JPS6289640A - Method for producing 1,4,4a,9a-tetrahydroanthraquinone - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for purifying crude 1,4-naphthoquinone obtained by catalytic vapor phase oxidation of naphthalene, and more specifically, relates to a method for purifying crude 1,4-naphthoquinone obtained by catalytic vapor phase oxidation of naphthalene. 1,4.4a,9a-tetrahydroanthraquinone (hereinafter referred to as THAQ) obtained by the Diels-Alder reaction of 1,4-naphthoquinone (hereinafter referred to as NQ) and 1,3-butadiene (hereinafter referred to as BD). The present invention relates to a method for purifying NQ used as a raw material in producing NQ (abbreviated).

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] T) IAQ 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 is washed and captured, hot NQ is extracted from the resulting NQ-containing aqueous slurry using an aromatic hydrocarbon, and the resulting NQ solution is used as is. It is convenient to subject it to the following Diels-Alder reaction. Next, a convenient 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, when the present inventors cooled the Diels-Alder reaction liquid obtained using industrial grade NQ and filtered the slurry obtained by crystallization, the filtration was extremely difficult, and the obtained product contained many impurities and the purity of THAQ was low.

[Means for Solving the Problem 1] As a result of intensive research into the causes of difficulty in filtration, the present inventors found that when the obtained reaction mixture is cooled and crystallized, T
It was found that in addition to relatively large crystals of HAQ, a small number of fine crystals were formed, which made filtration and washing difficult and increased the impurity content in the filter cake. Furthermore, as a result of investigating the cause of the fine crystals that inhibit the above-mentioned filtration, it was found that the fine crystals are 1,4-dihydroanthrahydroquinone (hereinafter abbreviated as DHAHQ) and 1.4-
It was determined that it was quinhydrone with dihydroanthraquinone (abbreviated as DHAQ). This quinhydrone.

DHAHQ, which is formed by isomerization of THAQ, and this DHA
It was discovered that HQ is further produced by reaction with DHAQ, which is produced by oxidation with an oxidizing agent such as NQ during the Diels-Alder reaction.In order to suppress the production of quinhydrone, it is necessary to suppress the isomerization reaction present in NQ. It became clear that the acid component that acts as a catalyst 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. They discovered that phthalic acid (which becomes phthalic acid) was included in the process, and investigated ways to remove these acid components.

As a result, it was found that a simple method of contacting an aromatic hydrocarbon solution of NQ with hot water of 60°C or more twice or more can remove filth and significantly improve filtration performance in the next process. Completed the invention.

That is, the present invention provides a method for purifying NQ used when producing THAQ by subjecting NQ and BD to a Diels-Argoux reaction, in which reaction product residue produced by catalytic gas phase oxidation of naphthalene is collected by washing with water. Hot N treatment using aromatic hydrocarbons from an aqueous slurry containing NQ and phthalic acid.
This is a method for purifying NQ, which is characterized by extracting Q and bringing the obtained NQ solution into contact with hot water of 60° C. or higher twice or more to remove the liquor.

The raw material NQ 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, it is obtained by washing and collecting the reaction product gas, and extracting NQ from the resulting aqueous slurry containing NQ and phthalic acid using an organic solvent. The organic solvent to be used is inert to NQ, BD and THAQ produced in the next step, NQ and THAQ have high solubility in the solvent, and the organic solvent is at a temperature of 90°C or less under normal pressure or reduced pressure. 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 aromatic hydrocarbon solution of NQ obtained in this way generally contains acid components generated by polycondensation such as phthalic acid, benzoic acid, phthalic anhydride, and NQ.
However, as mentioned above, THAQ isomerizes to DMAHQ in the presence of acid at elevated temperatures. Figure 2 shows the TH
The acid content in AQ is increased by isomerization of THAQ to DHAHQ.
1 is a graph depicting the effect of acid content in THAQ on the rate of production of THAQ, showing that the rate of this isomerization reaction is proportional to the content of the acid component. D) When IAHQ is produced, it is easily oxidized to DHAQ to produce a quinhydrone composition with DHAHQ, and after the Diels Φ Alder reaction in the next step, Il! make it difficult to pass. Therefore, in order to facilitate filtration after the Diels-Alder reaction, it is necessary to remove this acid component below a certain limit. As a result of research, it was found that the limit is 0.1z or less.

As a treatment method for removing this acid component, use 0.1 to 0.3 times the amount of warm water per solution, preferably about 0.2 times the amount of warm water, and wash with strong stirring, for example, using a mixer/settler system. Temperature: 60°C or higher, preferably 60-90°C, washing time or average residence time: 5 minutes or more, preferably 10-30°C
It may be necessary to wash at least two times per minute. FIG. 1 is a graph showing the influence of cleaning time on acid (phthalic acid and phthalic anhydride) removal in the case of hot NQ solution hot water cleaning and the acid removal effect of two-stage cleaning. However, in the symbols in Figure 1, ■ indicates the first stage of cleaning, ■ indicates that the second stage of cleaning was performed with fresh hot water, and A
and B indicate that the cleaning temperatures were 60°C and 60°C. 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 large, the removal of acid components is insufficient in one washing, and two or more washings are essential.

Furthermore, if necessary, it is further advantageous to perform NQ hot solution cleaning using a weakly basic aqueous solution such as a sodium bicarbonate aqueous solution as the cleaning water.

