阅读说明：本技术 一种选择性合成n-烷基氨基二丙酸盐溶液的方法 (Method for selectively synthesizing N-alkyl amino dipropionate solution ) 是由 周华 彭波 谭颖 于 2020-07-29 设计创作，主要内容包括：本发明属于有机合成技术领域,具体公开了一种选择性合成N-烷基氨基二丙酸盐溶液的方法,以烷基伯胺和丙烯酸酯为原料,通过将丙烯酸酯溶解在有机溶剂中制成丙烯酸酯溶液,再将烷基伯胺滴加至丙烯酸酯溶液,使得反应向生成N-烷基氨基二丙酸酯的方向进行,再加入碱金属氢氧化物水溶液将N-烷基氨基二丙酸酯转化为N-烷基氨基二丙酸盐,然后通过减压蒸馏除去有机溶剂,实现N-烷基氨基二丙酸盐的选择性合成。本发明可得到高纯度的N-烷基氨基二丙酸盐,杂质含量能降到5%以下；而且不需要高温高压和复杂的结晶纯化步骤,简便易行；使用到的原料和溶剂都可以回收再次利用,非常节能环保。(The invention belongs to the technical field of organic synthesis, and particularly discloses a method for selectively synthesizing an N-alkyl amino dipropionate solution. The invention can obtain high-purity N-alkyl amino dipropionate, and the impurity content can be reduced to below 5 percent; and does not need high temperature and high pressure and complicated crystallization purification steps, thus being simple and easy to operate; the used raw materials and the solvent can be recycled, so that the energy is saved and the environment is protected.)

1. A method for selectively synthesizing a solution of N-alkylaminodipropionic acid salts is characterized in that: the method comprises the following steps:

s1: dissolving acrylic ester in an organic solvent to prepare an acrylic ester solution;

s2: dropwise adding 1 molar equivalent of alkyl primary amine into 2-5 molar equivalents of acrylate solution; after the dropwise addition is finished, reacting for 10-48 hours at the temperature of 10-100 ℃;

s3: adding 2.0-4.0 molar equivalent of 0.5-2.0 mol/L alkali metal hydroxide solution into the reaction solution, and reacting at 10-100 ℃ for 10-48 hours;

s4: adding pure water with the mass 5-20 times of that of the primary alkylamine into the reaction liquid, and then carrying out reduced pressure distillation at the temperature of 30-80 ℃ and the pressure of 0-0.03 MPa until the weight content of the N-alkyl amino dipropionate is 10-50%.

2. The process for the selective synthesis of a solution of N-alkylaminodipropionic acid salts according to claim 1, characterized in that: the acrylate refers to a molecular formula of CH₂Compounds of formula i = CHCOOR1 wherein R1 denotes methyl, ethyl or propyl.

3. The process for the selective synthesis of a solution of N-alkylaminodipropionic acid salts according to claim 1 or 2, characterized in that: the alkyl primary amine refers to the molecular formula of RNH₂Wherein R denotes an alkane group consisting of from 6 to 24 carbon atoms.

4. The process for the selective synthesis of a solution of N-alkylaminodipropionic acid salts according to claim 1, characterized in that: in step S1, the organic solvent is an ester, an ether, an alcohol, or a halogenated alkane.

5. The process for the selective synthesis of a solution of N-alkylaminodipropionic acid salts according to claim 1, characterized in that: in step S1, the concentration of the acrylate solution is 1-4 mol/L.

6. The process for the selective synthesis of a solution of N-alkylaminodipropionic acid salts according to claim 1, characterized in that: in step S2, 1 molar equivalent of alkyl primary amine is added into 2.0-2.5 molar equivalent of acrylate solution; after the dropwise addition is finished, the reaction is carried out for 15-24 hours at the temperature of 20-40 ℃.

7. The process for the selective synthesis of a solution of N-alkylaminodipropionic acid salts according to claim 1 or 6, characterized in that: in step S2, the dropping speed of the primary alkyl amine is controlled to be 0.5-2 hours after the dropping is finished.

8. The process for the selective synthesis of a solution of N-alkylaminodipropionic acid salts according to claim 1, characterized in that: in step S3, an alkali metal hydroxide solution having a concentration of 0.8 to 1.2 mol/liter is added to the reaction solution in an amount of 2.0 to 2.2 mol equivalents, and the reaction is carried out at a temperature of 20 to 60 ℃ for 15 to 24 hours.

9. The process for the selective synthesis of a solution of N-alkylaminodipropionic acid salts according to claim 1 or 8, characterized in that: in step S3, the alkali metal hydroxide aqueous solution is a sodium hydroxide solution or a potassium hydroxide solution.

10. The process for the selective synthesis of a solution of N-alkylaminodipropionic acid salts according to claim 1, characterized in that: in the step S4, pure water with the mass 10-15 times of that of the alkyl primary amine is added into the reaction liquid, and then the mixture is subjected to reduced pressure distillation at the temperature of 40-80 ℃ and the pressure of 0-0.03 MPa until the weight content of the N-alkyl amino dipropionate is 10-30%.

Technical Field

The invention belongs to the technical field of organic synthesis, and particularly relates to a method for selectively synthesizing an N-alkyl amino dipropionate solution.

