Catalytic oxidation method of alkyl alcohol amine
The use of imidazolium-based Raney copper catalyst has solved the problems of low catalyst efficiency, insufficient selectivity, and environmental unfriendliness in existing alkyl alcohol amine catalytic oxidation methods, achieving high selectivity and high yield in the production of aminocarboxylic acids, which is suitable for industrial application.
Patent Information
- Application Number
- CN202511144349.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-15
- Publication Date
- 2025-11-14
AI Technical Summary
Existing catalytic oxidation methods for alkyl alcoholamines suffer from problems such as low catalyst efficiency, insufficient reaction selectivity, complex post-processing, and environmental unfriendliness.
The catalyst is an imidazole-based Raney copper catalyst, which modifies copper-aluminum alloy with imidazole ionic liquid to form a porous structure with high specific surface area, adjusts the electron density of copper, promotes the selective oxidation of alkyl alcoholamines, and has mild reaction conditions and simple operation.
It achieves highly selective and environmentally friendly alkyl alcoholamine oxidation with high product yield and good purity, making it suitable for industrial production.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic synthesis technology, and particularly relates to a catalytic oxidation method for alkyl alcoholamines. Background Technology
[0002] Aminocarboxylic acids are an important class of compounds in organic synthesis and chemical production, and are widely used in chelating agents, surfactants, pharmaceutical intermediates, water treatment agents and other fields.
[0003] Currently, there are three main traditional methods for synthesizing aminocarboxylic acids: The Strecker synthesis involves reacting aldehydes / ketones with hydrogen cyanide and ammonia to generate α-aminonitriles, which are then hydrolyzed to obtain the target product. However, this method uses highly toxic cyanide, posing a significant safety risk and producing numerous byproducts, resulting in a heavy environmental burden and poor environmental friendliness. The Bucherer-Bergs reaction uses aldehydes, potassium cyanide, and ammonium carbonate as raw materials, first hydrolyzing them to obtain hydantoin, which is then further hydrolyzed to generate aminocarboxylic acids. This route also relies on cyanide, and the complex reaction steps lead to low product yields, significantly limiting its industrial application. The catalytic oxidation of alkanolamines uses alkyl alkanolamines as raw materials, oxidizing them to aminocarboxylic acids under the action of a catalyst. Compared to the previous two methods, this route has the advantages of readily available raw materials, mild reaction conditions, and, more importantly, avoids the use of highly toxic reagents, demonstrating significant potential for industrial production.
[0004] However, the existing catalytic oxidation methods for alcohol amines still have the following problems: (1) Low catalyst efficiency: Traditional homogeneous catalysts are expensive, difficult to recover, and may generate saline wastewater; (2) Insufficient reaction selectivity: Under alkaline and high temperature conditions, alcohol amines are prone to side reactions (such as CN bond breakage, over-oxidation, etc.), which leads to a decrease in the yield of the target product; (3) Complex post-processing: Multiple acid-base adjustment and purification steps are required after the reaction, which increases energy consumption and waste liquid treatment burden.
[0005] Based on the above statements, this invention proposes a highly efficient, highly selective, and environmentally friendly catalytic oxidation method for alkyl alcoholamines. Summary of the Invention
[0006] The purpose of this invention is to overcome the shortcomings of existing catalytic oxidation methods for alkyl alcoholamines, such as harsh reaction conditions, complex operation, low product yield, and low purity, and to provide a catalytic oxidation method for alkyl alcoholamines that has the advantages of mild reaction conditions, simple operation, high product yield, and good purity.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: A catalytic oxidation method for alkylolamines includes the following steps: mixing alkylolamine, inorganic base, water and catalyst evenly, refluxing at 140-170℃ for 4-8 hours under nitrogen protection, cooling, filtering to remove catalyst, acidifying the filtrate to precipitate crystals, filtering, recrystallizing, and drying to obtain aminocarboxylic acid; The catalyst is imidazole-based Raney copper, which is obtained by modifying a copper-aluminum alloy with an imidazole-based ionic liquid.
[0008] Preferably, the alkyl alcoholamine is one of N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, N-octylethanolamine, and diethanolamine.
[0009] Preferably, the imidazole ionic liquid is at least one of 1-butyl-3-methylimidazolium chloride, 1-carboxymethyl-3-methylimidazolium chloride, 1-carboxyethyl-3-methylimidazolium chloride, and 1-propylsulfonic acid-3-methylimidazolium chloride.
