JP3350956B2 - Biphenyl derivative and ferroelectric liquid crystal composition containing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric liquid crystal material useful as an electro-optical display material, and more particularly, to a liquid crystal display device which is superior in orientation and response to conventional liquid crystal materials. The present invention relates to a compound useful as a material and a ferroelectric liquid crystal composition containing the compound.

[0002]

2. Description of the Related Art At present, liquid crystal display elements widely used are referred to as TN (twisted nematic) type or STN (super twisted nematic) type using mainly nematic liquid crystal. Although it has many advantages, it has a major drawback that its response is much slower than a light-emitting display system such as a CRT, and its application is greatly limited. Although other liquid crystal display systems are being studied from various perspectives, the reality is that little improvement has been made in their responsiveness.

However, a recently discovered liquid crystal display device using a ferroelectric chiral smectic liquid crystal has been able to achieve a high-speed response more than 100 times that of a conventional TN type display device. Further, it has been revealed that the display can be stored (memory effect) even when the power is turned off because of the bistability. Therefore, it is highly applicable to large-screen high-resolution displays, thin-screen televisions, optical shutters, printer heads, and the like. Currently, active research and development is being conducted toward practical use.

The liquid crystal phase of the ferroelectric liquid crystal belongs to a tilt type chiral smectic phase. Among them, a chiral smectic C (hereinafter abbreviated as SC ^* ) phase having the lowest viscosity is preferable. Liquid crystal compounds exhibiting many SC ^* phases (hereinafter abbreviated as SC ^* compounds) have already been synthesized,
Although it has been studied, an element having sufficient properties for use as an optical switching element for a ferroelectric liquid crystal display has not yet been known. Therefore, by mixing with other liquid crystal compounds, S
It is used as a liquid crystal composition exhibiting a C ^* phase (hereinafter abbreviated as SC ^* liquid crystal composition). Such SC ^* liquid crystal compositions are being actively studied, and at present, a matrix liquid crystal exhibiting a non-chiral smectic C (hereinafter abbreviated as SC) phase (hereinafter abbreviated as an SC matrix liquid crystal). To
A general method is to add a chiral dopant comprising an optically active compound. As a result, characteristics such as high-speed response, good orientation, and a wide operating temperature range were considerably improved.

[0005]

At present, compounds exhibiting the SC phase (hereinafter abbreviated as SC compounds) constituting the SC matrix liquid crystal are represented, for example, by the general formula (A)

[0006]

Embedded image

Wherein R ^a and R ^b represent an alkyl group, an alkoxyl group, an alkoxycarbonyl group, an alkanoyloxy group or an alkoxycarbonyloxy group, which may be the same or different. Phenyl benzoate derivative or general formula (B)

[0008]

Embedded image

(Wherein, R ^a and R ^b have the same meanings as in the general formula (A)), and a phenylpyrimidine derivative represented by the following formula is mainly used.

Among them, the compound represented by the general formula (A) has a relatively high viscosity due to the presence of an ester bond in the molecule, and is a liquid crystal display device using an SC matrix liquid crystal containing the compound as a main component. , It was difficult to obtain a sufficient high-speed response.

On the other hand, the compound represented by the general formula (B) has a relatively low viscosity when one of R ^a and R ^b is an alkyl group and the other is an alkoxyl group.
^a is a linear alkyl group, and R ^b is a linear alkoxyl group.

[0012]

Embedded image

Wherein R ^c and R ^d each independently represent a linear alkyl group.
It is currently widely used as the main component of the parent liquid crystal.

However, the compound represented by formula (C) has a problem that the melting point is relatively high. In general, liquid crystal materials are required to have a low melting point, but in ferroelectric liquid crystals, once crystallized in a cell, it is quite difficult to return to the original alignment state. It is particularly important to do so.

The lowering of the melting point of the liquid crystal material is usually achieved by mixing a multi-component liquid crystal compound.
When the compound of formula (C) is mixed, the melting point of the compound is not large, and it is difficult to lower the melting point of the compound of formula (C) to below freezing point, no matter how many components are mixed. Therefore, it was not easy to obtain an SC matrix liquid crystal having a compound of the general formula (C) as a main component and exhibiting a liquid crystal phase in a wide temperature range from a low temperature range to a high temperature range.

As means for obtaining a low melting point SC base liquid crystal,
JP-A-1-185390 discloses that a phenylpyrimidine-based compound of the general formula (B) is added to the compound of the general formula (D).

