Novel method for synthesizing 3-amino-N-ethyl carbazole
The existing 3-amino-N-ethylcarbazole is solved by reacting N-ethylcarbazole with sodium chloride and DMF to produce 3-chloro-N-ethylcarbazole and ammonized with acetamide and potassium carbonate. The high cost and contamination of carbazole synthesis process have achieved process simplification and reduced pollution, and improved process efficiency.
Patent Information
- Application Number
- CN202411735169.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-01-03
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The existing 3-amino-N-ethylcarbazole synthesis process has problems of high cost, pollution and high treatment cost, especially the reduction method of sulfide alkaline reduction produces a large amount of waste slag and wastewater, hydrazine hydrate has high prices and occupational hazards, Ni/ Mesoporous carbon catalysts have fire hazards, the cost of platinum carbon catalysts is high and the solvent dechlorination phenomenon affects subsequent synthesis.
N-ethylcarbazole reacts with sodium chloride and DMF at low temperature to form 3-chloro-N-ethylcarbazole, and then undergoes ammonization reaction with acetamide and potassium carbonate to obtain 3-amino group -N-ethylcarbazole, through this new route, simplifies the process flow and reduces contamination.
The process simplification, cost reduction and pollutability are achieved, process efficiency is improved, yield is high and safety is improved.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of chemical synthesis, and specifically relates to a new method for synthesizing 3-amino-N-ethylcarbazole. Background Art
[0002] 3-Amino-N-ethylcarbazole is an important intermediate for the synthesis of Permanent Purple RL. In the prior art, it is mainly prepared by reduction of 3-nitro-N-ethylcarbazole. The more classic method is the alkaline sulfide reduction method, but the alkaline sulfide reduction method produces a large amount of alkaline sulfur-containing waste residue and wastewater, and the treatment cost is high.
[0003] In addition, some researchers used hydrazine hydrate to reduce 3-nitro-N-ethylcarbazole to prepare 3-amino-N-ethylcarbazole. The hydrazine hydrate reduction method is relatively clean, but the price of hydrazine hydrate remains high, the production cost is high, and hydrazine hydrate has certain toxicity and occupational hazards. In addition, some researchers used Ni / mesoporous carbon, iron-containing Raney nickel or platinum carbon as catalysts to hydrogenate and reduce 3-nitro-N-ethylcarbazole to prepare 3-amino-N-ethylcarbazole. The hydrogenation reduction process has the advantages of cleanliness and low pollution, but there are certain defects: among them, nickel-containing catalysts have a greater fire hazard, and platinum-carbon catalysts or palladium-carbon catalysts are more expensive, and it is easy to cause the solvent o-dichlorobenzene to dechlorinate, which not only affects the subsequent synthesis of permanent violet but also is not conducive to the recovery of solvents.
[0004] In summary, the synthesis of 3-amino-N-ethylcarbazole is generally carried out by a reduction method using 3-nitro-N-ethylcarbazole as a raw material, which generally has defects in cost and process. In this case, how to develop a new method for synthesizing 3-amino-N-ethylcarbazole to improve process efficiency and reduce cost and pollution is a technical problem that needs to be solved in the art. Summary of the invention
[0005] The first technical problem to be solved by the present invention is: how to provide a new synthesis route of 3-amino-N-ethylcarbazole to expand the optional range of the synthesis process of 3-amino-N-ethylcarbazole.
[0006] The second technical problem to be solved by the present invention is: how to improve the process efficiency of 3-amino-N-ethylcarbazole synthesis and reduce the cost and pollution.
[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: A novel method for synthesizing 3-amino-N-ethylcarbazole comprises the following steps: 1) After mixing N-ethylcarbazole, sodium chloride and DMF, add phosphorus oxychloride dropwise at -5~5°C, then heat to 95~105°C, maintain for a certain period of time, cool to room temperature after the reaction, add water, mix well, adjust the pH to 7~8, add sodium chloride to saturate the reaction solution, separate the solid and liquid, wash with water, and dry to obtain white solid 3-chloro-N-ethylcarbazole; 2) The 3-chloro-N-ethylcarbazole obtained in step 1) is mixed with acetamide and potassium carbonate, heated and stirred, and the temperature is raised to 175-185° C., and the reaction is maintained for 1.5-2.5 hours. After the reaction is completed, it is cooled to room temperature, water is added thereto, and then solid-liquid separation, water washing, and drying are performed to obtain 3-amino-N-ethylcarbazole.
