A method for purifying crude alkoxydimethylpropionamide

Abstract

This application relates to the field of alkoxydimethylpropionamide processing technology, specifically disclosing a method for purifying crude alkoxydimethylpropionamide. The purification method includes the following steps: adding a UV initiator to the crude product and mixing, then irradiating with light, repeating the above steps or not repeating them, followed by vacuum distillation to obtain the finished product; the crude product is crude alkoxydimethylpropionamide, mainly comprising alkoxydimethylpropionamide and N,N-dimethylacrylamide; the finished product is finished alkoxydimethylpropionamide. The purification method of this application, by adding a UV initiator to the crude product and combining it with light irradiation, greatly reduces the difficulty of purification. Combined with vacuum distillation, the vacuum distillation is performed only once, without fractionation, and has the advantages of short vacuum distillation time, high purification efficiency, low energy consumption, and high product yield, making it suitable for industrial mass production needs.

Description

Technical Field

[0001] This application relates to the field of alkoxydimethylpropionamide processing technology, and more specifically, it relates to a method for purifying crude alkoxydimethylpropionamide. Background Technology

[0002] Lithium-ion rechargeable batteries have advantages such as high operating voltage, high specific energy density, long cycle life, low self-discharge rate, no memory effect, and low environmental pollution, and have been widely used in various consumer electronics and power batteries. Lithium-ion rechargeable batteries typically consist of electrode components, electrolyte, and a container. The positive electrode slurry of the electrode components usually contains active materials, conductive agents, binders, and organic solvents. N-methylpyrrolidone (NMP) is often used as an organic solvent. Although it has low viscosity, low volatility, and is miscible with other organic solvents, it also has a certain degree of toxicity. Thermal decomposition produces irritating or toxic gases, which have a significant impact on the environment and human health. It has been added to the restricted substances list of "REACH Annex XVII" by the European Union, and since May 2020, the EU has banned products containing more than 0.3% NMP.

[0003] Some researchers have proposed using alkoxydimethylacrylamide solvents as organic solvents. These are colorless and transparent solvents, mainly including methoxydimethylacrylamide and butoxydimethylacrylamide. These solvents contain amide and alkoxy groups, are miscible with a variety of organic solvents, and have the characteristics of high solubility, high permeability, high fluidity, low viscosity, and low surface tension. They are also non-irritating to the skin, safe and environmentally friendly, and can be a good substitute for N-methylpyrrolidone.

[0004] Because the lithium battery industry has very high purity requirements for organic solvents, the purity of the alkoxydimethylpropionamide product is generally required to reach 99.9% or higher. In the synthesis of alkoxydimethylpropionamide, existing methods mainly use methyl alkoxyacrylate and dimethylamine as raw materials, with diethylene glycol as a solvent, and catalyze the reaction in the presence of sodium alkoxide to obtain a mixture. The mixture is then subjected to crude distillation, specifically: a first distillation to remove low-boiling-point substances such as methanol, dimethylamine, and water; and a second distillation to collect the fractions, thus obtaining the crude product, which typically has a purity of 98.0%. The crude product is then subjected to rectification distillation, specifically: a first vacuum distillation and a second vacuum distillation, to obtain the finished product. Although the purity of the finished product can reach 99.9%, fractionation is unavoidable in the first and second vacuum distillations, resulting in high energy consumption, long distillation time, and low efficiency. Summary of the Invention

[0005] To improve the purification efficiency of crude alkoxydimethylpropionamide, this application provides a method for purifying crude alkoxydimethylpropionamide, employing the following technical solution:

[0006] A method for purifying crude alkoxydimethylpropionamide includes the following steps: adding a UV initiator to the crude product and mixing, then irradiating with light, repeating the above steps or not repeating the above steps, and then performing vacuum distillation to obtain the finished product;

[0007] The crude product is crude alkoxydimethylpropionamide, and mainly includes alkoxydimethylpropionamide and N,N-dimethylacrylamide; the finished product is finished alkoxydimethylpropionamide.

[0008] The applicant analyzed the components of crude alkoxydimethylpropionamide and found that in addition to the reaction of methyl alkoxyacrylate and dimethylamine to produce alkoxydimethylpropionamide, unsaturated N,N-dimethylacrylamide is also produced. Moreover, the boiling points of N,N-dimethylacrylamide and alkoxydimethylpropionamide are not much different, making purification difficult. In the purification of crude product, not only is it necessary to combine primary and secondary vacuum distillation, but also to perform fractionation in order to achieve a purity of 99.9% for the finished product.

