A preparation method of 3-methoxy-N,N-dimethylpropionamide

Abstract

The invention belongs to the field of chemical synthesis, and in particular to a method for preparing 3-methoxy-N, N-dimethylpropionamide, comprising the following steps: adding dimethylamine and 3-methoxy propionyl chloride to a reaction vessel, then adding a modified catalyst, and reacting to obtain 3-methoxy-N, N-dimethylpropionamide; the method for preparing the modified catalyst comprises the following steps: S1, preparing raw materials; S2, adding a basic catalyst to 4-aminostyrene to generate a modified basic catalyst; S3, adding nano-alumina to methyl methacrylate, and reacting to obtain a product modified carrier; S4, adding the modified basic catalyst and the modified carrier to an organic solvent, then adding divinylbenzene and an initiator, standing after the reaction, and then taking out the modified carrier to obtain a modified catalyst. The present invention constrains alkali metals by the framework of a three-dimensional mesh structure, thereby hindering the migration of metal nanoparticles, and is conducive to the synthesis of 3-methoxy-N, N-dimethylpropionamide.

Description

Technical Field

[0001] The invention belongs to the field of chemical synthesis, and specifically relates to a preparation method of 3-methoxy-N,N-dimethylpropionamide. Background Art

[0002] 3-Methoxy-N,N-dimethylpropionamide is a transparent liquid and an important organic synthesis intermediate and organic solvent. It has the characteristics of high solubility and high permeability, is non-irritating to the skin, and is environmentally friendly to install. It has a large potential application market in the pharmaceutical, chemical, coatings and other industries.

[0003] At present, the production method of 3-methoxy-N,N-dimethylpropionamide mainly uses chemical synthesis of dimethylamine and 3-methoxypropionyl chloride under the condition of adding a catalyst, and the catalyst is mostly a supported alkali metal catalyst.

[0004] However, supported alkali metal catalysts are prone to nanoparticle agglomeration. This is because the interaction between the alkali metal and the carrier is weak, so the metal nanoparticles are prone to migrate and merge to form larger agglomerated particles. The agglomeration of metal nanoparticles will seriously affect the performance of the catalyst and affect the preparation of 3-methoxy-N,N-dimethylpropionamide. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a method for preparing 3-methoxy-N,N-dimethylpropionamide, in which alkali metals are bound by a framework of a three-dimensional network structure, thereby hindering the migration of metal nanoparticles to avoid the formation of agglomerated particles, so that the catalyst in the present invention can still maintain a high catalytic activity after multiple uses, which is beneficial to the synthesis of 3-methoxy-N,N-dimethylpropionamide.

[0006] The specific technical solution adopted by the present invention is:

[0007] A method for preparing 3-methoxy-N,N-dimethylpropionamide comprises the following steps: adding dimethylamine and 3-methoxypropionyl chloride into a reaction container, then adding a modified catalyst, stirring evenly and heating to react, to obtain 3-methoxy-N,N-dimethylpropionamide;

[0008] The preparation method of the modified catalyst comprises the following steps:

[0009] S1, prepare raw materials;

[0010] S2, adding the alkaline catalyst to 4-aminostyrene, reacting at 40-50° C. for 1-2 h to generate a modified alkaline catalyst;

[0011] S3, adding nano-alumina to the toluene solution of methyl methacrylate, stirring evenly and reacting for 2-4 hours to obtain a dispersion, then centrifuging the dispersion, rinsing and drying the product to obtain a modified carrier;

[0012] S4. Add 70-85% of the total amount of the modified alkaline catalyst and all the modified carriers into an organic solvent, then add divinylbenzene, react for 30-60 minutes, then add the remaining modified alkaline catalyst, then add the initiator, react at 78-82°C for 120-150 minutes, then cool and let stand for 4-6 hours, then take out the modified carrier, age, dry and activate the modified carrier to obtain a modified catalyst.

[0013] Furthermore, the molar ratio of dimethylamine to 3-methoxypropionyl chloride is 2-3:1.

[0014] Furthermore, the added amount of the modified catalyst is 1-2 wt % of the mass of 3-methoxypropionyl chloride.

[0015] Furthermore, the alkaline catalyst is an alkali metal oxide or an alkali metal carbonate.

[0016] Furthermore, the nano-alumina is a nano-alumina having a porous structure. .

[0017] Furthermore, the initiator includes any one of ammonium persulfate, benzoyl peroxide and azobisisobutyronitrile.

