JPS6346060B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for producing 1,4,4a,9a-tetrahydroanthraquinone, and more specifically, the present invention relates to a method for producing 1,4,4a,9a-tetrahydroanthraquinone. 1,4,4a,9a-tetrahydroanthraquinone (hereinafter abbreviated as THAQ) obtained by the Diels-Alder reaction of 1,3-butadiene (hereinafter abbreviated as NQ) and 1,3-butadiene (hereinafter abbreviated as BD)
The present invention relates to a method for manufacturing.

THAQ is not only important as a raw material for anthraquinone, anthraquinone derivatives such as 1-aminoanthraquinone and 2-aminoanthraquinone, benzanthrone and anthrone, but also has recently attracted attention as a cooking aid for alkaline pulp.

[Prior Art] THAQ is generally produced by a Diels-Alder reaction between NQ obtained by oxidation of naphthalene and BD, and this reaction is usually carried out in an organic solvent. Therefore, the reaction product gas generated by catalytic gas-phase oxidation of naphthalene was washed and captured, and hot NQ was extracted from the resulting aqueous slurry containing NQ using an aromatic hydrocarbon.
It is convenient to subject the NQ solution directly to the next Diels-Alder reaction. Next, a simple method for separating THAQ from the reaction solution is to cool the reaction solution and separate the crystallized THAQ crystals by means such as filtration.

[Problems to be solved by the invention] However, the present inventors have developed an industrial-grade NQ.
When attempting to produce THAQ by conducting the Dale-Salder reaction with BD using NQ, isomerization of THAQ occurs due to the trace amount of acid contained in NQ, and the resulting isomer, 1,4- The raw material NQ was reduced by dihydroanthrahydroquinone to generate naphthohydroquinone that did not react with BD, resulting in a decrease in the yield of THAQ and the like, and also promoted the production of impurities as by-products. Furthermore, the generated THAQ
In the case of separating the product itself as crystals, the Diels-Alder reaction solution obtained in the above reaction was cooled and the slurry obtained by crystallization was filtered, but the filtration was extremely difficult, and the obtained product contained many impurities, and the purity of THAQ was low.

[Means for solving the problem] As a result of intensive research into the causes of difficulty in filtration, the present inventors found that when the obtained reaction mixture was cooled and crystallized, other than relatively large crystals of THAQ It was found that a small number of fine crystals were formed, which made filtration and washing difficult and increased the content of impurities in the filter cake. Furthermore, as a result of investigating the cause of the microcrystals that inhibit the filtration, the microcrystals are composed of 1,4-dihydroanthrahydroquinone (hereinafter abbreviated as DHAHQ) and 1,4-dihydroanthrahydroquinone (hereinafter abbreviated as DHAHQ).
4-dihydroanthraquinone (abbreviated as DHAQ)
It was determined that it was quinhydrone. This quinhydrone is produced by isomerization of THAQ.
They discovered that DHAHQ is produced by the reaction between DHAHQ and DHAQ, which is further oxidized by an oxidizing agent such as NQ during the Diels-Alder reaction.In order to suppress the production of quinhydrone, it is necessary to It was revealed that the acid component that catalyzes the isomerization reaction must be removed. The present inventors have discovered that in addition to phthalic acid and benzoic acid, quinone-based acidic components and phthalic anhydride (which is hydrated in a later process) are present in industrial-grade NQ produced by catalytic gas-phase oxidation of naphthalene. found that it contains phthalic acid).
We investigated methods to remove these acid components. As a result, the acid content was removed by a simple method of contacting the aromatic hydrocarbon solution of NQ with hot water of 60°C or more twice or more, and the filterability in the next step was significantly improved. It was found that the yield of the AQ skeleton compound contained therein was also improved, and the present invention was completed.

That is, the present invention collects the reaction product gas produced by catalytic gas phase oxidation of naphthalene by washing with water.
A 1,4-naphthoquinone solution obtained by hot extraction using an aromatic hydrocarbon from an aqueous slurry containing NQ is reacted with 1,3-butadiene to produce 1,4,4a,9a-tetrahydroanthraquinone. In the method for producing 1,4-naphthoquinone solution obtained by hot extraction, 60
After coming into contact with hot water over ℃ twice or more, 1,3
- 1, characterized in that it is reacted with butadiene;
This is a method for producing 4,4a,9a-tetrahydroanthraquinone.

The NQ solution used in the present invention is obtained by a known separation method from the reaction product gas obtained by catalytic gas phase oxidation of naphthalene. That is, the reaction product gas is collected by washing with water, and the resulting aqueous slurry containing NQ and phthalic acid is processed using an organic solvent.
Obtained by extracting NQ.

