JP4655197B2 - Difluorochroman derivative - Google Patents

Description

  The present invention relates to a difluorochroman derivative useful as an electro-optical liquid crystal display material, a liquid crystal composition containing the same, and a liquid crystal display element using the same.

  Liquid crystal display elements are currently widely used because of their excellent features such as low voltage operation and thin display. Conventional liquid crystal display element display methods include TN (twisted nematic), STN (super twisted nematic), or active matrix (TFT: thin film transistor) based on TN, and these have positive dielectric anisotropy values. The liquid crystal composition is used. However, one of the disadvantages of these display methods is a narrow viewing angle, and with the increasing demand for larger liquid crystal panels in recent years, the improvement has become a major issue.

  In recent years, display methods such as vertical alignment and IPS (in-plane switching) have been newly put to practical use as a solution. The vertical alignment method is a method in which the viewing angle is improved by utilizing the vertical alignment of liquid crystal molecules, and a liquid crystal material having a negative dielectric anisotropy value is used. IPS is a method of improving viewing angle by switching liquid crystal molecules using a horizontal electric field in the horizontal direction with respect to a glass substrate, and a liquid crystal material having a positive or negative dielectric anisotropy value is used. The As described above, the vertical alignment method and IPS, which are effective display methods for improving the viewing angle, require a liquid crystal material having a negative dielectric anisotropy value, and have been strongly demanded.

  By the way, liquid crystal materials used in all display systems are appropriately adjusted not only with appropriate dielectric anisotropy values but also with other properties such as refractive index anisotropy values and elastic constant ratios. It is necessary to have a suitable liquid crystal phase expression temperature range and low viscosity even at a low temperature. Until now, none of the known liquid crystal compounds satisfy all of these conditions alone. Therefore, the liquid crystal material is usually prepared by mixing a compound having several to twenty or more kinds of liquid crystal phases and, if necessary, a compound not having several kinds of liquid crystal phases. In general liquid crystal materials, so-called bicyclic, tricyclic and tetracyclic liquid crystalline compounds (see Patent Documents 1 and 2) containing 2 to 4 ring structures have been used. There were few application examples as a liquid crystal compound regarding a compound having only one.

  With respect to compounds having one ring structure, compounds having one naphthalene ring have been reported as a condensed ring system compound (see Patent Document 3). However, the compound reported here is a nonpolar liquid crystal compound having a dielectric anisotropy close to 0, and a compound having a negative dielectric anisotropy and a large absolute value has not been known. Further, no liquid crystal compound having only one chroman ring has been known.

  On the other hand, in the case of a liquid crystal compound, the manufacturing process generally becomes complicated as the number of rings increases. In addition, generally, the viscosity of the compound increases as the number of rings increases. On the other hand, a monocyclic compound having a single ring structure is not complicated in production process and is expected to have a low viscosity as compared with a 2- to 4-ring liquid crystal compound. Application examples are limited to nonpolar compounds, and little is known about liquid crystal compounds having negative dielectric anisotropy, and development has been delayed.

German Patent Application Publication No. 3,906,019 German Patent Application Publication No. 19522145 JP 11-335307 A

  The object is to provide a monocyclic liquid crystal compound having a negative dielectric anisotropy and a large absolute value, and to provide a liquid crystal composition and a display device containing the same.

  As a result of studying a difluorochroman derivative, a nematic liquid crystal composition using the same, and a display element, the present inventor has completed the present invention.

  The present invention relates to a general formula (1)

(In the formula, R ¹ and R ² are each independently an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms (one CH ₂ group present in these groups or adjacent to each other). And two or more CH ₂ groups which may not be substituted with O.), A ¹ and A ² each independently represent —CH═CH—, —OCH ₂ —, —OCO— or a single bond. To express.)
The difluorochroman derivative represented by these is provided.

  In addition, a liquid crystal composition containing the same and a display element are also provided.

