A method for preparing allyl amine compounds using microchannel technology

Abstract

The present application relates to a kind of allyl amine compound preparation method using microchannel technology, comprising the following steps: with allyl chloride and ammonia as raw material, raw material is pumped into microchannel reactor and carried out ammonolysis reaction, and reaction liquid is obtained, wherein the residence time of raw material in microchannel reactor is 38-90 seconds;The reaction liquid is rectified, and allyl amine compound is obtained.The present application uses allyl chloride and ammonia as raw material, does not add organic solvent and catalyst, material is punched into microchannel reactor, ammonolysis reaction is completed in microchannel reactor to obtain allyl amine compound, material flows in microchannel reactor approximately piston flow, back mixing is little, reduces side reaction and byproduct, improves product selectivity, especially the selectivity of monoallylamine, to improve the yield of main product.The present application method is high in safety, fast in reaction speed, short in overall residence time, small in equipment volume, more easily realizes continuous operation, and product selectivity is high, beneficial to improve yield.

Description

Technical Field

[0001] This invention relates to the field of organic compound synthesis, and in particular to a method for preparing allylamine compounds using microchannel technology. Background Technology

[0002] Allylamine is an important organic chemical intermediate. Its molecular structure contains reactive allyl and amino functional groups, making it widely used in the synthesis of various fine chemicals such as pharmaceuticals, dyes, resins, surfactants, and pesticides. It also plays an irreplaceable role in polymer modification and the construction of organic synthesis intermediates. With the rapid development of the fine chemical industry, the market demand for allylamine is increasing year by year, placing higher demands on the efficiency, environmental friendliness, and economy of its preparation process.

[0003] Although there are currently many methods for preparing allylamines, each method has significant technical drawbacks. The literature SCHMIDT JAR, SAMBLANET D C. Preparation of an allyl amine and quaternarydiallyl ammonium compounds therefrom [P]. US 4946996, 1990-08-07 describes the synthesis of allylamines from allyl alcohol and amine under high temperature and pressure using a phosphorus-containing catalyst system. Catalytic amination replaces the traditional haloalkane route. While allylamines exhibit high selectivity, the reaction conditions are harsh, energy consumption is high, and the catalyst materials are expensive. Patent: A method for preparing allylamines using a tubular reactor [P]. CN 1962607A, 2007-05-16 describes the continuous preparation of allylamines using ammonia and allyl chloride as raw materials in a tubular reactor, but this method suffers from problems such as organic solvent pollution and catalyst residue. The literature KATAOKA S, MORIMOTOH. Primary Allylic Amine Synthesis via Pd-Catalyzed Direct Amination of Allylic Alcohols with Ammonium Acetate[J]. Journal of Organic Chemistry, 2024, 89(16): 10693-10697 describes the direct amination of allylic alcohols catalyzed by metals such as Pd. This method generally relies on noble metal catalysts such as Pd and requires complex and expensive ligands. Catalyst recovery is difficult, resulting in extremely high costs for industrial production. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a method for preparing allylamine compounds using microchannel technology, thereby solving the technical problems of low yields due to expensive catalysts or poor product selectivity in the preparation of allylamines in the prior art.

[0005] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows: In a first aspect, the present invention provides a method for preparing allylamine compounds using microchannel technology, comprising the following steps: S1, using allyl chloride and ammonia as raw materials, pumping the raw materials into a microchannel reactor for ammonolysis reaction to obtain a reaction solution, wherein the residence time of the raw materials in the microchannel reactor is 38 to 90 seconds; S2, performing distillation on the reaction solution to obtain allylamine compounds.

[0006] Compared with the prior art, the beneficial effects of the present invention include: This invention uses allyl chloride and ammonia as raw materials, without adding organic solvents or catalysts. The materials are fed into a microchannel reactor, where the ammonolysis reaction is completed to obtain allyl amine compounds. The material flows in a near-plug flow within the microchannel reactor, resulting in minimal backmixing, reduced side reactions and byproducts, and improved product selectivity, especially for monoallyl amines, thereby increasing the yield of the main product. This method is highly safe, has a fast reaction rate, short overall residence time, and compact equipment, making it easier to implement continuous operation. Furthermore, its high product selectivity contributes to improved yield. Attached Figure Description