The organic solvent used is inert to NQ, BD, and THAQ produced in the next step, and NQ and THAQ have high solubility in the solvent, and the organic solvent used is at a temperature of 90°C or less under normal pressure or reduced pressure. A solvent that can be distilled off is preferred. Such solvents include aromatic hydrocarbons such as benzene, toluene, and xylene. The amount of aromatic hydrocarbon solvent to be used is appropriately determined in consideration of the solubility of NQ and THAQ.

The NQ aromatic hydrocarbon solution obtained in this way generally contains 1 to 5% of acid components generated by polycondensation such as phthalic acid, benzoic acid, phthalic anhydride, and NQ. However, as mentioned above, THAQ does not react well in the presence of acid at high temperatures.
Isomerizes to DHAHQ. Figure 2 is a graph showing the influence of the acid content in THAQ on the rate at which THAQ isomerizes to form DHAHQ. It shows that it is proportional.

When DHAHQ is produced, it is easily oxidized to DHAQ to form a quinhydrone composition with DHAHQ, making filtration difficult after the Diels-Alder reaction. Therefore, in order to facilitate filtration after the Diels-Alder reaction, it is necessary to remove this acid component below a certain limit. Research has shown that the limit is less than 0.1%.

As a treatment method for removing this acid component, use 0.1 to 0.3 times, preferably about 0.2 times the amount of hot water per solution, and use strong stirring, for example, a mixer-settler method, at a washing temperature of 60°C or higher, preferably 60-90
℃, the washing time or average residence time is 5 minutes or more,
It is necessary to wash at least twice, preferably for 10 to 30 minutes.

Figure 1 shows the cleaning time for acids (phthalic acid and phthalic anhydride) when cleaning NQ solution with hot water.
2 is a graph showing the effect of acid removal on acid removal and the effect of two-stage washing on acid removal. However, the symbols in Figure 1 indicate that the first stage of cleaning was followed by the second stage of cleaning with fresh hot water, and A and B indicate that the cleaning temperature was 80°C and 90°C. It shows that there is.

As can be seen from FIG. 1, one-time washing is insufficient to remove acid components. In addition, even if the amount of water used is increased in one washing, the removal of acid components is insufficient, and two or more washings are essential.

It is also possible to wash the NQ solution using a weakly basic aqueous solution such as sodium hydrogen carbonate aqueous solution, which is conventionally used in NQ purification methods, as the washing water, but it is possible to wash the NQ solution using a resin in the separation layer between the washing water and the NQ solution. A substance may be formed.

After the above treatment obtained by the method of the present invention
The Diels-Alder reaction between NQ and BD is generally performed at an NQ concentration of 20-40% in an aromatic solvent.
2.0 to 2.5 times mole BD to NQ, reaction temperature 110
The reaction is carried out according to known methods under reaction conditions of ~120°C and reaction time of 2.0 to 3.5 hours.

After the above reaction is completed, the excess amount present in the reaction solution is
BD is removed by stripping. That is,
An inert gas, such as water vapor or nitrogen, is introduced into the heated reaction solution while stirring to drive out the BD, and the vaporized gas is cooled and liquefied to recover the BD.

The reaction solution after BD removal is concentrated at a temperature of 90°C or lower, if necessary, to adjust the THAQ concentration to 55 to 65% by weight, and then heated to a temperature of 10°C or higher, preferably 30 to 50°C.
Cool to crystallize THAQ. Cooling temperature 10
It is not preferable to lower the temperature below 0.degree. C. because the purity of the THAQ obtained will decrease. The crystallized THAQ crystals are separated by known separation means such as filtration or centrifugation, washed with a solvent in an amount of about 0.1 to 0.3 times the amount of cake, and dried to obtain THAQ crystals.

When using the NQ solution treated by the method of the present invention, the amount recovered as THAQ in one step is about 40% of the amount of THAQ in the reaction solution before crystallization. Therefore, in order to improve the recovery rate of the crystallized crystals, a method is adopted in which the filtrate after separation is recycled to the next reaction solution. In this case, the amount of filtrate removed from the system is determined by considering the quality of THAQ.

[Operation and Effect] According to the present invention, an aromatic hydrocarbon solution of NQ is
A simple operation of contacting with hot water of 60℃ or more twice or more suppresses side reactions during the Diels-Alder reaction with BD, facilitates filtration of the resulting THAQ crystals, and increases its purity. effective. Although its effect is not clear, two stages of hot water washing are necessary to reduce the content of acid components. According to the present invention, acid components are reduced.
An NQ solution is obtained, which can advantageously be used directly to produce high purity THAQ.

In addition, since the acid component in the reaction solution in the Diels-Alder reaction and the resulting side reaction products are small, there is less accumulation of impurities due to recirculation of the reaction solution, and the amount removed from the system during recirculation can be reduced. , the yield of THAQ is also improved.