  The monocyclic liquid crystal compound of the present invention is characterized in that the dielectric anisotropy is negative, its absolute value is large, and its viscosity is low, and the display device using this is a liquid crystal for vertical alignment, IPS, etc. It is useful as a component of the composition. In addition, the liquid crystal composition of the present invention is characterized by having a negative dielectric anisotropy and a large absolute value, and a display element using the liquid crystal composition is useful as a liquid crystal display element such as a vertical alignment type or IPS. .

In the general formula (1), R ¹ and R ² are preferably alkyl groups having 1 to 10 carbon atoms. A ¹ and A ² are preferably —OCH ₂ —, —OCO— and a single bond.
In the present invention, production examples of the compound of the general formula (1) are given below. Of course, the gist and scope of the present invention are not limited by these production examples.

  (Production method 1) General formula (2)

(式中、R¹及びA¹は一般式（１）と同じ意味を表す。)で表されるベンゼン誘導体に対し、ハロゲン基を導入して一般式（３）

(Wherein R ¹ and A ¹ represent the same meaning as in general formula (1)), a halogen group is introduced into the benzene derivative represented by general formula (3)

(式中、R¹及びA¹は一般式（１）と同じ意味を表し、X¹はハロゲンを表す。)で表されるベンゼン誘導体を得る。このときX¹は塩素、臭素及びよう素が好例として挙げられるが、よう素がより好ましい。
得られた一般式（３）の化合物に、一般式（４）

(Wherein R ¹ and A ¹ represent the same meaning as in general formula (1), and X ¹ represents halogen). At this time, examples of X ¹ include chlorine, bromine and iodine, but iodine is more preferable.
The compound of the general formula (3) obtained was added to the general formula (4).

(式中、R²及びA²は一般式（１）と同じ意味を表す。)で表されるアセチレン誘導体をカップリング反応させ、一般式（５）

(Wherein R ² and A ² represent the same meaning as in general formula (1)), and the acetylene derivative represented by general formula (5) is subjected to a coupling reaction.

(式中、R¹、R²、A¹及びA²は一般式 (１)と同じ意味を表す。)で表されるアセチレン誘導体を得る。
得られた一般式（５）の化合物を水素添加して、一般式（６）

(Wherein R ¹ , R ² , A ¹ and A ² have the same meaning as in general formula (1)), an acetylene derivative represented by formula (1) is obtained.
The obtained compound of the general formula (5) is hydrogenated to give a general formula (6)

(式中、R¹、R²、A¹及びA²は一般式 (１)と同じ意味を表す。)で表されるアルコール誘導体を得る。
得られた一般式（６）の化合物に塩基を反応させ、一般式（７）

(Wherein R ¹ , R ² , A ¹ and A ² represent the same meaning as in the general formula (1)).
The compound of general formula (6) thus obtained is reacted with a base to give general formula (7)

(式中、R¹、R²、A¹及びA²は一般式 (１)と同じ意味を表し、M¹はリチウム、ナトリウム、カリウム等のアルカリ金属、マグネシウム、カルシウム等のアルカリ土類金属等の金属を表す。)で表されるアルコラートを得る。

(Wherein R ¹ , R ² , A ¹ and A ² represent the same meaning as in general formula (1), M ¹ is an alkali metal such as lithium, sodium and potassium, an alkaline earth metal such as magnesium and calcium, etc. An alcoholate represented by the following formula:

  By subjecting the obtained compound of the general formula (7) to a substitution reaction in the molecule, a compound represented by the general formula (1) can be obtained. This reaction is preferably carried out in the same system as the production reaction of the alcoholate represented by the general formula (7).

(Manufacturing method 2)
A compound represented by general formula (3) and 3-methyl-1-butyn-3-ol are subjected to a coupling reaction to form general formula (8)

(式中、R¹及びA¹は一般式 (１)と同じ意味を表す。)で表される化合物を得る。
得られた一般式（８）で表される化合物に塩基を作用させて一般式（９）

(Wherein R ¹ and A ¹ represent the same meaning as in general formula (1)).
A base is allowed to act on the resulting compound represented by the general formula (8) to give a general formula (9)

