JPH0339554B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a novel anthraquinone compound and its application. More specifically, the present invention relates to a novel anthraquinone compound useful as a dye for guest-host type liquid crystal display devices. ``Prior art'' A method of displaying by sandwiching a dichroic dye-containing dielectric or cholesteric liquid crystal with positive or negative dielectric anisotropy between two electrodes and applying a voltage has already been used as a guest-host display element. Are known. This display element has (1) a wider viewing range than twisted nematic (TN) elements used in calculators, watches, etc.; (2) Greater freedom in hue selection. (3) The number of polarizing plates used is reduced. (4) Cost can be reduced. There are advantages such as This guest-host display element displays by changing the molecular alignment direction of the dichroic dye and changing the absorption of light passing through the liquid crystal layer, so the dichroic dye used is based on the following items: It is necessary to satisfy the following. That is, (1) it should be dissolved in the host liquid crystal to an extent that a practical coloring density can be obtained; (2) High dichroism that contributes to display contrast. (3) Excellent in various durability including light resistance. etc. Although such dichroic dyes can be used alone, multicolor displays using light shutters created by dissolving black-based dyes obtained by blending various dyes into liquid crystals have been put to practical use in automobiles. ing. Conventionally, among the components of black-based pigments, azo pigments have been used for colors from yellow to red, and atraquinone pigments have been used for blue colors. However, although the solubility and dichroism of azo dyes are at good levels, the light fastness is at a somewhat insufficient level for use in automotive applications. Furthermore, among the anthraquinone dyes, which generally have better light fastness than azo dyes, there are few known anthraquinone dyes that have good solubility and dichroism and exhibit a yellow to red hue. "Problems to be Solved by the Invention" Most of the yellow to red pigments used alone as pigments for guest-host type liquid crystal display elements or as a compounding component of black pigments are azo compounds, and it is necessary to use them for automotive applications. It is difficult to say that the light fastness is at a sufficient level when used for purposes such as the following. Therefore, it is desired to develop an anthraquinone compound that has better light fastness than azo compounds, has a yellow to red hue, and has good solubility and dichroism. "Means for Solving the Problems" The present inventors have made extensive efforts to develop anthraquinone dyes for guest-host type liquid crystal display devices that exhibit a yellow to red hue and have good solubility, dichroism, and light fastness. After researching, I found that the formula () [Formula [], X is amino or hydroxyl,
Y represents hydrogen. Also, R ₁ is hydrogen, fluorine, chlorine,
Represents cyano, methyl, ethyl, methoxy, ethoxy, R ₂ is hydrogen; fluorine; chlorine; bromine; cyano; trifluoromethyl; C ₁ - C ₁₂ which may be substituted with cyclohexyl, cyclohexyloxy, phenyl, phenoxy alkyl or alkoxy (in which the carbon chain may be interrupted by 1 to 3 oxygen atoms); -(C ₂ H ₄ O) mCH ₂ CH
= _CHR3 ;-O( _C2H4O ) _{mCH2CH = CHR3} ;-
( _CH2 ) _nCOOR4 ; _−COR4 ; _−NHCOR4 ;−
NHCOOR ₄ ;

