A method for synthesizing 3-methoxy-n,n-dimethylpropanamide

Abstract

The application discloses a synthesis method of 3-methoxy-N,N-dimethylpropanamide, which is synthesized by using dimethylamine (DMA) and 3-methoxy methyl propionate (MMP) as raw materials, water as a solvent, and through an amidation reaction, and then refined by using a multistage rectification method. The method does not need to use a catalyst, but uses water to promote the transfer of protons in the reaction process, so that the DMA is self-catalyzed, and the influence of strong alkali or acidic catalysts and high-boiling-point solvents such as polyols on the reaction is avoided. The synthesis route has the characteristics of simplicity, mild reaction conditions and environmental friendliness, and the purity of the obtained 3-methoxy-N,N-dimethylpropanamide can reach more than 99.9 %, which meets the use standard of battery solvents.

Description

Technical Field

[0001] This invention belongs to the field of new energy technology, specifically relating to a method for synthesizing 3-methoxy-N,N-dimethylpropionamide. Background Technology

[0002] Against the backdrop of accelerated global energy transition, developing efficient and clean energy storage technologies has become a key path to ensure energy security and achieve "dual carbon" goals. Lithium-ion batteries, as the mainstay of electrochemical energy storage, occupy a core position in new energy vehicles and novel energy storage fields due to their high energy density, long cycle life, and rapid response characteristics. However, as market demands for battery performance increase, the electrolyte, as a core component determining the overall performance of the battery, urgently requires breakthroughs in innovative research and development. Currently, traditional solvents, represented by N-methylpyrrolidone (NMP), have limitations in terms of safety and environmental friendliness, making the development of high-performance alternative solvents an important direction for industrial upgrading. Among them, 3-methoxy-N,N-dimethylpropionamide (MDMPA) is a colorless and transparent liquid with excellent physical properties such as high boiling point, high polarity, low viscosity, and low surface tension. It is miscible with a variety of solvents, and its safety and environmental protection characteristics are significant, with no skin irritation, meeting the requirements of modern industry for green solvents, making it an ideal alternative to NMP.

[0003] There are currently many methods for synthesizing MDMPA. Patent CN 106966923A discloses a method for synthesizing MDMPA, which mainly uses acrylonitrile, anhydrous methanol, and metal alkoxides as starting materials to obtain methoxypropionitrile, which is then subjected to acidic hydrolysis to obtain 3-methoxypropionic acid, followed by amination to obtain MDMPA. This step uses sulfuric acid for acidification, but sulfuric acid easily corrodes equipment, and the amination process requires pressurization, resulting in harsh reaction conditions that are unfavorable for industrial production. Furthermore, it easily generates acidic wastewater, polluting the environment and failing to meet the requirements of modern green chemistry.

[0004]

[0005] Chinese patent CN 119775158A uses methyl 3-methoxypropionate, N,N-dimethylformamide, and water as raw materials to synthesize MDMPA. This reaction uses a Lewis acid catalyst, which easily produces strong acids or hydrolyzes into strong acids after the reaction, severely corroding equipment and increasing costs. Furthermore, the subsequent treatment of acidic wastewater is costly. Simultaneously, the low solubility of water and methyl 3-methoxypropionate makes it difficult to form a homogeneous system, resulting in poor mass transfer and easy side reactions under the action of acidic catalysts, leading to poor selectivity. In addition, this method requires high temperatures, which causes DMF decomposition during heating, resulting in low conversion rates and numerous side reactions. Vacuum distillation or multiple distillations are necessary to achieve high purity MDMPA. Moreover, the byproduct methyl formate is flammable and explosive, and both the raw material DMF and the byproduct methyl formate are biotoxic, which is detrimental to modern green chemical engineering concepts.

[0006]

[0007] Japanese Patent JP WO2008 / 102615 and Chinese Patent CN 116874385A use methyl 3-methoxypropionate and dimethylamine as starting materials, and polyols (such as ethylene glycol and glycerol) as solvents, to obtain MDMPA under the catalysis of a strong base (such as sodium tert-butoxide). This method uses polyols as solvents to dissolve dimethylamine, thereby increasing the reaction contact area between dimethylamine and methyl 3-methoxypropionate and improving the conversion rate. However, polyols have high viscosity and boiling points, and the reaction conversion rate is relatively low. The byproducts are complex and difficult to separate. Furthermore, the sodium alkoxide catalyst used is easily converted to Na₂CO₃ and deposited on the equipment, causing damage and hindering industrialization.