[0017]

Embedded image

(Wherein R ^c and R ^d have the same meanings as in the general formula (C)). However, the compound represented by the general formula (D) has a higher order smectic (Smectic F, Smectic G, Smectic H, hereinafter, SF,
Abbreviated as SG and SH. ) Phase, and also has a strong tendency to dissipate the nematic (hereinafter abbreviated as N) phase in the liquid crystal composition, so that a large amount can be added to the liquid crystal composition. However, the addition of a small amount did not always sufficiently lower the melting point of the liquid crystal composition.

An object of the present invention is to provide a compound having a low viscosity and a large melting point drop even when added in a small amount to a liquid crystal composition. A ferroelectric material that exhibits a SC phase in a wide temperature range and provides a host liquid crystal having a favorable phase series in a high temperature range, and a chiral dopant composed of an optically active compound is added to the liquid crystal to provide a high-speed response in a wide temperature range. It is to provide a liquid crystal composition.

[0020]

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

[0021]

Embedded image

(Wherein R ¹ represents a straight-chain alkyl group having 6 to 12 carbon atoms, and preferably has 7 to 1 carbon atoms)
0 represents a linear alkyl group, of the ring A and ring B,
One represents a 1,4-phenylene group substituted by a fluorine atom, and the other represents a 1,4-phenylene group. Preferably, ring A represents a 1,4-phenylene group substituted by a fluorine atom; B represents a 1,4-phenylene group; R ² represents a straight-chain alkyl group having 3 to 7 carbon atoms, preferably a straight-chain alkyl group having 3 to 5 carbon atoms; Represents a trans configuration. ) Is provided.

The compounds of the general formula (I) of the present invention can be prepared by the following general formulas (Ia) to (I)
Although it contains a skeleton such as d), the compound of the general formula (Ia) is particularly preferred.

[0024]

Embedded image

The compound represented by the general formula (I) of the present invention can be easily produced, for example, as follows. That is, the general formula (III)

[0026]

Embedded image

(Wherein R ¹ , ring A and ring B have the same meanings as in general formula (I)) and a phenol derivative represented by general formula (IV) in the presence of a base.

[0028]

Embedded image

Wherein R ² has the same meaning as in formula (I), X represents a leaving group such as chlorine, bromine, iodine or p-toluenesulfonyl (tosyl) group, Which represents a trans configuration).

The phenol derivative represented by the general formula (III) can be obtained, for example, as follows according to the combination of the ring A and the ring B.

[0031]

Embedded image

(Wherein R ¹ has the same meaning as in formula (I).) In the case of the compound of formula (IIIa), commercially available 1-bromo-3-fluoro-4-phenylbenzene is converted to Grignard The compound is alkylated in the presence of a copper salt or the like to give 1-alkyl-3 represented by the general formula (Va).
-Fluoro-4-phenylbenzene is obtained. Alternatively, a Grignard compound is acylated and then reduced, or 1- (1-hydroxyalkyl) -3-fluoro-4-phenylbenzene obtained by reacting with an aldehyde is tosylated and then reduced with lithium aluminum hydride. ,
Alternatively, it can be obtained by oxidizing after reacting with aldehyde to obtain an acyl form, and further reducing. Next, the compound of the general formula (III) is obtained by acetylating the compound of the general formula (Va), oxidizing the compound with a peracid and, if necessary, hydrolyzing the compound.
A phenol derivative represented by a) can be obtained.

[0033]

Embedded image

(Wherein R ¹ has the same meaning as in formula (I).) In the case of the compound of formula (IIIc), 1-bromo-
The 3-fluoro-4-phenylbenzene is acylated and then reduced to give 1-bromo-3-fluoro-4- (4-alkylphenyl) benzene. After converting this into a Grignard compound, it is acetylated, oxidized with a peracid, and hydrolyzed if necessary, whereby a phenol derivative represented by the general formula (IIIc) can be obtained.

[0035]

Embedded image

(Wherein R ¹ has the same meaning as in formula (I).) In the case of the compound of formula (IIIb), 1-bromo-
After acylating 3-fluorobenzene, it is reduced to 1
To obtain -alkyl-4-bromo-2-fluorobenzene. After converting this into a Grignard compound, it is reacted with iodobenzene in the presence of a catalyst such as palladium chloride to obtain 1-alkyl-2-fluoro-4-phenylbenzene of the general formula (Vb). This is acetylated and oxidized with peracid,
If necessary, hydrolysis is carried out to obtain a compound represented by the general formula (III)
The phenol derivative represented by b) can be obtained. Or, instead of iodobenzene, 1-iodo-4
-Methoxybenzene may be reacted, followed by demethylation.