[0010] Preferably, the method for preparing the imidazolyl ranicol includes the following steps: After activating the copper-aluminum alloy with an alkaline solution for 1-2 hours, the mixture is filtered, washed, and dried to obtain the activated copper-aluminum alloy. The activated copper-aluminum alloy and an imidazole ionic liquid are added to water and stirred at 50-70℃ for 2-6 hours. The mixture is then filtered, washed, and dried to obtain imidazole-based ranitidine copper.
[0011] Preferably, the mass ratio of the copper-aluminum alloy, alkaline solution, imidazole ionic liquid, and water is 1:(3-5):(1-2):10; and the concentration of the alkaline solution is 10-30 wt%.
[0012] Preferably, the inorganic base is sodium hydroxide and / or potassium hydroxide.
[0013] Preferably, the mass ratio of the alkylolamine, inorganic base, water and catalyst is 1:(0.5-2):(5-15):(0.01-0.1).
[0014] Preferably, the acid used in the acidification is at least one of hydrochloric acid, sulfuric acid, or nitric acid.
[0015] Preferably, the pH of the acidification is 2-4.
[0016] Preferably, the solvent used for recrystallization is at least one of diethyl ether, toluene, or chloroform.
[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) The catalyst of the present invention is imidazole Raney copper, which forms a porous structure with high specific surface area through base activation and imidazole ionic liquid modification, exposing more active sites and accelerating the oxidation reaction of alkyl alcohol amines. At the same time, the coordination of the imidazole group with the copper surface can regulate the electron density of copper, promote oxygen activation, selectively oxidize primary alcohols to carboxylic acids, and avoid the occurrence of side reactions.
[0018] (2) The alkyl alcoholamine catalytic oxidation method of the present invention, by strictly controlling the reactants, catalysts, reaction conditions, etc., enables the reaction to proceed smoothly under mild conditions, is easy to operate, and has a high product yield and good purity, making it suitable for industrial production. Attached Figure Description
[0019] The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this invention, illustrate exemplary embodiments and provide explanations, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is the infrared spectrum of the aminodiacetic acid prepared in Example 1 of this invention. Detailed Implementation
[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] Example 1 A method for the catalytic oxidation of alkyl alcoholamines, comprising the following steps: Alkyl alcoholamine (diethanolamine), inorganic base (sodium hydroxide), water and catalyst were mixed evenly in a mass ratio of 1:1:10:0.05. The mixture was refluxed at 150°C for 6 hours under nitrogen protection. After cooling, the catalyst was removed by filtration. The filtrate was acidified with hydrochloric acid to adjust the pH to 3, crystals were precipitated, filtered, recrystallized with toluene, and dried to obtain aminocarboxylic acid (iminodiacetic acid). The catalyst is imidazolium-based Raney copper, and its preparation method includes the following steps: 10g of copper-aluminum alloy (copper 54.3wt%, aluminum 45.7wt%) was activated at room temperature for 1h in 30g of alkaline solution (30wt% sodium hydroxide solution), then filtered, washed, and dried to obtain the activated copper-aluminum alloy. The activated copper-aluminum alloy was then added to 100g of water along with 10g of imidazole ionic liquid (1-carboxymethyl-3-methylimidazolium chloride), stirred at 60℃ for 6h, filtered, washed, and dried to obtain imidazole-based Raney copper.
[0022] Example 2 A method for the catalytic oxidation of alkyl alcoholamines, comprising the following steps: Alkyl alcoholamine (diethanolamine), inorganic base (potassium hydroxide), water and catalyst were mixed evenly in a mass ratio of 1:1:5:0.01. The mixture was refluxed at 140°C for 8 hours under nitrogen protection. After cooling, the catalyst was removed by filtration. The filtrate was acidified with hydrochloric acid, sulfuric acid or nitric acid to adjust the pH to 4, crystals were precipitated, filtered, recrystallized with toluene, and dried to obtain aminocarboxylic acid (iminodiacetic acid). The catalyst is imidazolium-based Raney copper, and its preparation method includes the following steps: 10g of copper-aluminum alloy (copper 54.3wt%, aluminum 45.7wt%) was activated at room temperature for 1.5h in 40g of alkaline solution (20wt% sodium hydroxide solution), then filtered, washed, and dried to obtain the activated copper-aluminum alloy. The activated copper-aluminum alloy was then added to 100g of water along with 15g of imidazole ionic liquid (1-propylsulfonic acid-3-methylimidazolium chloride), stirred at 50℃ for 4h, filtered, washed, and dried to obtain imidazole-based Raney copper.
