JPH08217706A - 2-fluorobiphenyl derivative - Google Patents

Abstract

(57) [Summary] [Structure] General Formula (I) (R: C1-10 alkyl, X, Y: each independently, H atoms, F atoms, Z: C1-10 alkyl, alkoxyl, F atom, Cl atom, -CF _3, -OCF _3, -O
CF ₂ H, —OCH ₂ CF ₃ ), a composition containing the compound, and a synthetic intermediate compound of the compound. [Effect] This compound has a high T _NI and a large Δn. Further, since it has excellent compatibility with other liquid crystal materials, it is possible to increase the T _NI of the composition and increase Δn by mixing it with a widely used host liquid crystal. Therefore, this compound is useful for liquid crystal displays, such as word processors and liquid crystal televisions, which emphasize fast response.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel liquid crystal compound which is a 2-fluorobiphenyl derivative and is useful as an electro-optical display material, and a liquid crystal composition containing the novel liquid crystal compound. It also relates to a novel 2-fluoro-4-alkyl-4′-ethynylbiphenyl which is a synthetic intermediate of the compound of the present invention.

[0002]

2. Description of the Related Art Liquid crystal display devices have recently been used as information display devices such as watches and calculators, word processors, computer terminal displays and the like, and have become increasingly important as interfaces between electronic devices and people.

A display method using liquid crystal is a field effect (FE).
M) type, dynamic scattering (DSM) type, and thermal effect (TEM) type. Various display systems have been proposed by utilizing these effects, but the display system using the field effect type has been put into practical use so far. The field effect type includes twisted nematic (TN) type, super twisted nematic (STN) type, and guest-host (G).
H) type, electric field controlled birefringence (ECB) type, cholesteric-nematic phase transition (CN-PT) type, surface stabilized ferroelectric liquid crystal (SSFLC) type and the like. Among these, the TN type and the STN type are currently the mainstream. Among them, in the STN type, the capacity can be increased to some extent by improving the driving method, etc., but it has become a limit to the recent large display capacity requirement. Therefore, M using a two-terminal non-linear element having a threshold characteristic for each display pixel
An active matrix method such as an IM (Metal Insurator Metal) method and a TFT (Thin Film Transistor) method using a three-terminal active element has been put into practical use, and is rapidly developing toward a large capacity.

Liquid crystal materials used in these liquid crystal display systems are required to have various characteristics according to the characteristics of each display system, but they must be able to operate in a wide temperature range and have a fast response. Is a particularly important required characteristic in common.

The response time can be shortened by lowering the viscosity of the liquid crystal composition, but the response time can also be shortened by the following method. In TN type liquid crystal display, square of cell thickness (d) and response time (τ)
There is a proportional relationship between and, and by reducing the value of d, it is possible to obtain a liquid crystal element having a fast response. However, in order to prevent the generation of interference fringes on the cell surface, which causes the cell appearance to be impaired, the product Δn · d of the refractive index anisotropy (Δn) of the liquid crystal material filled in the cell and the cell thickness is calculated. Must be set to a certain value. In a practically used liquid crystal cell, the value of Δn · d is set to 0.5, 1.0, 1.6 or 2.2. Since the value of Δn · d is set to a constant value in this way, in order to reduce d,
A liquid crystal material having a large Δn value is required. In addition, even for polymer-dispersed liquid crystal display devices that require strong white turbidity, Δ
A liquid crystal material having a large n is required.

Next, a compound having a high nematic phase-isotropic liquid phase transition temperature (T _NI ) is required to enable driving in a wide temperature range. For this purpose, a tricyclic or tetracyclic compound is usually used, but a tricyclic compound is desirable in order to suppress an increase in viscosity. It is also important that these compounds have excellent compatibility with host liquid crystals.

Further, the liquid crystal composition for TFT is required to have a high voltage holding ratio in addition to these required characteristics. At present, tolan compounds, pyrimidine compounds, and terphenyl compounds are known as compounds having a large Δn. Among these tolan compounds, compounds having particularly high T _NI are
For example, compound (a) is known.