[0037]

Embedded image

(Wherein, R ¹ has the same meaning as in formula (I).) In the case of the compound of formula (IIId), 1-bromo-
After converting 3-fluoro-4-methoxybenzene to a Grignard compound, it is reacted with iodobenzene in the presence of a catalyst such as palladium chloride to give 2-fluoro-1-methoxy-
4-phenylbenzene is obtained. This is acylated, reduced, and further demethylated to give a compound of the general formula (II)
A phenol derivative represented by Id) can be obtained. Alternatively, instead of iodobenzene, 1-alkyl-
4-Iodobenzene may be reacted, followed by demethylation.

On the other hand, the compound represented by the general formula (IV) is

[0040]

Embedded image

(Wherein, R ² has the same meaning as in formula (I), and the double bond represents a trans configuration).
Can be easily obtained by halogenating or tosylating the alcohol derivative represented by

Here, the alcohol derivative represented by the general formula (VI) is commercially available and can be obtained for a compound in which R ² is an alkyl group having 3 to 5 carbon atoms.
Other compounds can be easily obtained by half-reducing the corresponding alkynyl alcohol.

Thus, the compounds represented by the general formula (I) can be obtained. Specific compounds belonging to these compounds include a phase transition temperature such as a melting point and an infrared absorption spectrum (I
R), nuclear magnetic absorption spectrum (NMR) and the like can confirm the structure. Examples of typical compounds are shown below.

[0044]

Embedded image

Phase transition temperature (° C.) Cr17.9 N30.5 I (where Cr represents a crystal phase, N represents a nematic phase, and I represents an isotropic liquid phase, and the phase transition temperature is the left side thereof. And the phase on the right side, for example, Cr17.9 N has a transition temperature of 1 between the crystalline phase and the nematic phase.
7.9 ° C. The same applies hereinafter. )

The structural feature of the compound represented by the general formula (I) of the present invention is that it has an alkenyloxy group having 6 to 10 carbon atoms having a double bond at the 2-position. Compounds having an alkenyl group or an alkenyloxy group in the side chain are already known.
No. 3136 discloses a compound having a 4-pentenyloxy group on a phenylpyrimidine skeleton.

[0047]

Embedded image

The compound having a crotyloxy group is disclosed in JP-A-61-291536.

[0049]

Embedded image

The following compounds have been reported.

These compounds have the same skeletal structure as the compound of the general formula (C), and have a structure relatively similar to the compound of the general formula (I) of the present invention. Since it was developed for liquid crystal materials, it is fundamentally different in that the alkenyloxy group in the side chain is particularly short. Therefore, there is no description that such a compound is used for an SC matrix liquid crystal. Even when the compound is actually added, even if the addition amount is small, the upper limit temperature of the SC phase is significantly lowered. Is difficult to use.

On the other hand, JP-A-63-142091 discloses a large number of SC ^* having an alkenyloxy group and some SC compounds. However, most of these compounds are compounds in which a double bond in a side chain alkenyloxy group is present at the terminal, and two compounds having an allyloxy group are exemplified as compounds in which a double bond is present at the 2-position. Only. Further, a compound having a biphenyl skeleton is not exemplified. Furthermore, there is no example of using the liquid crystal as an SC matrix liquid crystal, and no electro-optical characteristics such as responsiveness as an SC ^* liquid crystal composition are shown, and the melting point and the temperature range of the liquid crystal phase are not sufficiently shown. Accordingly, the excellent properties of the compound of the general formula (I) of the present invention having a 2-alkenyloxy group having 6 to 10 carbon atoms as a side chain cannot be expected at all from this publication.

As an example having the same skeleton as the compound of the formula (Ia) and a side chain being a linear alkoxyl group, a compound of the formula (E-1) and its phase transition temperature (° C.) are shown.

[0054]

Embedded image

Phase transition temperature (° C.) Cr34.3 (SC17.8 SA27.2) N3
7.2 I (In the above, SA represents a smectic A phase, and () indicates that the phase is a monotropic phase that exists only when the temperature is lowered.)

The compound of the formula (E-1) and (No.
Comparing the compound of 1), the compound of formula (E-1)
Since the compound of (No. 1) does not show the SC phase while showing the C phase, the compound of the formula (E-
The compound of 1) seems to be superior. However, the effect of the compound of the general formula (I) is clear from the following examples.