[0023] Example 3 A method for the catalytic oxidation of alkyl alcoholamines, comprising the following steps: Alkyl alcoholamine (diethanolamine), inorganic base (sodium hydroxide), water and catalyst were mixed evenly in a mass ratio of 1:1:15:0.1. The mixture was refluxed at 170°C for 4 hours under nitrogen protection. After cooling, the catalyst was removed by filtration. The filtrate was acidified with hydrochloric acid, sulfuric acid or nitric acid to adjust the pH to 2, crystals were precipitated, filtered, recrystallized with toluene, and dried to obtain aminocarboxylic acid (iminodiacetic acid). The catalyst is imidazolium-based Raney copper, and its preparation method includes the following steps: 10g of copper-aluminum alloy (copper 54.3wt%, aluminum 45.7wt%) was activated at room temperature for 1h in 50g of alkaline solution (10wt% sodium hydroxide solution), then filtered, washed, and dried to obtain activated copper-aluminum alloy. The activated copper-aluminum alloy was then added to 100g of water along with 20g of imidazole ionic liquid (1-propylsulfonic acid-3-methylimidazolium chloride), stirred at 70℃ for 2h, filtered, washed, and dried to obtain imidazole-based Raney copper.
[0024] Example 4 A method for the catalytic oxidation of alkyl alcoholamines, comprising the following steps: Alkyl alcoholamine (N-methylethanolamine), inorganic base (potassium hydroxide), water and catalyst were mixed evenly in a mass ratio of 1:1.5:10:0.05. The mixture was refluxed at 155°C for 5 hours under nitrogen protection. After cooling, the catalyst was removed by filtration. The filtrate was acidified with sulfuric acid to adjust the pH to 4, crystals were precipitated, filtered, recrystallized with toluene, and dried to obtain aminocarboxylic acid (sarcosine). The catalyst is imidazolium-based Raney copper, and its preparation method includes the following steps: 10g of copper-aluminum alloy (copper 54.3wt%, aluminum 45.7wt%) was activated at room temperature for 1h in 30g of alkaline solution (30wt% sodium hydroxide solution), then filtered, washed, and dried to obtain the activated copper-aluminum alloy. The activated copper-aluminum alloy was then added to 100g of water along with 10g of imidazole ionic liquid (1-carboxymethyl-3-methylimidazolium chloride), stirred at 60℃ for 6h, filtered, washed, and dried to obtain imidazole-based Raney copper.
[0025] Example 5 A method for the catalytic oxidation of alkyl alcoholamines, comprising the following steps: Alkyl alcoholamine (N-ethylethanolamine), inorganic base (sodium hydroxide), water and catalyst were mixed evenly in a mass ratio of 1:1:10:0.01. The mixture was refluxed at 165°C for 7 hours under nitrogen protection. After cooling, the catalyst was removed by filtration. The filtrate was acidified with nitric acid to adjust the pH to 3, crystals were precipitated, filtered, recrystallized with toluene, and dried to obtain aminocarboxylic acid (N-ethylglycine). The catalyst is imidazolium-based Raney copper, and its preparation method includes the following steps: 10g of copper-aluminum alloy (copper 54.3wt%, aluminum 45.7wt%) was activated at room temperature for 1h in 30g of alkaline solution (30wt% sodium hydroxide solution), then filtered, washed, and dried to obtain the activated copper-aluminum alloy. The activated copper-aluminum alloy was then added to 100g of water along with 10g of imidazole ionic liquid (1-carboxymethyl-3-methylimidazolium chloride), stirred at 60℃ for 6h, filtered, washed, and dried to obtain imidazole-based Raney copper.
[0026] Comparative Example 1 A method for the catalytic oxidation of alkyl alcoholamines, comprising the following steps: Alkyl alcoholamine (diethanolamine), inorganic base (sodium hydroxide), water and catalyst were mixed evenly in a mass ratio of 1:1:10:0.05. The mixture was refluxed at 150°C for 6 hours under nitrogen protection. After cooling, the catalyst was removed by filtration. The filtrate was acidified with hydrochloric acid to adjust the pH to 3, and crystals were precipitated. The filtrate was then filtered, recrystallized with toluene, and dried to obtain aminocarboxylic acid (iminodiacetic acid). The catalyst is Raney copper.
[0027] Comparative Example 2 A method for the catalytic oxidation of alkyl alcoholamines, comprising the following steps: Add 0.5 g of sodium hydroxide and 0.1 g of imidazole-type ionic liquid (1-ethyl-3-methylimidazolium ferric chloride) to 10 mL of 0.5 mol / L diethanolamine solution, mix well, introduce oxygen at 0.5 MPa, set the temperature inside the reactor to 50 °C, stir the reaction for 2 h, adjust the pH to 6.0 with sulfuric acid solution, and recrystallize the obtained reaction solution with methanol to obtain aminocarboxylic acid (iminodiacetic acid).