[0008]

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Phase transition temperature (° C.) C 150 N 207 I (In the above, C represents a crystalline phase, N represents a nematic phase, and I represents an isotropic liquid phase.) This compound (a) has a large Δn. , T _{NI is} also high, and by mixing with a host liquid crystal that is currently widely used, T _NI can be increased and Δn can be increased.
However, since the compound (a) has an extremely high melting point and poor compatibility with the host liquid crystal, the amount that can be used is extremely limited, and the characteristics of the compound cannot be sufficiently obtained.

Compound (b) is known as a tolan compound having improved compatibility.

[0011]

[Chemical 4]

Phase transition temperature (° C.) C 89 N 148 I (In the above, C represents a crystalline phase, N represents a nematic phase, and I represents an isotropic liquid phase.) This compound (b) is also high. It has T _NI , has good compatibility with the host liquid crystal, and can increase T _NI . However, Δn is smaller than that of the compound (a) and cannot be said to be sufficient.

Therefore, a tolan compound having a high T _NI and excellent compatibility with the host liquid crystal, and a compound having a large Δn has been desired.

[0014]

The problem to be solved by the present invention is that it has a high compatibility with the host liquid crystal and a high T _NI.
To provide a novel liquid crystal compound having a large Δn and a novel synthetic intermediate thereof, and further to provide a liquid crystal composition containing the novel liquid crystal compound, showing a liquid crystal phase in a wide temperature range and having a large Δn. .

[0015]

In order to solve the above-mentioned problems, the present invention has the general formula (I)

[0016]

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(Wherein R represents an alkyl group having 1 to 10 carbon atoms, X and Y each independently represent a fluorine atom or a hydrogen atom, and Z represents an alkyl group having 1 to 10 carbon atoms, a carbon atom). Alkoxyl group having 1 to 10 atoms, fluorine atom, chlorine atom, trifluoromethyl group, trifluoromethoxy group, difluoromethoxy group or 2,2,2
Represents a trifluoroethoxy group. 2)
-Providing a fluorobiphenyl derivative.

Among the compounds represented by the general formula (I) according to the present invention, Z is an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, a fluorine atom, a chlorine atom, trifluoromethoxy. A compound represented by the above general formula (I), which is a group, is preferred, and among these, Z is a straight-chain alkyl group having 1 to 5 carbon atoms, and a straight-chain alkoxyl having 1 to 5 carbon atoms. Base,
A compound represented by the above general formula (I), which is a fluorine atom, a chlorine atom, or a trifluoromethoxy group, is preferable.

In the above-mentioned compound of the general formula (I) of the present invention, it is preferable that both X and Y are hydrogen atoms. Further, at least one of X and Y is preferably a fluorine atom, and at this time, Z is more preferably a fluorine atom or a chlorine atom.

Further, in the above-mentioned compound of the general formula (I) of the present invention, it is preferable that R is a straight chain alkyl group having 1 to 5 carbon atoms. The obtained compound can be produced, for example, as follows.

[0021]

[Chemical 6]

[0022]

[Chemical 7]

(From the above general formula (I) to the general formula (VII
In each formula of I), R, X, Y and Z have the same meanings as in formula (I), and R ′ is 2 depending on the number of carbon atoms of R.
It represents a small number of alkyl groups or hydrogen atoms, and Q represents an iodine atom or a bromine atom. ) First step: 4-bromo-2-fluorobiphenyl is produced by reacting 4-bromo-2-fluorobiphenyl with magnesium to give a Grignard reagent and then reacting with N, N-dimethylformamide (DMF). Second step: 4-formyl-2-fluorobiphenyl is reacted with the Wittig reaction agent of general formula (III) to produce a compound of general formula (IV). Third step: The compound of general formula (IV) is catalytically reduced with hydrogen in the presence of a catalyst such as palladium carbon (Pd / C) to produce a compound of general formula (V). Step 4: The compound of general formula (V) is reacted with acetyl chloride in the presence of a Lewis acid catalyst such as aluminum chloride to produce a compound of general formula (VI). Fifth step: The compound of general formula (VII) is produced by chlorinating the compound of general formula (VI) with phosphorus pentachloride. Step 6: Dehydrochlorinating the compound of general formula (VII) with a base such as potassium t-butoxy to produce 2-fluoro-4-alkyl-4′-ethynylbiphenyl of general formula (II). Step 7: 2-fluoro-4-alkyl-4′-ethynylbiphenyl of the general formula (II) and a compound of the general formula (VIII) are reacted in the presence of palladium and a copper catalyst to give a compound of the general formula ( The compound of I) is prepared.

