A multi-point feeding and solvent-free continuous production process of acetoacetanilide

Abstract

The invention discloses a multi-point feeding and solvent-free continuous production process of acetoacetanilide, comprising: after aniline is laid on the bottom of a reactor 1, aniline and diketene are continuously added in equal proportions for acylation reaction, after the reaction liquid enters a reactor 2, aniline and diketene are continuously added in equal proportions for acylation reaction, after the reaction liquid enters a reactor 3, aniline and diketene are continuously added in equal proportions for acylation reaction; the reaction temperature, reaction time and solid content are strictly controlled in each reactor; after the reaction is completed, the acetoacetanilide finished product is obtained by post-processing. The material contact time is shorter, the reaction rate is high, the acetylation impurity content is low, the solvent-free method reduces the use of alcohol and does not involve wastewater discharge, saves production costs, and has broad application prospects.

Description

Technical Field

[0001] The invention relates to a multi-point feeding and solvent-free continuous production process of acetoacetanilide, belonging to the technical field of chemical synthesis. Background Art

[0002] Appearance: White or slightly yellow powder.

[0003] Molecular weight: 177.2

[0004] Melting point: 83-88℃

[0005] Boiling point: 129°C

[0006] Density: 1.26

[0007] Flash point: 163℃

[0008] Water solubility: 5g / L (20℃)

[0009] Acetoacetanilide, referred to as AAA, is an intermediate for dyes, pigments and pesticides. It is used to manufacture pyrazolone, acid complex yellow GR, neutral dark yellow GL, neutral RL, pigment fast yellow G, etc. It has multiple nucleophilic and electrophilic active centers and can undergo alkylation, halogenation, diazotization, addition and condensation reactions. It is an important intermediate in the chemical, pharmaceutical, pigment and dye industries.

[0010] Acetoacetanilide is obtained by reacting diketene with aniline. Aniline and diketene react at 0-15℃ to generate acetoacetanilide. It has the advantages of simple process, high yield and good quality. It is the most widely used process in industry. The reaction equation is:

[0011]

[0012] At present, the intermittent batch production process using ethanol or acetone as the solvent is mostly adopted, which has the problem of batch instability. The contact time between aniline and diketene in the intermittent batch reactor is relatively long, which is easy to generate acetanilide impurities, affecting the performance of downstream products; with the increase of the number of times the alcohol mother liquor is used, the pigment and acetyl impurities are enriched, and they must be eliminated after a certain number of uses. After the alcohol is recovered, some products dissolved in the mother liquor cannot be recovered due to too many impurities and can only be incinerated, while a large amount of wastewater is generated, and the production cost is high.

[0013] The multi-point feeding process of continuous production can avoid the problem of batch stability of intermittent processes. It also has the characteristics of short material contact time, rapid reaction, mild reaction conditions, and low impurity generation. It has some applications in the production of diisobutyryl peroxide, aluminum sulfate, and sodium dehydroacetate. For example, patent CN201911371816 reports a method for continuous production of diisobutyryl peroxide by multi-point feeding and enhanced mixing. The invention uses multiple flow reactors for salt formation and synthesis reactions, which achieves second-level mixing of reaction materials and improves reaction efficiency, reduces the occurrence of side reactions such as easy hydrolysis of acyl chlorides, and reduces labor costs through continuous production, avoiding the problem of batch stability of intermittent processes; patent CN202111443940 reports a continuous production process and device for aluminum sulfate with by-product steam. The invention designs a tubular reactor with multi-point feeding and enhanced mixing, and uses concentrated sulfuric acid to pass through The multi-point feeding method reacts with the aluminum hydroxide suspension to react neutrally. The liquid phase extraction stream of the steam generating device undergoes two heat exchanges, and is successively cooled by the alkaline raw material and the concentrated acid raw material before entering the product separation device, thereby improving the production efficiency. At the same time, steam is produced as a by-product, which improves the economic benefits of the production process. Patent CN112876440A reports a method for preparing sodium dehydroacetate by multi-stage neutralization and distribution reaction. The method has a mild reaction rate, which not only avoids the problem of abnormal product appearance when the acid is too acidic, but also avoids the problem of reactor flushing when the alkalinity is too high. At the same time, the step-by-step neutralization and stage temperature control process reduce the generation and enrichment of impurities. Among these methods, multi-point feeding is only a means. The relevant production processes of different products are quite different and need to be improved in combination with the products in a targeted manner. It also cannot solve the problem of large wastewater treatment volume. At present, there is no efficient multi-point feeding process for the production of acetoacetanilide. Summary of the invention

[0014] Aiming at the problems that the acetoacetanilide product batches produced by the existing intermittent autoclave process are unstable, the acetoacetanilide impurity content is high, and the wastewater treatment volume is large, the present invention uses aniline and diketene to feed at multiple points and react without solvent, so that the material contact time is shorter, the reaction rate is improved, and the acetylated impurity content is reduced. At the same time, the solvent-free method reduces the use of alcohol and does not involve the problem of wastewater discharge, thus saving production costs and having broad application prospects.