[0028] Test Results The products obtained in Examples 1-5 and Comparative Examples 1 and 2 were subjected to qualitative and quantitative NMR analysis, as shown in Table 1.
[0029] Table 1
[0030] As shown in Table 1, the alkyl alcohol amine conversion rate, amino carboxylic acid yield, and amino carboxylic acid purity of Examples 1-5 are all better than those of Comparative Examples 1 and 2. In particular, comparing Example 1 with Comparative Examples 1 and 2, it can be seen that the present invention uses imidazole-based Raney copper as a catalyst, which has higher catalytic activity than Raney copper or imidazole-type ionic liquids as catalysts. This better promotes the conversion of diethanolamine to amino carboxylic acid, and the amino carboxylic acid has higher purity.
[0031] In addition, the iminodiacetic acid prepared in Example 1 was subjected to infrared spectroscopy, and the infrared spectrum is as follows: Figure 1 As shown in the figure, at 3086.92cm -1 The characteristic absorption peak of the OH stretching vibration of the carboxyl group appears at 1704.94 cm⁻¹. -1 The peak corresponds to the C=O stretching vibration of the carboxyl group; it is located at 1382.96 cm⁻¹. -1 and 1100.56cm -1 The strong absorption peak at 1574.18 cm⁻¹ is a result of the coupling vibrations of the stretching of the CO bond and the bending of the OH bond in the carboxyl group; the characteristic absorption peak of the NH bending vibration appears at 1574.18 cm⁻¹. -1 This fully demonstrates the formation of iminodiacetic acid.
[0032] It should be noted that the above-disclosed embodiments are only illustrative of the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, any person skilled in the art should understand that any modifications, changes, or equivalent substitutions made without departing from the scope of the technical solutions of the present invention should fall within the scope of protection of the present invention.
Claims
1. A method for the catalytic oxidation of alkyl alcoholamines, characterized in that, The process includes the following steps: alkyl alcoholamine, inorganic base, water and catalyst are mixed evenly, and under nitrogen protection, the mixture is refluxed at 140-170℃ for 4-8 hours. After cooling, the catalyst is removed by filtration, the filtrate is acidified to precipitate crystals, which are then filtered, recrystallized, and dried to obtain aminocarboxylic acid. The catalyst is imidazole-based Raney copper, which is obtained by modifying a copper-aluminum alloy with an imidazole-based ionic liquid.
2. The catalytic oxidation method for alkyl alcoholamines according to claim 1, characterized in that, The alkyl alcoholamine is one of N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, N-octylethanolamine, and diethanolamine.
3. The catalytic oxidation method for alkyl alcoholamines according to claim 1, characterized in that, The imidazole ionic liquid is at least one of 1-butyl-3-methylimidazolium chloride, 1-carboxymethyl-3-methylimidazolium chloride, 1-carboxyethyl-3-methylimidazolium chloride, and 1-propylsulfonic acid-3-methylimidazolium chloride.
4. The catalytic oxidation method for alkyl alcoholamines according to claim 3, characterized in that, The method for preparing the imidazolyl rani copper includes the following steps: After activating the copper-aluminum alloy with an alkaline solution for 1-2 hours, the mixture is filtered, washed, and dried to obtain the activated copper-aluminum alloy. The activated copper-aluminum alloy and an imidazole ionic liquid are added to water and stirred at 50-70℃ for 2-6 hours. The mixture is then filtered, washed, and dried to obtain imidazole-based ranitidine copper.
5. The catalytic oxidation method for alkyl alcoholamines according to claim 4, characterized in that, The mass ratio of the copper-aluminum alloy, alkaline solution, imidazole ionic liquid, and water is 1:(3-5):(1-2):10; the concentration of the alkaline solution is 10-30 wt%.
6. The catalytic oxidation method for alkyl alcoholamines according to claim 1, characterized in that, The inorganic base is sodium hydroxide and / or potassium hydroxide.
7. The catalytic oxidation method for alkyl alcoholamines according to claim 1, characterized in that, The mass ratio of the alkyl alcoholamine, inorganic base, water and catalyst is 1:(0.5-2):(5-15):(0.01-0.1).
8. The catalytic oxidation method for alkyl alcoholamines according to claim 1, characterized in that, The acid used in the acidification is at least one of hydrochloric acid, sulfuric acid, or nitric acid.
9. The catalytic oxidation method for alkyl alcoholamines according to claim 1, characterized in that, The pH of the acidification is 2-4.
10. The catalytic oxidation method of alkyl alcoholamines according to claim 1, characterized in that, The solvent used for recrystallization is at least one of diethyl ether, toluene, or chloroform.