JPH10324661A - Production of acetylated substance of polyhydric phenol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject high-purity acetylated substance in high yield even in the presence of a quinone derivative of a polyhydric phenol in a raw material, by acetylating a polyhydric phenol in the presence of a specific compound. SOLUTION: This method for producing an acetylated substance of a polyhydric phenol comprises acetylating at least one polyhydric phenol selected from 2,3,7,8,12,13-hexahydroxytruxene, 2,3,7,8,12,13-hexahydroxy5,10,15- trioxatruxene, hexahydroxybenzene and leucoquinizarin in the presence of a reducing agent. Zinc or magnesium is preferable as the reducing agent and the amount of it used is 0.0002-6 mol based on 100 g of the polyhydric phenol (in the case where a quinone derivative exists, the total amount of the polyhydric phenol and the quinone is 100 g). The acetylating reaction may be carried out in the presence of a tertiary amine such as pyridine or tripropylamine so as to increase the effect of the reducing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a phenol acetylated product which is used as an intermediate in producing a discotic liquid crystal compound useful as a display device. , 8,12,13
The present invention relates to a method for producing an acetylated product of phenol exemplified by hexahydroxyturxene, hexahydroxybenzene and the like.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been widely used in word processors, personal computers, televisions and the like, and a number of liquid crystal compounds have been developed accordingly. Among such liquid crystal compounds, discotic liquid crystal compounds in which the molecules exhibit a disk shape have recently attracted attention. Representative examples of discotic liquid crystal compounds include C. Destrade, Mol. Cryst. Liq. Cryst., 71,
111 (1981) and Takenaka Shunsuke, "Liquid Crystal Chemistry", Chemistry Review, 22, 60 (1994), for example, for example, a tolcene derivative, a triphenylene derivative, an oxytolcene derivative, a benzene derivative, an anthraquinone derivative, and the like. Can be mentioned. These discotic liquid crystal compounds can be said to have utility as optical materials such as display elements, optical elements, and conductive films in view of easy formation of a monodomain discotic nematic phase as a molecular orientation. . However, in order to utilize a discotic liquid crystal compound as an optical material, it is important to obtain it with high purity. This is because the performance of the display element, optical element, conductive film, etc. is affected by the purity of the liquid crystal compound used for it, for example, a compensation film of a liquid crystal display which is required to have no absorption of light. This is because, when a discotic liquid crystal compound is used as a material, if an impurity is contained in the discotic liquid crystal compound, it absorbs on the short wavelength side in the visible light region.

[0003] Discotic liquid crystal compounds exemplified by a tolcene derivative, a triphenylene derivative, an oxyturcene derivative, a benzene derivative, an anthraquinone derivative, and the like have a mother nucleus composed of tolcene, triphenylene, oxyturcene, benzene, anthraquinone, and the like. It has a structure in which side chains such as an alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially bonded to the straight chain by an ester bond. A compound having such a structure is obtained by first acetylating the hydroxyl group of a polyhydric phenol having a plurality of hydroxyl groups bonded to a skeleton of, for example, tolcene, triphenylene, oxytolcene, benzene, and anthraquinone. Reacting the resulting acetylated product with, for example, a carboxylic acid,
It can be produced by a deacetic acid reaction between an acetyl group and a carboxyl group. Therefore, one method of obtaining a high-purity discotic liquid crystal compound is to obtain, with high purity, an acetylated product of polyhydric phenol which is a raw material of the deacetic acid reaction, and obtain the acetylated product with high purity. For this purpose, a high-purity polyhydric phenol is used as the starting material. However, polyhydric phenols to be acetylated generally lack oxidative stability, hydroxyl groups are easily oxidized to form quinones, and even if polyphenols do not contain quinones, When acetylation is carried out as usual, quinones of polyhydric phenols are easily produced as by-products, and it is difficult to obtain high-purity acetylated products.

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, one of the objects of the present invention is to convert an acetylated polyhydric phenol which can be used as a raw material for producing a discotic liquid crystal compound to a quinone derivative of the polyhydric phenol. It is to produce with high purity without by-product.

