Green treatment method of dimethyl ether mother liquor in production of ae-active ester

Abstract

The application discloses a green treatment method for methyl ether mother liquor in AE-active ester production, which comprises the following steps: (1) acidification: adding concentrated sulfuric acid into the methyl ether mother liquor, stirring and reacting for 20-40 min to obtain reaction liquid A; (2) hydrolysis: adding liquid alkali into the reaction liquid A to perform reflux reaction, and obtaining reaction liquid B after the reaction is completed; (3) distillation and recovery of methanol: distilling the reaction liquid B to distill out dilute methanol generated in the hydrolysis reaction; (4) concentration and recovery of sodium sulfate: concentrating the water solution C after the methanol is distilled out, precipitating white solid, and obtaining sodium sulfate after filtration. The methyl ether mother liquor is harmlessly treated, the pollution of sodium monomethyl sulfate to water is reduced, sodium sulfate is recovered as a byproduct, the obtained sodium sulfate is high in purity and good in color.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of recycling, in particular to a green treatment method of methyl ether mother liquor in AE-active ester production. BACKGROUND

[0002] AE-active ester, 2-methoxyimino-2-(2-amino-4-thiazolyl)-(Z) benzothiazole thioacetate, molecular formula: C 13 H 10 N4O2S3, molecular weight: 350.45, is an important pharmaceutical intermediate, mainly used for the synthesis of cephalosporin drugs; the structural formula is as follows:

[0003]

[0004] At present, acetyl acetate is usually used as raw material to prepare AE-active ester through oximation, methylation, halogenation, cyclization, hydrolysis and condensation steps. Among them, acetyl acetate and sodium nitrite aqueous solution, dilute sulfuric acid undergoes oximation reaction to generate 2-hydroxy oxime acetyl acetate (referred to as oxime compound), which does not undergo separation and directly undergoes methylation reaction. Liquid alkali and dimethyl sulfate are sequentially added to the oximation reaction liquid to perform methylation reaction to generate 2-methoxy imine acetyl acetate (referred to as methylated compound). After the methylation reaction, toluene is usually added for extraction and separation, and after the organic phase is concentrated to recover toluene, the methylated compound undergoes the next step reaction; the water phase is methyl ether mother liquor.

[0005] According to the analysis of the reaction process, there are a large amount of by-products such as sodium sulfate and sodium methyl sulfate in the methyl ether mother liquor, and a small amount of sodium nitrite and other impurities. In patent CN103012312A, after the methylation reaction is completed, the waste water is recovered and discharged directly after the solvent is recovered, but the sodium methyl sulfate has a significant impact on the water body, and the economic value of the by-product sodium sulfate cannot be utilized. Patent CN109721513A reports a recovery process of by-product sodium methyl sulfate in the production process of ammonia thiooxime acid, according to the process description, the obtained sodium methyl sulfate solid inevitably contains a large amount of sodium sulfate, but the two are difficult to separate and have low purity. SUMMARY

[0006] The present application aims to overcome the above technical deficiencies, and provides a green treatment method of methyl ether mother liquor in AE-active ester production, which solves the technical problem of low purity of recovered by-products in the methyl ether mother liquor in the prior art.

[0007] To achieve the above technical purpose, the technical solution provided by the present application is:

[0008] In a first aspect, the present application provides a green treatment method of methyl ether mother liquor in AE-activated ester production, comprising the following steps: (1) acidification: adding concentrated sulfuric acid dropwise into the methyl ether mother liquor, stirring for 20-40 min to obtain reaction liquid A; wherein the methyl ether mother liquor mainly contains sodium methyl sulfate, sodium sulfate and sodium nitrite; (2) hydrolysis: adding liquid alkali into the reaction liquid A to perform reflux reaction, so that the sodium methyl sulfate in the methyl ether mother liquor is hydrolyzed, and reaction liquid B is obtained after the reaction is completed; (3) distillation to recover methanol: distilling the reaction liquid B to distill the dilute methanol generated in the hydrolysis reaction; (4) concentration and sodium sulfate recovery: concentrating the aqueous solution C after the methanol is distilled, and precipitating white solids, and obtaining sodium sulfate after filtration.