[0007] Figure 1 This is a gas phase spectrum of allylamines provided in Comparative Example 1 of this invention; Figure 2 This is a gas phase spectrum of allylamines provided in Example 1 of the present invention; Figure 3 This is the gas phase spectrum of allylamines from Example 2 of the present invention; Figure 4 This is a gas phase spectrum of allylamines provided in Example 3 of the present invention; Figure 5 This is a gas phase spectrum of allylamines provided in Example 4 of the present invention; Figure 6 This is a gas phase spectrum of allylamines provided in Example 5 of the present invention; Figure 7 This is a gas phase spectrum of allylamines provided in Example 6 of the present invention; Figure 8 This is a schematic diagram of a microchannel device. Detailed Implementation

[0008] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0009] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0010] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0011] To address the shortcomings of current methods for preparing allylamines, which require expensive catalysts or suffer from poor product selectivity leading to low yields, this invention provides a method for preparing allylamines using microchannel technology. This method leverages the advantages of microchannels, such as strong mixing capabilities, no backmixing, and good heat exchange, to improve the selectivity of allylamines. Furthermore, this invention employs a reaction system without organic solvents or catalysts, which significantly reduces the formation of triallylamine byproducts. The method is environmentally friendly and offers high product selectivity.

[0012] In a first aspect, the present invention provides a method for preparing allylamine compounds using microchannel technology, comprising the following steps: S1, using allyl chloride and ammonia as raw materials, the raw materials are pumped into a microchannel reactor for ammonolysis reaction to obtain a reaction solution, wherein the residence time of the raw materials in the microchannel reactor is 38 to 90 seconds; S2, the reaction solution is distilled to obtain allylamine compounds.

[0013] This invention uses allyl chloride and ammonia as raw materials, without adding organic solvents or catalysts. The materials are pumped into a microchannel reactor according to a certain ratio using a metering pump, and the ammonolysis reaction is completed in the microchannel reactor to obtain the target products monoallylamine and diallylamine.

[0014] In some embodiments, in step S1, the mass fraction of ammonia water is 25% to 28%. Specifically, the mass fraction of ammonia water includes, but is not limited to, 25%, 26%, 27%, 28%, etc.

[0015] In some embodiments, in step S1, the molar ratio of allyl chloride to NH3 in ammonia water is 1:(3-6). Insufficient or excessive ammonia water will affect the product yield. Specifically, the molar ratio of allyl chloride to NH3 in ammonia water includes, but is not limited to, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, etc.

[0016] In some embodiments, in step S1, the raw material is pumped into the microchannel reactor by a metering pump.

[0017] Furthermore, the metering pump is either a plunger pump or a gear pump.

[0018] In some embodiments, in step S1, the channel diameter of the microchannel reactor is 1.2 to 1.8 mm; and the microchannel reactor is equipped with a pressure relief valve.

[0019] It should be noted that the reaction of this invention is carried out in a microchannel system, see [link to relevant documentation]. Figure 8 The microchannel system includes two metering pumps, a tubular microchannel reactor, a temperature sensor, a pressure sensor, a back pressure valve, a condenser, and necessary connecting pipes. The microchannel system has a strong mixing component, such as a commercial mixer placed between the metering pumps and the microchannel reactor. The internal channels of the microchannel reactor are preferably 1.5 mm to achieve strong mass and heat transfer effects, and it has a jacket design to realize the heating function.

[0020] The microchannel reactor of this invention is small in size, with an inner diameter of 1.5 mm, resulting in a small unit reaction volume and high heat exchange efficiency. In addition, the device is equipped with a pressure relief valve, which automatically releases pressure when abnormal.

[0021] In some embodiments, during step S1, the conditions of the microchannel reactor during the ammonolysis reaction include: a pressure of 0–2 MPa, a temperature of 60–120°C, and a residence time of 38–60 seconds. Specifically, the pressure includes, but is not limited to, 0.1 MPa, 0.5 MPa, 0.8 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.5 MPa, 1.6 MPa, 1.8 MPa, 1.9 MPa, and 2.0 MPa; the temperature includes, but is not limited to, 60°C, 70°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, and 120°C; and the residence time includes, but is not limited to, 38s, 40s, 42s, 45s, 48s, 50s, 52s, 55s, 58s, and 60s.

[0022] Furthermore, the conditions for the microchannel reactor include: a pressure of 0.8–2.0 MPa and a temperature of 80–120 °C.

