Method for purifying hydroquinone waste residues

Abstract

The invention discloses a hydroquinone waste residue purification method, which comprises: mixing hydroquinone waste residue with alcohol, heating and stirring for a set time, and carrying out solid-liquid separation to obtain a clarified solution; adding dialkylamine into the clarified solution, heating to 30-80 DEG C, reacting for 1-5 hours, and after the reaction is finished, cooling, crystallizing and carrying out solid-liquid separation to obtain filtrate; and concentrating the filtrate, adding water into the concentrate, heating for dissolving, filtering while hot, cooling and crystallizing the filtrate, carrying out solid-liquid separation, and drying the filter cake to obtain purified hydroquinone. The recovery of hydroquinone in the mother liquor is realized, the purity of the recovered hydroquinone is greater than 99.8%, the individual impurity is less than 0.02%, and the requirements of related substances of medicinal hydroquinone are met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of purification of hydroquinone waste residue, and particularly relates to a purification method of hydroquinone waste residue. BACKGROUND

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] A common production method of hydroquinone is to perform a reduction reaction on p-benzoquinone and sodium pyrosulfite. Since the benzene ring is an electron-rich group, the ortho position is prone to electrophilic substitution sulfonation reaction, so that a large amount of hydroxybenzenesulfonic acid impurities are generated at the same time of generating hydroquinone. As shown in the following formula: .

[0004] The hydroquinone refining mother liquor contains 20% to 30% hydroxybenzenesulfonic acid and 65% to 75% hydroquinone. Due to the strong acidity and chemical stability of hydroxybenzenesulfonic acid, the traditional recovery process is difficult to effectively separate and purify hydroquinone. Currently, two treatment methods are mainly used in industry: one is to treat the mother liquor as waste liquid for harmless treatment, and the other is to form waste residue by evaporation and drying.

[0005] However, the hydroquinone waste liquid and waste residue are harmful to the environment. When the concentration of hydroquinone in the sewage exceeds a certain threshold, it will have a significant inhibitory effect on the microorganisms in the activated sludge. This inhibitory effect is strengthened with the increase of the concentration of hydroquinone. Due to the reduction or loss of microbial activity, the efficiency of sewage treatment will be seriously affected, which will lead to a decrease in water quality and may not meet the environmental emission standards. In the long run, it may have a negative impact on the entire ecological system.

[0006] In addition, as an important pharmaceutical intermediate, hydroquinone has wide application in the fields of antioxidants, developing agents, etc. The price of its pharmaceutical-grade raw material is relatively high. If it cannot be effectively recycled and reused, it will easily cause waste of resources. SUMMARY

[0007] In view of the deficiencies of the prior art, the purpose of the present application is to provide a purification method of hydroquinone waste residue.

[0008] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme: The present application provides a purification method of hydroquinone waste residue, comprising the following steps: Mixing the hydroquinone waste residue with alcohol, heating and stirring for a certain time, solid-liquid separation, and obtaining a clear solution; Adding dialkylamine to the clear solution, heating to 30-80℃, and reacting for 1-5h. After the reaction is completed, cooling and crystallization, solid-liquid separation, and obtaining a filtrate; After the filtrate is concentrated, water is added to the concentrate, heated to dissolve, and filtered while hot. The filtrate is cooled for crystallization, solid-liquid separation is performed, and the filter cake is dried to obtain purified hydroquinone.

[0009] The hydroquinone waste residue is dissolved in alcohol to make the hydroquinone therein soluble in the alcohol, so as to facilitate the removal of non-alcohol soluble impurities by filtering.

[0010] Adding dialkylamine to the clear solution after separation allows hydroxybenzenesulfonic acid to react with dialkylamine to generate dialkylamine hydroxybenzenesulfonate, which facilitates the separation of dialkylamine hydroxybenzenesulfonate and the main component of hydroquinone during cooling and crystallization, thereby improving the purity of hydroquinone.

[0011] In some embodiments, the mass ratio of hydroquinone waste residue to alcohol is 1:5-15, preferably 1:5-10.

[0012] Preferably, after the hydroquinone waste residue is mixed with the alcohol, the heating temperature is 30-80° C., and the heating and stirring time is 0.5-5 h.

[0013] Preferably, the alcohol is ethanol, methanol or isopropanol.

[0014] In some embodiments, the mass ratio of hydroquinone waste residue to dialkylamine is 100:5-15, preferably 100:5-10.

[0015] In some embodiments, the dialkylamine is diethylamine, dipropylamine, dibutylamine or diisopropylamine, preferably diethylamine.

[0016] In some embodiments, the mass ratio of the hydroquinone waste residue to water is 1:3-15.

[0017] Preferably, the mass ratio of the hydroquinone waste residue to water is 1:3-10.