【formula】

【formula】

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[Formula] or -OR represents ₇ . Further, R ₃ represents hydrogen, methyl or phenyl, and R ₄ represents C _1-4 alkyl. One of R ₅ and R ₆ represents hydrogen or C _1-4 alkyl, and the other represents
Represents C _1-4 alkyl. Furthermore, _R7 is _C2-9 in which at least three or more hydrogens are replaced with fluorine.
alkyl, m is 0, 1 or 2, n is 0, 1,
Represents 2 or 3. ] The present invention was completed by discovering that a novel anthraquinone compound represented by the following has these properties. The anthraquinone compound represented by formula () of the present invention can be synthesized by various methods, one example of which is shown below. formula() [In formula (), X and Y represent the same meanings as above, and Z represents chlorine or bromine. ] Anthraquinone compound represented by and formula () [In formula (), R ₁ and R ₂ represent the same meanings as above. ] A phenol derivative represented by the formula () is reacted with an acid binder under heating in the absence of a solvent or in the presence of a solvent, or in the formula () where X is hydroxy and Y
When is hydrogen, the formula () [In formula (), R ₁ and R ₂ represent the same meanings as above. ] The amino group of an anthraquinone compound represented by the formula (), or when X is amino and Y or hydrogen in the formula () [In formula (), R ₁ and R ₂ represent the same meanings as above. ] It can be synthesized by diazotizing one of the amino groups of an anthraquinone compound represented by the formula and then dediazotizing it. Specific examples of solvents optionally used when reacting the compound of formula () with the compound of formula () include N-methylpyrrolidone, N,N-dimethylformamide, dimethylsulfoxide, and the like. Also compounds of formula () and formula ()
Examples of the acid binder to be present when reacting the compound include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, etc., and the amount used is 1 mole of the anthraquinone compound of formula (). The amount is 2 moles or more, preferably 2 to 3 moles. The reaction temperature when the compound of formula () and the compound of formula () are reacted in the presence of an acid binder without a solvent or in a solvent is 100 to 250°C, preferably 120 to 250°C.
It is 200℃. To synthesize a compound of formula () from a compound of formula () or formula (), the compound of formula () or formula () is diazotized with sodium nitrite in a solvent such as nitric acid or acetic acid, and the resulting compound is diazotized with sodium nitrite. The diazonium salt can be dediazotized by adding it to a solvent such as ethanol, isopropanol or dimethylformamide at 50-100°C, or by diazotizing it with isoamyl nitrite in dimethylformamide for 30-100°C.
This is achieved by heating to 100°C. The anthraquinone compound represented by the formula () of the present invention is used as a dichroic dye, but when preparing a liquid crystal composition, one or more of these compounds is added in an amount of 0.01 to 25% by weight based on the host liquid crystal. ,
Preferably, it can be added in an amount of 0.1 to 5% by weight. The compound of the present invention can be blended with other dichroic dyes to be used as a black blended dye, and furthermore, other optically active substances may be used in combination with the liquid crystal composition of the present invention. As the host liquid crystal compound used in the liquid crystal composition of the present invention, biphenyl-based, phenylcyclohexane-based, ester-based, pyrimidine-based, dioxane-based, Schiff-based, azo-based, and azoxy-based liquid crystals are used. The liquid crystal may be of a nematic type, a twisted nematic type, a cholesteric-nematic phase transition type, a smectic type, etc., and the display method may be any method based on the positive or negative dielectric anisotropy of the liquid crystal. "Examples" The present invention will be explained in more detail with reference to Examples below. In the examples, "parts" means parts by weight. Example 1 21.5 parts of p-n-butylphenol and 1.5 parts of potassium carbonate are heated to 150° C. in a nitrogen stream to dehydrate them. Then, it was cooled to 100°C to give 1-amino-4,8
-dihydroxy 3,7-dibromoanthraquinone
Add 4.1 parts, raise the temperature to 180°C, and react at the same temperature for 5 hours. After the reaction is completed, the mixture is cooled to 70°C, 30 parts of methanol is added, and the precipitated crystals are separated, washed with methanol and water, and then dried. The obtained crude product was purified by column chromatography to obtain two parts of the dye of the following formula. Melting point 213-214.5°C λmax 528564 nm (in xylene) The color of this dye dissolved in acetone was red. The obtained dye was placed on Merck's liquid crystal ZLI-1565.
% doped and homogeneously aligned in a cell facing each other with an interval of about 10 μm, and when the voltage is turned on and off, a good contrast is obtained, and the dichroic ratio is 10.5. It was hot. In addition, the solubility of this dye in liquid crystal (5% dissolution in liquid crystal E-8 manufactured by Merck & Co., Ltd., room temperature) and light fastness were good. Example 2 The following formula After adding 5.7 parts of the compound to 70 parts of dimethylformamide and stirring for 1 hour, the temperature was raised to 50°C, 7 parts of isoamyl nitrite was added at the same temperature, and the mixture was reacted at 50 to 55°C for 3 hours. After the reaction is completed, the reaction solution is poured into ice water, washed with water, and dried. When the obtained crude product is purified by column chromatography, the dye of the following formula is obtained.
2.9 parts were obtained. Melting point 194-196°C λmax 496520 nm (in xylene) The color of this dye dissolved in acetone was yellow-orange. When the obtained dye was added at 1% to ZLI-1565 manufactured by Merck and sealed in a cell, and the voltage was turned on and off, a good contrast was obtained, and the dichroic ratio was 8.0. Furthermore, this dye had excellent solubility in liquid crystal and light fastness. Examples 3 to 114 Anthraquinone compounds represented by the formula () were synthesized and liquid crystal compositions were prepared in the same manner as in Examples 1 to 2. Tables 1 and 2 show the structural formulas and λmax in xylene of the anthraquinone compounds represented by formulas () and (). Regarding R ₁ , the ortho and meta positions relative to the oxygen atom are o
-, m-.