[0023] In some embodiments, in step S2, the allylamine compounds include monoallylamine and diallylamine.

[0024] Among them, the allylamine compounds generated by the ammonolysis reaction include monoallylamine, diallylamine and triallylamine, with monoallylamine being the main one and having the highest commercial value, followed by diallylamine. Therefore, the present invention mainly needs to improve the selectivity of monoallylamine; while triallylamine has basically no commercial value and, as a byproduct, its selectivity needs to be reduced as much as possible.

[0025] Furthermore, during the distillation process, the fraction at 50–55°C is monoallylamine, and the fraction at 105–110°C is diallylamine.

[0026] This invention uses a microchannel reactor to replace the traditional batch reactor, which has the following main advantages: (1) Significantly improved safety: The microchannel is small in size, with an inner diameter of 1.5 mm preferred, resulting in a small unit reaction volume and high heat exchange efficiency; in addition, the equipment is equipped with a pressure relief valve, which automatically relieves pressure when the pressure is abnormal.

[0027] (2) Good sealing performance and environmental protection: There are no moving parts, the flange connection is reliable and leak-free, which is conducive to environmental protection and civilized production.

[0028] (3) Higher main product yield: The material flow is similar to piston flow, with less backmixing, reducing side reactions and byproducts, and improving product selectivity, especially the selectivity of monoallylamine, thereby increasing the main product yield.

[0029] (4) High reaction efficiency: The microchannel has a strong mixing component, which enhances the mass transfer between the liquid and liquid phases, resulting in a faster reaction speed and higher production efficiency.

[0030] (5) Continuous production is easier to achieve: No need for multiple reactors in series, small equipment size, and easier to achieve continuous operation.

[0031] The present invention will be further described in detail below through specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0032] Comparative Example 1 (Traditional batch reactor) A method for preparing allylamines using a batch reactor, the reaction process of which is as follows: Add 4899 g (72.0 mol) of 25% ammonia solution to a high-pressure reactor, seal the reactor, and add 1000 g (13.1 mol) of allyl chloride to the dropping vessel of the high-pressure reactor. Start the hot water circulation bath to heat the reactor to 40–45°C. Open the balance valve and bottom valve of the dropping vessel, and add allyl chloride dropwise to the reactor while maintaining the temperature below 65°C. Continue to heat the reactor to 60–65°C and maintain the temperature for 2 hours to obtain the reaction solution.

[0033] Analysis of the reaction solution revealed that 1.0% of the allyl group remained in the raw material. Figure 1 The GC purity is shown as follows: monoallylamine purity 43.2%, diallylamine purity 35.0%, and triallylamine purity 17.4%. The reaction solution was distilled, and the fraction collected at 50-55℃ yielded allylamine with a relative yield of 44.7%, the fraction collected at 105-110℃ yielded diallylamine with a relative yield of 36.2%, and the byproduct triallylamine with a relative yield of 18.0%.

[0034] Example 1 (Allyl chloride to ammonia water ratio 1:6) A method for preparing allylamine compounds using a microchannel reactor includes the following steps: S1, take 1000g (13.1mol) of allyl chloride and 4899g (72.0mol) of 25% ammonia water. A microchannel reactor is used, and a metering pump is used for feeding. Maintain the reactor jacket temperature at 120℃, adjust the flow rate, and simultaneously feed the above raw materials into the microchannel reactor in two groups. The system pressure is 2.0 MPa, and the reaction residence time is 60 seconds to obtain the reaction solution.

[0035] S2, the distillation reaction liquid, the fraction collected at 50-55℃ yields monoallylamine, the fraction collected at 105-110℃ yields diallylamine.

[0036] The reaction solution obtained in step S1 was sampled and analyzed. The remaining conversion rate of the allyl chloride raw material was 1.3%. Figure 2 The GC purity is shown as follows: monoallylamine (MAA) purity 65.5%, diallylamine (DAA) purity 24.9%, and triallylamine (TAA) purity 5.2%.

[0037] After distillation, the reaction solution yielded monoallylamine with a relative yield of 67.6%, diallylamine with a relative yield of 25.7%, and triallylamine, a byproduct, with a relative yield of 5.4%.