[0005]

Means for Solving the Problems As a result of diligent studies, the present inventors have found that if acetylation of polyhydric phenol is carried out in the presence of a reducing agent, the quinone compound coexists in the raw material polyhydric phenol. It was found that high-purity acetylated product was obtained irrespective of whether or not the acetylated product was obtained. Therefore, one of the methods for producing the polyphenol acetylated product according to the present invention is:
Selected from 2,3,7,8,12,13-hexahydroxytorxcene, 2,3,7,8,12,13-hexahydroxy-5,10,15-trioxaturxen, hexahydroxybenzene and leucoquinizarin Acetylating at least one polyhydric phenol in the presence of a reducing agent;
7,8,12,13-hexahydroxyturquscene,
2,3,7,8,12,13-hexahydroxy-5,
It is characterized in that a mixture of at least one polyhydric phenol selected from 10,15-trioxatruxene, hexahydroxybenzene and leucoquinizarin and its quinone is acetylated in the presence of a reducing agent. In the present invention, the quinone compound means a compound in which one or more of the hydroxyl groups of the polyhydric phenol is oxidized, and when these compounds coexist in the raw material polyhydric phenol, the According to the method of the present invention, even if a by-product is produced during the acetylation reaction of the present invention, it can be reduced and converted to an acetylated polyhydric phenol.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a commercially available reagent can be used as a polyhydric phenol as a starting material, but a polyhydric phenol synthesized separately can also be used. One method of synthesizing polyhydric phenol is
A method of dealkylating an alkoxy compound corresponding to a polyhydric phenol in the presence of boron tribromide or hydrogen bromide,
For example, 2,3,7,8,12,13-hexahydroxyturqusene can be synthesized by the following procedure. 3- (3,4-dialkoxyphenyl)-in the presence of an acid catalyst
An intramolecular alkylation reaction is caused in propionic acid to prepare dialkoxyindanone, and then the dialkoxyindanone is subjected to aldol condensation in a polyphosphate to obtain a trimer of dialkoxyindanone, 2,3,7. ,
8,12,13-Hexaalkoxyoxytolcene is prepared and then dealkylated in the presence of boron tribromide or hydrogen bromide to give 2,3,7,
It is possible to obtain 8,12,13-hexahydroxyturqusene. In the present invention, even when a commercially available polyphenol is used as a polyhydric phenol or when a polyhydric phenol prepared separately is used, the polyhydric phenol containing a quinone derivative can be directly used without removing the quinone derivative contained therein. It can be used as a starting material for the invention.

In the present invention, acetyl chloride, acetylketene, ketene N-acetylimidazole, acetic anhydride and the like can be arbitrarily used as the acetylating agent. Among these, acetic anhydride is preferably used as the acetylating agent because a solvent is not required and acetic acid produced as a by-product is easily removed. The amount of the acetylating agent used is adjusted according to the type of the polyhydric phenol used as the starting material. For example, when the polyhydric phenol is hexahydroxyturxene, hexahydroxytrioxaturcene or leucoquinizarin, Polyphenol 100
g (when the quinone compound is present in the polyhydric phenol, the total amount of the polyhydric phenol and the quinone compound is 100 g).
The acetylating agent is usually used in an amount of 1 to 400 mol, preferably 1 to 7 mol.
0 mol, more preferably 1 to 20 mol is used. In the case of hexahydroxybenzene, the acetylating agent is usually used in an amount of 2 to 600 mol, preferably 2 to 120 mol per 100 g of hexahydroxybenzene (or 100 g including the quinone when a quinone is present). Mole,
More preferably 2 to 30 moles of acetylating agent are used. If the amount of the acetylating agent is less than the above range, the acetylation may be insufficient. If the amount is more than the above range, the treatment after the acetylation reaction becomes complicated, which is not preferable.

As the reducing agent, metals such as zinc, magnesium and aluminum, sodium hydrosulfite, hydrogen sulfide, sulfur dioxide, tin (II) chloride, hydrogen, formic acid, ascorbic acid and the like can be used. Zinc and magnesium are preferred from the viewpoint of simplicity of treatment and high reducing power. When the polyhydric phenol to be acetylated is hexahydroxyturxene, hexahydroxytrioxatolcene or leucoquinizarin, the amount of the reducing agent used is 100 g of the polyhydric phenol (when the quinone compound is present in the polyhydric phenol). Is usually 0.0002 to 6 mol, preferably 0.002 to 2 mol, per 100 g of the total amount of the polyhydric phenol and the quinone compound.
Mol, more preferably 0.01 to 1 mol. When the polyhydric phenol to be acetylated is hexahydroxybenzene, 100 g of hexahydroxybenzene is used.
(In the case where a quinone compound is present, 100 g including the quinone compound) is usually 0.0005 to 15 mol, preferably 0.005 to 5 mol, more preferably 0.03 mol.
３3 mol, most preferably 0.5-1.5 mol of reducing agent are used. When the amount of the reducing agent used is less than the above range, quinones of the polyhydric phenol may be by-produced during acetylation of the polyhydric phenol. It is not desirable because it requires.

