CN106966923B - A kind of synthetic method of 3-methoxy-N,N-dimethylpropionamide - Google Patents

Abstract

The invention relates to a method for synthesizing 3-methoxy-N,N-dimethylpropionamide, belonging to the technical field of chemical synthesis, comprising the following steps: adding acrylonitrile, anhydrous methanol and metal alkoxide into a reactor In the middle reaction, the unreacted anhydrous methanol is recovered again to obtain 3-methoxypropionitrile; acid catalyst and water are added to 3-methoxypropionitrile, and the hydrolysis reaction is heated to obtain 3-methoxypropionitrile after filtration. ; 3-methoxypropionic acid and dimethylamine are added in the closed reactor, and the temperature rise reaction obtains 3-methoxy-N,N-dimethylpropionamide. The invention uses cheap acrylonitrile as the starting material, alkoxylates the acrylonitrile to obtain methoxypropionitrile, then hydrolyzes to obtain methoxypropionic acid, and then reacts with acid and base to form salt and dehydrate to obtain the target product without polyol and alkalinity. The catalyst can be dehydrated at high temperature in a closed reactor, the reaction is simple and feasible, and the product has high yield and high purity.

Description

A kind of synthetic method of 3-methoxy-N,N-dimethylpropionamide

technical field

The invention relates to a method for synthesizing a chemical material intermediate, in particular to a method for synthesizing 3-methoxy-N,N-dimethylpropionamide, and belongs to the technical field of chemical synthesis.

Background technique

3-Methoxy-N,N-dimethylpropionamide (structural formula shown in formula I) is a colorless and transparent solvent with amide group and alkyl group, which can be mixed with various solvents and can Highly soluble polymer polyamide; it has the characteristics of high solubility, high permeability, high fluidity, low viscosity, low surface tension, etc., and is not irritating to the skin, safe and environmentally friendly, and can be a good substitute for the traditional solvent N-formaldehyde Pyrrolidone is widely used in electronics, medicine, pesticides, pigments, cleaning agents, insulating materials and other industries. In today's market of safe solvents, where competition is constantly refined, in addition to solubility, high volatility and low toxicity have also become important bargaining chips in solvent competition. Therefore, the product has a broad market prospect.

For the synthesis of 3-methoxy-N,N-dimethylpropionamide, the existing method mainly uses methyl 3-methoxypropionate and dimethylamine as raw materials, and diethylene glycol is a solvent in sodium alkoxide. catalyzed synthesis. However, the solvent diethylene glycol in this method cannot be reused because the boiling point of 245°C is too high and the recovery cost is high. In addition, the amount of the catalyst sodium alkoxide is relatively large, and it needs to be neutralized with sulfuric acid and then filtered. The process operation is troublesome, and a large amount of solid waste residue is generated, which does not meet the requirements of green environmental protection. Furthermore, the reaction yield and selectivity are not high, and the raw material of dimethylamine needs to be excessively large, and the production process produces a large amount of waste gas of dimethylamine, which requires high equipment for the recovery system of dimethylamine waste gas and requires a large investment.

The reaction equation is as follows:

For example, a Chinese patent (application number: 201380019269.8) discloses a method for producing β-alkoxy propionamides. In this patent, β-alkoxy acrylates are reacted with amines to produce β-alkoxy propionamides. , but the method takes β-alkoxy acrylates as raw materials, reacts with amines, and needs to reclaim the by-products after the reaction, and the recovered by-products contain a large amount of amines, which is difficult to handle, and the raw materials themselves are processed by acrylic acid. Esterification, methoxidation, the process is more complicated.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a low-cost, high-yield synthetic method of 3-methoxy-N,N-dimethylpropionamide for the deficiencies existing in the prior art.

The above-mentioned object of the present invention is achieved by the following technical solutions: a synthetic method of 3-methoxy-N,N-dimethylpropionamide, and the synthetic method comprises the following steps:

S1, the synthesis of 3-methoxypropionitrile: adding acrylonitrile, anhydrous methanol and metal alkoxide into the reactor to react, then reclaiming unreacted anhydrous methanol to obtain 3-methoxypropionitrile;

S2, the synthesis of 3-methoxypropionic acid: add acid catalyst and water to 3-methoxypropionitrile in step S1, heat to carry out hydrolysis reaction, and obtain 3-methoxypropionic acid by filtration;

Synthesis of S3, 3-methoxy-N,N-dimethylpropionamide: 3-methoxypropionic acid and dimethylamine are added to the closed reactor, and the temperature rises to react to obtain 3-methoxy-N, N-Dimethylpropionamide.

