 3-fluoro-4-trifluoromethoxy-4 ′-(5
-Hexenyl) biphenyl 3,5-difluoro-4-trifluoromethoxy-4 '
-(5-hexenyl) biphenyl 4-difluoromethoxy-4 '-(5-hexenyl) biphenyl 3-fluoro-4-difluoromethoxy-4'-(5-
Hexenyl) biphenyl 3,5-difluoro-4-difluoromethoxy-4'-
(5-hexenyl) biphenyl 4-trifluoromethyl-4 '-(5-hexenyl) biphenyl 3-fluoro-4-trifluoromethyl-4'-(5-
Hexenyl) biphenyl 3,5-difluoro-4-trifluoromethyl-4'-
(5-hexenyl) biphenyl 4-chloro-4 '-(5-hexenyl) biphenyl 3-fluoro-4-chloro-4'-(5-hexenyl)
Biphenyl 3,5-difluoro-4-chloro-4 '-(5-hexenyl) biphenyl 4- (2,2,2-trifluoroethoxy) -4'-
(5-hexenyl) biphenyl 3-fluoro-4- (2,2,2-trifluoroethoxy) -4 ′-(5-hexenyl) biphenyl 3,5-difluoro-4- (2,2,2-trifluoro Ethoxy) -4 '-(5-hexenyl) biphenyl 3,4,5-trifluoro-4'-(4-pentenyl)
Biphenyl 3,4-difluoro-4 '-(4-pentenyl) biphenyl 4-fluoro-4'-(4-pentenyl) biphenyl 4-trifluoromethoxy-4 '-(4-pentenyl)
Biphenyl 3-fluoro-4-trifluoromethoxy-4 ′-(4
-Pentenyl) biphenyl 3,5-difluoro-4-trifluoromethoxy-4 '
-(4-pentenyl) biphenyl 4-difluoromethoxy-4 '-(4-pentenyl) biphenyl 3-fluoro-4-difluoromethoxy-4'-(4-
Pentenyl) biphenyl 3,5-difluoro-4-difluoromethoxy-4'-
(4-pentenyl) biphenyl 4-trifluoromethyl-4 '-(4-pentenyl) biphenyl 3-fluoro-4-trifluoromethyl-4'-(4-
Pentenyl) biphenyl 3,5-difluoro-4-trifluoromethyl-4'-
(4-pentenyl) biphenyl 4-chloro-4 '-(4-pentenyl) biphenyl 3-fluoro-4-chloro-4'-(4-pentenyl)
Biphenyl 3,5-difluoro-4-chloro-4 '-(4-pentenyl) biphenyl 4- (2,2,2-trifluoroethoxy) -4'-
(4-pentenyl) biphenyl 3-fluoro-4- (2,2,2-trifluoroethoxy) -4 ′-(4-pentenyl) biphenyl 3,5-difluoro-4- (2,2,2-trifluoro Ethoxy) -4 '-(4-pentenyl) biphenyl 3,4,5-trifluoro-4'-(3-pentenyl)
Biphenyl 3,4-difluoro-4 '-(3-pentenyl) biphenyl 4-fluoro-4'-(3-pentenyl) biphenyl 4-trifluoromethoxy-4 '-(3-pentenyl)
Biphenyl 3-fluoro-4-trifluoromethoxy-4 ′-(3
-Pentenyl) biphenyl 3,5-difluoro-4-trifluoromethoxy-4 '
-(3-pentenyl) biphenyl 4-difluoromethoxy-4 '-(3-pentenyl) biphenyl 3-fluoro-4-difluoromethoxy-4'-(3-
Pentenyl) biphenyl 3,5-difluoro-4-difluoromethoxy-4'-
(3-pentenyl) biphenyl 4-trifluoromethyl-4 '-(3-pentenyl) biphenyl 3-fluoro-4-trifluoromethyl-4'-(3-
Pentenyl) biphenyl 3,5-difluoro-4-trifluoromethyl-4'-
(3-pentenyl) biphenyl 4-chloro-4 '-(3-pentenyl) biphenyl 3-fluoro-4-chloro-4'-(3-pentenyl)
Biphenyl 3,5-difluoro-4-chloro-4 '-(3-pentenyl) biphenyl 4- (2,2,2-trifluoroethoxy) -4'-
(3-pentenyl) biphenyl 3-fluoro-4- (2,2,2-trifluoroethoxy) -4 ′-(3-pentenyl) biphenyl 3,5-difluoro-4- (2,2,2-trifluoro (Ethoxy) -4 ′-(3-pentenyl) biphenyl (Example 2) Preparation of liquid crystal composition (1) General-purpose host liquid crystal (H)