(式中、R¹及びA¹は一般式 (１)と同じ意味を表す。)で表される化合物を得る。
得られた一般式（９）で表される化合物のアセチリドを調製した後一般式（１０）

(Wherein R ¹ and A ¹ represent the same meaning as in general formula (1)).
After preparing acetylide of the compound represented by the general formula (9) obtained, the general formula (10)

(式中、R²及びA²は一般式 (１)と同じ意味を表す。)で表されるアルデヒド化合物と反応させることにより、一般式（５）で表される化合物を得たのち、製法１で記載した経路と同一の方法により一般式（１）で表される化合物を得ることができる。

(In the formula, R ² and A ² represent the same meaning as in the general formula (1).) By reacting with the aldehyde compound represented by the general formula (1), a compound represented by the general formula (5) is obtained, and then the production method The compound represented by the general formula (1) can be obtained by the same method as the route described in 1.

(Manufacturing method 3)
By using 1,2,3-trifluorobenzene as a starting material, the same reaction as in production method 1 or production method 2 is carried out, whereby the general formula (11)

(式中、R²及びA²は一般式 (１)と同じ意味を表す。)で表されるクロマン誘導体を得る。
得られた一般式（１１）の化合物を酸化することで一般式（１２）

(Wherein R ² and A ² represent the same meaning as in general formula (1)).
By oxidizing the obtained compound of the general formula (11), the general formula (12)

(式中、R²及びA²は一般式 (１)と同じ意味を表す。)で表されるクロマン誘導体を得る。
得られた一般式（１２）の化合物に塩基を反応させ、一般式（１３）

(Wherein R ² and A ² represent the same meaning as in general formula (1)).
The obtained compound of the general formula (12) is reacted with a base to give a general formula (13)

(式中、R²及びA²は一般式 (１)と同じ意味を表し、M¹は一般式(17)と同じ意味を表す。) で表されるフェノラートを得る。
得られた一般式（１３） の化合物に一般式（１４）

(Wherein R ² and A ² represent the same meaning as in general formula (1), and M ¹ represents the same meaning as in general formula (17)).
The compound of the general formula (13) thus obtained is added to the general formula (14)

(式中、R¹は一般式(１)と同じ意味を表し、X²は塩素、臭素、よう素、ベンゼンスルホニル基、p-トルエンスルホニル基、メタンスルホニル基又はトリフルオロメタンスルホニル基を表す。)で表される化合物を反応させることで、一般式（１５）

(Wherein R ¹ represents the same meaning as in general formula (1), and X ² represents chlorine, bromine, iodine, benzenesulfonyl group, p-toluenesulfonyl group, methanesulfonyl group or trifluoromethanesulfonyl group.) By reacting the compound represented by general formula (15)

(式中、R¹、R²及びA²は一般式（１）と同じ意味を表す。) で表されるクロマン誘導体を得ることができる。

(Wherein R ¹ , R ² and A ² represent the same meaning as in general formula (1)).

(Manufacturing method 4)
Compound of general formula (12) and general formula (16)

（式中、R¹は一般式（１）と同じ意味を表す。）で表される化合物と脱水縮合することにより、一般式（１７）

(Wherein R ¹ represents the same meaning as in general formula (1)) and dehydration condensation with the compound represented by general formula (17)

（式中、R¹、R²及びA²は一般式（１）と同じ意味を表す。）で表される化合物を得ることができる。

(Wherein R ¹ , R ² and A ² represent the same meaning as in general formula (1)) can be obtained.

(Manufacturing method 5)
After lithiation of the compound of general formula (11), general formula (18)

（式中、R¹は一般式（１）と同じ意味を表す。）で表されるアルデヒド化合物と反応させることにより一般式（１９）

(Wherein R ¹ represents the same meaning as in general formula (1)), and is reacted with an aldehyde compound represented by general formula (19).

