阅读说明：本技术 沉淀法提纯2-氨基-4-乙酰氨基苯甲醚的方法 (Method for purifying 2-amino-4-acetamino anisole by precipitation method ) 是由 黄昊飞 张文淑 张琪 孟华杰 尹磊 张建军 李连伟 李玉超 左村村 傅忠君 王鸣 于 2021-09-13 设计创作，主要内容包括：本发明属于精细化工技术领域,具体涉及一种沉淀法提纯2-氨基-4-乙酰氨基苯甲醚的方法。在2-氨基-4-乙酰氨基苯甲醚生产母液中加入沉淀剂,过滤,得到的沉淀物进行解析,解析后得到水相和有机相,水相经调节pH值、干燥,得到2-氨基-4-乙酰氨基苯甲醚,有机相经蒸馏,得到的有机溶剂回收,得到的沉淀剂可重复使用。本发明采用沉淀法提纯2-氨基-4-乙酰氨基苯甲醚,具有能耗低、反应效率快的优点,能够实现高选择性的目的,得到高纯度和高收率的2-氨基-4-乙酰氨基苯甲醚；且操作简单,具有显著的经济价值和环境效益。(The invention belongs to the technical field of fine chemical engineering, and particularly relates to a method for purifying 2-amino-4-acetamino anisole by a precipitation method. Adding a precipitator into the mother liquor of the 2-amino-4-acetamino anisole production, filtering, resolving the obtained precipitate to obtain a water phase and an organic phase, adjusting the pH value of the water phase, drying to obtain the 2-amino-4-acetamino anisole, distilling the organic phase, recovering the obtained organic solvent, and recycling the obtained precipitator. The method adopts a precipitation method to purify the 2-amino-4-acetamino anisole, has the advantages of low energy consumption and high reaction efficiency, can realize the purpose of high selectivity, and obtains the 2-amino-4-acetamino anisole with high purity and high yield; and the method is simple to operate, and has remarkable economic value and environmental benefit.)

1. A method for purifying 2-amino-4-acetamino anisole by a precipitation method is characterized in that: adding a precipitator into the mother liquor in the production of the 2-amino-4-acetamino anisole, filtering, resolving the obtained precipitate to obtain a water phase and an organic phase, adjusting the pH value of the water phase, and drying to obtain the 2-amino-4-acetamino anisole.

2. The method for purifying 2-amino-4-acetamino anisole by precipitation according to claim 1, characterized in that: the mother liquor for producing the 2-amino-4-acetamino anisole contains 2-amino-4-acetamino anisole and 2, 4-diacetyl aminobenzyl ether; wherein the content of 2-amino-4-acetamino anisole is 93-96 wt.%, and the content of 2, 4-diacetyl amino anisole is 4-7 wt.%.

3. The method for purifying 2-amino-4-acetamino anisole by precipitation according to claim 1, characterized in that: the general formula of the precipitant is:

wherein: r₁、R₂＝-H、-CH₃、-OH、-OCH₃、-Cl、-Br、-NO₂or-NH₂。

4. The method for purifying 2-amino-4-acetamino anisole by precipitation according to claim 1, characterized in that: the molar ratio of the precipitant to the 2-amino-4-acetamino anisole in the mother liquor for producing the 2-amino-4-acetamino anisole is 1-5: 1.

5. The method for purifying 2-amino-4-acetamino anisole by precipitation according to claim 1, characterized in that: adopting a mixed solution of an acid aqueous solution and an organic solvent for analysis; the acid is hydrochloric acid, sulfuric acid or phosphoric acid; the organic solvent is non-water-soluble chlorohydrocarbon, ester or toluene.

6. The method for purifying 2-amino-4-acetamino anisole by precipitation according to claim 5, characterized in that: the concentration of the aqueous solution of the acid is 0.4-2mol/L, the molar ratio of the 2-amino-4-acetamino anisole to the acid in the mother liquor for producing the 2-amino-4-acetamino anisole is 1:1-5, and the volume ratio of the organic solvent to the aqueous solution of the acid is 1: 1-3; the organic solvent is dichloromethane, chloroform, ethyl acetate, butyl acetate or toluene.

7. The method for purifying 2-amino-4-acetamino anisole by precipitation according to claim 1, characterized in that: the resolving temperature is 10-40 ℃, and the resolving time is 1-2 h.

8. The method for purifying 2-amino-4-acetamino anisole by precipitation according to claim 1, characterized in that: adjusting pH value to 5-9 with pH regulator.