In the acetylation reaction of the present invention, in order to enhance the effect of the reducing agent, tertiary compounds exemplified by pyridine, tripropylamine, triethylamine, tributylamine, N, N-dimethylaniline, diazabicycloundecene, etc. The amine can coexist in the reaction system. In this case, the amount of the tertiary amine to be used is usually within 5 mol per mol of the reducing agent, preferably 0.2 to 3 mol, more preferably 0.4 to 2 mol, most preferably 0.5 to 1.5 mol.
In the molar range. When the amount exceeds 5 moles, the effect is not particularly changed without extra cost.

The acetylation reaction of the present invention proceeds without a solvent and does not necessarily require a reaction solvent. However, the solvent does not inhibit the acetylation reaction and is soluble in the acetylated product of the polyhydric phenol as the target product. If so, this can be used as needed. Examples of such a reaction solvent include ethyl acetate, toluene, xylene, dimethylformamide, N-methylpyrrolidone, diethyl ether, terahydrofuran, diethylene glycol dimethyl ether (diglyme), 1,4-dioxane, methylene chloride and mixtures thereof. be able to. The acetylation reaction of the present invention is carried out under normal pressure at a temperature of 80 to 1.
Proceeding at 40 ° C., preferably in the range of 120-135 ° C.,
The reaction time is 0.1 to 15 hours, preferably 0.2 to 12 hours.
Hours, more preferably in the range of 0.1 to 1 hour.
After completion of the reaction, the reaction mixture is cooled to room temperature to precipitate an acetylated product, or the reaction mixture is poured into ice water to precipitate an acetylated product, and the precipitate is collected by filtration. When insolubles are mixed in the reaction mixture,
The above reaction mixture is mixed with a suitable solvent such as N-methylpyrrolidone, diethylene glycol dimethyl ether (diglyme), dimethylformamide, dimethylacetamide, dimethylsulfoxide and the like, and the acetylated product is dissolved in the solvent. After cooling the filtrate to precipitate an acetylated product, this is collected by filtration. Subsequently, the acetylated product is washed with acetic anhydride, acetone, methyl ethyl ketone, methanol, or the like, whereby an acetylated product of polyhydric phenol can be obtained usually with a purity of 97% or more. When the acetylated product is hardly soluble in a solvent, impurities such as unreacted raw materials can be removed by washing with a solvent such as diethyl ether, methanol, ethanol, and acetone. Class purity can be increased.

[0011]

According to the method for acetylating polyhydric phenol according to the present invention, acetylated polyhydric phenol can be produced in high yield even if the quinone compound is mixed in the starting polyhydric phenol. From the obtained acetylation reaction mixture, high-purity acetylated polyhydric phenol can be obtained by a relatively simple operation.
Then, the acetylated product of the polyhydric phenol produced by the method of the present invention can be reacted with various carboxylic acids and the like to synthesize a discotic liquid crystal compound. It is extremely useful as a method for producing an intermediate of a discotic liquid crystal compound that can be used as various optical materials such as an element, an optical element, and a conductive film.

