CN1733702A - 3-(2-methoxyethoxy)-propylamine production process - Google Patents

Abstract

The invention relates to a process for the chemical synthesis of 3-(2-methoxyethoxy)propylamine, which comprises the steps of condensation reaction, distillation and hydrogenation reaction, the end product has good purity, high yield and low depreciation of raw materials.

Description

3-(2-methoxyethoxy)-propylamine production process

technical field

The present invention relates to a method for chemically synthesizing 3-(2-methoxyethoxy)-propylamine.

Background technique

3-(2-methoxyethoxy)-propylamine is a widely used primary amine compound. It can be used not only as an important intermediate for the synthesis of disperse dyes such as disperse turquoise blue S-GL, but also as a new type of corrosion inhibitor and ionizing emulsifier introduced from abroad. It has been gradually popularized and applied in the petrochemical industry, but there is no domestic manufacturer Production. Therefore, the synthesis of 3-(2-methoxyethoxy)-propylamine has very important practical significance. After consulting a large amount of literature, it is determined that its synthetic method is: ethylene glycol monomethyl ether and acrylonitrile are subjected to an addition condensation reaction under the action of a catalyst to obtain 3-(2-methoxyethoxy)-propionitrile, and then in Reduction of the nitrile group by hydrogenation under pressure affords 3-(2-methoxyethoxy)-propylamine. Its reaction equation is:

Although the above provides a design idea for the synthesis of 3-(2-methoxyethoxy)-propylamine, there is still a lot of work to be applied to actual production, such as parameters such as various technological processes and proportioning ratios. Only creative inventions can be applied to industrial production.

Contents of the invention

The purpose of the present invention is to invent a 3-(2-methoxyethoxy)-propylamine production process with simple process, easy manipulation and high yield.

The present invention comprises the following steps:

1) Condensation reaction: add sodium methoxide and hydroquinone to ethylene glycol monomethyl ether, stir, then add acrylonitrile dropwise, the ratio of ethylene glycol monomethyl ether to acrylonitrile feed (molar ratio) is 1:1 ～1.1, keep the reaction temperature at 25℃～30℃; after the dropwise addition, continue to keep warm for 60 minutes ± 10 minutes;

2) Distillation: Add concentrated H ₂ SO ₄ to the above reactants to neutralize to PH=7 to obtain a brown-yellow liquid; carry out atmospheric distillation on the brown-yellow liquid, slowly raise the temperature to 80°C to distill out low-boiling fractions; atmospheric distillation Carry out underpressure distillation again after finishing, obtain the intermediate product 3-(2-methoxyethoxy)-propionitrile colorless liquid before hydrogenation; The content (should be ≥ 98%) is used for follow-up hydrogenation reaction through gas chromatography detection . NaSO ₄ remains in the still bottoms.

3) Hydrogenation reaction: pass ammonia into the distillation to obtain 3-(2-methoxyethoxy)-propionitrile colorless liquid, under the effect of Raney nickel-cobalt-chromium composite catalyst, the reaction temperature is 90 ℃～100℃, under the pressure of 3～4MPa, liquid-phase catalytic hydrogenation reaction is carried out, the reaction time is 4 hours±0.5 hours, the weight ratio of each feeding 3-(2-methoxyethoxy)-propionitrile:catalyst : ammonia=4000～4500:20～30:8500～9000.

In order to improve the purity of the product, the crude product obtained in step 3) can be further rectified and purified.

The method of rectification and purification is: install the rectification column on the distillation pot, steam a small amount of low-boiling point fractions under normal pressure, the middle and large fractions are the purified products, and the residue of the still is a very small amount of unhydrogenated 3-(2-methoxy Ethoxy)-propionitrile and other high boiling fractions.

The process route of the present invention has mild operating conditions, high product purity and high yield, and basically no other losses except for a small amount of still residue. At the same time, the whole process does not produce any pollution, the social and economic benefits are remarkable, and it can be widely used in actual production.

specific embodiment

1. Main raw materials:

Industrial ethylene glycol monomethyl ether (concentration ≥ 95%); industrial acrylonitrile (purity ≥ 98%); sodium methoxide, hydroquinone, concentrated H ₂ SO ₄ , hydrogen, ammonia

2. Condensation reaction:

Add 410kg of ethylene glycol monomethyl ether, 5kg of sodium methoxide, and 0.33kg of hydroquinone into the container. After fully stirring, slowly add 284kg of acrylonitrile dropwise within 3 hours. The feed ratio of ethylene glycol monomethyl ether and acrylonitrile is 1 mol: 1.05 mol, during which the reaction temperature was kept at 25°C to 30°C. After the dropwise addition, continue to keep warm for 1 hour, and measure the end point with a gas chromatograph. The control index of the end point is that the content of acrylonitrile is ≤1%. If the end point is not reached, continue to keep warm.