[0055]

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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.
It is. The viscosity of this composition at 20 ° C. and the threshold voltage (V) of a TN cell having a cell thickness of 4.5 μm manufactured using the composition were measured.
_th ), and the refractive index anisotropy (Δn) at that time was as follows.

Viscosity (20 ° C.): 19.8 cp Dielectric anisotropy (Δε): 4.8 Threshold voltage (V _th ) 1.88 V Refractive index anisotropy (Δn): 0.090 The liquid crystal (H) was 80%, and the compound of the present invention was No. 1 in Table 1 above. (I-1)

[0058]

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A liquid crystal composition (M-
1) was prepared. The physical properties and electro-optical properties of (M-1) were as described below. T _NI : 72.5 ° C. Viscosity (20 ° C.): 15.2 cp Dielectric anisotropy (Δε): 5.7 Threshold voltage (V _th ): 1.35 V Refractive index anisotropy (Δn): 0.088 Therefore, although the maximum temperature of the nematic phase (T _NI ) is lowered, the dielectric anisotropy is increased, the threshold voltage is greatly reduced, and the viscosity is also significantly reduced, so that the responsiveness is improved. You can see that there is. (Comparative Example 1) (I-
Instead of the compound of 1), a compound of the general formula (I)
Formula (A) which is a typical compound represented by I)

[0060]

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Compound 20% and host liquid crystal (H) 80
% Of the composition (MA) was prepared. The characteristic values of this composition were as follows. T _NI : 69.0 ° C. Viscosity (20 ° C.): 16.0 cp Dielectric anisotropy (Δε): 5.7 Threshold voltage (V _th ): 1.33 V Refractive index anisotropy (Δn): 0.086 Accordingly, although the threshold voltage is slightly lower than (M-1), (M)
It can be seen that it does not reach -1). (Comparative Example 2) (I-
Instead of the compound of 1), a compound of the general formula (I)
Formula (B) which is a typical compound represented by II)

[0062]

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Compound 20% and host liquid crystal (H) 80
% Of a liquid crystal composition (MB). The characteristic values of this composition were as follows. T _NI : 70.5 ° C. Threshold voltage (V _th ): 1.46 V Viscosity (20 ° C.): 15.5 cp Dielectric anisotropy (Δε): 5.8 Refractive index anisotropy (Δn): 0.082 Therefore, although the viscosity is as low as that of (M-1), the maximum temperature of the nematic phase is low and the threshold voltage is about 0.1.
It can be seen that V is higher. (Example 3) Preparation of liquid crystal composition (2) In place of the compound (I-1), the compound of the present invention, No. 1 in Table 1 above, was used. (I-
4)

[0064]

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Compound 20% and host liquid crystal (H) 80
% Of a liquid crystal composition (M-4). The characteristic values of this composition were as follows. T _NI : 80.5 ° C. Threshold voltage (V _th ): 1.71 V Viscosity (20 ° C.): 14.0 cp Dielectric anisotropy (Δε): 5.0 Refractive index anisotropy (Δn): 0.097 Therefore, as compared with (M-1), the threshold voltage was slightly higher, but the maximum temperature of the nematic phase was higher, and the viscosity could be greatly reduced. (Example 4) Preparation of liquid crystal composition (3) In place of the compound (I-1), the compound of the present invention, No. 1 in Table 1 above, was used. (I-
3)