（式中、R¹、R²及びA²は一般式（１）と同じ意味を表す。）で表されるアルコール化合物を得る。得られた一般式（１９）の化合物を脱水することにより一般式（２０）

(Wherein R ¹ , R ² and A ² represent the same meaning as in general formula (1)). By dehydrating the obtained compound of the general formula (19), the general formula (20)

（式中、R¹、R²及びA²は一般式（１）と同じ意味を表す。）で表されるクロマン化合物を得ることができる。
得られた一般式（２０）の化合物を水素添加することにより一般式（２１）

(Wherein R ¹ , R ² and A ² represent the same meaning as in general formula (1)).
By hydrogenating the obtained compound of the general formula (20), the general formula (21)

（式中、R¹、R²及びA²は一般式（１）と同じ意味を表す。）で表されるクロマン化合物を得ることができる。

(Wherein R ¹ , R ² and A ² represent the same meaning as in general formula (1)).

  EXAMPLES Hereinafter, although an Example is given and this invention is further explained in full detail, this invention is not limited to these Examples. The structure of the compound was confirmed by nuclear magnetic resonance spectrum (NMR), mass spectrum (MS) and the like. Further, “%” in the compositions of the following examples and comparative examples means “mass%”.

The following abbreviations are used in compound descriptions.
THF: tetrahydrofuran
DMF: N, N-dimethylformamide
Me: methyl group
Et: ethyl group
Pr: Propyl group
Bu: Butyl group
Ac: Acetyl group
Hep: heptyl group
Pen: pentyl group
Ph: phenyl group
Hex: Hexyl group
p-TsOH: p-toluenesulfonic acid
WSC: N-ethyl-N ′-(3-dimethylaminopropyl) carbodiimide hydrochloride (Example 1) Synthesis of 7,8-difluoro-6-heptoxy-2-pentylchroman (Ia)

(1-1) Synthesis of 2,3,4-trifluoro-1- (3-hydroxy-1-octynyl) benzene Under nitrogen substitution, take 355 g of 2,3,4-trifluorobromobenzene in a reaction vessel, Dissolved in 710 mL of DMF. Thereto, 355 mL of triethylamine, 8.8 g of tetrakistriphenylphosphine palladium (0) and 5.8 g of copper (I) iodide were added. 193 g of 1-octin-3-ol was added dropwise at an internal temperature of 80 85 ° C., and the mixture was further stirred for 6 hours. Water was added to separate the organic layer, and the aqueous layer was extracted with ethyl acetate. The organic layers were combined and washed with water, 10% hydrochloric acid, water, saturated aqueous sodium hydrogen carbonate solution and saturated brine in this order. The solvent was distilled off under reduced pressure, and the residue was purified by column chromatography and distillation under reduced pressure (1.5 3.0 mmHg / 146 155 ° C) to give 2,3,4-trifluoro-1- (3-hydroxy-1 as a light brown oily substance. -Octynyl) benzene (258 g) was obtained.

(1-2) Synthesis of 2,3,4-trifluoro-1- (3-hydroxy-1-octyl) benzene
258 g of 2,3,4-trifluoro-1- (3-hydroxy-1-octynyl) benzene was dissolved in 850 mL of ethyl acetate, and 10 g of 5% palladium carbon (containing 50% water) was added. The mixture was stirred at room temperature and a hydrogen pressure of 0.1 0.5 MPa for 5 hours. After the catalyst was filtered off, the solvent was distilled off under reduced pressure to obtain 260 g of 2,3,4-trifluoro-1- (3-hydroxy-1-octyl) benzene as a pale yellow oily substance.

(1-3) Synthesis of 7,8-difluoro-2-pentylchroman Under nitrogen replacement, 25.8 g of sodium hydride (60%) was placed in a reaction vessel and suspended in 100 mL of DMF. A DMF (1.3 L) solution of 140 g of 2,3,4-trifluoro-1- (3-hydroxy-1-octyl) benzene was added dropwise at an internal temperature of 40 60 ° C., and the mixture was further stirred for 1 hour. The reaction mixture was poured into water and neutralized with 10% hydrochloric acid. This was extracted with hexane, washed with water and saturated brine, and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure, and the residue was purified by distillation under reduced pressure (0.7 0.8 mmHg / 80 118 ° C.) and column chromatography to obtain 97 g of 7,8-difluoro-2-pentylchroman as an almost colorless oily substance.