The reaction in the prior art is basically the reaction of an ester with an amine, and the source of the ester is obtained by acrylic esterification to obtain acrylic ester, followed by alkoxylation to obtain β-alkoxy acrylic ester, and then aminated. The invention adopts acrylonitrile with relatively low price as the starting material, alkoxylates the acrylonitrile to obtain methoxypropionitrile, then hydrolyzes to obtain methoxypropionic acid, and then reacts with acid and alkali to form salt and dehydrate to obtain the target product. In the present invention, the polyol is not required because there is no side reaction, the product itself can be used as a solvent, no further dilution is required, and no basic catalyst is required because the reaction is an acid-base neutralization reaction, and then dehydration at high temperature is easy to carry out. The introduction of a basic catalyst will not only not work, but will consume methoxypropionic acid and introduce impurities at the same time. Furthermore, in the present invention, in order to avoid the volatilization of the raw material amine and the reversible reaction under high temperature conditions, the reaction needs to be carried out in a closed space. The invention reduces pollution while realizing high yield, and meets the requirements of modern industrial green synthesis.

In the above-mentioned synthesis method of 3-methoxy-N,N-dimethylpropionamide, the metal alkoxide described in step S1 is sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, magnesium methoxide, magnesium ethoxide , one or more of sodium tert-butoxide and potassium tert-butoxide. The invention adopts the metal alkoxide with strong catalytic ability as the catalyst, and the source of the metal alkoxide is convenient, easy to obtain and low in cost.

Preferably, the metal alkoxide described in step S1 is one or both of sodium methoxide and sodium ethoxide. Compared with other metal alkoxides, sodium methoxide and sodium ethoxide have stronger activity, lower cost and better competitiveness.

In the above-mentioned synthetic method of 3-methoxy-N,N-dimethylpropionamide, in step S1, the material ratio of acrylonitrile, anhydrous methanol, and metal alkoxide is 1:(1-50):( 0.001-0.05). If the amount of the substance is too large, it will lead to a large amount of methanol recovered during post-processing, which will result in a large loss, and if the amount is too small, the concentration of the substrate in the reaction system will be large, resulting in an increase in side reactions and a decrease in yield.

Preferably, the material ratio of acrylonitrile, anhydrous methanol, and metal alkoxide is 1:(5-10):(0.005-0.02).

In the above-mentioned synthesis method of 3-methoxy-N,N-dimethylpropionamide, the temperature of the reaction in step S1 is 20-100°C.

Preferably, the temperature of the reaction in step S1 is 50-60°C.

In the above-mentioned synthesis method of 3-methoxy-N,N-dimethylpropionamide, the temperature of the hydrolysis reaction in step S2 is 80-120°C.

Preferably, the temperature of the hydrolysis reaction in step S2 is 90-100°C.

In the above-mentioned synthetic method of 3-methoxy-N,N-dimethylpropionamide, the material ratio of 3-methoxypropionitrile to acidic catalyst in step S2 is 1:1-15.

Preferably, the mass ratio of 3-methoxypropionitrile to the acidic catalyst is 1:1-3.

In the above-mentioned synthesis method of 3-methoxy-N,N-dimethylpropionamide, the acidic catalyst described in step S2 is one or more of concentrated sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid.

Preferably, the acidic catalyst is one or both of concentrated sulfuric acid and hydrochloric acid.

In the above-mentioned synthesis method of 3-methoxy-N,N-dimethylpropionamide, the reaction temperature in step S3 is 80-150°C. In the step S3 of the present invention, if the reaction temperature is too low, the acid-base reaction cannot be dehydrated; if the reaction temperature is too high, the reverse reaction will increase, resulting in an excessively high pressure, thereby affecting the yield and purity.

Preferably, the reaction temperature in step S3 is 90-110°C.

In the above-mentioned synthesis method of 3-methoxy-N,N-dimethylpropionamide, the pressure of the reactor in step S3 is 0.1-10.0MPa. In the present invention, the volatilization of the raw material amine under high temperature conditions is avoided by the high-pressure airtight reaction and the reversible reaction occurs. No waste gas is generated under the high-pressure airtight reaction, and the pressure in the reactor needs to be controlled. The equipment used in the present invention is a high-pressure closed equipment, such as one or more of an autoclave, a pressurized tower reactor, and a pressure pipeline reactor, preferably an autoclave. If the pressure is too high, the equipment requirements are higher, which will lead to a larger investment, and if the pressure is too small, the reaction will be incomplete and the yield will be low.