[0057]

Embedded image

An SC parent liquid crystal (HA) was prepared. (In the above, “%” means “% by weight.”) The parent liquid crystal has a melting point of 12 ° C., the SC phase up to 56.5 ° C., the SA phase up to 65.5 ° C., and 70.5 ° C. Up to the N phase.

When a liquid crystal composition (H-1) comprising 90% by weight of the SC parent liquid crystal (HA) and 10% by weight of the compound of (No. 1) was prepared, the melting point was lowered to -7 ° C. SC phase up to 50.5 ° C, SA phase up to 58 ° C, 6
Showed N phase up to 5.5 ° C.

On the other hand, in the liquid crystal composition (HR-1) composed of 10% by weight of the compound of the formula (E-1) and 90% by weight of the SC base liquid crystal (HA), the SC phase was heated up to 51 ° C.
Up to 67.degree. C., but its melting point dropped only to 5.5.degree.

From the above, it can be seen that the compound of No. 1 of the present invention significantly lowers the melting point of the base liquid crystal by adding a small amount thereof, and despite the fact that it does not show the SC phase, It can be seen that the upper limit temperature is not lowered much. Therefore, it can be seen that the temperature range is wide and is very useful for obtaining a practical SC mother liquid crystal.

Further, a feature of the compound of the general formula (I) of the present invention is that it has a relatively low viscosity. The formula (Q) comprising 90% by weight of the above-mentioned SC mother liquid crystal (HA) and the following composition:

[0063]

Embedded image

S comprising 10% by weight of the chiral dopant
When the C ^* liquid crystal composition (MA) was adjusted, it showed an SC ^* phase at 57 ° C. or lower, and the electro-optical response speed at 25 ° C. of a liquid crystal display device manufactured using the same was 83 μsec.

On the other hand, 90% by weight of SC liquid crystal (H-1) containing the compound of the formula (I) and the compound of the formula (Q)
SC ^* liquid crystal composition (M-1) comprising 10% by weight of a chiral dopant of the formula (1) exhibits an SC ^* phase at 51.5 ° C. or lower, and an electro-optical response speed at 25 ° C. of a liquid crystal display device manufactured using the same. Was 78 μs, which was much faster than that of the SC ^* liquid crystal composition (MA).

An SC ^* liquid crystal composition (MR-1) prepared in the same manner using an SC matrix liquid crystal (HR-1)
Shows an SC ^* phase at 52.5 ° C. or lower, and the electro-optical response speed at 25 ° C. of a liquid crystal display device manufactured using the same is 82 μsec, which is almost the same as that of the SC ^* liquid crystal composition (MA). Met.

From the above, it can be understood that the SC ^* liquid crystal composition containing the general formula (I) of the present invention has a high response speed and the compound of the general formula (I) has a very low viscosity.

The present invention also provides a liquid crystal composition containing the compound represented by the general formula (I). The liquid crystal composition of the present invention comprises (1) an SC matrix liquid crystal containing at least one compound represented by the general formula (I) and (2) an SC ^* liquid crystal composition containing a chiral dopant consisting of an optically active compound. And particularly preferably a phase series which undergoes a phase transition to an SC ^* phase via an N ^* phase and an SA phase upon cooling from an isotropic liquid (I) phase, has excellent orientation, and has a wide temperature range. It is a liquid crystal composition that can be used in a range and has low viscosity.

The compound represented by the general formula (I) of the present invention has a low viscosity itself, so that the SA phase is expanded or N
Since it has such a property that there is almost no tendency to lose a phase, a liquid crystal composition exhibiting the above-described excellent characteristics can be easily prepared.

In order to sufficiently exhibit such excellent properties, the compound represented by the general formula (I) of the present invention must be
It is preferable to contain 2% by weight or more in the base liquid crystal. Also, in order to lower the melting point of the liquid crystal composition and expand its temperature range to a lower temperature range, it is necessary to add another type of SC compound having a different skeleton or side chain shape of liquid crystal molecules,
The content of the compound represented by the general formula (I) is 2 to 30.
Preferably it is in the range of weight%.

The compound of formula (I) according to the present invention may be used together with the compound represented by the formula (I).
As the C compound, the compound represented by the general formula (II) having the same skeleton as that of the aforementioned general formula (C)

[0072]

Embedded image

(Wherein R ³ represents a linear alkyl group having 6 to 12 carbon atoms, and R ⁴ represents a linear or branched alkyl group having 6 to 12 carbon atoms, or a linear alkenyl group) Are particularly preferred.