(1-4) Synthesis of 7,8-difluoro-2-pentylchroman-6-ol Under nitrogen substitution, 100 g of 7,8-difluoro-2-pentylchroman was placed in a reaction vessel and dissolved in 1 L of THF. 188 mL of butyllithium (2.44 M in hexane) was added dropwise at an internal temperature of −40 ° C. or lower, and the mixture was further stirred at an internal temperature of −40 to −55 ° C. for 4 hours. At an internal temperature of −40 ° C. or lower, 52 g of trimethyl borate was added dropwise, stirred for 30 minutes, and heated to −10 ° C. After adding 36 mL of acetic acid, 71 mL of 30% aqueous hydrogen peroxide was added dropwise, and the mixture was stirred at an internal temperature of 20-40 ° C. for 2 hours. The reaction solution was poured into water, the organic layer was separated, and the aqueous layer was extracted with toluene. The organic layers were combined, washed with water and saturated brine, and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure, and the residue was purified by recrystallization to obtain 85 g of 7,8-difluoro-2-pentylchroman-6-ol as an almost colorless solid.

(1-5) Synthesis of 7,8-difluoro-6-heptoxy-2-pentylchroman (Ia) In a reaction vessel, 7,8-difluoro-2-pentylchroman-6-ol 10 g, 1-bromoheptane 8.4 g , 8.1 g of potassium carbonate, and 50 mL of methyl ethyl ketone were added, and the mixture was heated to reflux for 3 hours. The solvent was distilled off under reduced pressure, hexane and toluene were added to the residue, and the insoluble material was filtered off. The solvent was distilled off from the filtrate under reduced pressure, and the residue was recrystallized and purified by column chromatography to obtain 7.3 g of 7,8-difluoro-6-heptoxy-2-pentylchroman (Ia) as colorless crystals.
MS m / z: 354 (M ⁺ ), 55 (100)
Phase transition temperature C 33.5 I
¹ H-NMR (400 MHz, CDCl ₃ )
δ: 0.89 (t, J = 6.8 Hz, 3 H), 0.91 (t, J = 6.4 Hz, 3 H), 1.2 1.8 (m, 19 H), 1.9 2.1 (m, 1 H), 2.6 2.8 (m , 2 H) 3.93 (t, J = 6.8 Hz, 2 H), 3.9 4.0 (m, 1 H), 6.39 (d, J = 7.6 Hz, 1 H)

Example 2 Synthesis of 7,8-difluoro-6-hexyl-2-pentylchroman (IIa)

(2-1) Synthesis of 7,8-difluoro-6- (1-hydroxyhexyl) -2-pentylchroman Under nitrogen substitution, 7,8-difluoro-2-pentylchroman was taken in a reaction vessel and dissolved in THF. . Butyl lithium (2.44 M in hexane) was added dropwise at an internal temperature of −40 ° C. or lower, and the mixture was further stirred at an internal temperature of −40 to −55 ° C. for 4 hours. At an internal temperature of −40 ° C. or lower, hexanal was added dropwise, stirred for 30 minutes, and then warmed to room temperature. The reaction solution was poured into 10% hydrochloric acid, the organic layer was separated, and the aqueous layer was extracted with toluene. The organic layers were combined, washed with water and saturated brine, and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure to obtain 7,8-difluoro-6- (1-hydroxyhexyl) -2-pentylchroman.

(2-2) Synthesis of 7,8-difluoro-6- (1-hexenyl) -2-pentylchroman Take 7,8-difluoro-6- (1-hydroxyhexyl) -2-pentylchroman in a reaction vessel, Dissolved in toluene. p-Toluenesulfonic acid monohydrate was added, and the mixture was heated to reflux for 3 hours while removing water produced using Dean Stark. After cooling to room temperature, a saturated aqueous sodium hydrogen carbonate solution was added, and the organic layer was separated. This was washed with water and saturated brine, and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure to obtain 7,8-difluoro-6- (1-hexenyl) -2-pentylchroman.

