Method for synthesizing 4-acetylpyridine from pyridine
By reacting pyridine with acetic anhydride and iron powder, and by improving the stirring and oxidation reaction of xylene, the problems of low yield and inability to recover catalyst in the synthesis of 4-acetylpyridine were solved, and efficient and low-cost industrial production was achieved.
Patent Information
- Application Number
- CN202511823735.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-01-23
AI Technical Summary
In the existing technology, the synthesis process of 4-acetylpyridine has problems such as low yield, high raw material cost and inability to recycle the catalyst, which makes it difficult to meet the needs of industrial production.
The oxidation reaction was carried out by reacting pyridine with acetic anhydride and iron powder, followed by the addition of xylene and stirring. The temperature was controlled, and the conversion rate was improved by vacuum oxygen replacement and micro-positive pressure. N-hydroxyphthalimide was used as a catalyst and was recovered. Water was removed before distillation to solve the azeotropic problem.
The synthesis of 4-acetylpyridine with high yield (58-60%) and high purity (98.5-99.8% gas phase content) was achieved, reducing raw material costs. Furthermore, the catalyst N-hydroxyphthalimide can be recycled, and the reaction steps are simplified.
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Figure CN121378115A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of organic synthesis, in particular to a method for synthesizing 4-acetylpyridine from pyridine. BACKGROUND
[0002] 4-acetylpyridine (4-AP), CAS:1122-54-9, molecular formula C7H7NO, molecular weight 121.14, colorless to pale yellow liquid, melting point 13-16℃, boiling point 212.8℃, easily soluble in ethanol, diethyl ether, ethyl acetate, chloroform and water, and should be stored separately from oxidants and acids. It is an important intermediate in the pharmaceutical, pesticide and chemical industries. As an important raw material for the ion membrane project of the company, in order to improve profits and ensure the supply of raw materials, a process route with high yield and suitable for industrial production is urgently needed. SUMMARY
[0003] To solve the problems raised in the above background art, the present application discloses a method for synthesizing 4-acetylpyridine from pyridine. The raw materials used in this method are cheap, and the catalyst N-hydroxyphthalimide used in the oxidation reaction can be recycled.
[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme: The present application provides a method for synthesizing 4-acetylpyridine, comprising the following steps: (1) After nitrogen replacement, pyridine and acetic anhydride are added to the reaction bottle, and stirring is carried out to heat to 80℃. Iron powder A is added in 6 times with 1h interval. After the addition of iron powder is completed, water A is slowly added dropwise for 30-60min with temperature control at 80-97℃. Then, iron powder B is added in 4 times with 30-60min interval at a temperature of 85-90℃. After the addition of iron powder is completed, dimethylbenzene is added, and the temperature is raised to 135-140℃ for 3-5h of reaction. After the reaction is completed, the temperature is lowered to 70-80℃, water B is added, and then the pH is adjusted to 9-10 with sodium hydroxide aqueous solution. The reaction liquid is distilled, the distilled fraction is added to a saturated inorganic salt aqueous phase, and after standing and separation, the lower water layer is separated. The water layer is extracted with dimethylbenzene for 3 times, then the oil layer is combined, and after water removal with anhydrous magnesium sulfate or 3A molecular sieve, 4-ethylpyridine is obtained by distillation. (2) Oxidation reaction: 4-ethylpyridine, catalyst and butyl acetate are added to the reaction bottle. After the addition is completed, vacuum oxygen is replaced for 3 times, then oxygen is introduced from the liquid bottle to maintain a slight positive pressure of 0.1-0.2MPa in the reaction system, and stirring is carried out at 100℃ for 10-12h of reaction. After the reaction is completed, sodium carbonate aqueous solution is added, stirring is carried out, and then the lower water layer is separated. The water layer is extracted with butyl acetate for 2 times, the oil layer is combined, and after distillation, 4-acetylpyridine is obtained.