[0038] Example 2 (Allyl chloride to ammonia water ratio 1:4.5) A method for preparing allylamine compounds using a microchannel reactor includes the following steps: S1, take 1000g (13.1mol) of allyl chloride and 4008g (58.9mol) of 25% ammonia water. The reactor is a microchannel reactor, and the feed is metered by a pump. Maintain the reactor jacket temperature at 120℃, adjust the flow rate, and simultaneously pump the above raw materials into the microchannel reactor in two groups. The system pressure is 2.0 MPa, and the reaction residence time is 60 seconds to obtain the reaction solution.

[0039] S2, the distillation reaction liquid, the fraction collected at 50-55℃ yields monoallylamine, the fraction collected at 105-110℃ yields diallylamine.

[0040] The reaction solution obtained in step S1 was sampled and analyzed, and the remaining allyl chloride was 1.2%. Figure 3 The GC purity is shown as follows: monoallylamine purity 67.2%, diallylamine purity 26.5%, and triallylamine purity 2.3%.

[0041] After distillation, the reaction solution yielded monoallylamine with a relative yield of 69.1%, diallylamine with a relative yield of 27.3%, and triallylamine, a byproduct, with a relative yield of 2.4%.

[0042] Example 3 (Extended Stay Time) A method for preparing allylamine compounds using a microchannel reactor includes the following steps: S1, take 1000g (13.1mol) of allyl chloride and 4899g (72.0mol) of 25% ammonia water. The reactor is a microchannel reactor, and the feed is carried out by a metering pump. Maintain the reactor jacket temperature at 120℃, adjust the flow rate, and simultaneously pump the above raw materials into the microchannel reactor in two groups. The system pressure is 2.0 MPa, and the reaction residence time is 90 seconds to obtain the reaction solution.

[0043] S2, the distillation reaction liquid, the fraction collected at 50-55℃ yields monoallylamine, the fraction collected at 105-110℃ yields diallylamine.

[0044] The reaction solution obtained in step S1 was sampled and analyzed, and the remaining allyl chloride was 1.2%. Figure 4 The GC purity is shown as follows: monoallylamine purity 66.8%, diallylamine purity 23.4%, and triallylamine purity 3.7%.

[0045] After distillation, the reaction solution yielded a relative yield of 70.2% for monoallylamine, a relative yield of 24.6% for diallylamine, and a relative yield of 3.9% for the byproduct triallylamine.

[0046] It can be seen that further extending the residence time based on Example 1 does not significantly improve the yield of the target product. Therefore, the residence time of the present invention is preferably 38 to 90 seconds, and considering energy consumption and efficiency, the residence time is further preferably 38 to 60 seconds.

[0047] Example 4 (Lowering the reaction temperature) A method for preparing allylamine compounds using a microchannel reactor includes the following steps: S1, take 1000g (13.1mol) of allyl chloride and 4899g (72.0mol) of 25% ammonia water. A microchannel reactor is used, and a metering pump is used for feeding. Maintain the reactor jacket temperature at 100℃, adjust the flow rate, and simultaneously feed the above raw materials into the microchannel reactor in two groups. The system pressure is 2.0 MPa, and the reaction residence time is 60 seconds to obtain the reaction solution.

[0048] S2, the distillation reaction liquid, the fraction collected at 50-55℃ yields monoallylamine, the fraction collected at 105-110℃ yields diallylamine.

[0049] Analysis of the reaction solution obtained in step S1 revealed that 1.1% of the raw material allyl chloride remained. Figure 5 The GC purity is shown as follows: monoallylamine purity 63.4%, diallylamine purity 27.2%, and triallylamine purity 6.2%.

[0050] After distillation, the reaction solution yielded monoallylamine with a relative yield of 64.8%, diallylamine with a relative yield of 27.8%, and triallylamine, a byproduct, with a relative yield of 6.3%.

[0051] Example 5 A method for preparing allylamine compounds using a microchannel reactor includes the following steps: S1, take 500g (6.6mol) of allyl chloride and 2674g (39.3mol) of 25% ammonia water. The reactor is a microchannel reactor, and the feed is carried out by a metering pump. Maintain the reactor jacket temperature at 80℃, adjust the flow rate, and simultaneously pump the above raw materials into the microchannel reactor in two groups. The system pressure is 0.9 MPa, and the reaction residence time is 60 seconds to obtain the reaction solution.

[0052] S2, the distillation reaction liquid, the fraction collected at 50-55℃ yields monoallylamine, the fraction collected at 105-110℃ yields diallylamine.