[0018] In some embodiments, the filter cake is dried by vacuum drying at a temperature of 50-70°C.

[0019] The beneficial effects achieved by one or more embodiments of the present invention are as follows: 1. The present invention realizes the recovery of hydroquinone in the mother liquor by recycling the hydroquinone mother liquor waste residue. The purity of the recovered hydroquinone is greater than 99.8%, and the single impurity is less than 0.02%, which meets the requirements of pharmaceutical hydroquinone-related substances.

[0020] 3. The entire recycling process is conducted under mild conditions, without the use of special reagents or harsh production conditions, meeting the requirements of large-scale production recycling and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The embodiments of the application, and their

[0022] Figure 1 is a liquid chromatogram of the hydroquinone product prepared in Example 1; Figure 2 is a partial enlargement of Figure 1 ; Figure 3 is a liquid chromatogram of the hydroquinone product prepared in Example 2; Figure 4 is a partial enlargement of Figure 3 ; Figure 5 is a liquid chromatogram of the hydroquinone product prepared in Example 3; Figure 6 is a partial enlargement of Figure 5 ; Figure 7 is a liquid chromatogram of the hydroquinone product prepared in Example 4; Figure 8 is a partial enlargement of Figure 7 . DETAILED DESCRIPTION

[0023] It should be noted that the following detailed description is exemplary in nature only, and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0024] The application is further described in connection with the various embodiments.

[0025] Example 1 1) 1 kg of hydroquinone waste residue (waste residue after evaporation of the refined mother liquor) was added to 6 kg of ethanol, heated and stirred at 40°C for 0.5 h, and a clear solution was obtained by filtration.

[0026] 2) 60 g of diethylamine was added to the clear solution, and the reaction was carried out at 40°C for 3 h with stirring. The temperature was lowered to 10°C, and the solution was stirred for 2 h to induce crystallization. The filtrate was concentrated at 40°C under reduced pressure until no liquid flowed out.

[0027] 3) 5 kg of water was added to the remaining concentrate, and the solution was heated and stirred at 40°C for 1 h to dissolve completely. The solution was filtered while hot.

[0028] 4) The obtained filtrate was cooled to 10°C, and the solution was stirred for 3 h to induce crystallization. The solution was filtered.

[0029] 5) The filter cake was dried at 60°C under vacuum for 8 h to obtain 423 g of hydroquinone white solid.

[0030] The purity of the hydroquinone product was detected, and the purity of the hydroquinone product was 99.993% (HPLC), and the maximum single impurity was 0.003%, as shown in Figure 1 and Figure 2 The waste residue recovery rate was 42.3%.

[0031] Example 2 1) 1 kg of hydroquinone waste residue (waste residue after evaporation of the refined mother liquor) was added to 5 kg of methanol, heated and stirred at 70°C for 1 h, and a clear solution was obtained by filtration.

[0032] 2) 80 g of dibutylamine was added to the clear solution, and the reaction was stirred at 30°C for 4 h. The temperature was lowered to 30°C, and the crystal was separated by stirring for 2 h. The filtrate was concentrated under reduced pressure at 45°C until no liquid flowed out.

[0033] 3) 10 kg of water was added to the remaining concentrate, and the solution was dissolved at 80°C for 0.5 h to fully dissolve. The hot filtrate was filtered.

[0034] 4) The obtained filtrate was cooled to 20°C, and the crystal was separated by stirring for 4 h. The filtrate was filtered.

[0035] 5) The filter cake was vacuum dried at 60°C for 8 h to obtain 387 g of hydroquinone white solid.

[0036] The purity of the hydroquinone product was detected, and the purity of the hydroquinone product was 99.986% (HPLC), and the maximum single impurity was 0.011%, as shown in Figure 3 and Figure 4 The waste residue recovery rate was 38.7%.

[0037] Example 3 1) 1 kg of hydroquinone waste residue (waste residue after evaporation of the refined mother liquor) was added to 10 kg of isopropyl alcohol, heated and stirred at 30°C for 4 h, and a clear solution was obtained by filtration.

[0038] 2) 100 g of diisopropylamine was added to the clear solution, and the reaction was stirred at 70°C for 1 h. The temperature was lowered to 0°C, and the crystal was separated by stirring for 1 h. The filtrate was concentrated under reduced pressure at 50°C until no liquid flowed out.

[0039] 3) 3 kg of water was added to the remaining concentrate, and the solution was dissolved at 60°C for 1 h to fully dissolve. The hot filtrate was filtered.

[0040] 4) The obtained filtrate was cooled to 30°C, and the crystal was separated by stirring for 4 h. The filtrate was filtered.

[0041] 5) The filter cake was vacuum dried at 60°C for 8 h to obtain 396 g of hydroquinone white solid.