[0005] (3) Catalyst recovery of the oxidation reaction: the water phase separated in the oxidation reaction post-treatment is adjusted in pH with 37% hydrochloric acid, then distilled, suction filtered, the filter cake is washed with 30-40℃ water and then suction filtered again, and the recovered catalyst N-hydroxyphthalimide is obtained after vacuum drying at 40℃.
[0006] Further, the mass ratio of acetic anhydride to pyridine in step (1) is 3.2-4:1, the mass ratio of iron powder A to pyridine is 0.8-1:1, and the mesh number of the iron powder is 200-400.
[0007] Further, the mass ratio of water A to pyridine in step (1) is 0.1-0.2:1, the mass ratio of water B to pyridine is 5-10:1, and the mass ratio of dimethylbenzene to pyridine is 3-5:1.
[0008] Further, the inorganic salt used in the saturated water phase in step (1) is sodium chloride, potassium chloride, sodium carbonate or potassium carbonate, and the extraction temperature is 30-40℃.
[0009] Further, the concentration of the sodium hydroxide aqueous solution in step (1) is 30-50%.
[0010] Further, the distillation mode of the reaction liquid in step (1) is water vapor distillation or simple distillation under normal pressure.
[0011] Further, the catalyst in step (2) is cobalt acetate tetrahydrate or a mixture of cobalt acetate and N-hydroxyphthalimide.
[0012] Further, the molar ratio of cobalt acetate tetrahydrate or cobalt acetate to 4-ethylpyridine in step (2) is 0.01-0.03:1, and the molar ratio of N-hydroxyphthalimide to 4-ethylpyridine is 0.1-0.3:1.
[0013] Further, the mass ratio of butyl acetate to 4-ethylpyridine in step (2) is 6-10:1.
[0014] Further, the mass ratio of sodium carbonate to 4-ethylpyridine in step (2) is 0.5-0.8:1, and the concentration of the sodium carbonate aqueous solution is 5-20%.
[0015] Further, the extraction temperature in step (2) is 60-70℃.
[0016] Further, the pH range adjusted with 37% hydrochloric acid in step (3) is 1-2.
[0017] Compared with the prior art, the present application has the following beneficial effects: (1) The reaction steps of the present application are short, and the raw materials are cheap.
[0018] (2) The present application solves the problem that the reaction liquid flowability will become poor and the stirring paddle will be dead after adding iron powder when synthesizing 4-ethylpyridine by adding dimethylbenzene.
[0019] (3) The present application solves the problem of ternary azeotropy of water, pyridine and 4-ethylpyridine by removing water before rectification.
[0020] (4) The present application significantly improves the conversion rate by vacuum oxygen replacement and micro-positive pressure reaction before oxidation reaction, and the catalyst N-hydroxyphthalimide can be recycled. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 The gas phase spectrum of 4-acetylpyridine synthesized in Example 1 of the present application; Figure 2 The infrared spectrum of recycled N-hydroxyphthalimide in Example 1 of the present application. DETAILED DESCRIPTION
[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. Example 1
[0023] After nitrogen replacement, 70g of pyridine and 226.8g of acetic anhydride were added to the reaction bottle, and the temperature was raised to 80℃. 57.8g of iron powder was added in 6 times with 1h, and 10.5mL of water was slowly added dropwise for 30min, and the temperature was controlled at 80-97℃. Then the temperature was controlled at 85-90℃, 36g of iron powder was added in 4 times for 30min, 300g of dimethylbenzene was added after the iron powder was added, and the temperature was raised to 135-140℃ for 4h. After the reaction was completed, the temperature was lowered to 70-80℃, 600mL of water was added, and then the pH was adjusted to 9-10 with 30% sodium hydroxide aqueous solution. The reaction liquid was distilled, the distilled fraction was added to the saturated potassium carbonate aqueous phase, and after standing and layering, the lower water layer was separated, the water layer was extracted with dimethylbenzene for 3 times, then the oil layer was combined, and after drying with anhydrous magnesium sulfate, 55g of 4-ethylpyridine was obtained by rectification. The yield was 58%, and the gas phase content was 98.7%.