[0008] The synthetic route of the present invention is shown in the following formula 1 and formula 2:
[0009] Formula 1
[0010] Formula 2 Preferably, in step 1), the amounts of N-ethylcarbazole, sodium chloride and DMF are 1.0 g (5.1 mmol), 5.0 g and 15 mL respectively; the amount of phosphorus oxychloride is 2.0 mL (21.8 mmol); and the amount of water added is 35 mL.
[0011] Preferably, in step 2), the amounts of 3-chloro-N-ethylcarbazole, acetamide and potassium carbonate are 0.92 g (4.7 mmol), 6.0 g (101.7 mmol) and 4.0 g respectively; and the amount of water added is 30 mL.
[0012] Preferably, in step 1), the system temperature is 0°C when phosphorus oxychloride is added; the final heating temperature is 100°C; and the maintaining time is 8 hours.
[0013] Preferably, in step 1), the pH is adjusted using aqueous ammonia.
[0014] Preferably, in step 1), the solid-liquid separation is suction filtration.
[0015] Preferably, in step 2), the final temperature of the heating is 180° C. and the reaction is maintained for 2 hours.
[0016] Preferably, in step 2), the solid-liquid separation is filtration.
[0017] The invention provides a new method for synthesizing 3-amino-N-ethylcarbazole. The technical scheme uses N-ethylcarbazole as a raw material, first reacts with phosphorus oxychloride in a DMF environment to generate 3-chloro-N-ethylcarbazole, and then performs an amination reaction with acetamide and potassium carbonate to obtain 3-amino-N-ethylcarbazole. The invention has a simple process, a short synthesis route, a high yield, and significantly reduced pollution, and has outstanding technical advantages. DETAILED DESCRIPTION
[0018] The specific embodiments of the present invention will be described in detail below. In order to avoid too much unnecessary details, the well-known structures or functions will not be described in detail in the following examples. The approximate language used in the following examples can be used for quantitative expression, indicating that the quantity can be allowed to have a certain change without changing the basic function. Unless otherwise defined, the technical and scientific terms used in the following examples have the same meaning as those generally understood by those skilled in the art to which the present invention belongs.
[0019] Example 1 A novel method for synthesizing 3-amino-N-ethylcarbazole comprises the following steps: 1) In a 100mL three-necked flask, 1.0g (5.1mmol) of N-ethylcarbazole, 5.0g of sodium chloride and 15mL of DMF were added and mixed, and then phosphorus oxychloride was added dropwise at -5°C, and then heated to 95°C and maintained for 5h. After the reaction was completed, it was cooled to room temperature, 35ml of water was added, mixed, and then the pH of the reaction solution was adjusted to 7-8 with an ammonia solution, and then sodium chloride solid was added until the reaction solution was saturated, and then filtered under reduced pressure, washed with water, and dried to obtain 1.08g of white solid 3-chloro-N-ethylcarbazole, with a yield of 92%; 2) 1.08 g (4.7 mmol) of 3-chloro-N-ethylcarbazole obtained in step 1 was added to a 100 mL three-necked flask, mixed with 6.0 g (101.7 mmol) of acetamide and 4.0 g of potassium carbonate, heated and stirred, and the temperature was raised to 175 ° C. The reaction was maintained for 1.5 h. After the reaction was completed, it was cooled to room temperature, 30 ml of water was added thereto, and then crystallized, and then filtered under reduced pressure, washed with water, and dried to obtain 0.900 g of yellow solid 3-amino-N-ethylcarbazole with a yield of 91%.
[0020] Example 2 A novel method for synthesizing 3-amino-N-ethylcarbazole comprises the following steps: 1) In a 100mL three-necked flask, 1.0g (5.1mmol) of N-ethylcarbazole, 5.0g of sodium chloride and 15mL of DMF were added and mixed, and then phosphorus oxychloride was added dropwise at 5°C, and then heated to 105°C and maintained for 5h. After the reaction was completed, it was cooled to room temperature, 35ml of water was added, mixed, and then the pH of the reaction solution was adjusted to 7-8 with an ammonia solution, and then sodium chloride solid was added until the reaction solution was saturated, and then filtered under reduced pressure, washed with water, and dried to obtain 1.07g of white solid 3-chloro-N-ethylcarbazole, with a yield of 91%; 2) 1.08 g (4.7 mmol) of 3-chloro-N-ethylcarbazole obtained in step 1 was added to a 100 mL three-necked flask, mixed with 6.0 g (101.7 mmol) of acetamide and 4.0 g of potassium carbonate, heated and stirred, and the temperature was raised to 185°C. The reaction was maintained for 2.5 h. After the reaction was completed, it was cooled to room temperature, 30 ml of water was added thereto, and then crystallized, and then filtered under reduced pressure, washed with water, and dried to obtain 0.919 g of yellow solid 3-amino-N-ethylcarbazole with a yield of 93%.