(2-3) Synthesis of 7,8-difluoro-6-hexyl-2-pentylchroman (IIa)
7,8-Difluoro-6- (1-hexenyl) -2-pentylchroman was dissolved in toluene, and 5% palladium carbon (containing 50% water) was added. This was stirred at room temperature and a hydrogen pressure of 0.5 MPa for 5 hours. After the catalyst was filtered off, the solvent was distilled off under reduced pressure, and the residue was purified by column chromatography to obtain 7,8-difluoro-6-hexyl-2-pentylchroman (IIa).

Example 3 Synthesis of heptanoic acid 7,8-difluoro-2-pentylchroman-6-yl (IIIa)

  Take 7,8-difluoro-2-pentylchroman-6-ol, heptanoic acid, N-ethyl-N '-(3-dimethylaminopropyl) carbodiimide hydrochloride, 4-dimethylaminopyridine and dichloromethane in a reaction vessel, For 8 hours. Hexane and 10% hydrochloric acid were added to separate the organic layer, which was washed with 10% hydrochloric acid and saturated brine. After drying over anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by column chromatography to obtain 2-butoxy-1,7,8-trifluoronaphthalen-6-yl heptanoate (IIIa).

(Example 4) Preparation of liquid crystal composition Host liquid crystal composition (H) having the following composition

を調製した。ここで(H)の物性値は以下の通りである。

Was prepared. Here, the physical properties of (H) are as follows.

Nematic phase upper limit temperature (TN-I): 103.2 ℃
Dielectric anisotropy (Δε): 0.03
Refractive index anisotropy (Δn): 0.099
Viscosity (mPa · s): 15.2
A liquid crystal composition (M-1) comprising 80% of the host liquid crystal (H) and 20% of (Ia) obtained in Example 1 was prepared. The physical properties of this composition are as follows.

Nematic phase upper limit temperature (TN-I): 56.4 ℃
Dielectric anisotropy (Δε): −1.13
Refractive index anisotropy (Δn): 0.085
Viscosity (mPa · s): 19.2
In the liquid crystal composition (M-1) containing the compound (Ia) of the present invention, the dielectric anisotropy (Δε) decreased to a negative value as compared with the host liquid crystal (H). From this, it can be seen that the compound (Ia) of the present invention has a negative dielectric anisotropy and a large absolute value.
(Comparative Example 1)
Host liquid crystal prepared in Example 4 (H) 80% and bicyclic liquid crystal compound (Ib)

20％からなる液晶組成物(M-２)を調製した。この組成物の物性値は以下の通りである。

A liquid crystal composition (M-2) comprising 20% was prepared. The physical properties of this composition are as follows.

Nematic phase upper limit temperature (TN-I): 95.9 ℃
Dielectric anisotropy (Δε): −0.46
Refractive index anisotropy (Δn): 0.089
Viscosity (mPa · s): 23.0
The liquid crystal composition (M-2) containing the bicyclic liquid crystal compound (Ib) has a smaller absolute value of dielectric anisotropy and a higher viscosity than (M-1) described in Example 4. I understand.

The compound, the liquid crystal composition, and the display element of the present invention are useful as constituent members of a liquid crystal display element such as a vertical alignment method and IPS.

Claims (6)

General formula (1)

(In the formula, R ¹ and R ² are each independently an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms (one CH ₂ group present in these groups or adjacent to each other). And two or more CH ₂ groups which may not be substituted with O.), A ¹ and A ² each independently represent —CH═CH—, —OCH ₂ —, —OCO— or a single bond. To express.)
A difluorochroman derivative represented by: In the general formula (1), R ¹ and R ² are each independently an alkyl group having 1 to 10 carbon atoms (one CH ₂ group present in these groups or two or more non-adjacent CH groups). _2. The compound according to claim 1, wherein _two groups may be substituted with O.), and A ¹ and A ² each independently represent —OCH ₂ —, —OCO— or a single bond. A liquid crystal composition containing one or more compounds according to claim 1. A liquid crystal display device using the liquid crystal composition according to claim 3. The liquid crystal display element according to claim 4, which is driven in an active matrix. 6. The liquid crystal display element according to claim 5, wherein the liquid crystal display element is displayed in a vertical alignment method.