Continuous industrial production method of 2-nitro-4-acetamino anisole

Abstract

The invention belongs to the technical field of chemical production, and particularly relates to a continuous industrial production method of 2-nitro-4-acetamino anisole. According to the method, p-anisidine is used as a raw material, the acetylation efficiency is improved through the composite acetylation reagent, and the aminated activated carbon is matched for purification treatment, so that the purity of the product is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical production, and particularly relates to a continuous industrial production method of 2-nitro-4-acetamidoanisole. Background Art

[0002] Disperse dyes are currently the most important type of dyes. Due to their unique molecular structure, they have become the preferred dyes for PET dyeing. 2-Nitro-4-acetamidoanisole is a yellow solid powder with a needle-like crystal form, which is easily soluble in concentrated sulfuric acid, organic solvents such as benzene, dichloromethane, chloroform, alcohols, etc., and is hardly soluble in water. It is an important intermediate for synthesizing dyes, pigments, and coatings.

[0003] Chinese Patent (Publication No. CN116903487A) discloses a method and equipment for continuously preparing 2-nitro-4-acetamidoanisole. By continuously introducing p-acetamidoanisole, sulfuric acid, and nitric acid into a primary reactor for mixing and carrying out a nitration reaction to obtain a nitration reaction solution; the nitration reaction solution overflows into a secondary reactor for aging reaction to obtain 2-nitro-4-acetamidoanisole. This patented technology mainly improves the conversion rate of p-acetamidoanisole through a continuous flow method, but does not solve the problem of low product purity when using p-aminophenol as a raw material to produce 2-nitro-4-acetamidoanisole in the prior art.

[0004] Therefore, there is an urgent need for a continuous industrial production method of 2-nitro-4-acetamidoanisole, which uses p-aminophenol as a raw material, improves the acetylation and nitration efficiency, and simultaneously performs purification treatment to remove impurities, effectively improving the purity of the product. Summary of the Invention

[0005] The purpose of the present invention is to provide a continuous industrial production method of 2-nitro-4-acetamidoanisole, which uses p-aminophenol as a raw material, improves the acetylation efficiency through a composite acetylation reagent, and cooperates with amino-functionalized activated carbon for purification treatment, effectively improving the purity of the product.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: The present invention provides a continuous industrial production method of 2-nitro-4-acetamidoanisole, comprising the following steps: Step S1: By weight, add 2500 - 2800 parts of p-aminophenol to 3000 - 3200 parts of acetic acid, stir for 30 - 40 min, then add 5000 - 6000 parts of an acetylation reagent for an acetylation reaction. After the reaction is completed, remove the acetylation reagent through pseudoboehmite, then perform extraction, precipitate crystals, filter, wash with water until neutral, and dry to obtain an intermediate product; Step S2: Add 1000 - 1200 parts by weight of the intermediate product to 2800 - 3000 parts of the first acid solution, stir for 30 - 60 min, then add 600 - 800 parts of the second acid solution for nitration reaction. After the reaction is completed, perform purification treatment with amino-functionalized activated carbon, then carry out precipitation crystallization, suction filtration, washing with water, and drying to obtain 2-nitro-4-acetamidophenol methyl ether.

[0007] As a preferred embodiment, the acetylation reagent is acetic anhydride and acetyl chloride.

[0008] As a preferred embodiment, the mass ratio of acetic anhydride to acetyl chloride is (1 - 2):1.

[0009] As a preferred embodiment, the conditions for the acetylation reaction include: reaction temperature is 70 - 75 °C, and reaction time is 1 - 2 h.

[0010] Since the raw material contains a benzene ring and has a certain steric hindrance, by using acetic anhydride and acetyl chloride in combination, the selectivity and yield of the reaction are improved.

[0011] As a preferred embodiment, the pseudo-boehmite is modified pseudo-boehmite. The preparation method of the modified pseudo-boehmite includes: add 4 - 5 parts by weight of diammonium hydrogen phosphate to 20 - 30 parts of deionized water, stir and dissolve to obtain a diammonium hydrogen phosphate aqueous solution; add 20 - 30 parts of pseudo-boehmite to 80 - 100 parts of deionized water, stir for 0.5 - 0.8 h to obtain a pseudo-boehmite aqueous solution, then dropwise add the diammonium hydrogen phosphate aqueous solution, stir for 1 - 2 h, then dropwise add a nitric acid solution with a mass concentration of 20 - 30% to adjust the pH to 5 - 6, stir for 6 - 8 h, stand at room temperature for 15 - 20 h, and then perform heat treatment at 110 - 120 °C for 2 - 3 h, and cool to room temperature to obtain the modified pseudo-boehmite.