NQ and BD after the above treatment obtained by the method of the present invention
The Diels Φ Alder reaction with NQ is generally 20-40% NQ concentration in aromatic solvent and 2.0% NQ in aromatic solvent.
The reaction is carried out according to a known method under the reaction conditions of ~2.5 moles of BD, a reaction temperature of 110 to 120°C, and a reaction time of 2.0 to 3.5 hours.

After the above reaction is completed, excess BD present in the reaction solution 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 BD, and the vaporized gas is cooled and liquefied to produce B[l
Collect.

The reaction solution after BD removal is concentrated at a temperature of 30°C or lower if necessary, adjusted to a THAQ concentration of 55 to B5 weight 2, and then cooled to 10°C or higher, preferably 30 to 50°C, to remove THAQ. Let it crystallize. It is not preferable to lower the cooling temperature to 10° C. or lower because the purity of the THAQ obtained decreases. The crystallized THAQ crystals are separated by known separation means such as filtration or centrifugation, and are separated by approximately 0.0% based on the amount of cake.
Wash with 1 to 0.3 times the amount of solvent and dry to obtain THAQ crystals.

When NQ purified by the method of the present invention is used, 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 THAQ
The amount of filtrate removed from the system is determined by considering the quality of the filtrate.

[Action and Effect 1 According to the present invention, the aromatic hydrocarbon solution of NQ is heated at 60°C.
The simple operation of contacting the BD with hot water two or more times has the effect of suppressing side reactions during the Diels-Alder reaction of BD, making it easier to process the resulting THAQ crystals, and increasing their purity. . Although its effect is not clear, two steps of hot water washing are necessary to reduce the content of acid components. According to the present invention, highly pure NQ can be easily obtained and can be used to advantageously produce highly pure THAQ.

Furthermore, since there are few acid components and side-reactants resulting therefrom in the reaction solution, there is little accumulation of impurities due to recirculation of the reaction solution, and the amount removed from the system during recirculation can be reduced.

[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 The gas produced by the catalytic gas-phase oxidation reaction of naphthalene was collected by washing with water,
Ortho-xylene was added to the obtained aqueous slurry containing NQ, and NQ was extracted at about 60°C by heating.
% solution using 0.2 part of warm water per 1 part by weight of 60% solution.
The mixture was mixed at .degree. C. for 15 minutes with strong stirring, left to stand at the same temperature for 10 minutes, and the aqueous phase was separated, followed by the same washing operation using an additional 0.2 part of warm water.

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

The hot NQ solution was concentrated under reduced pressure to an NQ concentration of 40%, and 100 parts of the concentrated solution and 33 parts of B[] were charged into an autoclave and subjected to Diels Alder reaction at a reaction temperature of 120° C. for 2.5 hours. After the reaction was completed, the pressure of excess BD was released, and the butadiene was stripped for 30 minutes by blowing in nitrogen gas while keeping the liquid temperature at 110°C and stirring. The resulting reaction solution contained 51.7 parts of THAQ and DHAQt,
Part a was included.

The reaction solution was mixed with hydroanthraquinones (THAQ) under reduced pressure.
+DHAQ+DHAHQ) Concentration 8o$! te shrinks,'
73°C and cooled from 60°C to 45°C in about 1 hour.
HAQ was crystallized. The crystallized crystals were filtered off using a Nutsche, and the filter cake was then washed on the Metsche using 4 parts of oxoxylene to obtain a wet cake with an oil content of 22%. The cake was dried under reduced pressure to obtain 22.0 parts of THAQ. The crystals were analyzed by high performance liquid chromatography (4J), and the results showed that THAQ was 94$, DHAQ was 4g, anthraquinone was 0.5%, and impurities were 1.5z.

COMPARATIVE EXAMPLE Washing was carried out only once using 0.3 part of hot NQ solution obtained in the same manner as in Example in hot water. The resulting hot NQ solution contained 0.12% phthalic acid, 0.15% phthalic anhydride, and 0.03% benzoic acid based on NQ. The N
A Diels-Alder reaction was carried out according to the example using a Q warm solution, and after the reaction was completed, excess HD was removed, the mixture was cooled in the same manner as in the example, and the crystals that crystallized were filtered through a Nutsche filter.
Filtration was extremely difficult compared to the case of Example, and the filtration time was about 10 times longer. The oil content of the cake obtained by washing the obtained filter cake with 4 parts of ortho-xylene was 451.
The analysis results of 22.4 parts of black-purple crystals obtained by drying the cake were: THAQ 85%, DHAQ
11%, 77 traquinone IL impurity 3t.

[Brief explanation of drawings]

Figure 1 is a graph showing the influence of cleaning time on the removal of acids (phthalic acid and phthalic anhydride) and the acid removal effect of two-stage cleaning when cleaning with hot NQ solution in hot water. So, ■ is the first stage of cleaning, ■
indicates that a second stage of washing was subsequently performed with fresh hot water, and A and B indicate that the washing temperatures were 60°C and 60°C. FIG. 2 is a graph depicting the effect of acid content in THAQ on the rate at which THAQ isomerizes to form DHAHQ.

Claims (1)

[Claims] (1) 1,4,4a,9a-
1, used when producing tetrahydroanthraquinone
In the method for purifying 4-naphthoquinone, reaction product gas generated by catalytic gas phase oxidation of naphthalene is collected by washing with water,
1,4-naphthoquinone is extracted from the obtained aqueous slurry containing 1,4-naphthoquinone and phthalic acid using an aromatic hydrocarbon, and the obtained 1,4-naphthoquinone solution is infused with hot water at 60°C or higher. 1. A method for purifying 1,4-naphthoquinone, the method comprising removing acid content by bringing it into contact with 1,4-naphthoquinone twice or more.