[0018] Furthermore, the raw materials prepared in step S1 include, by weight:

[0019] 15-20 parts of alkaline catalyst, 30-40 parts of 4-aminostyrene, 100-120 parts of toluene solution of methyl methacrylate, 10-15 parts of nano-alumina, 1-3 parts of divinylbenzene, 0.1-0.2 parts of initiator, and 25-30 parts of organic solvent.

[0020] Furthermore, in step S4, the mass ratio of the total amount of the modified alkaline catalyst to the total amount of the modified carrier is 1-2:2-1.

[0021] Furthermore, the concentration of the toluene solution of methyl methacrylate is 80-100 mg / mL.

[0022] The beneficial effects of the present invention are:

[0023] 1. In order to improve the degree of bonding between the alkali metal and the carrier, the present invention binds the alkali metal through the framework of the three-dimensional network structure, thereby hindering the migration of metal nanoparticles to avoid the formation of agglomerated particles, so that the catalyst of the present invention can still maintain a high catalytic activity after repeated use, which is beneficial to the synthesis of 3-methoxy-N,N-dimethylpropionamide.

[0024] 2. In the present invention, alkaline metals are first coordinated with 4-aminostyrene to generate complex reactants, and then methyl methacrylate is adsorbed on a carrier to form a modified carrier. Finally, a copolymerization reaction between 4-aminostyrene and methyl methacrylate is used to generate chemical bonding. Multiple groups of network structures generated by 4-aminostyrene and methyl methacrylate bind and space individual metal nanoparticles, thereby hindering the migration of metal nanoparticles. At the same time, the complex reactants generated by the coordination of alkaline metals and 4-aminostyrene have better catalytic ability.

[0025] In addition, by combining chemical adsorption with physical adsorption, the alkali metal loading on the carrier can be increased, thereby further improving the activation performance of the modified catalyst. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. 1. Specific embodiments

[0028] Example 1

[0029] S1, prepare 18 parts of alkaline catalyst, 35 parts of 4-aminostyrene, 110 parts of toluene solution of methyl methacrylate, 12 parts of nano-alumina, 2 parts of divinylbenzene, 0.15 parts of initiator, and 28 parts of organic solvent;

[0030] The concentration of the toluene solution of methyl methacrylate is 90 mg / mL;

[0031] S2, adding sodium carbonate to 4-aminostyrene, reacting at 45°C for 1 hour to generate a modified alkaline catalyst;

[0032] S3, adding nano-alumina to the toluene solution of methyl methacrylate, stirring evenly and reacting for 3 hours to obtain a dispersion, then centrifuging the dispersion at a speed of 2000 r / min, rinsing and drying the product to obtain a modified carrier;

[0033] S4, adding 80% of the total amount of the modified alkaline catalyst and all the modified carriers into ethanol, then adding divinylbenzene, adding the remaining modified alkaline catalyst after reacting for 50 minutes, then adding ammonium persulfate, reacting at 80° C. for 130 minutes, then cooling and standing for 6 hours, then taking out the modified carrier, aging, drying and activating the modified carrier to obtain a modified catalyst;

[0034] The mass ratio of the total amount of the modified alkaline catalyst to the total amount of the modified carrier is 1:1.

[0035] Example 2

[0036] S1, prepare 15 parts of alkaline catalyst, 30 parts of 4-aminostyrene, 100 parts of toluene solution of methyl methacrylate, 10 parts of nano-alumina, 1 part of divinylbenzene, 0.1 parts of initiator, and 25 parts of organic solvent;

[0037] The concentration of the toluene solution of methyl methacrylate is 100 mg / mL;

[0038] S2, adding sodium carbonate to 4-aminostyrene, reacting at 40° C. for 2 h to generate a modified alkaline catalyst;

[0039] S3, adding nano-alumina to the toluene solution of methyl methacrylate, stirring evenly and reacting for 4 hours to obtain a dispersion, then centrifuging the dispersion at a speed of 2000 r / min, rinsing and drying the product to obtain a modified carrier;

[0040] S4, adding 70% of the total amount of the modified alkaline catalyst and all the modified carriers into ethanol, then adding divinylbenzene, adding the remaining modified alkaline catalyst after reacting for 30 minutes, then adding ammonium persulfate, reacting at 78° C. for 120 minutes, then cooling and standing for 4 hours, then taking out the modified carrier, aging, drying and activating the modified carrier to obtain a modified catalyst;

[0041] The mass ratio of the total amount of the modified alkaline catalyst to the total amount of the modified carrier is 1:2.