[0012]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but these examples do not limit the present invention. Synthesis Example 1 3- (3,4-dimethoxyphenyl) was placed in a 5-liter three-necked flask equipped with a stirrer and a reflux condenser.
300 g of propionic acid and 1500 g of polyphosphoric acid were added and reacted at 65 ° C. for 30 minutes under a nitrogen atmosphere. At the end of the reaction, the reaction mixture is cooled and then added to deionized water 2
000 ml was added slowly. After stirring at room temperature for 2 hours, the mixture was transferred to a 5-liter separating funnel, and chloroform 600 was added.
Extraction was performed in ml. The chloroform extract was washed with a saturated aqueous solution of sodium hydrogen carbonate, dried over anhydrous magnesium sulfate, and filtered. The filtrate was concentrated on a rotary evaporator to give 170 g of 5,6-dimethoxyindanone-1.
I got 170 g of 5,6-dimethoxyindanone-1
And 850 g of ethyl polyphosphate were placed in a 3 liter three-necked flask equipped with a stirrer and a reflux condenser, and reacted at 140 ° C. for 2 hours while stirring under a nitrogen atmosphere. After completion of the reaction, 1 liter of ethanol was gradually added while cooling the flask with ice. After completion of the addition, the mixture was stirred at room temperature for 1 hour, and the precipitate was collected by suction filtration and washed with acetone.
Thereafter, the precipitate was dried in a vacuum dryer at 50 ° C. overnight to obtain 140 g of crude crystals of 2,3,7,8,12,13-hexamethoxytorxene. The obtained crude crystals were recrystallized from dimethylformamide solvent at a recovery of 99%.
In a 1-liter three-necked flask equipped with a stirrer and a reflux condenser containing 400 ml of toluene, recrystallized 2,3,7,
8,12,13-hexamethoxytorxene 40.0 g
Was added and suspended, and 187 g of boron tribromide was gradually added while stirring and cooling with ice. Next, the temperature of the flask was gradually raised from 60 ° C to 120 ° C, and the reaction was performed at 120 ° C for 2 hours. Hydrogen bromide and the like generated during the reaction were absorbed in a trap containing an aqueous alkali solution. After the completion of the reaction, the flask was cooled to room temperature, and 200 ml of methanol was gradually added. At this time, a large amount of hydrogen bromide, methyl bromide, methyl borate and the like generated and recovered were collected by a trap cooled to -78 ° C, an alkali trap or the like. Then, the volatile components were removed at 60 ° C. under a high vacuum to obtain 25.3 g of black crude crystals of 2,3,7,8,12,13-hexahydroxyturquscene. The content of the quinone compound contained in the crude crystals was determined by H-NMR.
As a result of analysis, 17% of the quinone structure was contained. When a part of the obtained crude crystal was left in the air, it was immediately oxidized and generated heat. [Example 1] 250 ml of acetic anhydride, triethylamine 2
5.0 g and 5.0 g of zinc powder were placed in a 1-liter three-necked flask containing the 2,3,7,8,1 obtained in Synthesis Example 1.
14. Crude crystals of 2,13-hexahydroxytorxene
After adding 0 g, the mixture was stirred for 2 hours while heating under reflux. After the reaction was completed, the flask was cooled, the contents were filtered, and the cake was washed with 250 ml of diethyl ether to give 2,2.
21.4 g of crude crystals of 3,7,8,12,13-hexaacetoxytolcene were obtained (purity: 97%). After heating and dissolving the crude crystals in 4000 ml of dimethylacetamide,
Upon cooling, crystals were deposited. The precipitate was filtered, washed with 250 ml of diethyl ether, and dried under reduced pressure to obtain 17.3 g of yellow-white crystals having a purity of 99.5%. This crystal is
According to NMR analysis, there is no quinone structure at all, and since all the hydroxyl groups of the raw material have been substituted with acetyl groups,
It was confirmed to be 2,3,7,8,12,13-hexaacetoxytolcene. The yield was 75%. [Reference Example 1] The 2,3,7,8,1 obtained in Example 1 was placed in a 100 ml three-necked flask equipped with a stirrer and a condenser.
Crystal of 2,13-hexaacetoxy tolcene 17.3
g and 31.7 g of 4-pentyloxybenzoic acid, and 2