[0015] The present invention adopts multi-point feeding and solvent-free method to develop a new continuous process for preparing acetoacetanilide, improves the residence time and solid content of each reactor in a targeted manner, and obtains the best yield. The method combines the advantages of multi-point feeding and solvent-free process, does not use solvent in the reaction process, not only overcomes the harm of using solvent in the reaction to the environment, is conducive to reducing costs, but also greatly improves the selectivity and conversion rate of the reaction, shortens the reaction cycle, and greatly reduces the requirements of reaction conditions.

[0016] The technical scheme of the present invention is as follows: a multi-point feeding and solvent-free continuous production process of acetoacetanilide, the specific steps of which are as follows:

[0017] (1) After aniline is laid on the bottom of the reactor 1, aniline and diketene are continuously added in equal proportions to carry out acylation reaction at a reaction temperature of 15 to 20° C. for a reaction time of 0.5 h to 1 h, and the solid content is maintained at 10% to 15%;

[0018] (2) When the liquid level in reactor 1 reaches 1 / 2 and overflows into reactor 2, aniline and diketene are continuously added in equal proportions to carry out acylation reaction at a reaction temperature of 20 to 30° C. for a reaction time of 1 h to 1.5 h, and the solid content is maintained at 20% to 25%;

[0019] (3) When the liquid level in reactor 2 reaches 1 / 2 and overflows into reactor 3, aniline and diketene are continuously added in equal proportions to carry out acylation reaction at a reaction temperature of 30 to 35° C. for 1 to 2 hours, maintaining a solid content of 30% to 40%;

[0020] (4) After the reaction is completed, the mixture is placed in a heat preservation kettle for heat preservation at 30°C to 35°C for 1 to 3 hours;

[0021] (5) After the reaction is completed, the mixture is sent to a cooling kettle for cooling and crystallization, and the acetoacetanilide product is obtained after centrifugal washing and drying.

[0022] In one embodiment of the present invention, preferably, the amount of aniline base solution in the reaction kettle 1 in step (1) is 3 to 5 times the total amount of raw materials added to the reaction kettle 1.

[0023] In one embodiment of the present invention, preferably, the reaction temperature in the reaction vessel 1 of step (1) is 15-18°C.

[0024] In one embodiment of the present invention, preferably, the reaction time in the reactor 1 of step (1) is 0.5h to 0.8h.

[0025] In one embodiment of the present invention, preferably, in step (1), the solid content in the reactor 1 is maintained at 10% to 13%;

[0026] In one embodiment of the present invention, preferably, the reaction temperature in the reaction vessel 2 of step (2) is 25-30°C.

[0027] In one embodiment of the present invention, the reaction time in the reactor 2 of step (2) is 1 h to 1.2 h.

[0028] In one embodiment of the present invention, in step (2), the solid content in the reaction kettle 2 is maintained at 22% to 25%;

[0029] In one embodiment of the present invention, preferably, the reaction temperature in the reaction kettle 3 of step (3) is 30-33°C.

[0030] In one embodiment of the present invention, preferably, the reaction time in the reactor 3 of step (3) is 1 h to 1.5 h.

[0031] In one embodiment of the present invention, preferably, in step (3), the solid content in the reaction kettle 3 is maintained at 30% to 35%;

[0032] In one embodiment of the present invention, preferably, the heat preservation kettle in step (4) is kept at 30°C to 33°C for 1 to 2 hours.

[0033] The invention also provides acetoacetanilide produced by the process and its application in chemical industry, medicine, pigment and dye industries.

[0034] Beneficial effects of the present invention:

[0035] 1. The new continuous process for preparing acetoacetanilide developed by the present invention combines the advantages of multi-point feeding and solvent-free process, improves the production process in a targeted manner, especially the reaction time and solid content of each reactor, and obtains the best yield.

[0036] 2. The method of the present invention allows for a more sufficient contact time of the materials, shortens the acylation reaction time, increases the reaction rate and reduces the acetylation impurity content.