[0042] Example 3

[0043] S1, prepare 20 parts of alkaline catalyst, 40 parts of 4-aminostyrene, 120 parts of toluene solution of methyl methacrylate, 15 parts of nano-alumina, 3 parts of divinylbenzene, 0.2 parts of initiator, and 30 parts of organic solvent;

[0044] The concentration of the toluene solution of methyl methacrylate is 80 mg / mL;

[0045] S2, adding sodium carbonate to 4-aminostyrene, reacting at 50° C. for 2 h to generate a modified alkaline catalyst;

[0046] S3, adding nano-alumina to the toluene solution of methyl methacrylate, stirring evenly and reacting for 3 hours to obtain a dispersion, then centrifuging the dispersion at a speed of 2000 r / min, rinsing and drying the product to obtain a modified carrier;

[0047] S4, adding 85% of the total amount of the modified alkaline catalyst and all the modified carriers into ethanol, then adding divinylbenzene, adding the remaining modified alkaline catalyst after reacting for 60 minutes, then adding ammonium persulfate, reacting at 82° C. for 150 minutes, then cooling and standing for 6 hours, then taking out the modified carrier, aging, drying and activating the modified carrier to obtain a modified catalyst;

[0048] The mass ratio of the total amount of the modified alkaline catalyst to the total amount of the modified carrier is 2:1.

[0049] Example 4

[0050] S1, prepare 16 parts of alkaline catalyst, 38 parts of 4-aminostyrene, 115 parts of toluene solution of methyl methacrylate, 14 parts of nano-alumina, 1.8 parts of divinylbenzene, 0.18 parts of initiator, and 27 parts of organic solvent;

[0051] The concentration of the toluene solution of methyl methacrylate is 80 mg / mL;

[0052] S2, adding sodium carbonate to 4-aminostyrene, reacting at 48°C for 1.5h to generate a modified alkaline catalyst;

[0053] S3, adding nano-alumina to the toluene solution of methyl methacrylate, stirring evenly and reacting for 2 hours to obtain a dispersion, then centrifuging the dispersion at a speed of 2000 r / min, rinsing and drying the product to obtain a modified carrier;

[0054] S4, adding 82% of the total amount of the modified alkaline catalyst and all the modified carriers into ethanol, then adding divinylbenzene, adding the remaining modified alkaline catalyst after reacting for 40 minutes, then adding ammonium persulfate, reacting at 82° C. for 130 minutes, then cooling and standing for 5 hours, then taking out the modified carrier, aging, drying and activating the modified carrier to obtain a modified catalyst;

[0055] The mass ratio of the total amount of the modified alkaline catalyst to the total amount of the modified carrier is 1.5:1.

[0056] Example 5

[0057] S1, prepare 16 parts of alkaline catalyst, 32 parts of 4-aminostyrene, 106 parts of toluene solution of methyl methacrylate, 12 parts of nano-alumina, 1.5 parts of divinylbenzene, 0.12 parts of initiator, and 25 parts of organic solvent;

[0058] The concentration of the toluene solution of methyl methacrylate is 90 mg / mL;

[0059] S2, adding sodium carbonate to 4-aminostyrene, reacting at 42°C for 1.2h to generate a modified alkaline catalyst;

[0060] S3, adding nano-alumina to the toluene solution of methyl methacrylate, stirring evenly and reacting for 3 hours to obtain a dispersion, then centrifuging the dispersion at a speed of 2000 r / min, rinsing and drying the product to obtain a modified carrier;

[0061] S4, adding 75% of the total amount of the modified alkaline catalyst and all the modified carriers into ethanol, then adding divinylbenzene, adding the remaining modified alkaline catalyst after reacting for 30 minutes, then adding ammonium persulfate, reacting at 78° C. for 150 minutes, then cooling and standing for 4 hours, then taking out the modified carrier, aging, drying and activating the modified carrier to obtain a modified catalyst;

[0062] The mass ratio of the total amount of the modified alkaline catalyst to the total amount of the modified carrier is 1:1.

[0063] Comparative Example 1

[0064] The only difference between Comparative Example 1 and Example 1 is that the catalyst used in Comparative Example 1 is a common supported catalyst, which is prepared by directly immersing nano-alumina into a solution containing sodium ions, and then aging, drying and activating the catalyst.