[0066]

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Compound 20% and host liquid crystal (H) 80
% Of a liquid crystal composition (M-3). The characteristic values of this composition were as follows. T _NI : 78.5 ° C. Threshold voltage (V _th ): 1.86 V Viscosity (20 ° C.): 13.5 cp Dielectric anisotropy (Δε): 4.4 Refractive index anisotropy (Δn): 0.098 Therefore, since the dielectric anisotropy became smaller as compared with (M-1), its threshold voltage was further increased as compared with (M-4), but the maximum temperature of the nematic phase was still higher, and its viscosity was higher. Was able to be reduced further than (M-4). (Example 5) Preparation of liquid crystal composition (4) General-purpose host liquid crystal (J)

[0068]

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Was prepared. This host liquid crystal (J) has 5
It shows a nematic phase at 4.5 ° C. or lower. The viscosity, dielectric anisotropy, refractive index anisotropy, and threshold voltage of a TN cell having a cell thickness of 8 μm, which were measured in the same manner, were as follows.

Threshold voltage (V _th ): 1.60 V Viscosity (20 ° C.): 21.0 cp Dielectric anisotropy (Δε): 4.4 Refractive index anisotropy (Δn): 0.092 90% of the host liquid crystal (J) and
A liquid crystal composition (N-
1) was prepared. The physical properties and electro-optical properties of this composition were as follows.

T _NI : 41.2 ° C. Viscosity (20 ° C.): 19.6 cp Dielectric anisotropy (Δε): 7.3 Threshold voltage (V _th ): 1.27 V Refractive index anisotropy (Δn): 0.086 Accordingly, it can be seen that although the T _NI is slightly reduced as compared with the host liquid crystal (J), the threshold voltage is greatly reduced and the viscosity is also reduced. (Example 6) Preparation of liquid crystal composition (5) Host liquid crystal (J) 80% A liquid crystal composition (N-4) comprising 20% of the compound (I-4) was prepared. The physical properties and electro-optical properties of this composition were as follows.

T _NI : 40.9 ° C. Viscosity (20 ° C.): 17.5 cp Dielectric anisotropy (Δε): 6.8 Threshold voltage (V _th ): 1.38 V Refractive index anisotropy (Δn): 0.093 Therefore, it can be seen that although the threshold voltage is slightly higher than that of (N-1), the viscosity is further reduced.

As described above, the compound of the formula (I) of the present invention is superior to the conventional compound in obtaining a liquid crystal composition having a low viscosity, a wide nematic phase temperature range, and a low threshold voltage. It is clear that it shows an effect.

[0074]

The alkenylbiphenyl derivative provided by the present invention can be easily produced industrially as shown in the examples. The obtained alkenyl biphenyl derivative has a lower degree of decrease in the maximum temperature of the nematic phase as compared with a conventionally used liquid crystalline compound having a similar or similar structure, and has an effect of reducing the threshold voltage in addition to the effect of reducing the viscosity. Because of its excellent properties, the liquid crystal composition containing it is extremely useful as a practical liquid crystal, particularly for liquid crystal displays requiring high-speed response and low-voltage driving.

Claims (5)

[Claims] 1. A compound of the general formula (I) (Wherein, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, m represents an integer of 2 to 6, Z represents a fluorine atom, a chlorine atom, a trifluoromethyl group, a trifluoromethoxy group, a difluoro A methoxy group or a 2,2,2-trifluoroethoxy group, and X and Y each independently represent a hydrogen atom or a fluorine atom). 2. The compound according to claim 1, wherein in the formula (I), Z is a fluorine atom or a trifluoromethoxy group. 3. The compound according to claim 1, wherein m = 2 in the general formula (I). 4. The compound according to claim 1, wherein R in Formula (I) is a hydrogen atom. 5. A liquid crystal composition comprising the compound represented by the general formula (I) according to claim 1.