[0009] Based on the above findings, the technical solution of this application involves adding a UV initiator to the crude product and irradiating it with light to polymerize N,N-dimethylacrylamide into a macromolecule. This increases the boiling point difference between the macromolecule and alkoxydimethylacrylamide, significantly reducing the purification difficulty. The product can then be directly subjected to vacuum distillation, requiring only one distillation cycle without the need to set a fractionation ratio. This yields a high-purity, high-yield finished product with a purity ≥99.9% and a yield ≥95.0%. Furthermore, the vacuum distillation process is short, highly efficient, energy-saving, and yields a high product, demonstrating economic value and promising market application prospects.

[0010] Furthermore, the crude product is obtained by reacting methyl alkoxyacrylate and dimethylamine, followed by crude distillation.

[0011] Optionally, in the illumination treatment, the energy density of the light is 500-1200 MJ / cm³. 2 The time is 1-5 minutes.

[0012] By adopting the above technical solution, the energy density and time of light irradiation are limited, which facilitates the polymerization reaction of N,N-dimethylacrylamide in the crude product, and thus facilitates subsequent vacuum distillation.

[0013] Preferably, in the light treatment, the energy density of the light is 800-1000 MJ / cm³. 2 .

[0014] Preferably, the illumination time in the light treatment is 1-3 minutes.

[0015] Optionally, the UV initiator is one or more of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine, 2-isopropylthioxanthone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone, and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone.

[0016] By adopting the above technical solution, the UV initiator is limited, which facilitates the selection of UV initiators. Moreover, UV initiators are abundant and readily available.

[0017] Optionally, the UV initiator is either 1-hydroxycyclohexylphenyl ketone or diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride, and the weight ratio of 1-hydroxycyclohexylphenyl ketone to diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride is (2-3):(1-2).

[0018] In several embodiments, the weight ratio of 1-hydroxycyclohexylphenyl ketone to diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxyacetate is 5:3, but the weight ratio can also be set to 2:1, 1:1, 3:1, 3:2, etc. as needed.

[0019] Optionally, the amount of the UV initiator added is 0.05-0.2 wt% of the total crude product.

[0020] By adopting the above technical solution, the amount of UV initiator added to the crude product is limited, which facilitates the UV initiator to initiate the polymerization reaction of all N,N-dimethylacrylamide.

[0021] Optionally, in the purification method, the above steps are repeated once, and the weight ratio of the UV initiator used in the first light treatment and the UV initiator used in the second light treatment is (4-6):(3-5).

[0022] By adopting the above technical solution, the UV initiator is added to the crude product in two stages, and combined with two light irradiation treatments, the purity of the finished product is improved.

[0023] Preferably, the weight ratio of the UV initiator used in the first light treatment and the UV initiator used in the second light treatment is 5:(3-5).

[0024] In one embodiment, the weight ratio of the UV initiator used in the first light treatment to that used in the second light treatment is 5:5. In another embodiment, the weight ratio of the UV initiator used in the first light treatment to that used in the second light treatment is 5:3.

[0025] Optionally, in the vacuum distillation process, the vacuum pressure is 4-6 mmHg, the temperature is 80-120℃, and the time is 2-4 h.

[0026] By adopting the above technical solution, the pressure, temperature, and time of vacuum distillation are limited. The macromolecules formed by the polymerization of N,N-dimethylacrylamide do not volatilize, while alkoxydimethylpropionamide volatilizes. There is no need to set up fractionation, and rapid vacuum distillation is achieved, which reduces energy consumption and facilitates the purification of crude products.

[0027] Preferably, in the vacuum distillation process, the temperature of vacuum distillation is 90-100℃ and the time is 2-3h.

[0028] In several implementation schemes, the vacuum distillation process uses a vacuum pressure of 5 mmHg, a temperature of 100°C, and a time of 2 hours. Alternatively, the vacuum pressure can be set to 4 mmHg, 4.5 mmHg, 5.5 mmHg, 6 mmHg, etc., the temperature can be set to 80°C, 90°C, 110°C, 120°C, etc., and the time can be set to 2.5 hours, 3 hours, 3.5 hours, 4 hours, etc., as needed.