When R in the general formula (I) is a methyl group, for example, 4-formyl-2-fluorobiphenyl is reduced with hydrazine in the presence of a strong base to give a compound of the general formula (V). The compound of the general formula (I) and the general formula (II) of the present invention can be prepared in the same manner.

In the above production process, 2-fluoro-4-alkyl-4'-ethynylbiphenyl represented by the general formula (II) is a novel compound useful as a synthetic intermediate for the compound of the general formula (I), The present invention also provides this compound.

Table 1 shows examples of typical compounds represented by the general formula (I) thus produced.

[0027]

[Table 1]

(In Table 1, C represents a crystalline phase, SA represents a smectic A phase, N represents a nematic phase, and I represents an isotropic liquid phase.) In the general formula (I) of the present invention, The nematic liquid crystal composition containing the compound has the following excellent features.
An example is shown below.

Currently used host liquid crystal (A)

[0030]

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(In the formula, the cyclohexane ring has a trans configuration.) T _NI (upper limit temperature of nematic phase) is 55 ° C.
And Δn was 0.092.

Table 2 shows the nematic phase transition temperature (T _NI ) of the liquid crystal composition prepared by using the above host liquid crystal (A) and each of the compounds (I-1) to (I-7) in Table 1. , Anisotropy of refractive index (Δn), (I in the prepared liquid crystal composition)
1 shows the content of each compound of (-1) to (I-7). For comparison, also measured in the same manner for the liquid crystal composition containing the compound (a) and compound (b), it showed T _NI and [Delta] n.

[0033]

[Table 2]

(In Table 2, for example, Composition No. 1 is
20% by weight of the compound of (I-1) and the host liquid crystal (A) 8
It shows that the liquid crystal composition is 0% by weight. From Table 2, the compound (I-1) has excellent compatibility with the host liquid crystal and does not cause precipitation or phase separation even when mixed in an amount of 20% by weight. Moreover, T _NI rose to 69 ° C and Δn was 0.1.
It is clear that it has risen to 41.

On the other hand, the comparative compound (a) having a structure similar to that of (I-1) has a poor compatibility with the host liquid crystal, and therefore the amount that can be mixed is limited to 10% by weight. Could only rise to 0.118.

Next, the compound (I-2) also has excellent compatibility with the host liquid crystal, and does not cause precipitation or phase separation even when mixed in an amount of 20% by weight. Moreover, it is clear that T _NI has increased to 63 ° C. and Δn has increased to 0.134.

On the other hand, the comparative compound (b) having a similar structure to (I-2) is excellent in the compatibility with the host liquid crystal, and even if it is mixed at 20% by weight, precipitation or phase separation occurs. Does not happen. Moreover, T _NI is raised to 70 ° C. However, Δn is considerably smaller than that of the compound (I-2) having a similar structure to 0.121.

A host liquid crystal (B) for TFT having the following composition was prepared.

[0039]

[Chemical 9]

(In the formula, the cyclohexane ring has a trans configuration.) T _NI of this host liquid crystal (B) is 117 ° C., Δn is 0.
It was 090, and the voltage holding ratio was 99% or more. 70% by weight of this host liquid crystal (B) and compound 3 of (I-1)
The T _{NI of the} liquid crystal composition consisting of 0 wt% increased to 123 ° C., and Δn increased to 0.166. Further, the voltage holding ratio of this composition was measured and found to be 99% or more, and it was possible to use it for TFT.

From the above, the compound represented by the general formula (I) according to the present invention has excellent compatibility with other liquid crystal materials, and it is possible to increase the T _NI of the composition and increase Δn by adding it. It can be easily understood that the compound has superior properties to conventional compounds.