9. The method for purifying 2-amino-4-acetamino anisole by precipitation according to claim 8, characterized in that: the pH regulator is sodium hydroxide solution, sodium carbonate solution or sodium bicarbonate solution; the concentration of the pH regulator is 0.5-30 wt.%.

10. The method for purifying 2-amino-4-acetamino anisole by precipitation according to claim 1, characterized in that: and distilling the organic phase, and recovering the obtained solvent to obtain the precipitant for recycling.

Technical Field

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a method for purifying 2-amino-4-acetamino anisole by a precipitation method.

Background

2-amino-4-acetamino anisole (commonly called as a reducing substance) is a key intermediate in the disperse dye industry, and can be subsequently used for producing over ten dyes such as disperse blue, disperse violet, disperse yellow and the like. In the dye industry, the annual demand amount reaches more than 30 million tons, and the dye has important economic value. The synthesis process of the 2-amino-4-acetamino anisole mainly comprises two processes, wherein the traditional synthesis process comprises the steps of taking p-nitrochlorobenzene as a raw material, obtaining the p-acetamino anisole through etherification, hydrogenation reduction and acetylation, and obtaining a target product through nitration and hydrogenation reduction. The specific equation is as follows:

the traditional synthesis process is a mature process, and 2, 4-diacetyl amino anisole which is a byproduct is hardly generated in the synthesis process, but the process also has a plurality of problems, such as low yield, complex production steps, and the generation of a large amount of waste water and waste residues which pollute the environment. The new synthesis process uses 2, 4-dinitrochlorobenzene as an initial raw material to synthesize a target product through etherification reaction, hydrogenation reduction reaction and acetylation reaction. The specific equation is as follows:

the 2-amino-4-acetamino anisole improves the safety coefficient of industrialization and reduces the industrialization cost in the production and preparation of the new process, but a small amount of 2, 4-diacetyl aminobenzene ether byproduct can be generated in the process of synthesizing the 2-amino-4-acetamino anisole by the new process, and in order to obtain the 2-amino-4-acetamino anisole with higher purity, the 2-amino-4-acetamino anisole with higher purity can be obtained by a purification method.

Schwenlin, chuangyuhui, liu, a process for preparing 2-amino-4-acetamidoanisole [ P ]. Jiangsu: CN1861577A,2006-11-15, reports that 2-amino-4-acetamino anisole is purified by adopting a crystallization separation and purification method, a crude product of 2-amino-4-acetamino anisole is put into an evaporation crystallization kettle of a crystallization separator, methanol is added as a solvent for crystallization separation and purification, the using amount ratio of the 2-amino-4-acetamino anisole to the methanol is 100g:150mL, the temperature is raised to a reflux temperature, the operation temperature is kept between 20 ℃ and the methanol reflux temperature, the operation pressure is 0.2MPa, the operation pressure is kept for 30min under the reflux condition, and then the temperature is slowly reduced to 20 ℃, and the method does not refer to the purity and yield after purification.

3-amino-4-methoxyacetanilide is reported to be purified by adding concentrated hydrochloric acid to adjust the pH value to be 3-4 after the selective acylation reaction is finished, then precipitating a large amount of white precipitate, filtering and washing with methanol twice. Dissolving the obtained precipitate in 150mL of water, and adjusting pH value to 9-10 with dilute sodium hydroxide to obtain 3-amino-4-methoxyacetanilide with yield of 86% and purity of 98%.

At present, the industrial method for purifying 2-amino-4-acetamino anisole from the mother liquor of 2-amino-4-acetamino anisole production mainly adopts a recrystallization method, but the recrystallization method for purifying 2-amino-4-acetamino anisole has a plurality of problems: (1) it is difficult to select a suitable recrystallization solvent, resulting in a low purity; (2) the recrystallization needs reflux heating, cooling and crystallization separation, and a large amount of 2-amino-4-acetamino anisole still remains in the filtrate, which results in the reduction of yield.

Therefore, it is urgently needed to provide a purification method of 2-amino-4-acetamino anisole, which can improve the product yield, reduce the existence of byproducts, save energy consumption and is more environment-friendly.

Disclosure of Invention

The invention aims to provide a method for purifying 2-amino-4-acetamino anisole by a precipitation method, which can effectively purify the 2-amino-4-acetamino anisole by adding a precipitator into a mother liquor produced by the 2-amino-4-acetamino anisole and analyzing precipitates, and has high yield and high purity of products.