[0008] Summary of the Invention

[0009] In view of the shortcomings of the prior art, the present invention provides a new method for synthesizing 3-methoxy-N,N-dimethylpropionamide that is safe, environmentally friendly, highly selective, low in energy consumption, simple in process and with high raw material utilization. It can avoid the use of strong base or acid catalysts and high-boiling-point solvents such as polyols, and achieves excellent results with a product purity of over 99.9%.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A method for synthesizing 3-methoxy-N,N-dimethylpropionamide, which uses dimethylamine (DMA) and methyl 3-methoxypropionate (MMP) as raw materials, water as solvent, and synthesizes 3-methoxy-N,N-dimethylpropionamide (MDMPA) via an amidation reaction, followed by purification using a multi-stage distillation method; the method includes the following steps: 1) Synthesis of MDMPA: DMA and water are mixed to obtain an aqueous solution of dimethylamine, which is then fed together with MMP into reactor F1 for amidation reaction to obtain a mixture containing MDMPA; 2) DMA recovery: The mixture containing MDMPA obtained in step 1) is fed into distillation column T01. Under the heating of the reboiler, gas-liquid mass transfer occurs in the column. When the purity of DMA at the top of the distillation column reaches 99.9% or more and the purity of DMA at the bottom of the column is less than 0.1%, the product is collected from the bottom of the column and DMA is collected from the top of the column. The collected DMA is mixed with water according to step 1) and recycled to reactor F1 for further reaction. 3) Separation of methanol and water: The product collected from the bottom of distillation column T01 in step 2) is sent to distillation column T02, and water and methanol are collected from the top of distillation column T02. The product collected from the bottom of the column has a methanol and water purity of less than 0.1%. 4) MMP recovery: The product collected from the bottom of distillation column T02 in step 3) is sent to distillation column T03. Under the heating of the reboiler, vapor-liquid mass transfer is carried out in the column. The product with MMP purity of less than 0.1% is collected from the bottom of the column, and MMP is collected from the top of the column. The collected MMP is circulated to reactor F1 in step 1) through pump and heater to continue the reaction. 5) Purification of MDMPA: The product collected from the bottom of distillation column T03 in step 4) is sent to purification column T04. Under the heating action of the reboiler, vapor-liquid mass transfer is carried out in the column. MDMPA with a purity of 99.9% is collected from the top of the column, and 3-methoxypropionic acid, a byproduct, is collected from the bottom of the column.

[0011] Further, the mass concentration of the dimethylamine aqueous solution in step 1) is 30-60%.

[0012] Further, in step 1), the feed molar ratio of MMP to DMA is 1:(2.0~4.0).

[0013] Further, the reactor F1 mentioned in step 1) is a continuous stirred tank reactor. Preferably, the reactor volume is 15~20 m³. 3 The number of reactors is 5 to 10.

[0014] Furthermore, in step 1), the stirring speed of the reactor is 100-300 rpm.

[0015] Further, the amidation reaction in step 1) is carried out at a temperature of 0-25°C for a time of 15-24 h.

[0016] Further, the distillation column T01 mentioned in step 2) is a packed column or a plate column, with a theoretical plate number of 2~15 in the rectification section, a theoretical plate number of 10~15 in the stripping section, an operating pressure of 1.0 bar, a reflux ratio of 0.2~1, a top temperature of 5~7℃, and a bottom temperature of 93~95℃.

[0017] Further, the distillation column T02 in step 3) is a packed column or a plate column, with a theoretical plate number of 3~15 in the rectification section, a theoretical plate number of 10~15 in the stripping section, an operating pressure of 1.0 bar, a reflux ratio of 0.3~1, a top temperature of 90~93 ℃, and a bottom temperature of 159~161 ℃.

[0018] Further, in step 4), the distillation column T03 is a packed column or a plate column, with a theoretical plate number of 5~10 in the rectification section and 10~15 in the stripping section. It operates at atmospheric pressure, with a reflux ratio of 0.4~1, a top temperature of 140~143 ℃, and a bottom temperature of 206~209 ℃.

[0019] Further, the refining column T04 in step 5) is a packed column or a plate column, with a theoretical plate number of 28~35 in the rectification section and 30~35 in the stripping section. It operates at atmospheric pressure, with a reflux ratio of 3~6, ​​a top temperature of 205~207 ℃, and a bottom temperature of 218~220 ℃.

[0020] Furthermore, the packing used in the distillation columns T01~T03 and the purification column T04 during the operation is Sulzer Mellapak 250Y structured packing.