[0024] Into a reaction flask, 55 g of 4-ethylpyridine, 2.56 g of cobalt acetate tetrahydrate, 16.75 g of N-hydroxyphthalimide, and 440 g of butyl acetate were charged, after which the reaction system was replaced with oxygen three times in vacuum, and then oxygen was bubbled into the system to maintain a pressure of 0.15 MPa. The reaction was stirred at 100°C for 12 h, after which 770 g of a 5% sodium carbonate aqueous solution was added, and the lower aqueous layer was separated after stirring and standing. The aqueous layer was extracted twice with butyl acetate, and the oil layers were combined and distilled to obtain 4-acetylpyridine. The yield was 50% (based on 4-ethylpyridine), and the gas chromatogram is shown in Figure 1 .
[0025] The aqueous phase separated from the oxidation reaction was adjusted to a pH of 1-2 with 37% hydrochloric acid, and then distilled, suction filtered, and washed with water at 30-40°C. The filter cake was suction filtered again, and dried at 40°C in vacuum to obtain recovered N-hydroxyphthalimide. The recovery rate was 60%. The infrared spectrum of the recovered N-hydroxyphthalimide is shown in Figure 2 , which is consistent with the infrared spectrum of the new catalyst N-hydroxyphthalimide, and it was determined that the recovered product was N-hydroxyphthalimide. Example 2
[0026] After nitrogen replacement, 70 g of pyridine and 226.8 g of acetic anhydride were charged into a reaction flask, and stirred to warm to 80°C. 57.8 g of iron powder was added in six portions over 1 h, and 10.5 mL of water was slowly added dropwise over 30 min while controlling the temperature at 80-97°C. Then, 36 g of iron powder was added in four portions over 30 min while controlling the temperature at 85-90°C. After the addition of the iron powder was completed, 300 g of dimethylbenzene was added, and the temperature was raised to 135-140°C for reaction for 4 h. After the reaction was completed, the temperature was lowered to 70-80°C, 600 mL of water was added, and then the pH was adjusted to 9-10 with a 50% sodium hydroxide aqueous solution. The reaction liquid was distilled, and the fraction distilled was added to a saturated sodium chloride aqueous phase, and the lower aqueous layer was separated after standing. The aqueous layer was extracted three times with dimethylbenzene, and then the oil layers were combined, dried with anhydrous magnesium sulfate, and distilled to obtain 54 g of 4-ethylpyridine. The yield was 57%, and the gas chromatographic content was 98.5%.
[0027] Into a reaction flask, 54 g of 4-ethylpyridine, 1.78 g of cobalt acetate, 16.44 g of N-hydroxyphthalimide, and 432 g of butyl acetate were charged, after which the reaction system was replaced with oxygen three times in vacuum, and then oxygen was bubbled into the system to maintain a pressure of 0.15 MPa. The reaction was stirred at 100°C for 12 h, after which 380 g of a 10% sodium carbonate aqueous solution was added, and the lower aqueous layer was separated after stirring and standing. The aqueous layer was extracted twice with butyl acetate, and the oil layers were combined and distilled to obtain 4-acetylpyridine. The yield was 48% (based on 4-ethylpyridine), and the gas chromatographic content was 98.5%.
[0028] The water phase separated from the oxidation reaction was adjusted to pH 1-2 with 37% hydrochloric acid, then distilled, suction filtered, the filter cake was washed with 30-40°C water and then suction filtered again, and then dried at 40°C under vacuum to obtain recovered N-hydroxyphthalimide with a recovery rate of 58%. Example 3
[0029] After nitrogen replacement, 70 g of pyridine and 226.8 g of acetic anhydride were added to the reaction bottle, and stirring was performed to raise the temperature to 80°C. 57.8 g of iron powder was added in 6 portions over 1 h, and 15 mL of water was slowly added dropwise over 45 min while controlling the temperature at 80-97°C. Then, 36 g of iron powder was added in 4 portions over 30 min while controlling the temperature at 85-90°C. After the addition of the iron powder was completed, 300 g of dimethylbenzene was added, and the temperature was raised to 135-140°C for reaction for 4 h. After the reaction was completed, the temperature was lowered to 70-80°C, 600 mL of water was added, and then the pH was adjusted to 9-10 with 30% sodium hydroxide aqueous solution. The reaction liquid was distilled, and the distilled fraction was added to a potassium carbonate saturated water phase. After standing and separation, the lower water layer was separated, and then the water layer was extracted with dimethylbenzene 3 times. Then, the oil layer was combined, and then anhydrous magnesium sulfate was added to remove water, and then refined to obtain 52.2 g of 4-ethylpyridine. The yield was 55%, and the gas phase content was 99.2%.