[0037] 3. The method of the present invention does not use solvents during the reaction process, reduces the use of alcohol and does not involve wastewater discharge problems, saves production costs, adopts a continuous production method instead of intermittent production, improves production efficiency, is easy to realize automatic control, and has good product quality stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0039] Test / Calculation Method:

[0040] Yield = actual product output / theoretical product output

[0041] Content determination and calculation: Weigh 0.025g of the product into a 25ml volumetric flask, dilute with equal volumes of methanol and water, filter and enter into a high performance liquid chromatograph, the peak appearing at 14min is the main peak of N-acetoacetanilide; content = peak area of ​​target peak (peak appearing at 14min) / peak area of ​​all peaks.

[0042] Example 1

[0043] A multi-point feeding and solvent-free continuous production process of acetoacetanilide comprises the following steps:

[0044] 720g of aniline was added to reactor 1 as a bottom, and 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 15°C, the reaction time was 0.5h, and the solid content was controlled to be 10%. When the liquid level of reactor 1 reached 1 / 2 and overflowed into reactor 2, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 25°C, the reaction time was 1h, and the solid content was controlled to be 22%. When the liquid level of reactor 2 reached 1 / 2 and overflowed into reactor 3, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 30°C, and the reaction time was 1.5h. The feed liquid with a solid content of 30% was moved into an insulation kettle and insulation began. It was kept at 30°C for 2h. After the insulation was completed, it was put into a cooling crystallization kettle for cooling and crystallization. After centrifugation, washing and drying, the acetoacetanilide product was obtained with a yield of 98.71% and a content of 99.85%.

[0045] Embodiment 2:

[0046] A multi-point feeding and solvent-free continuous production process of acetoacetanilide comprises the following steps:

[0047] 800g of aniline was added to reactor 1 as a bottom, and 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 18°C, the reaction time was 0.8h, and the solid content was controlled to be 13%. When the liquid level of reactor 1 reached 1 / 2 and overflowed into reactor 2, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 30°C, the reaction time was 1.2h, and the solid content was controlled to be 25%. When the liquid level of reactor 2 reached 1 / 2 and overflowed into reactor 3, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 33°C, and the reaction time was 1h. The feed liquid with a solid content of 33% was moved into an insulation kettle and insulation was started. It was kept at 35°C for 1h. After the insulation was completed, it was put into a cooling crystallization kettle for cooling and crystallization. After centrifugation, washing and drying, the acetoacetanilide product was obtained with a yield of 98.79% and a content of 99.89%.

[0048] Embodiment 3:

[0049] A multi-point feeding and solvent-free continuous production process of acetoacetanilide comprises the following steps:

[0050] 600g of aniline was added to reactor 1 as a bottom, and 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 16°C, the reaction time was 1h, and the solid content was controlled to be 15%. When the liquid level of reactor 1 reached 1 / 2 and overflowed into reactor 2, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 30°C, the reaction time was 1h, and the solid content was controlled to be 24%. When the liquid level of reactor 2 reached 1 / 2 and overflowed into reactor 3, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 35°C, and the reaction time was 1.5h. The feed liquid with a solid content of 40% was moved into an insulation kettle and insulation began. It was kept at 35°C for 1.5h. After the insulation was completed, it was put into a cooling crystallization kettle for cooling and crystallization. After centrifugation, washing and drying, the acetoacetanilide product was obtained with a yield of 98.65% and a content of 99.78%.

[0051] Embodiment 4:

[0052] A multi-point feeding and solvent-free continuous production process of acetoacetanilide comprises the following steps:

[0053] 850g of aniline was added to reactor 1 as a bottom, and 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 20°C, the reaction time was 0.5h, and the solid content was controlled to be 13%. When the liquid level of reactor 1 reached 1 / 2 and overflowed into reactor 2, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 30°C, the reaction time was 1h, and the solid content was controlled to be 25%. When the liquid level of reactor 2 reached 1 / 2 and overflowed into reactor 3, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 31°C, the reaction time was 1h, and the feed liquid with a solid content of 35% was moved into an insulation kettle and insulation began. It was kept at 31°C for 2h. After the insulation was completed, it was put into a cooling crystallization kettle for cooling and crystallization. After centrifugation, washing and drying, the acetoacetanilide product was obtained with a yield of 98.85% and a content of 99.91%.