Now, as a preferable representative example of the nematic liquid crystal compound which can be used as a liquid crystal composition by mixing with the compound represented by the general formula (I), 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) benzoic acid-4-substituted phenyl, 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 phenyl) -4-substituted cyclohexane, 4,4 ″ -substituted terphenyl, 1- (4 '-Substituted biphenylyl) -4
-Substituted cyclohexane, 1- (4-substituted cyclohexyl) -4- (4-substituted phenyl) cyclohexane, 2-
(4-Substituted phenyl) -5-substituted pyrimidine, 2- (4
-Substituted biphenylyl) -5-substituted pyrimidine, 1- (4
-Substituted cyclohexyl) -2- (4-substituted cyclohexyl) ethane, 1- (4-substituted cyclohexyl) -2-
(4-Substituted phenyl) ethane, 1- [4- (4-substituted cyclohexyl) cyclohexyl] -2- (4-substituted phenyl) ethane, 1- [4- (4-substituted phenyl) cyclohexyl] -2- (4 -Substituted cyclohexyl) ethane,
1- (4-substituted phenyl) -2- (4-substituted phenyl)
Ethine, 1- [4- (4-substituted cyclohexyl)]-2
Examples thereof include-(4-substituted phenyl) ethyne.

[0043]

EXAMPLES The present invention will be further described below by showing Examples of the present invention. However, the invention is not limited to these examples. (Example 1) 2-fluoro-4-propyl-4'-
Synthesis of ethynylbiphenyl (1) Synthesis of 4-formyl-2-fluorobiphenyl

[0044]

[Chemical 10]

5.5 g of magnesium was suspended in 25 ml of tetrahydrofuran (THF), and a solution of 50 g of 2-fluoro-4-bromobiphenyl in 250 ml of THF was suspended in THF.
Was slowly added at a refluxing speed, and the mixture was stirred at room temperature for 1 hour. After completion of the reaction, N, N-dimethylformamide (DM
F) 22.0 g of a THF 75 ml solution was added dropwise at room temperature,
After further stirring at room temperature for 1 hour, 250 ml of 10% hydrochloric acid
Was added and the mixture was stirred at room temperature for 1 hour. After completion of the reaction, the mixture was extracted with 250 ml of toluene, the organic layer was washed successively with saturated sodium hydrogen carbonate, water and saturated brine, and dried over anhydrous sodium sulfate. The solvent was distilled off, and the residue was purified by silica gel column chromatography (solvent: hexane / ethyl acetate = 9/1) to obtain 41.9 g of 4-formyl-2-fluorobiphenyl. (2) Synthesis of 2-fluoro-4- (1-propenyl) biphenyl

[0046]

[Chemical 11]

Ethyltriphenylphosphonium iodide 1
00 g was suspended in 400 ml of THF and cooled to 10 ° C or lower. 26.8 g of potassium t-butoxide was added, and a solution of 4-formyl-2-fluorobiphenyl obtained in (1) above in 150 ml of THF was added dropwise at a rate such that the liquid temperature did not exceed 10 ° C., and the mixture was stirred at the same temperature for 1 hour. . After the reaction was completed, 400 ml of water was added, the organic layer was separated, and the solvent was distilled off.
200 ml of hexane was added, the insoluble material was filtered off, the filtrate was washed successively with water and saturated brine, and dried over anhydrous sodium sulfate. The solvent was distilled off, and the residue was purified using silica gel column chromatography (solvent: hexane) to obtain 36.6 g of 2-fluoro-4- (1-propenyl) biphenyl. (3) Synthesis of 2-fluoro-4-propylbiphenyl

[0048]

[Chemical 12]

2-fluoro-4- (1 obtained in the above (2)
-Propenyl) biphenyl 36.6 g was added to ethyl acetate 20
Dissolved in 0 ml, 5% palladium carbon (Pd / C) 4 g
Was added and catalytic reduction was carried out at room temperature under a hydrogen pressure of 1 atm. The catalyst was filtered off and the solvent was distilled off to obtain 36.5 g of 2-fluoro-4-propylbiphenyl. (4) Synthesis of 2-fluoro-4-propyl-4′-acetylbiphenyl

[0050]

[Chemical 13]