[0012] As a material with a high specific surface area and a rich pore structure, modified boehmite exhibits excellent performance in the adsorption field. By introducing phosphates for modification, the acidity of the boehmite surface is enhanced, thereby improving the adsorption capacity for acetylation reagents such as acetyl chloride, reducing impurities, and improving the purity of the final product.

[0013] As a preferred embodiment, the first acid solution is a sulfuric acid solution with a mass concentration of 90 - 93%.

[0014] As a preferred embodiment, the second acid solution is a nitric acid solution with a mass concentration of 60 - 65%.

[0015] As a preferred embodiment, the conditions for the nitration reaction include: reaction temperature is 10 - 20 °C, and reaction time is 50 - 60 min.

[0016] The nitrating reagent uses a nitric acid solution and a sulfuric acid solution with specific mass fractions in combination. The sulfuric acid solution plays a role in dehydration and acidification, making it easier for nitric acid to generate nitronium ions (NO2⁺), thereby increasing the rate of the nitration reaction and further improving the product purity.

[0017] As a preferred solution, the preparation method of the amino-functionalized activated carbon includes: by weight, adding 3 - 5 parts of activated carbon to 16 - 20 parts of a nitric acid solution with a mass concentration of 10%, performing amino-functionalization treatment at 70 - 75°C for 4 - 6 hours, filtering, washing, and drying the product to obtain the amino-functionalized activated carbon.

[0018] The amino-functionalized activated carbon enhances the adsorption capacity for acids and other impurities by introducing amino groups, effectively reducing impurities and improving the purity of 2-nitro-4-acetamidoanisole.

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. In the present invention, acetic anhydride and acetyl chloride are used in combination as the acetylation reagent. Since the raw material contains a benzene ring with a certain steric hindrance, the use of acetic anhydride and acetyl chloride in combination improves the selectivity and yield of the reaction.

[0020] 2. The modified boehmite of the present invention, as a material with a high specific surface area and a rich pore structure, exhibits excellent performance in the adsorption field. By introducing phosphates for modification, the acidity on the surface of boehmite is enhanced, thereby improving the adsorption capacity for acetylation reagents such as acetyl chloride, reducing impurities, and improving the purity of the final product.

[0021] 3. The nitrating reagent of the present invention uses a nitric acid solution and a sulfuric acid solution with specific mass fractions in combination. The sulfuric acid solution plays a role in dehydration and acidification, making it easier for nitric acid to generate nitronium ions (NO2⁺), thereby increasing the rate of the nitration reaction and further increasing the product purity.

[0022] 4. The amino-functionalized activated carbon of the invention enhances the adsorption capacity for acids and other impurities by introducing amino groups, effectively reducing impurities in the product and improving the purity of 2-nitro-4-acetamidoanisole. Specific Embodiments

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] The sources of some components in the examples and comparative examples are as follows: p-Anisidine, CAS No. 104-94-9, purchased from Sinopharm Chemical Reagent Co., Ltd.; Acetic acid, CAS No. 64-19-7, purchased from Sinopharm Chemical Reagent Co., Ltd.; Acetic anhydride, CAS No. 108-24-7, purchased from Sinopharm Chemical Reagent Co., Ltd.; Acetyl chloride, CAS No. 75-36-5, purchased from Sinopharm Chemical Reagent Co., Ltd.; Commercially available pseudo-boehmite, product number P-DF-07-LSi, purchased from Shandong Aluminum Co., Ltd.; Sulfuric acid, CAS No. 7664-93-9, purchased from Sinopharm Chemical Reagent Co., Ltd.; Nitric acid, CAS No. 7697-37-2, purchased from Sinopharm Chemical Reagent Co., Ltd.; Commercially available activated carbon, product number I11113, purchased from Beijing Innochem Science & Technology Co., Ltd.; Diammonium hydrogen phosphate, CAS No. 7783-28-0, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0025] Example 1 This example provides a continuous industrial production method of 2-nitro-4-acetamidoanisole, including the following steps: Preparation of modified pseudo-boehmite: By weight, add 5 parts of diammonium hydrogen phosphate to 30 parts of deionized water, stir and dissolve to obtain an aqueous solution of diammonium hydrogen phosphate; add 30 parts of pseudo-boehmite to 100 parts of deionized water, stir for 0.8 h to obtain an aqueous solution of pseudo-boehmite, then dropwise add the above-mentioned aqueous solution of diammonium hydrogen phosphate, stir for 2 h, then dropwise add a nitric acid solution with a mass concentration of 30% to adjust the pH to 6, stir for 8 h, stand still at room temperature for 20 h, and then perform heat treatment at 120 °C for 3 h, and cool to room temperature to obtain modified pseudo-boehmite.