Preferably, the pressure of the reactor in step S3 is 0.5-2Mpa.

In the above-mentioned synthetic method of 3-methoxy-N,N-dimethylpropionamide, the material ratio of 3-methoxypropionic acid and dimethylamine in step S3 is 1:1-8.

Preferably, the material ratio of 3-methoxypropionic acid and dimethylamine in step S3 is 1:1-2.

Reaction formula of the present invention is as follows:

To sum up, the present invention takes cheap acrylonitrile as the starting material, alkoxylates acrylonitrile to obtain methoxypropionitrile, then hydrolyzes to obtain methoxypropionic acid, and then reacts with acid and alkali to form salt and dehydrate to obtain the target product without the need for Polyols and basic catalysts can be dehydrated at high temperature in a closed reactor. The reaction is simple and feasible, and the product has high yield and high purity. While achieving high yield, it has less pollution and low cost, which is in line with modern industrial green synthesis. Require.

Detailed ways

The following are specific embodiments of the present invention to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

Synthesize 3-methoxy-N,N-dimethylpropionamide according to the parameters in Examples 1-38 and Comparative Examples 3-20 in Table 1 and adopt the following method of the present invention:

Synthesis of S1, 3-methoxypropionitrile: add acrylonitrile, anhydrous methanol and metal alkoxide into the reactor to react first, and then distill and recover unreacted anhydrous methanol to obtain 3-methoxypropionitrile ;

S2, the synthesis of 3-methoxypropionic acid: add acid catalyst and water to 3-methoxypropionitrile in step S1, carry out hydrolysis reaction, and obtain 3-methoxypropionic acid through filtration;

Synthesis of S3, 3-methoxy-N,N-dimethylpropionamide: 3-methoxypropionic acid and dimethylamine are added to the closed reactor, and the temperature rises to react to obtain 3-methoxy-N, N-Dimethylpropionamide.

Table 1:

It can be obtained from Table 1 Examples 1-8 and Comparative Examples 8-11 that the temperature in step S3 in the synthesis method of 3-methoxy-N,N-dimethylpropionamide of the present invention is at 80-150° C. The rate is relatively high, preferably 90-110 °C, and the most preferred is 100 °C. If the temperature is lower than 80 °C or higher than 150 °C, the yield of the final product will be significantly affected. It can be obtained from Examples 9-14 and Comparative Examples 3-7 in Table 1 that in the synthesis method of 3-methoxy-N,N-dimethylpropionamide of the present invention, the pressure in the closed reactor of step S3 is 0.1-10.0 The yield is higher in the range of MPa, preferably 0.5-2Mpa, and the best is preferably 1.5MPa. It can be obtained from Examples 15-18 and Comparative Examples 12-14 in Table 1 that the reaction temperature in step S2 in the synthesis method of 3-methoxy-N,N-dimethylpropionamide of the present invention is at 80-120° C. The yield is higher, preferably 90-100°C, and the most preferably 95°C. It can be obtained from Examples 19-24 and Comparative Examples 15-17 in Table 1 that the reaction temperature in step S1 in the synthesis method of 3-methoxy-N,N-dimethylpropionamide of the present invention is at 20-100° C. The yield is higher, preferably 50-60 °C, and the most preferred is 55 °C. It can be obtained from Examples 25-29 and Comparative Example 18 in Table 1 that in the synthesis method of 3-methoxy-N,N-dimethylpropionamide of the present invention, acrylonitrile, anhydrous methanol, metal alkoxides in step S1 The product yield is higher in the range of 1:(1-50):(0.001-0.05). Available from Examples 30-34 in Table 1 and Comparative Example 19, in the synthesis method of 3-methoxy-N,N-dimethylpropionamide of the present invention, the difference between 3-methoxypropionitrile and the acidic catalyst in step S2 The product yield is higher when the material ratio is in the range of 1:(1-15). Available from Table 1 Examples 35-38 and Comparative Example 20, 3-methoxypropionic acid and dimethylamine in step S3 in the synthetic method of 3-methoxy-N,N-dimethylpropionamide of the present invention The product yield is higher in the range of 1:(1-8).