[0021] 1) This invention uses water as a solvent. In this system, water can promote proton transfer and has an auxiliary catalytic effect, effectively promoting the reaction. Therefore, no catalyst is needed, which reduces costs and is less likely to cause environmental pollution. At the same time, dimethylamine and water easily form hydrogen bonds, forming a stable hydrate with water. Compared with polyols, it is more stable in the reaction process. In addition, mixing dimethylamine with water to form a solution avoids the disadvantages of high safety risks, severe equipment corrosion, and high transportation costs associated with the gas transportation of dimethylamine.

[0022] 2) Regarding the problem of low solubility of methyl 3-methoxypropionate in water, this invention strengthens the dispersion effect of methyl 3-methoxypropionate in water by adjusting the temperature (0-10℃) and stirring speed (100-300rpm), and increases the contact area between the two, thereby solving the problem of low solubility of methyl 3-methoxypropionate in water and realizing the stable application of water as the reaction solvent.

[0023] 3) In a reaction system with water as the solvent, the amidation reaction conditions are mild, and high selectivity and conversion can be achieved at room temperature and pressure. Moreover, the generated byproduct is singular, consisting only of 3-methoxypropionic acid, which is beneficial for subsequent separation operations, reduces separation costs, simplifies the process flow, and avoids the problems of high solvent boiling point, high viscosity, and difficulty in separation that exist when using polyols (such as ethylene glycol, glycerol, etc.) as solvents.

[0024] 4) The present invention uses atmospheric distillation in the separation process, which makes the process more convenient and reduces separation energy consumption. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the process flow for synthesizing 3-methoxy-N,N-dimethylpropionamide according to the present invention; Wherein: M1 and M2 are mixers, F1 is a continuous batch reactor, T01 is a distillation column for dimethylamine recovery, T02 is a distillation column for removing methanol and water, T03 is a distillation column for methyl 3-methoxypropionate recovery, and T04 is a purification column for 3-methoxy-N,N-dimethylpropionamide recovery. Detailed Implementation

[0026] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto. Example 1

[0027] like Figure 1A 40 wt.% fresh DMA aqueous solution S1 and fresh MMP S2 were fed into mixer M1 at mass flow rates of 626.61 kg / hr and 819.88 kg / hr, respectively (controlling the molar ratio of DMA to MMP after mixing to be 2.5:1). The solution temperature was then lowered to 0℃, and the mixed solution S3 was fed into a continuous batch reactor F1 and reacted at 0℃ for 24 h. The resulting reaction mixture S4 had a flow rate of 5392.80 kg / hr, with a conversion rate of 50.1% and a selectivity of 81.6% for the key component MMP. The resulting reaction mixture S4 was pumped to distillation column T01 (column T01 is packed with Sulzer Mellapak 250Y structured packing, with a total of 17 theoretical plates, 4 theoretical plates in the rectification section and 13 theoretical plates in the stripping section), operating at atmospheric pressure with a reflux ratio of 0.3, a top temperature of 6.78 ℃, and a bottom temperature of 94.17 ℃. The flow rate of S5 collected from the top of the column was 1268.53 kg / hr, and the flow rate of S6 collected from the bottom of the column was 4124.27 kg / hr. The S5 collected from the top of the column was mixed again with fresh water to form a 40 wt.% DMA aqueous solution, which was then cooled to room temperature through a heat exchanger to obtain S7 at a flow rate of 3170.27 kg / hr, and then sent to the reaction section to continue participating in the reaction.

[0028] S6, collected from the bottom of distillation column T01, is fed into distillation column T02 (distillation column T02 is packed with Sulzer Mellapak 250Y structured packing, with a total of 23 theoretical plates, 13 in the rectifying section and 10 in the stripping section). The column operates at atmospheric pressure with a reflux ratio of 0.46, a top temperature of 91.86 ℃, and a bottom temperature of 160.84 ℃. The flow rate of S8 collected from the top of the column is 2477.54 kg / hr, and the flow rate of S9 collected from the bottom is 1646.73 kg / hr.

[0029] S9 collected from the bottom of distillation column T02 is fed into distillation column T03 (distillation column T03 is packed with Sulzer Mellapak 250Y structured packing, with a total of 20 theoretical plates, 7 in the rectifying section and 13 in the stripping section), operating at atmospheric pressure with a reflux ratio of 0.47. The top temperature is 140.54 ℃, and the bottom temperature is 208.04 ℃. The flow rate of S10 collected from the top is 776.01 kg / hr, and the flow rate of S11 collected from the bottom is 870.72 kg / hr. S10 is pumped to a heat exchanger to be cooled to room temperature to obtain S12, which is then sent to the reaction section to continue participating in the reaction.