3. Distillation:

If the acrylonitrile has reacted substantially completely, add about 2kg of concentrated H ₂ SO ₄ to neutralize the feed solution, and adjust the pH to 7. The reaction product obtained at this time was brownish yellow, still liquid and soluble in water. Since the product will precipitate solid NaSO ₄ at low temperature, it must be removed by distillation before the hydrogenation reaction.

First carry out atmospheric distillation, and slowly heat up to 80°C to distill out low-boiling fractions. Carry out underpressure distillation again after atmospheric distillation finishes, thereby obtain the intermediate product 3-(2-methoxyethoxy)-propionitrile before hydrogenation, be colorless liquid, detect content through gas chromatography (should be ≥ 98%) for subsequent hydrogenation reactions. NaSO ₄ remains in the still bottoms.

4. Hydrogenation reaction:

The hydrogenation reaction equipment is a stainless steel pressure kettle, the catalyst is a Raney nickel-cobalt-chromium composite catalyst, the reaction temperature is 90-100°C, and the liquid-phase catalytic hydrogenation is carried out in an ethanol solvent under a hydrogen pressure of 3-4MPa (during the reaction Ammonia gas is introduced).

The specific feed ratio is: about 440 kg of intermediate product 3-(2-methoxyethoxy)-propionitrile, 2.5 kg of catalyst, and 880 kg of ammonia gas. The reaction time is about 4 hours. The crude product was obtained.

After the reaction, the ammonia gas is exported through another tower and can be recycled for the next reaction.

5. Purification:

Install the rectification column on the distillation pot, steam a small amount of low-boiling point fractions under normal pressure, and the large fraction in the middle is the purified product. Nitrile and other high boiling point fractions.

The crude product was purified by rectification to obtain the final product 3-(2-methoxyethoxy)-propylamine with a content greater than 99.5%, and the total yield was 91%.

Claims (7)

1. The production process of 3- (2-methoxyethoxy) -propylamine is characterized by comprising the following steps of:

1) condensation reaction: adding sodium methoxide and hydroquinone into ethylene glycol monomethyl ether, stirring, and then dropwise adding acrylonitrile, wherein the molar ratio of the ethylene glycol monomethyl ether to the acrylonitrile is 1: 1-1.1, and the reaction temperature is kept between 25 and 30 ℃; after the dropwiseaddition is finished, the reaction is continued for 60 minutes +/-10 minutes under heat preservation;

2) and (3) distillation: adding concentrated H into the reaction mass liquid₂SO₄Neutralizing until pH is 7 to obtain a brown yellow liquid; distilling the brown yellow liquid at normal pressure, slowly heating to 80 ℃, and distilling out low-boiling-point fractions; after the atmospheric distillation is finished, carrying out reduced pressure distillation to obtain a colorless liquid of an intermediate product 3- (2-methoxyethoxy) -propionitrile before hydrogenation;

3) hydrogenation reaction: introducing ammonia into 3- (2-methoxyethoxy) -propionitrile colorless liquid, and carrying out liquid-phase catalytic hydrogenation reaction at the reaction temperature of 90-100 ℃ under the action of a Raney nickel-cobalt-chromium composite catalyst and under the pressure of 3-4 MPa for 4 hours +/-0.5 hours, wherein the weight ratio of the 3- (2-methoxyethoxy) -propionitrile to the catalyst to the ammonia is 4000-4500: 20-30: 8500-9000.

2. The process for the production of 3- (2-methoxyethoxy) -propylamine according to claim 1, wherein the catalyst in the step 1) is sodium methoxide.

3. The process for the production of 3- (2-methoxyethoxy) -propylamine according to claim 2, characterized in that the concentration of sodium methoxide in step 1) is 27%.

4. The process for producing 3- (2-methoxyethoxy) -propylamine according to claim 1, wherein the polymerization inhibitor used in the step 1) is hydroquinone.

5. The process for producing 3- (2-methoxyethoxy) -propylamine according to claim 1, wherein the weight ratio of ethylene glycol monomethyl ether to acrylonitrile in step 1) is 410-415: 280-285.

6. The process for producing 3- (2-methoxyethoxy) -propylamine according to claim 1, wherein the crude product obtained in the step 3) is purified by rectification.

7. The process for producing 3- (2-methoxyethoxy) -propylamine according to claim 6, wherein the rectification and purification are carried out by: and (3) installing a distillation kettle on a rectifying column, distilling a small amount of low-boiling fraction at normal pressure, and obtaining a large middle fraction which is a purified product.