[0054] Example 5: Effect of reaction conditions on products

[0055] Compared with Example 1, the reaction temperature of step 1 was changed, and other processes and parameters remained the same, specifically:

[0056] 720g of aniline was added to reactor 1 as a bottom, and 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 5°C, the reaction time was 0.5h, and the solid content was controlled to be 10%. When the liquid level of reactor 1 reached 1 / 2 and overflowed into reactor 2, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 25°C, the reaction time was 1h, and the solid content was controlled to be 22%. When the liquid level of reactor 2 reached 1 / 2 and overflowed into reactor 3, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 30°C, and the reaction time was 1.5h. The feed liquid with a solid content of 30% was moved into an insulation kettle and insulation began. It was kept at 30°C for 2h. After the insulation was completed, it was put into a cooling crystallization kettle for cooling and crystallization. After centrifugation, washing and drying, the acetoacetanilide product was obtained with a yield of 97.72% and a content of 99.81%.

[0057] Example 6: Effect of reaction conditions on products

[0058] Compared with Example 1, the reaction time of step 2 was changed, and other processes and parameters remained the same, specifically:

[0059] 720g of aniline was added to reactor 1 as a bottom, and 93.13g of aniline and 87.04g of diketene were added in equal proportions. The reaction temperature was 15°C, the reaction time was 0.5h, and the solid content was controlled to be 10%. When the liquid level of reactor 1 reached 1 / 2 and overflowed into reactor 2, 93.13g of aniline and 87.04g of diketene were added in equal proportions. The reaction temperature was 25°C, the reaction time was 0.5h, and the solid content was controlled to be 22%. When the liquid level of reactor 2 reached 1 / 2 and overflowed into reactor 3, 93.13g of aniline and 87.04g of diketene were added in equal proportions. The reaction temperature was 30°C, and the reaction time was 1.5h. The feed liquid with a solid content of 30% was moved into an insulation kettle and insulation began. It was kept at 30°C for 2h. After the insulation was completed, it was put into a cooling crystallization kettle for cooling and crystallization. After centrifugation, washing and drying, the acetoacetanilide product was obtained with a yield of 98.51% and a content of 99.89%.

[0060] Comparative Example 1: Effect of feeding method on product

[0061] Compared with Example 1, a one-time feeding method is adopted, and other processes and parameters are kept consistent, specifically:

[0062] 720g of aniline was added to the reactor 1 as the bottom, and 93.13g of aniline and 87.04g of diketene were added in equal proportions. The reaction temperature was 30°C and the reaction time was 1.5h. The feed liquid with a solid content of 30% was transferred into the insulation kettle and insulation began. It was kept at 30°C for 3h. After the insulation was completed, it was placed in a cooling crystallization kettle for cooling and crystallization. After centrifugation, washing and drying, the acetoacetanilide product was obtained with a yield of 95.27% and a content of 96.85%.

[0063] Comparative Example 2: Effect of reaction time on product in step 1

[0064] Compared with Example 1, the reaction time of step 1 is changed, specifically:

[0065] 720g of aniline was added to reactor 1 as a bottom, and 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 15°C, the reaction time was 0.3h, and the solid content was controlled to be 10%. When the liquid level of reactor 1 reached 1 / 2 and overflowed into reactor 2, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 25°C, the reaction time was 1h, and the solid content was controlled to be 22%. When the liquid level of reactor 2 reached 1 / 2 and overflowed into reactor 3, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 30°C, and the reaction time was 1.5h. The feed liquid with a solid content of 30% was moved into an insulation kettle and insulation began. It was kept at 30°C for 2h. After the insulation was completed, it was put into a cooling crystallization kettle for cooling and crystallization. After centrifugation, washing and drying, the acetoacetanilide product was obtained with a yield of 95.71% and a content of 99.23%.

[0066] Comparative Example 3: Effect of solid content in step 1 on the product

[0067] Compared with Example 1, the solid content of step 1 was changed, and other processes and parameters remained the same, specifically:

[0068] 720g of aniline was added to reactor 1 as a bottom, and 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 15°C, the reaction time was 0.5h, and the solid content was controlled to be 8%. When the liquid level of reactor 1 reached 1 / 2 and overflowed into reactor 2, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 25°C, the reaction time was 1h, and the solid content was controlled to be 22%. When the liquid level of reactor 2 reached 1 / 2 and overflowed into reactor 3, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 30°C, and the reaction time was 1.5h. The feed liquid with a solid content of 30% was moved into an insulation kettle and insulation began. It was kept at 30°C for 2h. After the insulation was completed, it was put into a cooling crystallization kettle for cooling and crystallization. After centrifugation, washing and drying, the acetoacetanilide product was obtained with a yield of 94.23% and a content of 98.65%.