[0029] Optionally, the crude product contains 98.0-99.5% alkoxydimethylpropionamide.

[0030] By adopting the above technical solution, the content of alkoxydimethylpropionamide in the crude product is limited, that is, the purity of the crude product is limited, thereby reducing the impact of large fluctuations in the purity of the crude product on the stability of the purification method.

[0031] Optionally, the finished product contains ≥99.9% alkoxydimethylpropionamide.

[0032] By adopting the above technical solution, the purity of the finished product is ≥99.9%, which can be applied to the lithium battery industry.

[0033] In summary, this application has at least the following beneficial effects:

[0034] The purification method for crude alkoxydimethylpropionamide disclosed in this application involves adding a UV initiator to the crude product and irradiating it with light to polymerize the N,N-dimethylacrylamide in the crude product into a large molecule, which greatly reduces the difficulty of purification. Combined with vacuum distillation, which only requires one distillation cycle and eliminates the need for fractionation, a high-purity, high-yield finished product can be obtained. The finished product has a purity of ≥99.9% and a yield of ≥95.0%. Furthermore, the vacuum distillation method is characterized by short distillation time, high purification efficiency, low energy consumption, and high finished product yield, making it suitable for industrial mass production. Detailed Implementation

[0035] To make this application easier to understand, the following detailed description will be provided with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of application of this application. Unless otherwise specified, the raw materials or components used in this application can be obtained commercially or by conventional methods.

[0036] Example

[0037] Example 1

[0038] A method for purifying crude alkoxydimethylpropionamide includes the following steps:

[0039] Add 0.5g of UV initiator to 1000g of crude product and stir for 10min. Then, at an energy density of 800MJ / cm³, [the process is repeated]. 2 Under light, the sample was treated for 1 minute. Then it was transferred to a rotary evaporator and distilled under reduced pressure at 5 mmHg and 100°C for 2 hours. The distillate was collected to obtain the final product.

[0040] The UV initiator is 1-hydroxycyclohexylphenyl ketone; the crude product is crude alkoxydimethylpropionamide, which is obtained by reacting methyl alkoxyacrylate and dimethylamine and then distilling it. The crude product mainly includes alkoxydimethylpropionamide and N,N-dimethylacrylamide, and the content of alkoxydimethylpropionamide in the crude alkoxydimethylpropionamide is 99.5%.

[0041] Example 2

[0042] A method for purifying crude alkoxydimethylpropionamide differs from Example 1 in that the amount of UV initiator added is different; the amount of UV initiator added is 1g.

[0043] Example 3

[0044] A method for purifying crude alkoxydimethylpropionamide differs from Example 1 in that the amount of UV initiator added is different; the amount of UV initiator added is 2g.

[0045] Example 4

[0046] A method for purifying crude alkoxydimethylpropionamide, which differs from Example 1 in that the energy density of the light irradiation is different; the energy density of the light irradiation is 1000 MJ / cm³. 2 .

[0047] Example 5

[0048] A method for purifying crude alkoxydimethylpropionamide, which differs from Example 1 in that the energy density of the light irradiation is different; the energy density of the light irradiation is 1200 MJ / cm³.2 .

[0049] Example 6

[0050] A method for purifying crude alkoxydimethylpropionamide, which differs from Example 1 in that the energy density of the light irradiation is different; the energy density of the light irradiation is 500 MJ / cm². 2 .

[0051] Example 7

[0052] A method for purifying crude alkoxydimethylpropionamide differs from Example 1 in that the source of the UV initiator is different. The UV initiator is either 1-hydroxycyclohexylphenyl ketone or diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride, and the weight ratio of 1-hydroxycyclohexylphenyl ketone to diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride is 5:3.

[0053] Example 8

[0054] A method for purifying crude alkoxydimethylpropionamide differs from Example 1 in that the amount and source of the UV initiator are different. The amount of UV initiator added is 0.8g, and the UV initiator is either 1-hydroxycyclohexylphenyl ketone or diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride, with a weight ratio of 5:3 between the two.