2-fluoro-4-propylbiphenyl obtained in the above (3) was dissolved in 50 ml of dichloromethane, and 1
After cooling below 0 ° C, 8.1 g of anhydrous aluminum chloride
Add acetyl chloride 4.1 at a rate that keeps the temperature below 10 ° C.
A 16 ml solution of g in dichloromethane was added dropwise. The mixture was further stirred at the same temperature for 1 hour and added to ice water. Hexane 100m
The organic layer was washed with saturated sodium carbonate, water and saturated saline in this order. It was dried over anhydrous sodium sulfate and the solvent was distilled off to obtain 11.8 g of 2-fluoro-4-propyl-4'-acetylbiphenyl. (5) 2-fluoro-4-propyl-4 '-(1-
Synthesis of chloroethenyl) biphenyl

[0052]

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11.5 g of phosphorus pentachloride and 50 m of carbon tetrachloride
A solution of 11.8 g of 2-fluoro-4-propyl-4′-acetylbiphenyl obtained in (4) above in 50 ml of carbon tetrachloride was added dropwise over 30 minutes, and the mixture was suspended at room temperature for 10 minutes.
Stir for hours. After the reaction was completed, this solution was slowly poured into 100 ml of water, the organic layer was separated, and dried over anhydrous sodium sulfate. The solvent was distilled off, and the residue was purified by silica gel column chromatography (solvent: hexane), 2-fluoro-4-propyl-4 '-(1-chloroethenyl).
3.8 g of biphenyl was obtained. (6) Synthesis of 2-fluoro-4-propyl-4′-ethynylbiphenyl

[0054]

[Chemical 15]

2-Fluoro-4-propyl-4 '-(1-chloroethenyl) biphenyl 3.8 obtained in the above (5).
g was dissolved in 20 ml of DMF, and 1.6 g of potassium t-butoxide was added at a rate such that the liquid temperature did not exceed 40 ° C. Further, the mixture was stirred at room temperature for 1 hour, and 20 ml of water was added. The mixture was extracted with 40 ml of ethyl acetate, the organic layer was washed successively with water and saturated brine, and dried over anhydrous sodium sulfate. The solvent was distilled off, and the residue was purified by silica gel column chromatography (solvent: hexane), 2-fluoro-4-propyl-
2.0 g of 4'-ethynylbiphenyl was obtained. The melting point of this compound was 42.4 ° C. (Example 2) 2-Fluoro-4-propyl-4'-
Synthesis of (4-fluorophenylethynyl) biphenyl

[0056]

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2.0 g of 2-fluoro-4-propyl-4'-ethynylbiphenyl obtained in Example 1 and 4-fluoro-1-iodobenzene were dissolved in 20 ml of DMF and 2 ml of triethylamine. 0.2 g of tetrakis (triphenylphosphine) palladium (0) and copper (I) iodide 0.
03 g was added, and the mixture was stirred at room temperature for 2 hours. After completion of the reaction, 20 ml of toluene was added, the organic layer was washed successively with water and saturated brine, and dried over anhydrous sodium sulfate. The solvent was distilled off, the residue was purified by silica gel column chromatography (solvent: hexane), recrystallized from ethanol, and 2-fluoro-4-propyl-4 ′-(4-fluorophenylethynyl) biphenyl 2. 0 g was obtained. When the phase transition temperature was measured, the crystal phase was changed to a nematic phase at 92 ° C. and the nematic phase was changed to an isotropic liquid phase at 164 ° C. (Example 3) 2-Fluoro-4-propyl-4'-
Synthesis of (3,4-difluorophenylethynyl) biphenyl (compound of (I-2) in Table 1)

[0058]

[Chemical 17]

In the same manner as in Example 2, except that 3,4-difluoro-1-bromobenzene was used in place of 4-fluoro-1-iodobenzene in Example 2,
Fluoro-4-propyl-4 '-(3,4-difluorophenylethynyl) biphenyl was obtained. The phase transition temperature is shown in Table 1. (Example 4) 2-Fluoro-4-propyl-4'-
Synthesis of (3,4,5-trifluorophenylethynyl) biphenyl (compound of (I-3) in Table 1)

[0060]

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In Example 2, instead of 4-fluoro-1-iodobenzene, 3,4,5-trifluoro-
2-Fluoro-4-propyl-4 ′-(3,4,5) was prepared in the same manner as in Example 2 except that 1-bromobenzene was used.
-Trifluorophenylethynyl) biphenyl was obtained.
The phase transition temperature is shown in Table 1. (Example 5) 2-Fluoro-4-propyl-4'-
Synthesis of (4-trifluoromethoxyphenylethynyl) biphenyl (compound of (I-4) in Table 1)