[0030] S11 collected from the bottom of distillation column T03 is fed into purification column T04 (purification column T04 is packed with Sulzer Mellapak 250Y structured packing, with a total of 62 theoretical plates, 32 in the rectification section and 30 in the stripping section), operating at atmospheric pressure with a reflux ratio of 3.5. The top temperature is 205.74 ℃, and the bottom temperature is 219.90 ℃. The flow rate of S13 collected from the top of the column is 727.02 kg / hr, which is MDMPA, and the flow rate of S14 collected from the bottom of the column is 143.70 kg / hr, which is the byproduct 3-methoxypropionic acid.

[0031] Some logistics information is shown in Table 1-3.

[0032] Table 1 Implementation Conditions-1

[0033] Table 2 Implementation Conditions-2 Example 2

[0034] The 40 wt.% fresh DMA aqueous solution was adjusted to a 40 wt.% fresh DMA methanol solution, with other conditions the same as in Example 1. The results are shown in Table 3. Example 3

[0035] The 40 wt.% fresh DMA aqueous solution was adjusted to a 40 wt.% fresh DMA glycol solution, with other conditions the same as in Example 1. The results are shown in Table 3.

[0036] Table 3 Reaction Results

[0037] As shown in Table 3, using water as a solvent yields higher MMP conversion, selectivity, and yield. This is because water has the strongest polarity, allowing it to better dissolve DMA. Furthermore, its small molecular size and low viscosity facilitate the diffusion and collision of reactant molecules. In contrast, alcohols have weaker polarity and much higher viscosity than water, severely hindering molecular diffusion and mass transfer. Additionally, water acts more effectively as a proton transfer medium in aminolysis reactions, promoting the formation and transformation of reaction intermediates. Alcohols or ethylene glycol, under similar conditions, may participate in side reactions or alter the acid-base environment of the system, thereby reducing the selectivity and yield of the target product. Example 4

[0038] The mass concentration of the DMA aqueous solution was adjusted to 30 wt.%, and the feed rate was adjusted to ensure that the molar ratio of DMA to MMP was the same as in Example 1. Other conditions were the same as in Example 1. The results are shown in Table 4. Example 5

[0039] The mass concentration of the DMA aqueous solution was adjusted to 50 wt.%, and the feed rate was adjusted to ensure that the molar ratio of DMA to MMP was the same as in Example 1. Other conditions were the same as in Example 1. The results are shown in Table 4. Example 6

[0040] The feed ratio of DMA and MMP was adjusted to 3:1, and other conditions were the same as in Example 1. The results are shown in Table 4. Example 7

[0041] The temperature of the amidation reaction was adjusted to 10 °C, and other conditions were the same as in Example 1. The results are shown in Table 4.

[0042] Table 4 Reactor Results Example 8

[0043] The reflux ratio of distillation column T01 was adjusted to 0.2, and other conditions were the same as in Example 1. The results are shown in Table 5. Example 9

[0044] The reflux ratio of distillation column T01 was adjusted to 0.5, and other conditions were the same as in Example 1. The results are shown in Table 5. Example 10

[0045] The number of trays in the T01 rectification section of the distillation column was adjusted to 2, and other conditions were the same as in Example 1. The results are shown in Table 5. Example 11

[0046] The number of trays in the T01 rectification section of the distillation column was adjusted to 5, and other conditions were the same as in Example 1. The results are shown in Table 5.

[0047] Table 5 T01 Operating Condition Example 12

[0048] The reflux ratio of distillation TO2 was adjusted to 0.3, and other conditions were the same as in Example 1. The results are shown in Table 6. Example 13

[0049] The reflux ratio of distillation TO2 was adjusted to 0.6, and other conditions were the same as in Example 1. The results are shown in Table 6. Example 14

[0050] The number of trays in the T02 rectification section was adjusted to 10, and other conditions were the same as in Example 1. The results are shown in Table 6. Example 15

[0051] The number of trays in the T02 rectification section was adjusted to 15, and other conditions were the same as in Example 1. The results are shown in Table 6.

[0052] Table 6 T02 Operating Condition Example 16

[0053] The reflux ratio of distillation column T03 was adjusted to 0.3, and other conditions were the same as in Example 1. The results are shown in Table 7. Example 17

[0054] The reflux ratio of distillation column T03 was adjusted to 0.5, and other conditions were the same as in Example 1. The results are shown in Table 7. Example 18

[0055] The number of trays in the T03 rectification section of the distillation column was adjusted to 5, and other conditions were the same as in Example 1. The results are shown in Table 7. Example 19

[0056] The number of trays in the T03 rectification section of the distillation column was adjusted to 10, and other conditions were changed to the same as in Example 1. The results are shown in Table 7.