[0053] Analysis of the reaction solution obtained in step S1 revealed that 1.2% of the raw material allyl chloride remained. Figure 6 The GC purity is shown as follows: monoallylamine purity 65.7%, diallylamine purity 23.0%, and triallylamine purity 3.2%.

[0054] After distillation, the reaction solution yielded a relative yield of 70.6% for monoallylamine, a relative yield of 24.7% for diallylamine, and a relative yield of 3.4% for the byproduct triallylamine.

[0055] Example 6 A method for preparing allylamine compounds using a microchannel reactor includes the following steps: S1, take 1000g (13.1mol) of allyl chloride and 4008g (59mol) of 25% ammonia water. The reactor is a microchannel reactor, and the feed is metered by a pump. Maintain the reactor jacket temperature at 80℃, adjust the flow rate, and simultaneously pump the above raw materials into the microchannel reactor in two groups. The system pressure is 0.9 MPa, and the reaction residence time is 38 seconds to obtain the reaction solution.

[0056] S2, the distillation reaction liquid, the fraction collected at 50-55℃ yields monoallylamine, the fraction collected at 105-110℃ yields diallylamine.

[0057] Analysis of the reaction solution obtained in step S1 revealed that 0.78% of the raw material allyl chloride remained. Figure 7 The GC purity is shown as follows: monoallylamine purity 57.4%, diallylamine purity 27.3%, and triallylamine purity 8.7%.

[0058] After distillation, the reaction solution yielded monoallylamine with a relative yield of 60.9%, diallylamine with a relative yield of 29.0%, and triallylamine, a byproduct, with a relative yield of 9.2%.

[0059] In summary, this invention uses allyl chloride and ammonia as raw materials, without adding organic solvents or catalysts. The materials are metered and pumped into a microchannel reactor according to the specified ratio. By controlling the pressure, temperature, and residence time of the raw materials in the microchannel system, the ammonolysis reaction is completed in the microchannel reactor to obtain high yields of allylamine and diallylamine. This invention's reaction system is solvent-free and catalyst-free, environmentally friendly, and produces no metal ion-containing wastewater. It has advantages such as high reaction efficiency, improved production efficiency, and high product selectivity.

[0060] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing allylamine compounds using microchannel technology, characterized in that, Includes the following steps: S1, using allyl chloride and ammonia as raw materials, the raw materials are pumped into a microchannel reactor for ammonolysis reaction to obtain a reaction solution, wherein the residence time of the raw materials in the microchannel reactor is 38 to 90 seconds; S2, the reaction solution is distilled to obtain allylamine compounds.

2. The method for preparing allylamine compounds using microchannel technology according to claim 1, characterized in that, In step S1, the mass fraction of the ammonia water is 25% to 28%.

3. The method for preparing allylamine compounds using microchannel technology according to claim 1, characterized in that, In step S1, the molar ratio of allyl chloride to NH3 in ammonia water is 1:(3-6).

4. The method for preparing allylamine compounds using microchannel technology according to claim 1, characterized in that, In step S1, the raw material is pumped into the microchannel reactor by a metering pump; the metering pump is a plunger pump or a gear pump.

5. The method for preparing allylamine compounds using microchannel technology according to claim 4, characterized in that, A mixer is installed between the metering pump and the microchannel reactor; the microchannel reactor is equipped with a pressure relief valve.

6. The method for preparing allylamine compounds using microchannel technology according to claim 1, characterized in that, In step S1, the channel diameter of the microchannel reactor is 1.2 to 1.8 mm.

7. The method for preparing allylamine compounds using microchannel technology according to claim 1, characterized in that, In step S1, the conditions of the microchannel reactor during the ammonolysis reaction include: pressure of 0-2 MPa, temperature of 60-120°C, and residence time of 38-60 seconds.

8. The method for preparing allylamine compounds using microchannel technology according to claim 7, characterized in that, The conditions for the microchannel reactor include: pressure of 0.8–2.0 MPa and temperature of 80–120 °C.

9. The method for preparing allylamine compounds using microchannel technology according to claim 1, characterized in that, In step S2, the allylamine compounds include monoallylamine and diallylamine.

10. The method for preparing allylamine compounds using microchannel technology according to claim 9, characterized in that, During the distillation process, the fraction distilled at 50–55°C is monoallylamine, and the fraction distilled at 105–110°C is diallylamine.

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