CN111362827A

CN111362827A - Process for catalytically synthesizing N, N-dimethylacrylamide

Info

Publication number: CN111362827A
Application number: CN202010336947.5A
Authority: CN
Inventors: 庄严; 张韦; 鲍迎庆
Original assignee: Jiangsu University of Technology
Current assignee: Jiangsu University of Technology
Priority date: 2020-04-26
Filing date: 2020-04-26
Publication date: 2020-07-03

Abstract

The invention discloses a process for catalytically synthesizing N, N-dimethylacrylamide, which mainly comprises the following steps: firstly, under the condition of low-temperature stirring, dropwise adding dimethylamine into methyl acrylate to perform addition reaction, then adding sodium methoxide to perform amidation reaction, then adding an acid catalyst to perform cracking reaction, obtaining a crude product, and then purifying the crude product by times to complete the whole synthesis process. The synthesis process method adopts a thermal cracking reaction mode, and overcomes the defect of excessive byproducts caused by exothermic reaction; the low-temperature stirring technology is adopted in the addition reaction stage, so that the uncertainty caused by the fact that dimethylamine is more active than other amide compounds in property is overcome, and the experimental error is reduced; the crude product is purified by adopting a small quantity of multiple times in consideration of the characteristics of higher boiling point and easiness in polymerization of the product, so that the yield of the target product can be improved.

Description

Process for catalytically synthesizing N, N-dimethylacrylamide

Technical Field

The invention belongs to the technical field of chemical synthesis, and relates to a process for catalytically synthesizing N, N-dimethylacrylamide.

Background

N, N-dimethylacrylamide is an important chemical raw material and has very wide application; the polymer can be used as a water treatment scale inhibitor, a temperature-resistant and salt-resistant drilling fluid filtrate reducer, an oil well cement filtrate reducer and a temperature-resistant and salt-resistant polymer oil displacement agent; it can also be used for modification of fiber materials, daily chemicals, printing and photography, medical and sanitary materials, and the like; the polymer or the adduct thereof is excellent in moisture absorption, antistatic property, dispersibility, compatibility, protective stability, adhesiveness and the like.

The synthesis process route using methyl acrylate and dimethylamine as starting materials is the most common method for producing the compound in industry at present, the process is relatively mature overall, but the synthesis precision, yield and the like are still required to be further improved.

Disclosure of Invention

The invention aims to solve the defects in the prior art and provide a process for catalytically synthesizing N, N-dimethylacrylamide, which has few side reactions, high synthesis precision and effectively ensured yield.

The invention discloses a process for catalytically synthesizing N, N-dimethylacrylamide, which comprises the following specific steps:

(1) dropwise adding dimethylamine into methyl acrylate while stirring at low temperature by using a low-temperature magnetic stirring reaction device, and carrying out addition reaction to generate an ester adduct 3-methoxy-N, N-dimethylpropionamide;

(2) continuously adding 5% sodium methoxide as a catalyst to perform amidation reaction to generate an intermediate product 3-dimethylamino-N, N-dimethyl propionamide (DMDMAA);

(3) purifying the generated 3-dimethylamino-N, N-dimethyl propionamide crude product, adding the purified crude product into a three-neck flask with a thermometer and a spherical condenser pipe, connecting the other side of the condenser pipe with normal-temperature distilled water, dropwise adding an acid catalyst into the flask, placing the flask in an electric heating jacket distillation device for heating up, stopping heating when the temperature is 100 ℃, adding a polymerization inhibitor hydroquinone, continuing heating up to 110 ℃, keeping the temperature for 30min to obtain a thermal cracking solution containing N, N-dimethyl acrylamide (DMAA), continuing heating up to 300 ℃, keeping for 1h, and stopping reaction;

(4) and adding a methanol solution and hydroquinone into the obtained thermal cracking solution for three times, purifying in a rotary evaporator, and taking out to obtain a purified target product N, N-dimethylacrylamide.

Further, in the step (1), the temperature of the low-temperature stirring was 5 ℃.

Further, in the step (1), dimethylamine was added to methyl acrylate at a rate of 2 seconds per drop under low-temperature stirring.

Further, in the step (1), the addition reaction time is 2-3 h.

Further, in the step (2), during the amidation reaction, after a sodium methoxide catalyst is added, the mixture is heated at 100 ℃ for 2 to 3 hours, then the temperature is raised to 150 ℃ for 2 to 3 hours, and then the mixture is continuously heated to 200 ℃ for 3 to 4 hours.

Further, after the ester adduct 3-dimethylamino-N, N-dimethyl propionamide is produced in the step (1) and the final product N, N-dimethyl acrylamide is produced in the step (4), the structures of the products are respectively characterized by infrared absorption spectrum, hydrogen spectrum and mass spectrum-chromatography.

Further, in the step (3), the acidic catalyst used is concentrated HCl.

Further, in the step (4), the reaction temperature at the time of purification in a rotary evaporator is 60 to 70 ℃.