[0065] 2. Performance Test

[0066] The modified catalysts prepared in Examples 1-5 and Comparative Example 1 were used to prepare 3-methoxy-N,N-dimethylpropionamide. After the preparation was completed, the modified catalyst was taken out, and then the modified catalyst was used for a new round of 3-methoxy-N,N-dimethylpropionamide preparation. The process was repeated multiple times, and the conversion rate of 3-methoxypropionyl chloride was tested for each reaction. The test results are shown in Table 1.

[0067] The preparation process of 3-methoxy-N,N-dimethylpropionamide is as follows: dimethylamine and 3-methoxypropionyl chloride in a molar ratio of 2.4:1 are added into a reactor, and then a modified catalyst in an amount of 0.6wt% of the mass of 3-methoxypropionyl chloride is added, mixed evenly, and reacted at 75°C for 3h to obtain the finished 3-methoxy-N,N-dimethylpropionamide.

[0068] Table 1

[0069]

[0070] As can be seen from Table 1, when the catalysts prepared in Examples 1-5 were used for the fifth time, the conversion rate of 3-methoxypropionyl chloride was still above 95%, while during use, although the catalyst prepared in Comparative Example 1 had a higher conversion rate of 3-methoxypropionyl chloride at the beginning, after the catalyst was used for 5 times, the conversion rate of 3-methoxypropionyl chloride was less than 80%, and the catalyst could not be used further.

[0071] This is because during the long-term use of the catalyst in Comparative Example 1, not only did some of the metal nanoparticles detach, but some of the metal nanoparticles also migrated to form agglomerated particles, thus affecting the performance of the catalyst.

[0072] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing 3-methoxy-N,N-dimethylpropionamide, characterized in that: The method comprises the following steps: adding dimethylamine and 3-methoxypropionyl chloride into a reaction container, then adding a modified catalyst, stirring evenly and heating to react, so as to obtain 3-methoxy-N,N-dimethylpropionamide; The preparation method of the modified catalyst comprises the following steps: S1, prepare raw materials; S2, adding the alkaline catalyst to 4-aminostyrene, reacting at 40-50° C. for 1-2 h to generate a modified alkaline catalyst; S3, adding nano-alumina to the toluene solution of methyl methacrylate, stirring evenly and reacting for 2-4 hours to obtain a dispersion, then centrifuging the dispersion at a speed of 2000 r / min, rinsing and drying the product to obtain a modified carrier; S4, adding 70-85% of the total amount of the modified alkaline catalyst and all the modified carriers into an organic solvent, then adding divinylbenzene, reacting for 30-60 minutes, adding the remaining modified alkaline catalyst, then adding an initiator, reacting at 78-82° C. for 120-150 minutes, then cooling and standing for 4-6 hours, taking out the modified carrier, aging, drying and activating the modified carrier to obtain a modified catalyst; The raw materials prepared in step S1 include, by weight: 15-20 parts of alkaline catalyst, 30-40 parts of 4-aminostyrene, 100-120 parts of toluene solution of methyl methacrylate, 10-15 parts of nano-alumina, 1-3 parts of divinylbenzene, 0.1-0.2 parts of initiator, 25-30 parts of organic solvent; The alkaline catalyst is sodium carbonate; The organic solvent is ethanol.

2. The method for preparing 3-methoxy-N,N-dimethylpropionamide according to claim 1, characterized in that: The molar ratio of dimethylamine to 3-methoxypropionyl chloride is 2-3:

1.

3. The method for preparing 3-methoxy-N,N-dimethylpropionamide according to claim 1, characterized in that: The added amount of the modified catalyst is 0.5-0.8 wt % of the mass of 3-methoxypropionyl chloride.

4. The method for preparing 3-methoxy-N,N-dimethylpropionamide according to claim 1, characterized in that: The nano-alumina is a nano-alumina having a porous structure. .

5. The method for preparing 3-methoxy-N,N-dimethylpropionamide according to claim 1, characterized in that: The initiator includes any one of ammonium persulfate, benzoyl peroxide and azobisisobutyronitrile.

6. The method for preparing 3-methoxy-N,N-dimethylpropionamide according to claim 1, characterized in that: The mass ratio of the total amount of the modified alkaline catalyst to the total amount of the modified carrier in step S4 is 1-2:2-1.

7. The method for preparing 3-methoxy-N,N-dimethylpropionamide according to claim 1, characterized in that: The concentration of the toluene solution of methyl methacrylate is 80-100 mg / mL.

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