[0055] Example 9

[0056] A method for purifying crude alkoxydimethylpropionamide includes the following steps:

[0057] Add 0.8 g of UV initiator to 1000 g of crude product and stir for 10 min. Then, at an energy density of 1000 MJ / cm³, [the process is repeated]. 2 Under light, the sample was treated for 1 minute. Then it was transferred to a rotary evaporator and distilled under reduced pressure at 5 mmHg and 100°C for 2 hours. The distillate was collected to obtain the final product.

[0058] The UV initiators are 1-hydroxycyclohexylphenyl ketone and diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride, with a weight ratio of 5:3. The crude product mainly contains alkoxydimethylpropionamide and N,N-dimethylacrylamide, with an alkoxydimethylpropionamide content of 98.0%.

[0059] Example 10

[0060] A method for purifying crude alkoxydimethylpropionamide includes the following steps:

[0061] Add 0.5g of UV initiator to 1000g of crude product and stir for 10min. Then, at an energy density of 800MJ / cm³, [the process is repeated]. 2 Under light, the sample was treated for 1 minute. Then, 0.5 g of UV initiator was added, and the mixture was stirred for 10 minutes. Finally, the sample was heated to an energy density of 800 MJ / cm². 2 Under light, the sample was treated for 1 minute. Then it was transferred to a rotary evaporator and distilled under reduced pressure at 5 mmHg and 100°C for 2 hours. The distillate was collected to obtain the final product.

[0062] The UV initiator is 1-hydroxycyclohexylphenyl ketone; the crude product mainly includes alkoxydimethylpropionamide and N,N-dimethylacrylamide, and the content of alkoxydimethylpropionamide in the crude product is 98.0%.

[0063] Example 11

[0064] A method for purifying crude alkoxydimethylpropionamide includes the following steps:

[0065] Add 0.5g of UV initiator to 1000g of crude product and stir for 10min. Then, at an energy density of 800MJ / cm³, [the process is repeated]. 2 Under light, the sample was treated for 2 minutes. Then, 0.3 g of UV initiator was added, and the mixture was stirred for 10 minutes. Finally, the sample was heated to an energy density of 800 MJ / cm². 2 Under light, the sample was treated for 1 minute. Then it was transferred to a rotary evaporator and distilled under reduced pressure at 5 mmHg and 100°C for 2 hours. The distillate was collected to obtain the final product.

[0066] The UV initiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxide; the crude product mainly includes alkoxydimethylpropionamide and N,N-dimethylacrylamide, and the content of alkoxydimethylpropionamide in the crude product is 98.0%.

[0067] Comparative Example

[0068] Comparative Example 1

[0069] A method for purifying crude alkoxydimethylpropionamide includes the following steps:

[0070] 1000g of crude product was transferred to a rotary evaporator and distilled under reduced pressure at 5mmHg and 100℃, with a fractionation ratio of 3:1. When the content reached 99.9%, the fraction was collected. The reduced pressure distillation time was 4.5h to obtain the finished product.

[0071] The crude product mainly contains alkoxydimethylpropionamide and N,N-dimethylacrylamide, and the content of alkoxydimethylpropionamide in the crude product is 99.5%.

[0072] Comparative Example 2

[0073] A method for purifying crude alkoxydimethylpropionamide includes the following steps:

[0074] 1000g of crude product was transferred to a rotary evaporator and distilled under reduced pressure at 5mmHg and 100℃, with a fractionation ratio controlled at 2:1. When the purity reached 99.0%, the fraction was collected for 3 hours. Then, the fraction was transferred back to the rotary evaporator and distilled under reduced pressure at 5mmHg and 100℃, with a fractionation ratio controlled at 2:1. When the purity reached 99.9%, the fraction was collected for 2 hours to obtain the final product.

[0075] The crude product mainly contains alkoxydimethylpropionamide and N,N-dimethylacrylamide, with alkoxydimethylpropionamide content of 98.0%.

[0076] Performance testing

[0077] The finished products obtained in Examples 1-11 and Comparative Examples 1-2 were weighed and the yields were calculated. Simultaneously, the alkoxydimethylpropionamide content in the finished products was tested, and the results are shown in Table 1.

[0078] The purity of the crude product is the content of alkoxydimethylpropionamide in the crude product; the purity of the finished product is the content of alkoxydimethylpropionamide in the finished product.