The THAQ product liquid obtained according to the present invention can be extracted as a 9,10-dihydroxyanthraquinone-disodium salt aqueous solution by contacting it with an aqueous caustic alkali solution such as an aqueous sodium hydroxide solution, and then extracted by a conventional method. By air oxidation, anthraquinone can be produced in good yield.

[Example] Hereinafter, the method of the present invention will be specifically explained with reference to Examples. "Parts" and "%" used in the examples represent parts by weight and % by weight unless otherwise specified.

Example A 20% solution of NQ obtained by washing and collecting the product gas from the catalytic gas-phase oxidation reaction of naphthalene, adding ortho-xylene to the resulting aqueous slurry containing NQ, and extracting NQ by heating at approximately 90°C. were mixed at 80°C for 15 minutes with strong stirring using 0.2 parts of hot water per 1 part by weight,
After standing at the same temperature for 10 minutes to separate the aqueous phase, the same washing operation was performed using 0.2 parts of warm water.

The resulting NQ solution contained 0.01% phthalic acid and 0.03% benzoic acid based on NQ.

The NQ solution was concentrated under reduced pressure to an NQ concentration of 40%, 100 parts of the concentrated solution and 33 parts of BD were charged into an autoclave, and a Diels-Alder reaction was carried out at a reaction temperature of 120° C. for 2.5 hours. After the reaction is complete, excess BD
After releasing the pressure, the liquid temperature was maintained at 110°C, nitrogen gas was blown in while stirring, and butadiene was stripped for 30 minutes.

The resulting reaction solution contained 51.7 parts of THAQ and
Contained 1.8 parts of DHAQ. The yield per NQ is
THAQ is 96.4 mol% and DHAQ is 3.4 mol%, so the yield of anthraquinone skeleton compound is
It was 99.8 mol%.

The reaction solution was concentrated under reduced pressure to a hydroanthraquinone (THAQ+DHAQ+DHAHQ) concentration of 60%, and then cooled from 80°C to 45°C over about 1 hour to crystallize THAQ. The crystals that have crystallized are filtered off using a nutsie, and the filter cake is then washed on the nutsie using 4 parts of ortho-xylene.
A wet cake with an oil content of 22% was obtained. The cake was dried under reduced pressure to obtain 22.0 parts of THAQ. As a result of analyzing the crystals by high performance liquid chromatography,
THAQ94%, DHAQ4%, anthraquinone 0.5%,
The impurity was 1.5%.

Comparative Example An NQ solution obtained in the same manner as in the example was washed only once using 0.3 part of warm water. The resulting NQ solution contained 0.12% phthalic acid, 0.15% phthalic anhydride, and 0.03% benzoic acid based on NQ. A Diels-Alder reaction was carried out using the NQ solution according to the example, and after the reaction was completed, BD was removed in the same manner as in the example.

When the obtained reaction solution was analyzed, THAQ and DHAQ in the reaction solution were 48.8 parts and 3.4 parts, respectively.
The yield per NQ is 90.9 mol% for THAQ and 90.9 mol% for DHAQ.
The yield of anthraquinone skeleton compound was 97.2 mol%.

The reaction solution was cooled and crystallized in the same manner as in the example. The crystals that formed were filtered through Nutsuchie,
Filtration is extremely difficult compared to the case of the example, and approximately
It took 10 times more filtration time. The oil content of the cake obtained by washing the obtained filter cake with 4 parts of ortho-xylene was 45%, and the analysis results of 22.4 parts of black-purple crystals obtained by drying the cake were as follows.
THAQ85%, DHAQ11%, anthraquinone 1%,
It contained 3% impurities.

[Brief explanation of the drawing]

Figure 1 shows the cleaning time for acids (phthalic acid and phthalic anhydride) when cleaning NQ solution with hot water.
2 is a graph showing the effect of acid removal on acid removal and the effect of two-stage washing on acid removal. The symbols in the figure indicate that the first stage of cleaning was followed by the second stage of cleaning using fresh hot water, and A and B indicate that the cleaning temperature was 80°C and 90°C. There is. Figure 2 shows that the acid content in THAQ is
1 is a graph showing the influence of THAQ on the rate of isomerization to produce DHAHQ.

Claims (1)

[Claims] 1. The reaction product gas generated by catalytic gas phase oxidation of naphthalene was collected by washing with water, and the resulting aqueous slurry containing 1,4-naphthoquinone was subjected to hot extraction using an aromatic hydrocarbon. - In a method for producing 1,4,4a,9a-tetrahydroanthraquinone by subjecting a naphthoquinone solution to a Diels-Alder reaction with 1,3-butadiene, the 1,4-naphthoquinone solution obtained by hot extraction is heated at 60°C or higher. After contact with hot water more than once,
A method for producing 1,4,4a,9a-tetrahydroanthraquinone, which comprises reacting it with 1,3-butadiene.