[0009] Compared with the prior art, the present application has the following beneficial effects:

[0010] The present application harmless treatment of methyl ether mother liquor, reduce the pollution of sodium monomethyl sulfate to water, recovery of sodium sulfate as by-product. The sodium sulfate obtained by the method of the present application has high purity and good color, and can be used for preparing water glass, glass, enamel, paper pulp, refrigeration mixture and the like, thereby realizing certain economic value. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0012] The present application is aimed at treating the aqueous methyl ether mother liquor generated in the preparation process of AE-activated ester; the specific source is:

[0013] (1) oximation reaction

[0014] A certain amount of sodium nitrite and water solution is added into the oximation reaction kettle, then the feeding amount of ethyl acetoacetate is added and stirred uniformly. At-5-30℃, the proportionally prepared sulfuric acid and water are added into the above system, and the temperature is maintained at-5-30℃ to perform the reaction. After the reaction is completed, the oximation reaction product 2-hydroxyoxime ethyl acetoacetate (abbreviated as oximation product) enters the methylation reaction process; the chemical reaction formula is as follows:

[0015]

[0016] (2) methylation reaction

[0017] The temperature is maintained at-5-30℃, liquid alkali and dimethyl sulfate are added into the reaction kettle after the oximation reaction of the above step is completed, to perform the methylation reaction, and 2-methoxy imine ethyl acetoacetate (abbreviated as methylation product) is generated; the chemical reaction formula is as follows:

[0018]

[0019] After the methylation reaction is completed, a certain amount of toluene is added to perform extraction layering, and after the organic phase is concentrated to recover toluene, it is transferred into a chlorination reaction kettle to perform the next halogenation reaction to prepare the final product, aminothiooxime acid; and the water phase is the dimethyl ether mother liquor to be treated in the application.

[0020] The dimethyl ether mother liquor mainly contains sodium methyl sulfate, sodium sulfate, and sodium nitrite.

[0021] The main treatment steps of the application include the following steps:

[0022] (1) Acidification: drop concentrated sulfuric acid into the dimethyl ether mother liquor, and stir for 20-40 min to obtain reaction liquid A;

[0023] (2) Hydrolysis: add liquid alkali to the reaction liquid A to perform reflux reaction to hydrolyze the sodium methyl sulfate therein, and obtain reaction liquid B after the reaction is completed; the chemical reaction formula is as follows:

[0024] NaMeSO4+NaOH→MeOH+Na2SO4

[0025] (3) Distillation to recover methanol: distill the reaction liquid B to distill dilute methanol, which is used for comprehensive utilization as a byproduct;

[0026] (4) Concentration and sodium sulfate recovery: concentrate the water solution C after the methanol is distilled to obtain water, which is treated in a sewage treatment system; the white solid separated out is filtered to obtain sodium sulfate, which is used as a byproduct for the preparation of water glass, glass, enamel, paper pulp, and refrigeration mixture. The sewage treatment system is relatively common, and as long as the distilled water can be treated, it is not limited here.

[0027] Preferably, in step (1), the volume ratio of the dimethyl ether mother liquor to concentrated sulfuric acid is (50-100):1; further preferably (60-90):1, and more preferably (70-80):1.

[0028] Preferably, in step (1), the stirring reaction temperature is 95-100℃.

[0029] Preferably, in step (1), the stirring reaction time is 20-40 min.

[0030] Preferably, in step (2), the reaction liquid A is cooled to below 80℃ before the liquid alkali is added.

[0031] Preferably, in step (2), the volume ratio of the added liquid alkali to the dimethyl ether mother liquor is 1:(4-6).

[0032] Preferably, in step (2), the reflux reaction is performed at 80-102℃ for 2-3 hours.

[0033] Preferably, in step (3), the distilled dilute methanol has a concentration of 25-30% and a volume of 20-40% of the methanol ether mother liquor; the dilute methanol is collected as a byproduct and recycled.

[0034] Preferably, in step (4), the aqueous solution C is introduced into a double-effect evaporation system for concentration.

[0035] Main mechanism and advantages of the present application:

[0036] In the present application, most of the excess unreacted sodium nitrite can be removed by acidifying the methanol ether mother liquor, thereby avoiding high residual sodium in the final obtained sodium sulfate; after adding sodium hydroxide to the methanol ether mother liquor, dimethyl sulfate and sodium methyl sulfate are hydrolyzed and then concentrated until solid is precipitated, the solid is separated and dried to obtain the byproduct sodium sulfate. The methanol ether mother liquor is harmlessly treated, the pollution of sodium monomethyl sulfate to water is reduced, and sodium sulfate is recycled as a byproduct. The sodium sulfate obtained by the method has high purity and good color, and can be used for the preparation of water glass, glass, porcelain glaze, paper pulp, refrigeration mixture, etc., thereby realizing certain economic value.

[0037] The present application is further described in detail below through specific examples.

[0038] The parameters of the methanol ether mother liquor treated in the following examples and comparative examples are as follows: in each batch of 3000 liters of methanol ether mother liquor, about 804 kilograms of sodium methyl sulfate, 436 kilograms of sodium sulfate and 91 kilograms of sodium nitrite are contained; the equipment used in the present application, such as the recovery kettle, is a conventional equipment.