[0026] Preparation of amino-functionalized activated carbon: By weight, add 5 parts of activated carbon to 20 parts of a nitric acid solution with a mass concentration of 10%, perform amino-functionalization treatment at 5 °C for 6 h, filter the product by suction, wash, and dry to obtain amino-functionalized activated carbon.

[0027] Step S1: By weight, add 2800 parts of p-anisidine to 3200 parts of acetic acid, stir for 40 min, then add 6000 parts of acetylation reagent (4000 parts of acetic anhydride and 2000 parts of acetyl chloride) for acetylation reaction (reaction temperature is 75 °C, reaction time is 1 h), after the reaction is completed, remove the acetylation reagent through modified pseudo-boehmite, then perform extraction, precipitate crystals, filter, wash with water until neutral, and dry to obtain an intermediate product; Step S2: Add 1200 parts of the intermediate product by weight to 3000 parts of a sulfuric acid solution with a mass concentration of 93%, stir for 60 min, then add 800 parts of a nitric acid solution with a mass concentration of 65% for nitration reaction (reaction temperature: 20°C, reaction time: 50 min). After the reaction is completed, carry out purification treatment with amino-functionalized activated carbon, then carry out precipitation crystallization, suction filtration, water washing, and drying to obtain 2-nitro-4-acetamidoanisole.

[0028] Example 2 This example provides a continuous industrial production method of 2-nitro-4-acetamidoanisole, including the following steps: Preparation of modified pseudo-boehmite: Add 4 parts of diammonium hydrogen phosphate by weight to 20 parts of deionized water, stir and dissolve to obtain an aqueous solution of diammonium hydrogen phosphate; add 20 parts of pseudo-boehmite to 80 parts of deionized water, stir for 0.5 h to obtain an aqueous solution of pseudo-boehmite, then dropwise add the above-mentioned aqueous solution of diammonium hydrogen phosphate, stir for 1 h, then dropwise add a nitric acid solution with a mass concentration of 20% to adjust the pH to 5, stir for 6 h, stand still at room temperature for 15 h, and then carry out heat treatment at 110°C for 2 h, and cool to room temperature to obtain modified pseudo-boehmite.

[0029] Preparation of amino-functionalized activated carbon: Add 3 parts of activated carbon by weight to 16 parts of a nitric acid solution with a mass concentration of 10%, carry out amino-functionalization treatment at 70°C for 6 h, filter the product by suction, wash, and dry to obtain amino-functionalized activated carbon.

[0030] Step S1: Add 2500 parts of p-aminoanisole by weight to 3000 parts of acetic acid, stir for 30 min, then add 5000 parts of an acetylation reagent (2500 parts of acetic anhydride and 2500 parts of acetyl chloride) for acetylation reaction (reaction temperature: 70°C, reaction time: 2 h). After the reaction is completed, remove the acetylation reagent with modified pseudo-boehmite, then carry out extraction, precipitation crystallization, filtration, water washing until neutral, and drying to obtain the intermediate product; Step S2: Add 1000 parts of the intermediate product by weight to 2800 parts of a sulfuric acid solution with a mass concentration of 90%, stir for 30 min, then add 600 parts of a nitric acid solution with a mass concentration of 60% for nitration reaction (reaction temperature: 10°C, reaction time: 60 min). After the reaction is completed, carry out purification treatment with amino-functionalized activated carbon, then carry out precipitation crystallization, suction filtration, water washing, and drying to obtain 2-nitro-4-acetamidoanisole.

[0031] Example 3 This example provides a continuous industrial production method of 2-nitro-4-acetamidoanisole, including the following steps: Preparation of modified pseudoboehmite: By weight, add 5 parts of diammonium hydrogen phosphate to 25 parts of deionized water, stir and dissolve to obtain an aqueous solution of diammonium hydrogen phosphate; add 25 parts of pseudoboehmite to 90 parts of deionized water, stir for 0.6 h to obtain an aqueous solution of pseudoboehmite, then dropwise add the above-mentioned aqueous solution of diammonium hydrogen phosphate, stir for 2 h, then dropwise add a nitric acid solution with a mass concentration fraction of 25% to adjust the pH to 6, stir for 8 h, stand at room temperature for 18 h, and then perform heat treatment at 115 °C for 3 h, and cool to room temperature to obtain modified pseudoboehmite.

[0032] Preparation of aminated activated carbon: By weight, add 4 parts of activated carbon to 18 parts of a nitric acid solution with a mass concentration fraction of 10%, perform amination treatment at 72 °C for 5 h, filter the product by suction, wash, and dry to obtain aminated activated carbon.