[0069] Comparative Example 4: Effect of solid content in step 2 on the product

[0070] Compared with Example 1, the solid content of step 2 was changed, and other processes and parameters remained the same, specifically:

[0071] 720g of aniline was added to reactor 1 as a bottom, and 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 15°C, the reaction time was 0.5h, and the solid content was controlled to be 10%. When the liquid level of reactor 1 reached 1 / 2 and overflowed into reactor 2, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 25°C, the reaction time was 1h, and the solid content was controlled to be 15%. When the liquid level of reactor 2 reached 1 / 2 and overflowed into reactor 3, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 30°C, and the reaction time was 1.5h. The feed liquid with a solid content of 30% was moved into an insulation kettle and insulation began. It was kept at 30°C for 2h. After the insulation was completed, it was put into a cooling crystallization kettle for cooling and crystallization. After centrifugation, washing and drying, the acetoacetanilide product was obtained with a yield of 95.51% and a content of 97.73%.

[0072] Comparative Example 5: Effect of reaction time in step 3 on the product

[0073] Compared with Example 1, the reaction time in step 3 was changed, and other processes and parameters remained the same, specifically:

[0074] 720g of aniline was added to reactor 1 as a bottom, and 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 15°C, the reaction time was 0.5h, and the solid content was controlled to be 10%. When the liquid level of reactor 1 reached 1 / 2 and overflowed into reactor 2, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 25°C, the reaction time was 1h, and the solid content was controlled to be 22%. When the liquid level of reactor 2 reached 1 / 2 and overflowed into reactor 3, 93.13g of aniline and 87.04g of diketone were added in equal proportions. The reaction temperature was 30°C, and the reaction time was 0.5h. The feed liquid with a solid content of 30% was moved into an insulation kettle and insulation began. It was kept at 30°C for 2h. After the insulation was completed, it was put into a cooling crystallization kettle for cooling and crystallization. After centrifugation, washing and drying, the acetoacetanilide product was obtained with a yield of 96.71% and a content of 98.19%.

[0075] The present invention is disclosed above with preferred embodiments, which are not intended to limit the present invention. Any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the protection scope of the present invention.

Claims

1. A multi-point feeding and solvent-free continuous production process of acetoacetanilide, characterized in that: The steps of the process are as follows: (1) After aniline is laid on the bottom of the reactor 1, aniline and diketene are continuously added in equal proportions to carry out acylation reaction at a reaction temperature of 15 to 20° C. for a reaction time of 0.5 h to 1 h, and the solid content is maintained at 10% to 15%; (2) When the liquid level in reactor 1 reaches 1 / 2 and overflows into reactor 2, aniline and diketene are continuously added in equal proportions to carry out acylation reaction at a reaction temperature of 20 to 30° C. for a reaction time of 1 h to 1.5 h, and the solid content is maintained at 20% to 25%; (3) When the liquid level in reactor 2 reaches 1 / 2 and overflows into reactor 3, aniline and diketene are continuously added in equal proportions to carry out acylation reaction at a reaction temperature of 30 to 35° C. for 1 to 2 hours, maintaining a solid content of 30% to 40%; (4) After the reaction is completed, the mixture is placed in a heat preservation kettle for heat preservation at 30°C to 35°C for 1 to 3 hours; (5) After the reaction is completed, the mixture is sent to a cooling kettle for cooling and crystallization, and the acetoacetanilide product is obtained after centrifugal washing and drying.

2. The process according to claim 1, characterized in that Step (1) The amount of aniline base solution in the reaction kettle 1 is 3 to 5 times the total amount of raw materials added to the reaction kettle 1.

3. The process according to claim 1, characterized in that Step (1) The reaction temperature in the reactor 1 is 15-18°C.

4. The process according to claim 1, characterized in that The reaction time in step (1) reactor 1 is 0.5h to 0.8h.

5. The process according to claim 1, characterized in that Step (1) The solid content in the reactor 1 is maintained at 10% to 13%.

6. The process according to claim 1, characterized in that Step (2) The reaction temperature in the reactor 2 is 25-30° C. and the reaction time is 1 h to 1.2 h.

7. The process according to claim 1, characterized in that Step (2) The solid content in the reactor 2 is maintained at 22% to 25%.

8. The process according to claim 1, characterized in that Step (3) The reaction temperature in the reactor 3 is 30-33° C., the reaction time is 1 h-1.5 h, and the solid content is maintained at 30%-35%.

9. The process according to claim 1, characterized in that In step (4), the kettle is kept warm at 30°C to 33°C for 1 to 2 hours.

Images