The technical scheme adopted by the invention for solving the technical problems is as follows:

the method for purifying the 2-amino-4-acetamino anisole by the precipitation method comprises the steps of adding a precipitator into a mother liquor produced by the 2-amino-4-acetamino anisole, filtering, resolving the obtained precipitate to obtain a water phase and an organic phase, adjusting the pH value of the water phase, and drying to obtain the 2-amino-4-acetamino anisole.

Wherein:

the mother liquor for producing the 2-amino-4-acetamino anisole contains 2-amino-4-acetamino anisole and 2, 4-diacetyl aminobenzyl ether; wherein the content of 2-amino-4-acetamino anisole is 93-96 wt.%, and the content of 2, 4-diacetyl amino anisole is 4-7 wt.%; the preparation method is characterized in that 2, 4-dinitroanisole is used as a raw material, ethyl acetate is used as a solvent, and the preparation method comprises the following steps of hydrogenation reduction reaction and selective acylation reaction:

taking 2, 4-dinitroanisole as a raw material, taking ethyl acetate as a reaction solvent, adding 5% Pd/C as a catalyst, and introducing hydrogen for reaction at the temperature of 75-80 ℃ and the pressure of 2-3MPa to obtain 2, 4-diaminoanisole reaction liquid; adding acetic anhydride with the molar ratio of 1:1-1.1 to the raw material into the 2, 4-diaminoanisole reaction liquid for selective acylation to obtain a 2-amino-4-acetamino anisole production mother liquor.

The general formula of the precipitant is:

wherein: r₁、R₂＝-H、-CH₃、-OH、-OCH₃、-Cl、-Br、-NO₂or-NH₂。

The molar ratio of the precipitant to the 2-amino-4-acetamino anisole in the mother liquor for producing the 2-amino-4-acetamino anisole is 1-5: 1.

Adopting a mixed solution of an acid aqueous solution and an organic solvent for analysis; the acid is hydrochloric acid, sulfuric acid or phosphoric acid; the organic solvent is non-water-soluble chlorohydrocarbon, ester or toluene, preferably dichloromethane, chloroform, ethyl acetate, butyl acetate or toluene.

The concentration of the aqueous solution of the acid is 0.4-2mol/L, the molar ratio of the 2-amino-4-acetamino anisole to the acid in the mother liquor for producing the 2-amino-4-acetamino anisole is 1:1-5, and the volume ratio of the organic solvent to the aqueous solution of the acid is 1: 1-3.

The resolving temperature is 10-40 ℃, and the resolving time is 1-2 h.

Adjusting pH value to 5-9 with pH regulator. The pH regulator is sodium hydroxide solution, sodium carbonate solution or sodium bicarbonate solution; the concentration of the pH regulator is 0.5-30 wt.%.

And distilling the organic phase, and recovering the obtained solvent to obtain the precipitant for recycling. The drying is spray drying.

The invention takes acetophenone as an example of a precipitator, which is used for purifying 2-amino-4-acetamino anisole production mother liquor, and the reaction process is as follows:

the invention has the following beneficial effects:

according to the invention, the characteristic of Lewis base of amino in 2-amino-4-acetamino anisole is utilized, so that Schiff base structure can be formed with ketone group in a precipitator, and precipitation is generated, thereby realizing solid-liquid separation of 2-amino-4-acetamino anisole and mother liquor; then carrying out acid precipitation hydrolysis on the obtained solid precipitate by using an aqueous solution of acid and an organic solvent, wherein the precipitator has hydrophobicity and can be better dissolved in the organic solvent, the precipitator is promoted to enter an organic phase, the acid precipitation hydrolysis is facilitated, the organic phase can be repeatedly utilized, and 2-amino-4-acetamino anisole enters a water phase; and the byproduct 2, 4-diacetyl amino anisole can not react with a precipitator due to no amino group, so that no precipitate is generated, the purification and separation of the main product and the byproduct are realized, the aim of high selectivity is fulfilled, and the 2-amino-4-acetamino anisole with higher purity is obtained.

Compared with the recrystallization method, the precipitation method carries out reaction at normal temperature through chemical reaction, while the recrystallization method needs to be heated to reflux temperature, and the temperature is higher; the main product can react with the precipitator to separate out the precipitate by a chemical reaction in the precipitation method, the byproduct is continuously remained in the mother liquor, the yield of the 2-amino-4-acetamino anisole is greatly improved, the recrystallization method needs cooling and separation, part of the 2-amino-4-acetamino anisole is still remained in the filtrate, and the influence on the yield of the finished product is large; the organic phase and the water phase can be recycled by using a precipitation method.