[0057] Table 7 T03 Operating Condition Example 20

[0058] The reflux ratio of the purification tower T04 was adjusted to 3.3, and other conditions were the same as in Example 1. The results are shown in Table 8. Example 21

[0059] The reflux ratio of the purification tower T04 was adjusted to 3.8, and other conditions were the same as in Example 1. The results are shown in Table 8. Example 22

[0060] The number of trays in the T04 rectification section of the refining column was adjusted to 30, and other conditions were the same as in Example 1. The results are shown in Table 8. Example 23

[0061] The number of trays in the T04 rectification section of the refining column was adjusted to 34, and other conditions were the same as in Example 1. The results are shown in Table 8.

[0062] Table 8 T04 Operating Condition

[0063] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for synthesizing 3-methoxy-N,N-dimethylpropionamide, characterized in that: MDMPA was synthesized from DMA and MMP as raw materials and water as solvent via amidation reaction, and then purified by multi-stage distillation.

2. The method for synthesizing 3-methoxy-N,N-dimethylpropionamide according to claim 1, characterized in that: Includes the following steps: 1) Synthesis of MDMPA: DMA and water are mixed to obtain an aqueous solution of dimethylamine, which is then fed together with MMP into reactor F1 for amidation reaction to obtain a mixture containing MDMPA; 2) DMA recovery: The mixture containing MDMPA obtained in step 1) is fed into distillation column T01 for gas-liquid mass transfer. When the purity of DMA at the top of the distillation column reaches 99.9% or more and the purity of DMA at the bottom of the column is less than 0.1%, DMA is collected from the top of the column and the product is collected from the bottom of the column. 3) Separation of methanol and water: The product collected from the bottom of distillation column T01 in step 2) is sent to distillation column T02, and water and methanol are collected from the top of distillation column T02, while the product is collected from the bottom of the column. 4) MMP recovery: The product collected from the bottom of distillation column T02 in step 3) is sent to distillation column T03 for vapor-liquid mass transfer. MMP is collected from the top of the column and the product is collected from the bottom of the column. 5) Refining of MDMPA: The product collected from the bottom of distillation column T03 in step 4) is sent to refining column T04 for vapor-liquid mass transfer, and MDMPA with a purity of 99.9% is collected from the top of the column.

3. The method for synthesizing 3-methoxy-N,N-dimethylpropionamide according to claim 2, characterized in that: Step 1) The mass concentration of the dimethylamine aqueous solution is 30-60%; the feed molar ratio of MMP to DMA is 1:(2.0-4.0); the reactor F1 is a continuous stirred tank reactor; the stirring speed of the reactor is 100-300 rpm; the temperature of the amidation reaction is 0-25℃ and the time is 15-24 h.

4. The method for synthesizing 3-methoxy-N,N-dimethylpropionamide according to claim 2, characterized in that: The distillation column T01 mentioned in step 2) is a packed column or a plate column, with a theoretical plate number of 2~15 in the rectification section and 10~15 in the stripping section. The operating pressure is 1.0 bar, the reflux ratio is 0.2~1, the top temperature is 5~7℃, and the bottom temperature is 93~95℃.

5. The method for synthesizing 3-methoxy-N,N-dimethylpropionamide according to claim 2, characterized in that: Step 3) The distillation column T02 is a packed column or a plate column, with a theoretical plate number of 3~15 in the rectification section and 10~15 in the stripping section. The operating pressure is 1.0 bar, the reflux ratio is 0.3~1, the top temperature is 90~93 ℃, and the bottom temperature is 159~161 ℃.

6. The method for synthesizing 3-methoxy-N,N-dimethylpropionamide according to claim 2, characterized in that: Step 4) The distillation column T03 is a packed column or a plate column, with a theoretical plate number of 5~10 in the rectification section and 10~15 in the stripping section. It operates at atmospheric pressure, with a reflux ratio of 0.4~1, a top temperature of 140~143 ℃, and a bottom temperature of 206~209 ℃.

7. The method for synthesizing 3-methoxy-N,N-dimethylpropionamide according to claim 2, characterized in that: Step 5) The refining column T04 is a packed column or a plate column, with a theoretical plate number of 28~35 in the rectification section and 30~35 in the stripping section. It operates at atmospheric pressure, with a reflux ratio of 3~6, ​​a top temperature of 205~207 ℃, and a bottom temperature of 218~220 ℃.

Images