[0033] Step S1: By weight, add 2600 parts of p-anisidine to 3100 parts of acetic acid, stir for 35 min, then add 5500 parts of an acetylation reagent (3000 parts of acetic anhydride and 2500 parts of acetyl chloride) for acetylation reaction (reaction temperature is 72 °C, reaction time is 2 h). After the reaction is completed, remove the acetylation reagent through modified pseudoboehmite, then perform extraction, precipitate crystals, filter, wash with water until neutral, and dry to obtain an intermediate product. Step S2: By weight, add 1100 parts of the intermediate product to 2900 parts of a sulfuric acid solution with a mass concentration fraction of 92%, stir for 50 min, then add 700 parts of a nitric acid solution with a mass concentration fraction of 62% for nitration reaction (reaction temperature is 15 °C, reaction time is 55 min). After the reaction is completed, perform purification treatment through aminated activated carbon, then perform precipitation of crystals, suction filtration, washing with water, and drying to obtain 2-nitro-4-acetamidoanisole.

[0034] Comparative Example 1 This comparative example provides a continuous industrial production method of 2-nitro-4-acetamidoanisole. The difference between this comparative example and Example 1 is that commercially available pseudoboehmite is used to replace the modified pseudoboehmite.

[0035] Comparative Example 2 This comparative example provides a continuous industrial production method of 2-nitro-4-acetamidoanisole. The difference between this comparative example and Example 1 is that commercially available activated carbon is used to replace the aminated activated carbon.

[0036] Comparative Example 3 This comparative example provides a continuous industrial production method of 2-nitro-4-acetamidoanisole. The difference between this comparative example and Example 1 is that the amount of acetic anhydride is adjusted from 4000 parts to 2000 parts, and the amount of acetyl chloride is adjusted from 2000 parts to 4000 parts.

[0037] Comparative Example 4 This comparative example provides a continuous industrial production method of 2-nitro-4-acetamidoanisole. The difference between this comparative example and Example 1 is that the dosage of acetic anhydride is adjusted from 4000 parts to 5000 parts, and the dosage of acetyl chloride is adjusted from 2000 parts to 1000 parts.

[0038] Comparative Example 5 This comparative example provides a continuous industrial production method of 2-nitro-4-acetamidoanisole. The difference between this comparative example and Example 1 is that the nitric acid solution with a mass concentration of 40% is used to replace the nitric acid solution with a mass concentration of 65%.

[0039] Comparative Example 6 This comparative example provides a continuous industrial production method of 2-nitro-4-acetamidoanisole. The difference between this comparative example and Example 1 is that the nitric acid solution with a mass concentration of 80% is used to replace the nitric acid solution with a mass concentration of 65%.

[0040] Performance Test The 2-nitro-4-acetamidoanisole of the above examples and comparative examples was subjected to the following tests: (1) Purity test: High performance liquid chromatography was used. The chromatographic column was Apollo-C18 (250×4.6mm, 5μm), the column temperature was 30°C, the mobile phase was ethanol:acetonitrile = 90:10 (v / v), the flow rate was 1ml / min, and the injection volume was 10μL; for the preparation of the sample solution, 10mg of 2-nitro-4-acetamidoanisole prepared in the examples and comparative examples was weighed and diluted to 10mL with the mobile phase for testing.

[0041] Table 1 Performance Test Results

[0042] From the above performance test results, it can be seen that the effects of Examples 1-3 are good, and the purity is 99.1~99.6%; this is because p-anisidine is used as the raw material, the acetylation efficiency is improved by a composite acetylation reagent, and purification treatment is carried out in cooperation with amino-activated carbon, effectively improving the purity of the product.