The method adopts a precipitation method to purify the 2-amino-4-acetamino anisole, has the advantages of low energy consumption and high reaction efficiency, can realize the purpose of high selectivity, and obtains the 2-amino-4-acetamino anisole with higher purity and higher yield; and the method is simple to operate, and has remarkable economic value and environmental benefit.

Detailed Description

The present invention is further described below with reference to examples.

Example 1

Weighing 300g of 2, 4-dinitroanisole as a raw material, taking ethyl acetate as a reaction solvent, adding 5% Pd/C as a catalyst, and introducing hydrogen for reaction at the temperature of 75 ℃ and the pressure of 2MPa to obtain a 2, 4-diaminoanisole reaction solution; adding acetic anhydride with a molar ratio of 1:1 to the raw material into the 2, 4-diaminoanisole reaction liquid for selective acylation to obtain a 2-amino-4-acetamino anisole production mother liquor, wherein the content of 2-amino-4-acetamino anisole is 95.5 wt.%, the content of 2, 4-diacetyl aminobenzene ether is 4.0 wt.%, and the balance is impurities.

Taking 500g of the mother liquor produced by the 2-amino-4-acetamino anisole, adding acetophenone at normal temperature, wherein the molar ratio of 2-amino-4-acetamino anisole in the mother liquor produced by the acetophenone and the 2-amino-4-acetamino anisole is 1:1, at the moment, a solid precipitate is separated out from the mother liquor, filtering the solid precipitate by using a Buchner funnel, carrying out acid hydrolysis on the precipitate, adding a mixed solution of dilute hydrochloric acid and toluene (the concentration of the dilute hydrochloric acid solution is 2mol/L, the volume dosage is 2.65L, and the dosage of toluene is 2.5L), controlling the molar ratio of the 2-amino-4-acetamino anisole to the hydrochloric acid to be 1:2, stirring for 1h at 30 ℃, moving to a separating funnel, standing for 20min, generating layering, wherein the upper layer is organic phase toluene, the lower layer is an aqueous phase, and the organic phase is distilled to recover an organic solvent, the obtained precipitant can be reused, and the obtained water phase is sampled and detected by high performance liquid chromatography, and the result shows that the purity of the 2-amino-4-acetamino anisole reaches 98.8%, the pH value of the water phase is adjusted to be neutral by 10 wt.% sodium hydroxide solution, and the spray drying is carried out to obtain 464.5g of pure solid product 2-amino-4-acetamino anisole, and the calculated yield is 96.1%.

Example 2

Taking 500g of the mother liquor produced by the 2-amino-4-acetamino anisole in example 1, adding propiophenone at normal temperature, wherein the molar ratio of the propiophenone to the 2-amino-4-acetamino anisole in the mother liquor produced by the 2-amino-4-acetamino anisole is 1:1, at this time, a solid precipitate is separated out from the mother liquor, filtering the solid precipitate by using a Buchner funnel, carrying out acid hydrolysis on the precipitate, adding a mixed solution of dilute sulfuric acid and ethyl acetate (the concentration of the dilute sulfuric acid solution is 0.8mol/L, the volume dosage is 3.31L, and the dosage of the ethyl acetate is 2L), controlling the molar ratio of the 2-amino-4-acetamino anisole to the sulfuric acid to be 1:1, stirring for 1h at 30 ℃, transferring to a separating funnel and standing for 20min to generate a delamination, wherein the upper layer is organic phase ethyl acetate, the lower layer is a water phase, the organic phase is distilled to recover the organic solvent, the obtained precipitator can be reused, the obtained water phase is sampled and detected by high performance liquid chromatography, the result shows that the purity of the 2-amino-4-acetamino anisole reaches 98.4%, the pH value of the water phase is adjusted to 5 by 10 wt.% of sodium hydroxide solution, and spray drying is carried out to obtain 465.3g of pure solid product 2-amino-4-acetamino anisole, and the calculated yield is 95.9%.