The invention has the beneficial effects that:

1. compared with the prior art, the method has the advantages that a low-temperature stirring technology is adopted in the addition reaction stage, so that the uncertainty caused by the fact that dimethylamine is more active than other amide compounds is overcome, and the experimental error is reduced;

2. the synthesis process method adopts thermal cracking reaction, belongs to endothermic reaction, overcomes the defect of excessive byproducts caused by exothermic reaction, and lays a foundation for later-stage industrialization;

3. the traditional product identification is innovated, and the latest infrared absorption spectrum, hydrogen spectrum and mass spectrum-chromatography combination are utilized to characterize the structures of the intermediate products 3-dimethylamino-N, N-dimethyl propionamide and N, N-dimethyl acrylamide, so that the synthesis accuracy is improved;

4. the crude product is purified by adopting a small quantity of multiple times in consideration of the characteristics of higher boiling point and easiness in polymerization of the product, so that the yield of the target product can be improved.

Detailed Description

The following examples further illustrate the present invention but are not to be construed as limiting the invention. Modifications and substitutions to methods, procedures, or conditions of the invention may be made without departing from the spirit of the invention.

Example one

(1) Stirring at low temperature by using a low-temperature magnetic stirring reaction device at 5 ℃, dropwise adding dimethylamine into methyl acrylate at the speed of 2 seconds per drop, carrying out addition reaction for 2 hours to generate an ester adduct 3-methoxy-N, N-dimethylpropionamide, and analyzing a base solution by infrared absorption spectroscopy, hydrogen spectroscopy and mass spectrum-chromatography;

(2) adding 5% sodium methoxide as a catalyst, heating at 100 ℃ for 2 h, heating to 150 ℃ for 2 h, then continuing heating to 200 ℃ for 3h, and carrying out amidation reaction to generate an intermediate product 3-dimethylamino-N, N-dimethyl propionamide;

(3) purifying the generated crude product of 3-dimethylamino-N, N-dimethyl propionamide, adding the purified crude product into a three-neck flask with a thermometer and a spherical condenser pipe, connecting the other side of the condenser pipe with normal-temperature distilled water, dropwise adding concentrated HCl (hydrochloric acid) serving as an acid catalyst into the flask, putting the flask into an electric heating jacket distillation device for heating up, stopping heating when the temperature is 100 ℃, adding hydroquinone serving as a polymerization inhibitor, continuously heating up to 110 ℃, keeping for 30min to obtain a thermal cracking solution containing N, N-dimethyl acrylamide (DMAA), and keeping for 1h when the temperature is continuously raised to 300 ℃, and stopping the reaction;

(3) adding methanol solution and hydroquinone into the obtained thermal cracking solution for three times, purifying in a rotary evaporator, taking out, controlling the reaction temperature to be 60-70 ℃, obtaining a purified target product N, N-dimethylacrylamide, and analyzing the product by infrared absorption spectrum, hydrogen spectrum and mass spectrum-chromatography combination.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. However, the above description is only an example of the present invention, the technical features of the present invention are not limited thereto, and any other embodiments that can be obtained by those skilled in the art without departing from the technical solution of the present invention should be covered by the claims of the present invention.

Claims

1. A process for catalytically synthesizing N, N-dimethylacrylamide is characterized by comprising the following specific synthesis steps:

2. The process for the catalytic synthesis of N, N-dimethylacrylamide according to claim 1, wherein in step (1), the temperature of the low-temperature stirring is 5 ℃.

3. The process for the catalytic synthesis of N, N-dimethylacrylamide of claim 1, wherein in step (1), dimethylamine is added to the methyl acrylate at a rate of 2 seconds per drop with low temperature stirring.

4. The process for catalytically synthesizing N, N-dimethylacrylamide according to claim 1, wherein in step (1), the addition reaction time is 2 to 3 hours.

5. The process for catalytically synthesizing N, N-dimethylacrylamide according to claim 1, wherein in step (2), during the amidation reaction, after adding sodium methoxide catalyst, the reaction mixture is heated at 100 ℃ for 2-3h, then heated to 150 ℃ for 2-3h, and then further heated to 200 ℃ for 3-4 h.

6. The process for the catalytic synthesis of N, N-dimethylacrylamide according to claim 1, wherein the ester adduct 3-dimethylamino-N, N-dimethylpropionamide produced in step (1) and the final product N, N-dimethylacrylamide produced in step (4) are subjected to infrared absorption spectroscopy, hydrogen spectroscopy and mass spectrometry-chromatography.

7. The process for the catalytic synthesis of N, N-dimethylacrylamide according to claim 1, wherein in step (3), the acidic catalyst used is concentrated HCl.

8. The process for catalytically synthesizing N, N-dimethylacrylamide according to claim 1, wherein in the step (4), the reaction temperature for purification in a rotary evaporator is 60 to 70 ℃.