[0043] In the comparative examples, since the necessary technical solutions were not adopted, their corresponding performance tests were significantly worse than those of the examples. Compared with Example 1, in Comparative Example 1, commercially available pseudo-boehmite was used to replace the modified pseudo-boehmite, resulting in a decrease in the purity of 2-nitro-4-acetamidobenzene; compared with Example 1, in Comparative Example 2, commercially available activated carbon was used to replace the aminated activated carbon, resulting in a decrease in the purity of 2-nitro-4-acetamidobenzene; compared with Example 1, in Comparative Example 3, the amount of acetic anhydride was adjusted from 4000 parts to 2000 parts, and the amount of acetyl chloride was adjusted from 2000 parts to 4000 parts. As a result, the amount of acetic anhydride was too small, and the compounding effect of the acetylation reagent was poor, resulting in a decrease in the purity of 2-nitro-4-acetamidobenzene; compared with Example 1, in Comparative Example 4, the amount of acetic anhydride was adjusted from 4000 parts to 5000 parts, and the amount of acetyl chloride was adjusted from 2000 parts to 1000 parts. As a result, the amount of acetic anhydride was too small, and the compounding effect of the acetylation reagent was poor, resulting in a decrease in the purity of 2-nitro-4-acetamidobenzene; compared with Example 1, in Comparative Example 5, a nitric acid solution with a mass concentration of 40% was used to replace the nitric acid solution with a mass concentration of 65%, resulting in a decrease in the purity of 2-nitro-4-acetamidobenzene; compared with Example 1, in Comparative Example 6, a nitric acid solution with a mass concentration of 80% was used to replace the nitric acid solution with a mass concentration of 65%, resulting in a decrease in the purity of 2-nitro-4-acetamidobenzene. The above experimental results further prove the importance of the technical solutions defined in the present invention for its technical effects.

[0044] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A continuous industrial production method of 2-nitro-4-acetamidoanisole, characterized in that: The following steps are involved: Step S1: adding 2500-2800 parts of p-aminoanisole to 3000-3200 parts of acetic acid by weight and stirring for 30-40 minutes, then adding 5000-6000 parts of acetylating agent to carry out acetylation reaction, removing the acetylating agent through pseudo-boehmite after the reaction is completed, then extracting, precipitating crystals, filtering, washing with water to neutrality, and drying to obtain an intermediate product; Step S2: In parts by weight, 1000-1200 parts of the intermediate product are added to 2800-3000 parts of the first acid solution, stirred for 30-60 minutes, and then 600-800 parts of the second acid solution are added to carry out nitration reaction. After the reaction is completed, purification treatment is carried out by amino activated carbon, and then crystallization is precipitated, filtered, washed with water, and dried to obtain 2-nitro-4-acetamidoanisole.

2. A continuous industrial production method of 2-nitro-4-acetamidoanisole according to claim 1, characterized in that: The acetylating agents are acetic anhydride and acetyl chloride.

3. A continuous industrial production method of 2-nitro-4-acetamidoanisole according to claim 2, characterized in that, The mass ratio of the acetic anhydride to acetyl chloride is (1-2):

1.

4. A continuous industrial production method of 2-nitro-4-acetamidoanisole according to claim 1, characterized in that: The conditions of the acetylation reaction include: a reaction temperature of 70-75° C. and a reaction time of 1-2 h.

5. A continuous industrial production method of 2-nitro-4-acetamidoanisole according to claim 1, characterized in that: The pseudo-boehmite is modified pseudo-boehmite.

6. A continuous industrial production method of 2-nitro-4-acetamidoanisole according to claim 5, characterized in that: The preparation method of the modified pseudo-boehmite comprises: In parts by weight, 4 to 5 parts of diammonium hydrogen phosphate are added to 20 to 30 parts of deionized water, and stirred to dissolve to obtain a diammonium hydrogen phosphate aqueous solution; 20 to 30 parts of pseudo-boehmite are added to 80 to 100 parts of deionized water, and stirred for 0.5 to 0.8 hours to obtain a pseudo-boehmite aqueous solution, and then the diammonium hydrogen phosphate aqueous solution is added dropwise, stirred for 1 to 2 hours, and then a nitric acid solution with a mass concentration of 20 to 30% is added dropwise to adjust the pH to 5 to 6, stirred for 6 to 8 hours, and allowed to stand at room temperature for 15 to 20 hours, and then heat treated at 110 to 120° C. for 2 to 3 hours, and cooled to room temperature to obtain modified pseudo-boehmite.

7. A continuous industrial production method of 2-nitro-4-acetamidoanisole according to claim 1, characterized in that: The first acid solution is a sulfuric acid solution with a mass concentration of 90-93%.

8. A continuous industrial production method of 2-nitro-4-acetamidoanisole according to claim 1, characterized in that: The second acid solution is a nitric acid solution with a mass concentration of 60-65%.

9. A continuous industrial production method of 2-nitro-4-acetamidoanisole according to claim 1, characterized in that: The conditions of the nitration reaction include: reaction temperature of 10-20° C., and reaction time of 50-60 min.

10. A continuous industrial production method of 2-nitro-4-acetamidoanisole according to claim 1, characterized in that: The preparation method of the aminated activated carbon comprises: adding 3 to 5 parts of activated carbon to 16 to 20 parts of nitric acid solution with a mass concentration of 10% by weight, performing an amination treatment at 70 to 75° C. for 4 to 6 hours, and filtering, washing and drying the product to obtain the aminated activated carbon.

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