[0042] The purity of the hydroquinone product was detected, and the purity of the hydroquinone product was 99.965% (HPLC), and the maximum single impurity was 0.018%, as shown in Figure 5and Figure 6 , the recovery rate of waste residue: 39.6%.

[0043] Example 4 1) 1 kg of hydroquinone waste residue (waste residue after the mother liquor was evaporated to dryness) was added to 8 kg of ethanol, heated and stirred at 50°C for 0.5 h, and a clear solution was obtained by filtration.

[0044] 2) 50 g of dipropylamine was added to the clear solution, and the reaction was stirred at 50°C for 3 h. The temperature was lowered to 15°C, and the crystal was separated by stirring for 2 h. The filtrate was concentrated under reduced pressure at 50°C until no liquid flowed out.

[0045] 3) 8 kg of water was added to the remaining concentrate, heated at 45°C for 1 h to make it fully dissolved, and filtered while hot.

[0046] 4) The obtained filtrate was cooled to 5°C, and the crystal was separated by stirring for 3 h, and filtered.

[0047] 5) The filter cake was dried at 60°C under vacuum for 8 h to obtain 412 g of hydroquinone white solid.

[0048] The purity of the hydroquinone product was detected, and the purity of the hydroquinone product was 99.952% (HPLC), and the maximum single impurity was 0.017%, as shown in Figure 7 and Figure 8 , the recovery rate of waste residue: 41.2%.

[0049] Comparative Example 1 The difference from Example 1 is that the diethylamine in step 2) is replaced by dipentylamine, and the others are the same as Example 1.

[0050] The purity of the recovered hydroquinone product was detected, and the purity of the hydroquinone product was 99.061% (HPLC), and the maximum single impurity was 0.836%, and the recovery rate of waste residue was 28.4%.

[0051] Comparative Example 2 The difference from Example 1 is that the diethylamine in step 2) is replaced by isopropylamine, and the others are the same as Example 1.

[0052] The purity of the recovered hydroquinone product was detected, and the purity of the hydroquinone product was 74.240% (HPLC), and the maximum single impurity was 25.760%, and the recovery rate of waste residue was 17.6%.

[0053] Comparative Example 3 The difference from Example 1 is that the ethanol in step 1) is replaced by tert-butanol, and the others are the same as Example 1.

[0054] The purity of the recovered hydroquinone product was detected, and the purity of the hydroquinone product was 71.465% (HPLC), the maximum single impurity was 28.535%, and the waste residue recovery rate was 11.6%.

[0055] Comparative Example 4 The difference from Example 1 was that the ethanol in step 1) was replaced with n-butanol, and the others were the same as Example 1. No recovered hydroquinone product was obtained.

[0056] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Various modifications and changes can be made by those skilled in the art to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for purifying hydroquinone waste residue, characterized in that: The steps include: The hydroquinone waste residue is mixed with alcohol, heated and stirred for a set time, and the solid and liquid are separated to obtain a clear solution; Add dialkylamine to the clear solution, heat to 30-80°C, react for 1-5 hours, and after the reaction is complete, cool and crystallize, separate the solid and liquid, and obtain a filtrate; After the filtrate is concentrated, water is added to the concentrate, heated to dissolve, and filtered while hot. The filtrate is cooled for crystallization, solid-liquid separation is performed, and the filter cake is dried to obtain purified hydroquinone.

2. The method for purifying hydroquinone waste residue according to claim 1, wherein: The mass ratio of hydroquinone waste residue to alcohol is 1:5-15, preferably 1:5-10.

3. The method for purifying hydroquinone waste residue according to claim 2, wherein: After the hydroquinone waste residue is mixed with alcohol, the heating temperature is 30-80° C. and the heating and stirring time is 0.5-5 hours.

4. The method for purifying hydroquinone waste residue according to claim 1, wherein: The alcohol is ethanol, methanol or isopropanol.

5. The method for purifying hydroquinone waste residue according to claim 1, wherein: The mass ratio of hydroquinone waste residue to dialkylamine is 100:5-15, preferably 100:5-10.

6. The method for purifying hydroquinone waste residue according to claim 5, wherein: The dialkylamine is diethylamine, dipropylamine, dibutylamine or diisopropylamine, preferably diethylamine.

7. The method for purifying hydroquinone waste residue according to claim 1, wherein: The mass ratio of the hydroquinone waste residue to water is 1:3-15.

8. The method for purifying hydroquinone waste residue according to claim 7, wherein: The mass ratio of the hydroquinone waste residue to water is 1:3-10.

9. The method for purifying hydroquinone waste residue according to claim 1, wherein: The filter cake is dried in vacuum.

10. The method for purifying hydroquinone waste residue according to claim 9, wherein: The vacuum drying temperature is 50-70°C.

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