The present invention provides a second liquid crystal composition comprising (1)
It contains at least one kind of the compound represented by the general formula (I) and at least one kind of the compound represented by the general formula (II), and contains a host liquid crystal exhibiting an SC phase and (2) a chiral dopant composed of an optically active compound. To provide an SC ^* liquid crystal composition.

Here, typical examples of the compound represented by the general formula (II) are shown in Tables 1 and 2 below.

[0076]

[Table 1]

[0077]

[Table 2]

The compound represented by the general formula (II) has a low viscosity, although the maximum temperature of the SC phase is not so high, and when the compound is formed into a liquid crystal composition, the SA phase can be expanded or N
Since there is not much tendency to lose the (N ^* ) phase,
The compound is particularly suitable as a main component of the parent liquid crystal used together with the compound of the formula (I) of the present invention.

The SC ^* liquid crystal composition containing the compound represented by the general formula (II) and the compound represented by the general formula (I) of the present invention also shows the following properties upon cooling from the isotropic liquid (I) phase: It is a liquid crystal composition that can exhibit a desirable phase sequence of undergoing a phase transition to an SC ^* phase through an N ^* phase and an SA phase, has excellent orientation, can be used in a wide temperature range, and has a low viscosity. In this composition, the compound of general formula (II) is
%, Preferably 10 to 6% by weight.
A range of 0% by weight is preferred.

In the above composition, in addition to the compounds of the general formulas (I) and (II), examples of the bicyclic compound exhibiting the SC phase include the following general formulas (VIIa) to (VIa).
Id)

[0081]

Embedded image

(Wherein R ³ and R ⁴ have the same meanings as in general formula (II), R ⁵ and R ⁶ each independently represent an alkyl group or an alkoxyl group, and p and q
Each independently represents 0 or 1. ), And in a small amount, a compound of the general formula (A) can also be used.

Further, in order to improve the responsiveness of the above composition, the following general formulas (VIIIa) to (VIIId)

[0084]

Embedded image

(Wherein R ⁷ and R ⁸ each independently represent a straight-chain alkyl group, and the cyclohexane ring has a trans configuration).

Further, for the purpose of expanding the temperature range to a high temperature range, the following general formulas (IXa) to (IXg)

[0087]

Embedded image

(Wherein R ⁹ and R ¹⁰ each independently represent an alkyl group or an alkoxyl group, at least one of which represents an alkyl group, preferably both represent an alkyl group, and p and q each independently represent 0 or 1
Represents ) Can also be used.

[0089]

EXAMPLES The present invention will be specifically described below with reference to examples, but the gist and scope of the present invention are not limited by these examples.

In this example, the measurement of the phase transition temperature was carried out using a polarizing microscope equipped with a temperature control stage and a differential scanning calorimeter (DSC). In addition, all “%” in the composition represent “% by weight”.

The structure of the compound was confirmed by a nuclear magnetic resonance spectrum (NMR). In addition, C in NMR
DCl ₃ represents a solvent, s represents a singlet, d represents a doublet, t represents a triplet, and m represents a multiplet.

Example 1 2-Fluoro-1- [4-
Synthesis of (2-heptenyloxy) phenyl] -4-nonylbenzene (No. 1 compound)

[0093]

Embedded image

(1-a) Synthesis of 2-fluoro-4- (1-hydroxynonyl) -1-phenylbenzene 0.93 g of cut metal magnesium was suspended in 10 ml of dry tetrahydrofuran (THF). In addition, THF
8.0 g of 1-bromo-3-fluoro-4-phenylbenzene dissolved in 80 ml was added dropwise at 60 ° C for 20 minutes. After heating and stirring at 60 ° C. for another hour, the temperature was returned to room temperature. Next, 5.1 g of nonanol was dissolved in 10 ml of THF and added dropwise at room temperature for 10 minutes. After stirring at 60 ° C. for 3 hours, water and then diluted hydrochloric acid were added to make the mixture weakly acidic. The mixture was extracted with ethyl acetate, and the organic layer was washed with water and then with a saturated saline solution, and dried and dried over anhydrous sodium sulfate. The crude product obtained by evaporating the solvent under reduced pressure was purified by silica gel column chromatography (hexane / ethyl acetate = 5/1) to give 2-fluoro-4- (1-hydroxynonyl)- 7.5 g of white crystals of 1-phenylbenzene were obtained.