[0062]

[Chemical 19]

In Example 2, 4-trifluoromethoxy- was used instead of 4-fluoro-1-iodobenzene.
2-Fluoro-4-propyl-4 ′-(4-trifluoromethoxyphenylethynyl) biphenyl was obtained in the same manner as in Example 2 except that 1-bromobenzene was used.
The phase transition temperature is shown in Table 1. (Example 6) 2-Fluoro-4-propyl-4'-
Synthesis of (3-fluoro-4-chlorophenylethynyl) biphenyl (compound of (I-5) in Table 1)

[0064]

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In Example 2, instead of 4-fluoro-1-iodobenzene, 3-fluoro-4-chloro-
2-Fluoro-4-propyl-4 ′-(3-fluoro-4-chlorophenylethynyl) biphenyl was obtained in the same manner as in Example 2 except that 1-bromobenzene was used.
The phase transition temperature is shown in Table 1. (Example 7) 2-Fluoro-4-propyl-4'-
Synthesis of (4-methylphenylethynyl) biphenyl (compound of (I-6) in Table 1)

[0066]

[Chemical 21]

In the same manner as in Example 2, except that 4-iodotoluene was used in place of 4-fluoro-1-iodobenzene in Example 2, 2-fluoro-4-propyl-4 '-(4 -Methylphenylethynyl) biphenyl was obtained. The phase transition temperature is shown in Table 1. (Example 8) 2-Fluoro-4-propyl-4'-
Synthesis of (4-methoxyphenylethynyl) biphenyl (compound of (I-7) in Table 1)

[0068]

[Chemical formula 22]

In the same manner as in Example 2, except that 4-iodo-iodobenzene was used in place of 4-fluoro-1-iodobenzene in Example 2, 2-fluoro-4-propyl-4 '-(4 -Methylmethoxyphenylethynyl)
Biphenyl was obtained. The phase transition temperature is shown in Table 1. (Example 9) Preparation of liquid crystal composition (1) A host liquid crystal (A) having the following composition was prepared.

[0070]

[Chemical formula 23]

(In the formula, the cyclohexane ring has a trans configuration.) The T _NI and Δn of this host liquid crystal (A) were measured and the results were as follows.

T _NI 55 ° C. Δn 0.092 80% by weight of this host liquid crystal (A) and 20% by weight of 2-fluoro-4-propyl-4 ′-(4-fluorophenylethynyl) biphenyl synthesized in Example 2. The T _NI and Δn of the liquid crystal composition consisting of were measured as follows.

T _NI 69 ° C. Δn 0.141 From the above results, the compound synthesized in Example 2 increased T _{NI of} the composition obtained when mixed with the host liquid crystal and increased Δn. Understand that Comparative Example 1 For comparison, the host liquid crystal (A) is 80% by weight.
And a compound having a similar structure to the compounds of (I-1), having a high T _NI and having a large Δn, was prepared as a comparative composition comprising 20% by weight of the compound (a), and precipitation immediately occurred at room temperature. . Further, when the amount of the compound (a) mixed with the host liquid crystal (A) was reduced, precipitation did not occur at 10% by weight or less. Therefore, the T _{NI of the} liquid crystal composition comprising 90% by weight of the host liquid crystal (A) and 10% by weight of the compound (a)
And the measurement of Δn were as follows.

T _NI 69 ° C. Δn 0.118 From the above results, it can be understood that Δn cannot be greatly increased because the compound (a) has a small proportion that can be mixed with the host liquid crystal. (Example 10) Preparation of liquid crystal composition (2) Synthesized in Example 3 with 80% by weight of host liquid crystal (A),
A liquid crystal composition consisting of 20% by weight of 2-fluoro-4-propyl-4 ′-(3,4-difluorophenylethynyl) biphenyl was prepared, and T _NI and Δn were measured.

T _NI 63 ° C. Δn 0.134 From the above results, the compound synthesized in Example 3 increases T _{NI of} the composition obtained when mixed with the host liquid crystal and increases Δn. Understand that Comparative Example 2 For comparison, the host liquid crystal (A) is 80% by weight and the compound (b) is 20% by weight, which has a similar structure to the compound of (I-2) and has a high T _NI and a large Δn. When a comparative liquid crystal composition was prepared and T _NI and Δn were measured, the results were as follows.