[0030] To the reaction bottle, 52.2 g of 4-ethylpyridine, 1.82 g of cobalt acetate tetrahydrate, 19.87 g of N-hydroxyphthalimide, and 418 g of butyl acetate were added. After the addition was completed, the system was vacuumed and replaced with oxygen 3 times, and then oxygen was bubbled under liquid to maintain the pressure of the reaction system at 0.15 MPa. Stirring was performed at 100°C for 12 h. After the reaction was completed, 731 g of 5% sodium carbonate aqueous solution was added, stirring was performed, and then the lower water layer was separated. The water layer was extracted with butyl acetate 2 times, the oil layer was combined, and then refined to obtain 4-acetylpyridine. The yield was 48.8% (based on 4-ethylpyridine), and the gas phase content was 99%.
[0031] The water phase separated from the oxidation reaction was adjusted to pH 1-2 with 37% hydrochloric acid, then distilled, suction filtered, the filter cake was washed with 30-40°C water and then suction filtered again, and then dried at 40°C under vacuum to obtain recovered N-hydroxyphthalimide with a recovery rate of 58%. Example 4
[0032] After nitrogen replacement, 70 g of pyridine and 245 g of acetic anhydride were put into the reaction bottle, stirred and heated to 80°C, 57.8 g of iron powder was added in 6 times within 1 h, 10.5 mL of water was slowly added dropwise within 30 min, and the temperature was controlled at 80-97°C; then the temperature was controlled at 85-90°C, 36 g of iron powder was added in 4 times within 30 min, 300 g of dimethylbenzene was added after the addition of iron powder was completed, and the temperature was increased to 135-140°C for 4 h of reaction. After the reaction was completed, the temperature was decreased to 70-80°C, 600 mL of water was added, and then 30% sodium hydroxide aqueous solution was used to adjust the pH to 9-10. The reaction liquid was distilled, the distilled fraction was added to a potassium carbonate saturated aqueous phase, and after standing and layer separation, the lower aqueous layer was separated, the aqueous layer was extracted with dimethylbenzene for 3 times, then the oil layer was combined, anhydrous magnesium sulfate was used to remove water, and then 54.2 g of 4-ethylpyridine was obtained by distillation. The yield was 57.2%, and the gas phase content was 98.4%.
[0033] After nitrogen replacement, 70 g of pyridine and 245 g of acetic anhydride were put into the reaction bottle, stirred and heated to 80°C, 57.8 g of iron powder was added in 6 times within 1 h, 10.5 mL of water was slowly added dropwise within 30 min, and the temperature was controlled at 80-97°C; then the temperature was controlled at 85-90°C, 36 g of iron powder was added in 4 times within 30 min, 300 g of dimethylbenzene was added after the addition of iron powder was completed, and the temperature was increased to 135-140°C for 4 h of reaction. After the reaction was completed, the temperature was decreased to 70-80°C, 600 mL of water was added, and then 30% sodium hydroxide aqueous solution was used to adjust the pH to 9-10. The reaction liquid was distilled, the distilled fraction was added to a potassium carbonate saturated aqueous phase, and after standing and layer separation, the lower aqueous layer was separated, the aqueous layer was extracted with dimethylbenzene for 3 times, then the oil layer was combined, anhydrous magnesium sulfate was used to remove water, and then 54.2 g of 4-ethylpyridine was obtained by distillation. The yield was 57.2%, and the gas phase content was 98.4%.