Example 3

Taking 500g of the mother liquor produced by the 2-amino-4-acetamino anisole in example 1, adding acetophenone at normal temperature, wherein the molar ratio of the acetophenone to the 2-amino-4-acetamino anisole in the mother liquor produced by the 2-amino-4-acetamino anisole is 1:1, at this time, a solid precipitate is separated out from the mother liquor, filtering the solid precipitate by using a Buchner funnel, carrying out acid hydrolysis on the precipitate, adding a mixed solution of dilute hydrochloric acid and ethyl acetate (the concentration of the dilute hydrochloric acid solution is 1mol/L, the volume dosage is 2.65L, and the dosage of the ethyl acetate is 2L), controlling the molar ratio of the 2-amino-4-acetamino anisole to the hydrochloric acid to be 1:1, stirring for 1h at 30 ℃, transferring to a separating funnel and standing for 20min to generate a layering, wherein the upper layer is an organic phase ethyl acetate, the lower layer is a water phase, the organic phase is distilled to recover the organic solvent, and the obtained precipitator can be reused; the obtained aqueous phase was sampled and examined by high performance liquid chromatography, and the results showed that the purity of 2-amino-4-acetamino anisole reached 99.3%, the pH of the aqueous phase was adjusted to neutral with 10 wt.% sodium hydroxide solution, and spray-dried to obtain 465.9g of pure solid product 2-amino-4-acetamino anisole, the yield of which was calculated to be 96.9%.

Example 4

Taking 500g of the mother liquor produced by the 2-amino-4-acetamino anisole in example 1, adding benzophenone at normal temperature, wherein the molar ratio of the benzophenone to the 2-amino-4-acetamino anisole in the mother liquor produced by the 2-amino-4-acetamino anisole is 3:1, at this time, a solid precipitate is separated out from the mother liquor, filtering the solid precipitate by using a Buchner funnel, carrying out acid hydrolysis on the precipitate, adding a mixed solution of dilute hydrochloric acid and dichloromethane (the concentration of the dilute hydrochloric acid solution is 1.5mol/L, the volume amount is 3.53L, and the amount of the dichloromethane is 1.7L), controlling the molar ratio of the 2-amino-4-acetamino anisole to the hydrochloric acid to be 1:2, stirring for 1h at 30 ℃, transferring to a separating funnel and standing for 20min to generate layering, wherein the upper layer is an aqueous phase, the lower layer is an organic phase dichloromethane, the organic phase is distilled to recover the organic solvent, and the obtained precipitator can be reused; the obtained aqueous phase was sampled and examined by high performance liquid chromatography, and the results showed that the purity of 2-amino-4-acetamino anisole was 98.8%, the pH of the aqueous phase was adjusted to 9 with 10 wt.% sodium hydroxide solution, and spray-dried to obtain 465.9g of pure solid product 2-amino-4-acetamino anisole, the yield of which was calculated to be 96.4%.

Example 5

Taking 500g of the mother liquor produced by the 2-amino-4-acetamino anisole in example 1, adding acetophenone at normal temperature, wherein the molar ratio of the acetophenone to the 2-amino-4-acetamino anisole in the mother liquor produced by the 2-amino-4-acetamino anisole is 2:1, at this time, a solid precipitate is separated out from the mother liquor, filtering the solid precipitate by using a Buchner funnel, carrying out acid hydrolysis on the precipitate, adding a mixed solution of dilute hydrochloric acid and ethyl acetate (the concentration of the dilute hydrochloric acid solution is 1.5mol/L, the volume dosage is 5.3L, and the dosage of the ethyl acetate is 3.5L), controlling the molar ratio of the 2-amino-4-acetamino anisole to the hydrochloric acid to be 1:3, stirring for 1h at 30 ℃, transferring to a separating funnel and standing for 20min to generate layering, wherein the upper layer is organic phase ethyl acetate, the lower layer is a water phase, the organic phase is distilled to recover the organic solvent, and the obtained precipitator can be reused; the obtained aqueous phase was sampled and examined by high performance liquid chromatography, and the results showed that the purity of 2-amino-4-acetamino anisole was 98.5%, the pH of the aqueous phase was adjusted to neutral with 10 wt.% sodium hydroxide solution, and spray-dried to obtain 462.1g of pure solid product 2-amino-4-acetamino anisole, the yield of which was calculated to be 95.3%.