(1-b) Synthesis of 2-fluoro-4-nonanoyl-1-phenylbenzene 2-fluoro-4- (1-hydroxynonyl) -1-phenylbenzene 7 obtained in the above (1-a) 0.5 g was dissolved in 150 ml of acetone. 6 ml of sulfuric acid at room temperature
And 5.5 g of chromium trioxide dissolved in 30 ml of water for 20 minutes.
In minutes. After reducing excess chromium trioxide by adding methanol, it is poured into water, extracted with dichloromethane,
The extract was washed with a saturated aqueous solution of sodium hydrogencarbonate, water and then with a saturated saline solution, dried over anhydrous sodium sulfate and dried. The crude product obtained by evaporating the solvent under reduced pressure was subjected to silica gel column chromatography (hexane / ethyl acetate = 10/10).
Purification was carried out using 1) to obtain 7.0 g of 2-fluoro-4-nonanoyl-1-phenylbenzene as white crystals.

The results measured by NMR and IR are as follows:
It was as follows. NMR (CDCl ₃ ): δ = 0.85 (t, 3H),
1.0 to 2.0 (m, 12H), 2.90 (t, 2
H), 7.20-7.87 (m, 7H)

(1-c) 2-fluoro-4-nonyl-
Synthesis of 1-phenylbenzene To a solution of 7.0 g of 2-fluoro-4-nonanoyl-1-phenylbenzene obtained in (1-b) above in 35 ml of trifluoroacetic acid, 8.3 g of triethylsilane was added dropwise at 5 ° C. did. The mixture was further stirred at room temperature for 1 hour. Hexane and water (50 ml each) were added, and the organic layer was washed with a saturated aqueous solution of sodium hydrogen carbonate, water, and then with a saturated saline solution, and dried over anhydrous sodium sulfate and dried. The crude product obtained by evaporating the solvent under reduced pressure was purified by silica gel column chromatography (hexane) to give 2-fluoro-4-nonyl-1.
6.6 g of white crystals of -phenylbenzene were obtained.

(1-d) Synthesis of 1- (4-acetylphenyl) -2-fluoro-4-nonylbenzene 2-fluoro-4-nonyl- obtained in the above (1-c)
6.6 g of 1-phenylbenzene and 3.6 g of anhydrous aluminum chloride were dissolved in 50 ml of dichloromethane. 1.8 g of acetyl chloride was added dropwise thereto over 10 minutes. After stirring at room temperature for 3 hours, the mixture was poured into ice water. Extraction with dichloromethane and post-treatment similarly gave 6.8 g of white crystals of 1- (4-acetylphenyl) -2-fluoro-4-nonylbenzene.

(1-e) Synthesis of 2-fluoro-1- (4-hydroxyphenyl) -4-nonylbenzene 1- (4-acetylphenyl) -2-fluoro- obtained in the above (1-d) 6.8 g of white crystals of 4-nonylbenzene were dissolved in 120 ml of formic acid. This at 5 ℃ 3
16 ml of 0% hydrogen peroxide solution was added dropwise over 30 minutes,
Stirred at 0 ° C. for 4 hours. The mixture was poured into water, and sodium peroxide was added to decompose excess peroxide, and extracted with hexane. After washing with a saturated aqueous solution of sodium hydrogen carbonate, the solvent was distilled off. The residue was dissolved in 80 ml of ethanol, 4 g of potassium hydroxide was dissolved in 10 ml of water, and the mixture was heated under reflux for 2 hours. Dilute hydrochloric acid was added for neutralization, ethanol was distilled off under reduced pressure, ethyl acetate was added, and the mixture was washed with water and saturated saline,
It was dehydrated and dried with anhydrous sodium sulfate. The crude product obtained by evaporating the solvent under reduced pressure was recrystallized from hexane and purified to obtain 2-fluoro-1- (4-hydroxyphenyl).
3.3 g of white crystals of -4-nonylbenzene were obtained.