The mixture was heated and stirred at 60 ° C. for 6 hours. Acetic acid was distilled off as the reaction progressed, and 37.8 g of 2,3,7,8,12,13-hexa (4-pentyloxybenzoyloxy) tolcene was obtained. When the phase transition temperature of this compound was measured by observation with a polarizing microscope, the crystal phase was −272 ° C.−
Nematic discotic liquid crystal phase-351 ° C. or higher—isotropic phase. [Synthesis Example 2] 2,3,7,8,12,13-hexamethoxy-5,10,15-trioxatorxene 40.0
g, reacted with 283 g of boron tribromide in the same manner as in Example 1, to give 2,3,7,8,12,13-hexahydroxy-
Thus, 38.2 g of a black crude crystal of 5,10,15-trioxatorcene was obtained. H-NMR analysis of the crude crystals revealed that they contained 16% of a quinone compound. Example 2 500 ml of acetic anhydride, 5 of triethylamine
The 2,3,7,8,1 obtained in Synthesis Example 2 was placed in a 2-liter three-necked flask containing 0.0 g and 10.0 g of zinc powder.
After adding 30.0 g of crude crystals of 2,13-hexahydroxy-5,10,15-trioxatorxene, the mixture was stirred under heating and reflux for 2 hours. Then, the flask was cooled, the contents were filtered, and the cake was washed with 500 ml of diethyl ether, whereby crude crystals of 2,3,7,8,12,13-hexaacetoxy-5,10,15-trioxatorxene were obtained. 43.6 g were obtained (purity 97%). The crude crystals were dissolved in 8000 ml of dimethylacetamide by heating, and then cooled to precipitate crystals. The precipitate was collected by filtration, washed with diethyl ether (500 ml), dried under reduced pressure, and yellow-white with a purity of 99.6% 2,3,7,8,12,13-hexaacetoxy-5,10,15-trioxatoluxene. Thus, 35.8 g of a crystal was obtained (purity: 99.7%). 74% yield
Met. Reference Example 2 2,3,7,8,1 obtained in Example 2
Crystals of 2,13-hexaacetoxy-5,10,15-trioxatolcene and 7-heptyloxybenzoic acid were reacted in an equivalent amount. 10 g of the obtained product was dissolved in a 3: 1 mixed solution of triethylene glycol dimethyl ether and hexylene glycol to prepare a 15% solution. The solution was applied on a glass substrate having a rubbing polyimide film. After coating, the solvent was removed, and after heat treatment at 230 ° C., cooling was performed to form a film. When the obtained film was mounted between a driving liquid crystal cell of a twisted nematic liquid crystal display device and a polarizing plate, the viewing angle was greatly improved. Example 3 500 ml of acetic anhydride, triethylamine 5
10 g of tetrahydroxyhydroquinone and 30 g of hexahydroxybenzene were added to a two-liter three-necked flask containing 0.0 g and 20.0 g of zinc powder, and the mixture was stirred under heating and reflux for 2 hours. Thereafter, the flask was cooled, the contents were filtered, and the cake was washed with 100 ml of methanol to give crude crystals of hexaacetoxybenzene.
2 g (97% purity) were obtained. After recrystallization, methanol 1
Wash with 00 ml and dry under reduced pressure to give 25.6 g of white crystals.
(Purity 99.5%). When the crystal was analyzed by H-NMR, absorption due to the quinone structure was not confirmed, and the crystal was found to be hexaacetoxybenzene.
The yield was 70%. [Example 4] 500 ml of acetic anhydride, triethylamine 2
To a 2-liter three-necked flask containing 0.0 g and 5.0 g of granular zinc, 13.1 g of crude crystals of leucoquinizarin was added, and the mixture was stirred under heating and reflux for 2 hours. Thereafter, the flask was cooled, and the content was filtered using a 200-mesh stainless steel wire mesh. The filtrate was concentrated to obtain 18.5 g of crude crystals of tetraacetoxyleucoquinizarin (purity: 96%).
I got After recrystallization, the precipitate was washed with 100 ml of methanol to obtain 15.6 g of white tetraacetoxyleucoquinizarin having a purity of 99.6%.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Komatsu 8 Chidori-cho, Naka-ku, Yokohama City Inside Central Research Laboratory of Japan Petroleum Corporation

Claims (2)

[Claims] 1, 2,3,7,8,12,13-hexahydroxytorxene, 2,3,7,8,12,13-hexahydroxy-5,10,15-trioxatorxen, hexahydroxybenzene And acetylation of at least one polyhydric phenol selected from leucoquinizarin in the presence of a reducing agent. 2. 2,3,7,8,12,13-hexahydroxyturqucene, 2,3,7,8,12,13-hexahydroxy-5,10,15-trioxaturcene, hexahydroxybenzene A process for producing an acetylated product of a polyhydric phenol, comprising acetylating a mixture of at least one polyhydric phenol selected from leucoquinizarin and a quinone thereof in the presence of a reducing agent.