Example 6

Taking 500g of the mother liquor produced by the 2-amino-4-acetamino anisole in example 1, adding acetophenone at normal temperature, wherein the molar ratio of the acetophenone to the 2-amino-4-acetamino anisole in the mother liquor produced by the 2-amino-4-acetamino anisole is 5:1, at this time, a solid precipitate is separated out from the mother liquor, filtering the solid precipitate by using a Buchner funnel, carrying out acid precipitation hydrolysis on the precipitate, adding a mixed solution of dilute hydrochloric acid and butyl acetate (the concentration of the dilute hydrochloric acid solution is 2mol/L, the volume dosage is 5.3L, and the dosage of the butyl acetate is 2.5L), controlling the molar ratio of the 2-amino-4-acetamino anisole to the hydrochloric acid to be 1:4, stirring for 1h at 30 ℃, transferring to a separating funnel and standing for 20min to generate a layering, wherein the upper layer is an organic phase butyl acetate, the lower layer is a water phase, the organic phase is distilled to recover the organic solvent, and the obtained precipitator can be reused; the obtained aqueous phase was sampled and examined by high performance liquid chromatography, and the results showed that the purity of 2-amino-4-acetamino anisole was 98.5%, the pH of the aqueous phase was adjusted to neutral with 10 wt.% sodium hydroxide solution, and spray-dried to obtain 464.2g of pure solid product 2-amino-4-acetamino anisole, the yield of which was calculated to be 95.8%.

Example 7

Taking 500g of mother liquor produced by the 2-amino-4-acetamino anisole in example 1, adding dicyclohexyl ketone at normal temperature, wherein the molar ratio of dicyclohexyl ketone to 2-amino-4-acetamino anisole in the mother liquor produced by the 2-amino-4-acetamino anisole is 3:1, at this time, solid precipitate is separated out in the mother liquor, filtering the solid precipitate by using a Buchner funnel, performing acid hydrolysis on the precipitate, adding a mixed solution of dilute hydrochloric acid and chloroform (the concentration of the dilute hydrochloric acid solution is 1.2mol/L, the volume dosage is 4.42L, and the dosage of the chloroform is 2L), controlling the molar ratio of the 2-amino-4-acetamino anisole to the hydrochloric acid to be 1:2, stirring for 2h at 20 ℃, transferring to a separating funnel and standing for 20min to generate layering, wherein the upper layer is an aqueous phase, the lower layer is an organic phase of chloroform, the organic phase is distilled to recover the organic solvent, and the obtained precipitator can be reused; the obtained aqueous phase was sampled and examined by high performance liquid chromatography, and the results showed that the purity of 2-amino-4-acetamino anisole was 98.6%, the pH of the aqueous phase was adjusted to neutral with 10 wt.% sodium carbonate solution, and spray-dried to obtain 466.5g of pure solid product 2-amino-4-acetamino anisole, the yield of which was 96.3% by calculation.

Example 8

Taking 500g of the mother liquor produced by the 2-amino-4-acetamino anisole in example 1, adding cyclohexylethanone at normal temperature, wherein the molar ratio of the cyclohexylethanone to the 2-amino-4-acetamino anisole in the mother liquor produced by the 2-amino-4-acetamino anisole is 3:1, at this time, a solid precipitate is separated out from the mother liquor, filtering the solid precipitate by using a Buchner funnel, carrying out acid hydrolysis on the precipitate, adding a mixed solution of dilute hydrochloric acid and ethyl acetate (the concentration of the dilute hydrochloric acid solution is 0.4mol/L, the volume dosage is 6.63L, and the dosage of the ethyl acetate is 2.21L), controlling the molar ratio of the 2-amino-4-acetamino anisole to the hydrochloric acid to be 1:1, stirring for 2h at 20 ℃, transferring to a separating funnel, standing for 20min to generate layering, wherein the upper layer is organic phase ethyl acetate, the lower layer is a water phase, the organic phase is distilled to recover the organic solvent, and the obtained precipitator can be reused; the obtained aqueous phase was sampled and examined by high performance liquid chromatography, and the results showed that the purity of 2-amino-4-acetamino anisole was 98.9%, the pH of the aqueous phase was adjusted to neutral with 10 wt.% sodium carbonate solution and spray-dried to obtain 463.2g of pure solid product 2-amino-4-acetamino anisole, the yield of which was 95.9% by calculation.

Comparative example 1

Taking 500g of mother liquor produced by the 2-amino-4-acetamino anisole in example 1, carrying out reduced pressure distillation to remove an organic solvent in the mother liquor, using deionized water as a recrystallization solvent, adding 800mL of deionized water into the recrystallization solvent, stirring to completely dissolve the deionized water, heating to 85 ℃, refluxing for 1h, cooling at room temperature to crystallize after recrystallization is finished, further precipitating the crystals by cooling to ensure that the crystals are more completely precipitated, filtering out the solids after precipitation, drying to obtain solids, and sampling and detecting by using a High Performance Liquid Chromatography (HPLC) method, wherein the result shows that 393.8g of the 2-amino-4-acetamino anisole has the purity of 97.0 percent and the calculated yield of 80 percent.