The results measured by NMR and IR are as follows:
It was as follows. NMR (CDCl ₃ ): δ = 0.83 (t, 3H),
1.0 to 1.8 (m, 14H), 2.57 (t, 2
H), 4.80 (s, 1H), 6.67-7.47.
(M, 7H)

(1-f) 2-fluoro-1- [4-
Synthesis of (2-heptenyloxy) phenyl] -4-nonylbenzene 500 mg of 2-fluoro-1- (4-hydroxyphenyl) -4-nonylbenzene obtained in (1-e) above
Was dissolved in 5 ml of N, N-dimethylformamide (DMF). This solution is added with potassium t-butoxide 18 at room temperature.
0 mg was added and the mixture was stirred for 30 minutes. To this mixture,
1-bromo-2-heptene 2 synthesized from heptenol
A solution of 82 mg in 5 ml of DMF was added dropwise at room temperature over 10 minutes, and the mixture was further stirred for 3 hours. After completion of the reaction, ether was added, and the organic layer was washed with diluted hydrochloric acid, water, and then with saturated saline,
After drying over anhydrous sodium sulfate, the solvent was distilled off to obtain 511 mg of a crude product. This crude product was subjected to column chromatography (silica gel, hexane / ethyl acetate = 1).
0/1) to give 2-fluoro-1- [4-
445 mg of white crystals of (2-heptenyloxy) phenyl] -4-nonylbenzene were obtained. This was further recrystallized from ethanol to obtain a purified product. The phase transition temperature of this purified product was as follows.

Phase transition temperature (° C.) Cr17.9 N3
0.5 I The results of NMR measurement were as follows. NMR (CDCl ₃ ): δ = 0.85 (m, 6H),
1.00 to 2.09 (m, 22H), 2.60 (t, 2
H), 4.50 (d, 2H), 5.60-5.87.
(M, 2H), 6.57 to 7.53 (m, 7H)

Example 2 Preparation of SC Base Liquid Crystal

[0104]

Embedded image

An SC composition (HA) was prepared. This composition showed a SC phase up to 56.5 ° C at a melting point of 12 ° C, an SA phase up to 65.5 ° C, and an N phase up to 70.5 ° C.

An SC base liquid crystal (H-1) composed of 90% of the SC base liquid crystal (HA) and 10% of the compound (No. 1) obtained in Example 1 was prepared.
The temperature dropped to 5 ° C., showing the SC phase up to 50.5 ° C., showing the SA phase up to 58 ° C., and showing the N phase up to 65.5 ° C.

Next, when an SC base liquid crystal (H-2) comprising 80% of the SC base liquid crystal (HA) and 20% of the compound of (No. 1) was prepared, the melting point dropped to about -10 ° C. Then, it showed the SC phase up to 47.5 ° C, the SA phase up to 50 ° C, and the N phase up to 61.5 ° C.

Comparative Example 1 In Example 2, the same amount of the compound of the formula (E-1) was used in place of the compound of the general formula (I), and 10% of the compound of the formula (E-1) and an SC matrix SC consisting of 90% liquid crystal (HA)
Base liquid crystal (HR-1), SC base liquid crystal (HR-2) composed of 20% of compound of formula (E-1) and 80% of SC base liquid crystal (HA) were respectively prepared. The phase transition temperature (° C.) was as follows.

(HR-1): Cr6 SC51 SA6
1 N67 I (HR-2): Cr-0.5 SC47.5 SA5
In each case of 6.5 N63.5 I, the melting point is lower than that of the SC parent liquid crystal (HA), but is not so remarkable as when the compound of the general formula (I) is added.

(Example 3) SC ^* Preparation of liquid crystal composition Formula (Q) comprising 90% of the base liquid crystal (H-1) obtained in Example 2 and the following composition:

[0111]

Embedded image

SC ^* comprising 10% of a chiral dopant of
A liquid crystal composition (M-1) was prepared. This liquid crystal composition has 5
The SC ^* phase was shown at 1.5 ° C or less, the SA phase was shown at 58 ° C or less, and the N ^* phase was shown at 62.5 ° C or less. Its melting point was unclear.

Next, 95% of the base liquid crystal (H-2) and the compound of the formula (P)

[0114]

Embedded image

An SC ^* liquid crystal composition (M-2) comprising 5% of the optically active compound was prepared. This liquid crystal composition has a temperature of 45 ° C.
The SC ^* phase was shown below, the SA phase was shown at 54.5 ° C. or less, the N ^* phase was shown at 60 ° C. or less, and the melting point was as low as −10 ° C. or less.

(Comparative Example 2) In the same manner as in Example 3, SC
An SC ^* liquid crystal composition (MR-1) comprising 90% of the base liquid crystal (HR-1) and 10% of the chiral dopant of the formula (Q) was prepared. Similarly, SC matrix liquid crystal (HR-2) 95%
And an SC ^* liquid crystal composition (MR-2) comprising 5% of an optically active compound of the formula (P). These phase transition temperatures were as follows.