[0021] Example 3 A new method for synthesizing 3-amino-N-ethylcarbazole, the route of which is shown in the following formula 1 and formula 2:
[0022] Formula 1
[0023] Formula 2 The method comprises the following steps: In a 100mL three-necked flask, 1.0g (5.1mmol) of N-ethylcarbazole, 5.0g of sodium chloride and 15.0mL of DMF were added respectively. 2.0mL (21.8mmol) of phosphorus oxychloride was carefully added with a dropper at 0℃, and then heated to 100℃ for 8h. After the reaction was completed, it was cooled to room temperature, 35mL of water was added, and it was shaken well. Then, the pH was adjusted to 7-8 with ammonia water, and then sodium chloride solid was added to saturate the reaction solution. It was filtered under reduced pressure, washed with water, and dried to obtain 1.125g of white solid 3-chloro-N-ethylcarbazole solid with a yield of 96%.
[0024] In a 100 mL three-necked flask, add 0.92 g (4.7 mmol) of 3-chloro-N-ethylcarbazole, 6.0 g (101.7 mmol) of acetamide and 4.0 g of potassium carbonate, heat and stir, raise the temperature to 180 ° C and maintain the reaction for 2.0 h. After the reaction, cool to room temperature, add 30 mL of water, and then filter under reduced pressure, wash with water, and dry to obtain 0.939 g of yellow solid 3-amino-N-ethylcarbazole with a yield of 95%.
[0025] The embodiments of the present invention are described in detail above, but the contents are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the scope of the present invention shall be included in the protection scope of the present invention.
Claims
1. A novel method for synthesizing 3-amino-N-ethylcarbazole, characterized in that: The method comprises the following steps: 1) After mixing N-ethylcarbazole, sodium chloride and DMF, add phosphorus oxychloride dropwise at -5~5°C, then heat to 95~105°C and maintain for a certain period of time. After the reaction is completed, cool to room temperature, add water, mix well, adjust the pH to 7~8, add sodium chloride to saturate the reaction solution, separate the solid and liquid, and obtain 3-chloro-N-ethylcarbazole; 2) The 3-chloro-N-ethylcarbazole obtained in step 1) is mixed with acetamide and potassium carbonate, heated and stirred, and the temperature is raised to 175-185° C., and the reaction is maintained for 1.5-2.5 hours. After the reaction is completed, it is cooled to room temperature, water is added thereto, and then solid-liquid separation, water washing, and drying are performed to obtain 3-amino-N-ethylcarbazole.
2. A novel method for synthesizing 3-amino-N-ethylcarbazole according to claim 1, characterized in that: In step 1), the amounts of N-ethylcarbazole, sodium chloride and DMF are 1.0 g, 5.0 g and 15 mL respectively; the amount of phosphorus oxychloride is 2.0 mL; and the amount of water added is 35 mL.
3. A novel method for synthesizing 3-amino-N-ethylcarbazole according to claim 2, characterized in that: In step 2), the amounts of 3-chloro-N-ethylcarbazole, acetamide and potassium carbonate used are 0.92 g, 6.0 g and 4.0 g respectively; and the amount of water added is 30 mL.
4. A novel method for synthesizing 3-amino-N-ethylcarbazole according to claim 1, characterized in that: In step 1), the system temperature is 0°C when phosphorus oxychloride is added; the final temperature of the heating is 100°C; and the maintaining time is 8 hours.
5. A novel method for synthesizing 3-amino-N-ethylcarbazole according to claim 1, characterized in that: In step 1), the pH is adjusted using aqueous ammonia.
6. A novel method for synthesizing 3-amino-N-ethylcarbazole according to claim 1, characterized in that: In step 1), the solid-liquid separation is suction filtration.
7. A novel method for synthesizing 3-amino-N-ethylcarbazole according to claim 1, characterized in that: In step 2), the final temperature of the heating is 180° C. and the reaction is maintained for 2 hours.
8. A novel method for synthesizing 3-amino-N-ethylcarbazole according to claim 1, characterized in that: In step 2), the solid-liquid separation is filtration.