T _NI 70 ° C. Δn 0.121 From the above results, it can be understood that the compound (b) significantly increases T _NI , but does not significantly increase Δn. (Example 11) Preparation of liquid crystal composition (3) Synthesized in Example 4 with 80% by weight of host liquid crystal (A),
A liquid crystal composition consisting of 20% by weight of 2-fluoro-4-propyl-4 ′-(3,4,5-trifluorophenylethynyl) biphenyl was prepared and T _NI and Δn were measured. It was

T _NI 58 ° C. Δn 0.127 From the above results, the compound synthesized in Example 4 increased T _{NI of} the composition obtained when mixed with the host liquid crystal and increased Δn. Understand that (Example 12) Preparation of liquid crystal composition (4) 80% by weight of host liquid crystal (A) and synthesized in Example 5,
A liquid crystal composition comprising 20% by weight of 2-fluoro-4-propyl-4 ′-(4-trifluoromethoxyphenylethynyl) biphenyl was prepared, and T _NI and Δn were measured.

T _NI 71 ° C. Δn 0.135 From the above results, the compound synthesized in Example 5 increases T _{NI of} the composition obtained when mixed with the host liquid crystal and increases Δn. Can understand. (Example 13) Preparation of liquid crystal composition (5) Synthesized in Example 6 with 80% by weight of host liquid crystal (A),
2-fluoro-4-propyl-4 '-(3-fluoro-
A liquid crystal composition containing 20% by weight of 4-chlorophenylethynyl) biphenyl was prepared, and T _NI and Δn were measured. The results were as follows.

T _NI 63 ° C. Δn 0.143 From the above results, the compound synthesized in Example 6 raises T _{NI of} the composition obtained when mixed with the host liquid crystal and increases Δn. Understand that (Example 14) Preparation of liquid crystal composition (6) Synthesized in Example 7 with 85% by weight of host liquid crystal (A),
A liquid crystal composition consisting of 15% by weight of 2-fluoro-4-propyl-4 ′-(4-methylphenylethynyl) biphenyl was prepared, and T _NI and Δn were measured.

T _NI 71 ° C. Δn 0.136 From the above results, the compound synthesized in Example 7 increased T _{NI of} the composition obtained when mixed with the host liquid crystal and increased Δn. Understand that (Example 15) Preparation of liquid crystal composition (7) Synthesized in Example 8 with 85% by weight of host liquid crystal (A),
A liquid crystal composition containing 15% by weight of 2-fluoro-4-propyl-4 ′-(4-methoxyphenylethynyl) biphenyl was prepared, and T _NI and Δn were measured.

T _NI 74 ° C. Δn 0.139 From the above results, the compound synthesized in Example 8 increased T _{NI of} the composition obtained when mixed with the host liquid crystal and increased Δn. Understand that (Example 16) Preparation of liquid crystal composition (8) A host liquid crystal (B) for TFT having the following composition was prepared.

[0082]

[Chemical formula 24]

(In the formula, the cyclohexane ring represents a trans configuration.) The T _NI point, Δn and voltage holding ratio of this host liquid crystal (B) were measured and the results were as follows.

T _NI 117 ° C. Δn 0.090 Voltage holding ratio 99% or more 70 wt% of this host liquid crystal (B) and 2-fluoro-4-propyl-4 ′-(4-fluorophenyl) synthesized in Example 2 A liquid crystal composition containing 30% by weight of ethynyl) biphenyl was prepared, and the T _NI point, Δn, and voltage holding ratio were measured.

T _NI 123 ° C. Δn 0.166 Voltage holding ratio 99% or more From the above results, the compound synthesized in Example 2 was
Raising the T _NI of the composition obtained on mixing with use host liquid crystal, [Delta] n also increased, it can be understood that maintains and a high voltage holding ratio. (Example 17) Preparation of liquid crystal composition (9) Synthesized in Example 5 with 70% by weight of host liquid crystal (B),
A liquid crystal composition consisting of 30% by weight of 2-fluoro-4-propyl-4 ′-(4-trifluoromethoxyphenylethynyl) biphenyl was prepared, and T _NI, Δn and voltage holding ratio were measured. there were.