[0034] The aqueous phase separated from the oxidation reaction was adjusted to pH 1-2 with 37% hydrochloric acid, then distilled, filtered, and the filter cake was washed with 30-40°C water, then filtered again, and dried at 40°C under vacuum to obtain recovered N-hydroxyphthalimide. The recovery rate was 59.6%. Example 5
[0035] After nitrogen replacement, 70 g of pyridine and 245 g of acetic anhydride were put into the reaction bottle, stirred and heated to 80°C, 57.8 g of iron powder was added in 6 times within 1 h, 10.5 mL of water was slowly added dropwise within 30 min, and the temperature was controlled at 80-97°C; then the temperature was controlled at 85-90°C, 36 g of iron powder was added in 4 times within 30 min, 300 g of dimethylbenzene was added after the addition of iron powder was completed, and the temperature was increased to 135-140°C for 4 h of reaction. After the reaction was completed, the temperature was decreased to 70-80°C, 600 mL of water was added, and then 30% sodium hydroxide aqueous solution was used to adjust the pH to 9-10. The reaction liquid was distilled, the distilled fraction was added to a potassium carbonate saturated aqueous phase, and after standing and layer separation, the lower aqueous layer was separated, the aqueous layer was extracted with dimethylbenzene for 3 times, then the oil layer was combined, anhydrous magnesium sulfate was used to remove water, and then 54.2 g of 4-ethylpyridine was obtained by distillation. The yield was 57.2%, and the gas phase content was 98.4%.
[0036] Into a reaction flask, 53.9 g of 4-ethylpyridine, 1.25 g of cobalt acetate tetrahydrate, 16.4 g of N-hydroxyphthalimide and 430 g of butyl acetate were charged, after which the reaction system was replaced with oxygen for 3 times under vacuum, and then oxygen was bubbled into the system under liquid phase to maintain the pressure at 0.15 MPa. The reaction was stirred at 100°C for 12 h. After the reaction was completed, 475 g of 8% sodium carbonate aqueous solution was added, and after stirring and standing, the lower water layer was separated. The water layer was extracted with butyl acetate for 2 times, and the oil layers were combined and subjected to rectification to obtain 4-acetylpyridine. The yield was 49% (based on 4-ethylpyridine), and the gas phase content was 98.7%.
[0037] The water phase separated from the oxidation reaction was adjusted to pH 1-2 with 37% hydrochloric acid, and then subjected to distillation, suction filtration, and washing of the filter cake with water at 30-40°C, followed by suction filtration again, vacuum drying at 40°C to obtain recovered N-hydroxyphthalimide. The recovery rate was 58.3%. Comparative Example 1
[0038] After nitrogen replacement, 50 g of pyridine and 150 mL of acetic anhydride were charged into a reaction flask, and the temperature was raised to 80°C while stirring. Then, 41.25 g of iron powder was added over 1 h, and 7.5 mL of water was added over 0.5 h while controlling the temperature at 80-97°C. Subsequently, the temperature was lowered to 90°C, and 25.75 g of iron powder was added over 0.5 h while controlling the temperature at 80-90°C. After the addition of the iron powder was completed, the temperature was raised to 136°C over 0.5 h. After 30 min of reaction (from the completion of the addition of the iron powder), the reaction liquid had very poor flowability, and after 10 min of continuous reaction, the reaction liquid became lumpy and the stirring paddle was stuck. The reaction liquid could not be transferred from the reaction flask, and the reaction liquid could not be transferred by adding water or alkaline water, and the experiment failed. Comparative Example 2