To sum up, the present invention takes cheap acrylonitrile as the starting material, alkoxylates acrylonitrile to obtain methoxypropionitrile, then hydrolyzes to obtain methoxypropionic acid, and then reacts with acid and alkali to form salt and dehydrate to obtain the target product without the need for The polyol and the basic catalyst can be dehydrated at high temperature in a closed reactor, the reaction is simple and feasible, and the product yield is high, up to more than 92%.

A sample of 3-methoxy-N,N-dimethylpropionamide synthesized by the method of the present invention is randomly selected and detected by gas chromatography. The gas chromatographic analysis results of the samples after detection are shown in Table 2.

Table 2: chromatographic analysis results of the 3-methoxy-N,N-dimethylpropionamide sample synthesized by the method of the present invention

Peak number keep time Peak area (uV*s) Peak height (uV) purity(%) 1 13.363 59.276 1390.806 0.0388 2 16.427 359842.781 3579131.250 99.9612 total 359902.057 3580522.056 100.0000

As can be seen from Table 2: the 3-methoxy-N,N-dimethylpropionamide synthesized by the method of the present invention has a higher purity, reaching 99.9612%.

In the above embodiment, the metal alkoxide can be one or more of sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, magnesium methoxide, magnesium ethoxide, sodium tert-butoxide, and potassium tert-butoxide. The acidic catalyst can be one or more of concentrated sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. Wherein, the amount of substance=mass/molecular weight, for example, if the metal alkoxide in the embodiment is sodium methoxide, the substance mass ratio of acrylonitrile, anhydrous methanol, and sodium methoxide is (m acrylonitrile g/53g/mol): (m Methanol g/32g/mol): (m sodium methoxide g/54g/mol), this conversion method is also used for calculation in other embodiments.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which the present invention pertains can make various modifications or additions to the described specific embodiments or substitute in similar manners, but will not deviate from the spirit of the present invention or go beyond the scope defined by the appended claims.

Although the present invention has been described in detail and cited some specific embodiments, it will be apparent to those skilled in the art that various changes or modifications can be made without departing from the spirit and scope of the present invention.

Claims (7)

1. a kind of synthetic method of 3- methoxyl group-N, N- dimethylpropionamide, which is characterized in that the synthetic method includes such as Lower step:

The synthesis of S1,3- methoxypropionitrile: acrylonitrile, anhydrous methanol and metal alkoxide are added in reactor instead It answers, the unreacted anhydrous methanol of recycling obtains 3- methoxypropionitrile；

The synthesis of S2,3- methoxypropionic acid: acidic catalyst and water is added in the 3- methoxypropionitrile into step S1, and heating carries out Hydrolysis is filtered to obtain 3- methoxypropionic acid；

The synthesis of S3,3- methoxyl group-N, N- dimethylpropionamide: 3- methoxypropionic acid and dimethylamine are added to closed reactor In, temperature reaction obtains 3- methoxyl group-N, N- dimethylpropionamide；Wherein 3- methoxypropionic acid and the amount of substance of dimethylamine ratio are 1: 1-2；The pressure of reactor is 0.5-2MPa；Reaction temperature is 90-110 DEG C.

2. the synthetic method of 3- methoxyl group-N, N- dimethylpropionamide according to claim 1, which is characterized in that step Metal alkoxide described in S1 is sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, magnesium methoxide, magnesium ethylate, sodium tert-butoxide, uncle One of butanol potassium is a variety of.

3. the synthetic method of 3- methoxyl group-N, N- dimethylpropionamide according to claim 1, which is characterized in that step Acrylonitrile in S1, anhydrous methanol, metal alkoxide amount of substance ratio be 1:(1-50): (0.001-0.05).

4. the synthetic method of 3- methoxyl group-N, N- dimethylpropionamide according to claim 1, which is characterized in that step The temperature of reaction described in S1 is 20-100 DEG C.

5. the synthetic method of 3- methoxyl group-N, N- dimethylpropionamide according to claim 1, which is characterized in that step The temperature of hydrolysis is 80-120 DEG C in S2.

6. the synthetic method of 3- methoxyl group-N, N- dimethylpropionamide according to claim 1, which is characterized in that step The amount of substance of 3- methoxypropionitrile and acidic catalyst ratio is 1:1-15 in S2.

7. the synthetic method of 3- methoxyl group-N, N- dimethylpropionamide according to claim 1 or 6, which is characterized in that step Acidic catalyst described in rapid S2 is one of the concentrated sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid or a variety of.