T _NI 126 ° C. Δn 0.156 Voltage holding ratio 99% or more From the above results, the compound synthesized in Example 5 was TFT.
Raising the T _NI of the composition obtained on mixing with use host liquid crystal, [Delta] n also increased, it can be understood that maintains and a high voltage holding ratio. (Example 18) Preparation of liquid crystal composition (10) 70% by weight of host liquid crystal (B) and synthesized in Example 6,
2-fluoro-4-propyl-4 '-(3-fluoro-
A liquid crystal composition containing 30% by weight of 4-chlorophenylethynyl) biphenyl was prepared, and T _NI, Δn, and voltage holding ratio were measured.

T _NI 122 ° C. Δn 0.169 Voltage holding ratio 99% or more From the above results, the compound synthesized in Example 6 was
Raising the T _NI of the composition obtained on mixing with use host liquid crystal, [Delta] n also increased, it can be understood that maintains and a high voltage holding ratio. (Example 19) Preparation of liquid crystal composition (11) 75% by weight of host liquid crystal (B) and synthesized in Example 7,
A liquid crystal composition consisting of 25% by weight of 2-fluoro-4-propyl-4 ′-(4-methylphenylethynyl) biphenyl was prepared, and _TNI, Δn, and voltage holding ratio were measured. .

T _NI 130 ° C. Δn 0.157 Voltage holding ratio 99% or more From the above results, the compound synthesized in Example 7 was TFT.
Raising the T _NI of the composition obtained on mixing with use host liquid crystal, [Delta] n also increased, it can be understood that maintains and a high voltage holding ratio. (Example 20) Preparation of liquid crystal composition (12) Synthesized in Example 8 with 85% by weight of host liquid crystal (B),
A liquid crystal composition consisting of 15% by weight of 2-fluoro-4-propyl-4 ′-(4-methoxyphenylethynyl) biphenyl was prepared, and _TNI, Δn, and voltage holding ratio were measured. .

T _NI 127 ° C. Δn 0.135 Voltage holding ratio 99% or more From the above results, the compound synthesized in Example 8 was
Raising the T _NI of the composition obtained on mixing with use host liquid crystal, [Delta] n also increased, it can be understood that maintains and a high voltage holding ratio.

[0090]

INDUSTRIAL APPLICABILITY The compound represented by the general formula (I) of the present invention has a high maximum temperature of a nematic phase, has excellent compatibility with a host liquid crystal which is currently widely used as a liquid crystal, and a liquid crystal containing it. The composition can increase T _NI and increase Δn, and can also obtain a high voltage holding ratio.

Therefore, the compound represented by the general formula (I) of the present invention is a liquid crystal material useful for a liquid crystal display such as a word processor and a liquid crystal television in which high speed response is important.

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Claims (8)

[Claims] 1. A compound of the general formula (I) (In the formula, R represents an alkyl group having 1 to 10 carbon atoms, X and Y each independently represent a fluorine atom or a hydrogen atom, and Z is an alkyl group having 1 to 10 carbon atoms or 1 carbon atom. To 10 represents an alkoxyl group, a fluorine atom, a chlorine atom, a trifluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group or a 2,2,2-trifluoroethoxy group.). 2. A compound represented by the general formula (II): (In the formula, R represents an alkyl group having 1 to 10 carbon atoms). 3. The general according to claim 1, wherein Z is an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, a fluorine atom, a chlorine atom, or a trifluoromethoxy group. A compound represented by formula (I). 4. The compound represented by formula (I) according to claim 1 or 3, wherein at least one of X and Y is a fluorine atom. 5. The compound represented by the general formula (I) according to claim 4, wherein Z is a fluorine atom or a chlorine atom. 6. A compound represented by the general formula (I) according to claim 1 or 3, wherein both X and Y are hydrogen atoms. 7. The compound represented by the general formula (I) according to claim 3, 4, 5 or 6, wherein R is a linear alkyl group having 1 to 5 carbon atoms. 8. A liquid crystal composition containing a compound represented by formula (I) according to claim 1, 3, 4, 5, 6 or 7.