[0039] After nitrogen replacement, 50 g of pyridine and 150 mL of acetic anhydride were charged into a reaction flask, and the temperature was raised to 80°C while stirring. Then, 41.25 g of iron powder was added over 1 h, and 7.5 mL of water was added over 0.5 h while controlling the temperature at 80-97°C. Subsequently, the temperature was lowered to 90°C, and 25.75 g of iron powder was added over 0.5 h while controlling the temperature at 80-90°C. After the addition of the iron powder was completed, the temperature was raised, and 125 mL of water was slowly added dropwise. After the addition of the water was completed, the reaction was stirred at 100°C for 1.5 h. After the reaction was completed, the pH was adjusted to 9.5-10 with 50% sodium hydroxide aqueous solution, and the reaction was subjected to steam distillation. The distilled fraction was allowed to stand and separate into layers, and the oil layer was separated. The saturated potassium carbonate aqueous phase was extracted with benzene for 3 times, and the oil layers were combined. After drying with anhydrous potassium carbonate, the water was removed, and the product was subjected to rectification. The yield was 31%, and the gas phase content was 97.4%. Comparative Example 3
[0040] Into a reaction flask were put 55 g of 4-ethylpyridine, 2.56 g of cobalt acetate tetrahydrate, 16.75 g of N-hydroxyphthalimide, and 440 g of n-butanol, after the completion of the feeding, the vacuum was replaced with oxygen for 3 times, then the reaction system pressure was maintained at 0.15 MPa by oxygen injection from a cylinder, and the reaction was stirred at 100°C for 12 h. After the reaction was completed, gas phase analysis was performed (the conversion rate was too low, and no post-treatment was performed), the conversion rate was 16%, and the selectivity was 12.5%. Comparative Example 4
[0041] Into a reaction flask were put 55 g of 4-ethylpyridine, 2.56 g of cobalt acetate tetrahydrate, 16.75 g of N-hydroxyphthalimide, and 440 g of n-butanol, after the completion of the feeding, the vacuum was replaced with oxygen for 3 times, then the reaction system pressure was maintained at 0.15 MPa by oxygen injection from a cylinder, and the reaction was stirred at 100°C for 12 h. After the reaction was completed, gas phase analysis was performed (the conversion rate was too low, and no post-treatment was performed), the conversion rate was 16%, and the selectivity was 12.5%. Comparative Example 5
[0042] Into a reaction flask were put 55 g of 4-ethylpyridine, 2.56 g of cobalt acetate tetrahydrate, 16.75 g of N-hydroxyphthalimide, and 440 g of n-butanol, after the completion of the feeding, the vacuum was replaced with oxygen for 3 times, then the reaction system pressure was maintained at 0.15 MPa by oxygen injection from a cylinder, and the reaction was stirred at 100°C for 12 h. After the reaction was completed, gas phase analysis was performed (the conversion rate was too low, and no post-treatment was performed), the conversion rate was 16%, and the selectivity was 12.5%. Comparative Example 6
[0043] Into a reaction flask were put 55 g of 4-ethylpyridine, 2.56 g of cobalt acetate tetrahydrate, 16.75 g of N-hydroxyphthalimide, and 440 g of n-butanol, after the completion of the feeding, the vacuum was replaced with oxygen for 3 times, then the reaction system pressure was maintained at 0.15 MPa by oxygen injection from a cylinder, and the reaction was stirred at 100°C for 12 h. After the reaction was completed, gas phase analysis was performed (the conversion rate was too low, and no post-treatment was performed), the conversion rate was 16%, and the selectivity was 12.5%. Comparative Example 7
[0044] Into a reaction flask were put 55 g of 4-ethylpyridine, 2.56 g of cobalt acetate tetrahydrate, 16.75 g of N-hydroxyphthalimide, and 440 g of n-butanol, after the completion of the feeding, the vacuum was replaced with oxygen for 3 times, then the reaction system pressure was maintained at 0.15 MPa by oxygen injection from a cylinder, and the reaction was stirred at 100°C for 12 h. After the reaction was completed, gas phase analysis was performed (the conversion rate was too low, and no post-treatment was performed), the conversion rate was 16%, and the selectivity was 12.5%.
[0045] It is to be noted that the terms such as first and second, etc. are used herein merely to differentiate one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between such entities or operations. Also, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.
[0046] It is to be noted that the above merely illustrates the technical idea of the present application, and cannot limit the protection scope of the present application. For those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements all fall within the protection scope of the claims of the present application.