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[Table] "Effects of the Invention" A yellow to red anthraquinone compound was obtained which showed excellent solubility in liquid crystal substances and excellent dichroism. This product also has good light fastness, so it has extremely high utility value in preparing liquid crystal compositions.

Claims (1)

[Claims] 1 Formula () [Formula [], X is amino or hydroxy, Y
represents hydrogen. Also, R ₁ is hydrogen, fluorine, chlorine,
Cyano, methyl, ethyl, methoxy or ethoxy, R ₂ is hydrogen; fluorine; chlorine; bromine; cyano;
trifluoromethyl; _C1 - _C12 alkyl or alkoxy optionally substituted with cyclohexyl, cyclohexyloxy, phenyl, phenoxy (in which the carbon chain may be interrupted by 1 to 3 oxygen atoms); −(C ₂ H ₄ O) mCH ₂ CH=
CHR ₃ ;-O-(C ₂ H ₄ O)mCH ₂ CH=CHR ₃ ;-
( _CH2 ) _nCOOR4 ;−− _COR4 ; _−NHCOR4 ;−
NHCOOR ₄ ; [Formula] [Formula] [Formula] [Formula] or −OR ₇ . Further, R ₃ represents hydrogen, methyl or phenyl, and R ₄ represents C _1-4 alkyl. One of R ₅ and R ₆ represents hydrogen or C _1-4 alkyl, and the other represents C _1-4 alkyl. Furthermore, R ₇ has at least three or more hydrogens replaced by fluorine.
_C2-9 alkyl, m represents 0, 1 or 2, and n represents 0, 1, 2 or 3; ] An anthraquinone compound represented by 2 formula () [Formula [], X is amino or hydroxy, Y
represents hydrogen. Also, R ₁ is hydrogen, fluorine, chlorine,
cyano, methyl, ethyl, methoxy or ethoxy; R ₂ is hydrogen; fluorine; chlorine; bromine; cyano;
trifluoromethyl; _C1 - _C12 alkyl or alkoxy optionally substituted with cyclohexyl, cyclohexyloxy, phenyl, phenoxy (in which the carbon chain may be interrupted by 1 to 3 oxygen atoms); −(C ₂ H ₄ O) mCH ₂ CH=
CHR ₃ ;-O(C ₂ H ₄ O)mCH ₂ CH=CHR ₃ ;-
( _CH2 ) _nCOOR4 ; _−COR4 ; _−NHCOR4 ;−
NHCOOR ₄ ; [Formula] [Formula] [Formula] [Formula] or −OR ₇ . Further, R ₃ represents hydrogen, methyl or phenyl, and R ₄ represents C _1-4 alkyl. One of R ₅ and R ₆ represents hydrogen or C _1-4 alkyl, and the other represents C _1-4 alkyl. Furthermore, R ₇ is C _{2 to 9} in which at least three or more hydrogens are substituted with fluorine.
alkyl, m is 0, 1 or 2, n is 0,
Represents 1, 2 or 3. A liquid crystal composition containing one or more anthraquinone compounds represented by the following.