[0039] Example 1

[0040] 1. Acidification: open the water layer feed valve of the recovery kettle, add 3000 liters of methanol ether mother liquor, open the stirring, drop 40 liters of concentrated sulfuric acid, open the reflux device, open the steam to heat and keep the temperature in the kettle at 100℃, and stir for 30 min to obtain reaction liquid A. During the process, brown-red nitrogen oxide gas is overflowed and should be paid attention to be absorbed by the induced draft tube.

[0041] 2. Hydrolysis: cool the reaction liquid A to below 80℃, open the liquid alkali feed valve, and quantitatively add 600 liters of liquid alkali. Open the steam, heat to 100-102℃, and reflux for 2-3 hours to obtain reaction liquid B.

[0042] 3. Distillation and recovery of methanol: close the reflux device, open the distillation device, and distill reaction liquid B to distill 1000 liters of dilute methanol with a concentration of about 28% as a byproduct for comprehensive utilization.

[0043] 4. Concentration and Sodium Sulfate Recovery: The aqueous solution C after methanol distillation enters a double-effect evaporation system for concentration, and the distilled water enters the wastewater treatment system. The precipitated white solid is filtered to obtain sodium sulfate, which is used as a byproduct in the production of water glass, glass, porcelain enamel, pulp, and refrigeration mixtures.

[0044] On average, each batch of dimethyl ether mother liquor yields 1300 kg of white sodium sulfate solid, with a purity of over 99%.

[0045] Comparative Example 1

[0046] The only difference from Example 1 is that the acidification step in step 1 is omitted, and liquid alkali is directly added to the dimethyl ether mother liquor. The other steps and conditions are the same as in Example 1.

[0047] The results showed that a small amount of sodium nitrite was present in the sodium sulfate solid, resulting in a decrease in purity. Subsequent use would produce a toxic brownish-red nitrogen oxide gas.

[0048] Comparative Example 2

[0049] The only difference from Example 1 is that the cooling step in step 2 is omitted, and liquid alkali is added directly; the other steps and conditions are the same as in Example 1.

[0050] The results showed that the reaction was too violent and affected production safety.

[0051] Comparative Example 3

[0052] The only difference from Example 1 is that step 3, the distillation step, is omitted, and reaction solution B directly enters step 4 for concentration and sodium sulfate recovery; the other steps and conditions are the same as in Example 1.

[0053] The results showed that 25-30% of the dilute methanol could not be recycled, which increased costs.

[0054] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A green process for the treatment of dimethyl ether mother liquor in the production of AE-active esters, characterized by, It consists of the following steps: (1) Acidification: drop methyl ether mother liquor into concentrated sulfuric acid, the volume ratio of methyl ether mother liquor to concentrated sulfuric acid is (50-100):1, stir at 95-100℃ for 20-40min to obtain reaction liquid A; wherein, the methyl ether mother liquor mainly contains sodium methyl sulfate, sodium sulfate and sodium nitrite; (2) Hydrolysis: add liquid alkali to the reaction liquid A cooled to below 80℃, reflux at 80-102℃ for 2-3h to hydrolyze sodium methyl sulfate in the methyl ether mother liquor, and obtain reaction liquid B after reaction; (3) Distillation to recover methanol: distill reaction liquid B to distill the dilute methanol produced in the hydrolysis reaction; (4) Concentration and sodium sulfate recovery: concentrate the aqueous solution C after distilling methanol, precipitate white solid, and obtain sodium sulfate after filtration.

2. The green process for the treatment of methanol mother liquor in the production of AE- active esters according to claim 1, characterized in that, In step (1), the stirring reaction time is 20-30min.

3. The green process for the treatment of dimethyl ether mother liquor in the production of AE- active esters according to claim 1, characterized in that, In step (2), the volume ratio of liquid alkali to methyl ether mother liquor is 1:(4-6).

4. The green process for the treatment of dimethyl ether mother liquor in the production of AE- active esters according to claim 1, characterized in that, In step (3), the concentration of the distilled dilute methanol is 25-30%, and the volume of the distilled dilute methanol is 20-40% of the methyl ether mother liquor; the dilute methanol is recycled.

5. The green process for the treatment of dimethyl ether mother liquor in the production of AE- active esters according to claim 1, characterized in that, In step (4), the aqueous solution C enters a double-effect evaporation system for concentration.

6. The green process for the treatment of dimethyl ether mother liquor in the production of AE- active esters according to claim 1, characterized in that, In step (4), the distilled water from the concentrated aqueous solution C enters a sewage treatment system.

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