Claims
1. A process for the synthesis of 4-acetylpyridine from pyridine, characterized in that, Comprising the following steps: After nitrogen replacement, pyridine and acetic anhydride are added to the reaction bottle, stirred and heated to 80℃, and iron powder A is added in 6 portions in 1h, and water A is slowly added dropwise in 30-60min after the addition of iron powder A is completed, and the temperature is controlled at 80-97℃; then iron powder B is added in 4 portions in 30-60min while controlling the temperature at 85-90℃, and after the addition of iron powder is completed, dimethylbenzene is added, and the temperature is raised to 135-140℃ and reacted for 3-5h; after the reaction is completed, the temperature is lowered to 70-80℃, water B is added, and then the pH is adjusted to 9-10; distillation, add inorganic salt saturated water phase in the fraction, after standing and separating into two layers, separate the lower water layer, then extract the water layer with dimethylbenzene for 3 times, then combine the oil layer, remove water with anhydrous magnesium sulfate or 3A molecular sieve, and then distill to obtain 4-ethylpyridine; 4-ethylpyridine, catalyst and butyl acetate are added to the reaction bottle, vacuumed, replaced with oxygen for 3 times, then oxygen is passed through the liquid in the gas cylinder to maintain the pressure of the reaction system at 0.1-0.2MPa, stirred at 100℃ for 10-12h, after the reaction is completed, add sodium carbonate aqueous solution, stir and stand, then separate the lower water layer, extract the water layer with butyl acetate for 2 times, combine the oil layer, and distill to obtain 4-acetylpyridine.
2. The process for synthesis of 4-acetylpyridine from pyridine as claimed in claim 1 wherein, In step (1), the mass ratio of acetic anhydride to pyridine is 3.2-4:1, the mass ratio of iron powder A to pyridine is 0.8-1:1; the mass ratio of iron powder B to pyridine is 0.5-0.6:1, and the mesh number of iron powder is 200-400.
3. The process for synthesis of 4-acetylpyridine from pyridine as claimed in claim 2 wherein, In step (1), the mass ratio of water A to pyridine is 0.1-0.2:1, the mass ratio of water B to pyridine is 5-10:1, and the mass ratio of dimethylbenzene to pyridine is 3-5:
1.
4. The method of synthesizing 4-acetylpyridine from pyridine according to claim 1, wherein, In step (1), 30-50% sodium hydroxide aqueous solution is used to adjust the pH to 9-10.
5. The process for synthesis of 4-acetylpyridine from pyridine as claimed in claim 1, wherein, In step (2), the mass ratio of butyl acetate to 4-ethylpyridine is 6-10:
1.
6. The method of synthesizing 4-acetylpyridine from pyridine according to claim 1, wherein, In step (2), the catalyst is cobalt acetate tetrahydrate or cobalt acetate and N-hydroxyphthalimide, the molar ratio of cobalt acetate tetrahydrate to 4-ethylpyridine is 0.01-0.03:1, the molar ratio of cobalt acetate to 4-ethylpyridine is 0.01-0.03:1, and the molar ratio of N-hydroxyphthalimide to 4-ethylpyridine is 0.1-0.3:
1.
7. The method of synthesizing 4-acetylpyridine from pyridine according to claim 1, wherein, In step (2), the concentration of sodium carbonate aqueous solution is 5-20%.
8. The process for synthesis of 4-acetylpyridine from pyridine as claimed in claim 1, wherein, In step (2), the extraction temperature is 60-70℃.
9. The process for synthesis of 4-acetylpyridine from pyridine as claimed in claim 1, wherein, It also includes catalyst recovery: the water phase separated during the post-treatment of step (2) is adjusted to pH with 37% hydrochloric acid, then distilled, filtered, the filter cake is washed with 30-40℃ water, then filtered again, and dried at 40℃ under vacuum to obtain the recovered catalyst N-hydroxyphthalimide.
10. The process for synthesis of 4-acetylpyridine from pyridine as claimed in claim 9 wherein, Adjust the pH to 1-2.