(MR-1): SC ^* 52.5 SA60 N ^* 64 I (MR-2): SC ^* 46.5 SA59 N ^* 62 I Further, 90% of SC parent liquid crystal (HA) and the formula ( SC ^* liquid crystal composition (MR) comprising 10% of a chiral dopant Q)
-3) was prepared. The phase transition temperature was as follows. (MR-3): SC ^* 57 SA64.5 N ^* 67I

Example 4 Production of Liquid Crystal Display Element First, a polyimide forming solution was applied to an ITO vapor-deposited glass plate (electrode area: 70 mm ² ) to form a polyimide film (substrate A). Similarly, a polyimide film containing spacers was formed using the above-described polyimide forming solution mixed with glass fiber spacers (substrate B). The substrate A and the substrate B were rubbed with a nylon cloth.
A thermosetting epoxy adhesive was applied to one of the substrates, the substrates A and B were overlapped so that their rubbing directions were parallel and opposite to each other, and were heated and cured to produce a cell.

The SC ^* liquid crystal composition (M-1) obtained in Example 3 was injected into the thus obtained cell in a state where the SC ^* liquid crystal composition (M-1) was converted into an isotropic liquid (I) phase, and then slowly cooled. Done, N ^*
The phase, SA phase, and then SC ^* phase were oriented to obtain a liquid crystal display device. The orientation state was very good. When the cell thickness of this cell was measured, it was about 2.0 μm.

When a rectangular wave having an electric field strength of 10 V _pp / μm was applied to this cell and its electro-optical response speed was measured, a high-speed response of 78 μs at 25 ° C. was confirmed. At this time, the spontaneous polarization was 5.7 nC / cm ² , and the tilt angle was 22.
It was 8 ゜. The contrast was very good.

Next, a device was produced in the same manner using the SC ^* liquid crystal composition (M-2), and its electro-optical response speed was measured. As a result, a high-speed response of 55 μsec at 25 ° C. was confirmed. , Its contrast was very good.

(Comparative Example 3) The SC ^* liquid crystal composition (MR) obtained in Comparative Example 2 was added to a cell manufactured in the same manner as in Example 4.
-1), (MR-2) and (MR-3) were used to fabricate respective liquid crystal display elements.

The electro-optical response speed measured in the same manner as in Example 4 was 82 μsec at 25 ° C. for the SC ^* liquid crystal composition (MR-1), and 83% for the SC ^* liquid crystal composition (MR-3).
μsec, which was slower than that of the SC ^* liquid crystal composition (M-1).

[0124]

The compound represented by the general formula (I) of the present invention has a low viscosity, and lowers the melting point when used in a SC parent liquid crystal as compared with a compound having a corresponding side chain. Since the effect is large, it is excellent as a constituent material of a low-viscosity base liquid crystal having a wide temperature range from a low temperature range to a high temperature range.

Further, the ferroelectric liquid crystal composition to which the chiral dopant is added exhibits an SC ^* phase in a wide temperature range, and a high-speed response of about 50 μsec at room temperature is possible. Furthermore, it is excellent in orientation and can obtain good contrast, and is extremely useful as a material for an optical switching element for display.

Continuation of the front page (56) References JP-A-2-51586 (JP, A) JP-A-5-59366 (JP, A) JP-A-2-503430 (JP, A) WO 89/2425 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 43/225 C09K 19/12 C09K 19/42 C09K 19/58 G02F 1/13 500 CA (STN) CAOLD (STN) REGISTRY (STN )

Claims (5)

(57) [Claims] 1. A compound represented by the general formula (Ia), the general formula (Ib),
Formula (Ic) or Formula (Id) (Wherein, R ¹ represents a linear alkyl group having 6 to 12 carbon atoms, and R ² represents a linear alkyl group having 3 to 7 carbon atoms). 2. The compound according to claim 1, which is represented by the general formula (Ia) . (1) The general formula (Ia) according to claim 1 ,
A ferroelectric liquid crystal composition containing a compound represented by the general formula (Ib), (Ic) or (Id) and (2) a chiral dopant comprising an optically active compound. 4. A compound of the general formula (II) (Wherein, R ³ represents a straight-chain alkyl group having 6 to 12 carbon atoms, and R ⁴ represents an alkyl group or a straight-chain alkenyl group having 6 to 12 carbon atoms). The ferroelectric liquid crystal composition according to claim 3, wherein 5. A liquid crystal display device comprising the ferroelectric liquid crystal composition according to claim 3 as a constituent element.