[0079] Yield = (Quantity of finished product / Quantity of crude product) × 100%.

[0080] Table 1 Test Results

[0081]

[0082]

[0083] As can be seen from Table 1, the purity of the finished product obtained by the purification method of this application can reach over 99.9%, and it also has a high yield and yield, with a yield of 951-956g and a yield of 95.1-95.6%.

[0084] Example 1 and Comparative Example 1 were compared. Comparative Example 1 had a crude product purity of 99.5%, a vacuum distillation time of 4.5 hours, a fractionation ratio of 3:1, and a final product yield of 88.1%. Example 1 had a crude product purity of 99.5%, a vacuum distillation time of 2 hours, and no fractionation, and a final product yield of 95.2%. This demonstrates that the purification method of this application not only significantly reduces vacuum distillation time but also increases yield.

[0085] Example 9 and Comparative Example 2 were compared. Comparative Example 2 had a crude product purity of 98.0%, a single vacuum distillation time of 3 hours, a fractionation ratio of 2:1, a second vacuum distillation time of 2 hours, and a fractionation ratio of 2:1, yielding a final product of 77.1%. Example 9 had a crude product purity of 98.0%, a vacuum distillation time of 2 hours, no fractionation, and a yield of 95.4%. This demonstrates that the purification method of this application has the advantages of reducing vacuum distillation time, reducing energy consumption, improving purification efficiency, and increasing yield.

[0086] It should be noted that the embodiments described above are only for explaining this application and do not constitute any limitation on this application. This application has been described with reference to typical embodiments, but it should be understood that the terms used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to this application within the scope of the claims, and revisions can be made to the invention without departing from the scope and spirit of this application. Although the application described herein relates to specific methods, materials, and embodiments, it does not mean that this application is limited to the specific examples disclosed herein; on the contrary, this application can be extended to all other methods and applications with the same function.

Claims

1. A method for purifying crude alkoxydimethylpropionamide characterized in that: The method comprises the following steps: adding a UV initiator into the crude product, mixing, then irradiating, repeating the above steps or not, and then performing vacuum distillation to obtain the finished product. The crude product is an alkoxydimethylpropionamide crude product, which comprises alkoxydimethylpropionamide and N,N-dimethylacrylamide; and the finished product is an alkoxydimethylpropionamide finished product.

2. The method of purifying crude alkoxydimethyl propanamide according to claim 1, characterized in that: In the light treatment, the energy density of the light is 500-1200 MJ / cm 2 , and the time is 1-5 min.

3. The method of purifying crude alkoxydimethyl propanamide according to claim 2, characterized in that: In the light treatment, the energy density of the light is 800-1000 MJ / cm 2 .

4. The method of purifying crude alkoxydimethyl propanamide according to claim 1, characterized in that: The UV initiator is one or more of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide, 2-isopropylthioxanthone, 2-phenylbenz-2-dimethylamine-1-(4-morpholinobenzyl phenyl) butanone, and 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone.

5. The method of purifying crude alkoxydimethyl propanamide according to claim 4, characterized in that: The UV initiator is 1-hydroxycyclohexyl phenyl ketone and diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide, and the weight ratio of 1-hydroxycyclohexyl phenyl ketone to diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide is (2-3):(1-2).

6. The method of purifying crude alkoxydimethyl propanamide according to claim 1, characterized in that: The added amount of the UV initiator is 0.05-0.2wt% of the total amount of the crude product.

7. The method of purifying crude alkoxydimethyl propanamide according to claim 1, wherein: In the purification method, the above steps are repeated once, and the weight ratio of the UV initiator used in the first irradiation treatment to the UV initiator used in the second irradiation treatment is (4-6):(3-5).

8. The method of purifying crude alkoxydimethyl propanamide according to claim 1, characterized in that: In the vacuum distillation treatment, the vacuum pressure of the vacuum distillation is 4-6mmHg, the temperature is 80-120℃, and the time is 2-4h.

9. The method of purifying crude alkoxydimethyl propanamide according to claim 1, wherein: The content of the alkoxydimethylpropionamide in the crude product is 98.0-99.5%.

10. The method of purifying crude alkoxydimethyl propanamide according to claim 1, characterized in that: The content of the alkoxydimethylpropionamide in the finished product is ≥99.9%.

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