Background

N-alkyl aminopropionates and N-alkyl aminopropionates are two very useful classes of surfactants, widely used as cleaning agents, emulsifiers, flotation agents, and plating additives, among others. At present, the two compounds are synthesized by basically converting aliphatic amine and alpha, beta-unsaturated acid, nitrile or ester under certain conditions, but the reaction products are mixed with N-alkyl amino propionate and N-alkyl amino dipropionate, and the two substances with high purity are required to be selectively prepared due to the difference of hydrophilic and lipophilic properties of the N-alkyl amino propionate and the N-alkyl amino dipropionate and the wide application in daily chemicals such as household detergents, cosmetics and the like.

There is no method for producing high purity N-alkylaminopropionates or N-alkylaminopropionates, and selective production of N-alkylaminopropionates has been studied (e.g., US2468012, US 2816911); U.S. Pat. No. 5,5922909 describes a method of adjusting the ratio of N-alkylaminopropionate to N-alkylaminopropionate by controlling the pH of the reaction, but the adjustment range is not so large that an absolute advantage cannot be obtained. Therefore, it is difficult to obtain N-alkylaminodipropionic acid salts singly by the conventional synthetic method.

Disclosure of Invention

In order to solve the problems, the invention provides a method for selectively synthesizing the solution of the N-alkyl amino dipropionate, which can obtain the high-purity N-alkyl amino dipropionate and has simple process.

A method for selectively synthesizing a solution of an N-alkylaminodipropionic acid salt, comprising the steps of:

s1: dissolving acrylic ester in an organic solvent to prepare an acrylic ester solution;

s2: dropwise adding 1 molar equivalent of alkyl primary amine into 2-5 molar equivalents of acrylate solution; after the dropwise addition is finished, reacting for 10-48 hours at the temperature of 10-100 ℃;

s3: adding 2.0-4.0 molar equivalent of 0.5-2.0 mol/L alkali metal hydroxide solution into the reaction solution, and reacting at 10-100 ℃ for 10-48 hours;

s4: adding pure water with the mass 5-20 times of that of the primary alkylamine into the reaction liquid, and then carrying out reduced pressure distillation at the temperature of 30-80 ℃ and the pressure of 0-0.03 MPa until the weight content of the N-alkyl amino dipropionate is 10-50%.

Note: the molar equivalents are a relative term, specifically referring to primary alkyl amines in the present invention: acrylate ester: the molar ratio of alkali metal hydroxide is 1: (2-5): (2.0-4.0).

Preferably, the acrylate refers to the formula CH₂Compounds of formula i = CHCOOR1 wherein R1 denotes methyl, ethyl or propyl.

Preferably, the alkyl primary amine is represented by the formula RNH₂Wherein R denotes an alkane group consisting of from 6 to 24 carbon atoms.

Preferably, in step S1, the organic solvent is an ester, an ether, an alcohol or a halogenated alkane. Wherein: esters such as ethyl acetate, butyl acetate, etc., ethers such as diethyl ether, methyl t-butyl ether, etc., alcohols such as methanol, ethanol, etc., halogenated alkanes such as methylene chloride, chloroform, etc.

Preferably, in the step S1, the concentration of the acrylate solution is 1 to 4 mol/l.

Preferably, in step S2, 1 molar equivalent of primary alkylamine is added dropwise to 2.0 to 2.5 molar equivalents of acrylate solution; after the dropwise addition is finished, the reaction is carried out for 15-24 hours at the temperature of 20-40 ℃.

Preferably, in step S2, the dropping rate of the primary alkylamine is controlled to be 0.5 to 2 hours after the completion of the dropping.

Preferably, in step S3, an alkali metal hydroxide solution having a concentration of 0.8 to 1.2 mol/l is added to the reaction solution in an amount of 2.0 to 2.2 mol equivalents, and the reaction is carried out at a temperature of 20 to 60 ℃ for 15 to 24 hours.

Preferably, in step S3, the alkali metal hydroxide aqueous solution is a sodium hydroxide solution or a potassium hydroxide solution.

Preferably, in step S4, pure water with the mass 10-15 times that of the alkyl primary amine is added into the reaction solution, and then the mixture is subjected to reduced pressure distillation at the temperature of 40-80 ℃ and the pressure of 0-0.03 MPa until the weight content of the N-alkyl amino dipropionate is 10-30%.

The method comprises the steps of taking primary alkyl amine and acrylic ester as raw materials, dissolving the acrylic ester in an organic solvent to prepare an acrylic ester solution, then dropwise adding the primary alkyl amine into the acrylic ester solution to enable the reaction to proceed in the direction of generating N-alkyl amino dipropionate, then adding an alkali metal hydroxide aqueous solution to convert the N-alkyl amino dipropionate into N-alkyl amino dipropionate, and then removing the organic solvent through reduced pressure distillation to realize the selective synthesis of the N-alkyl amino dipropionate.

The invention has the following beneficial effects:

1. the acrylic ester is firstly dissolved in the organic solvent, and then the alkyl primary amine is dripped into the acrylic ester solution, so that the reaction is carried out in the direction of generating the N-alkyl amino dipropionate, the generation of the N-alkyl amino propionate is obviously reduced, and the purity is improved.

2. The N-alkyl amino dipropionate is converted into N-alkyl amino dipropionate by adding the alkali metal hydroxide aqueous solution, and simultaneously, the reaction of the acrylate and the alkyl primary amine is more thorough, so that the conversion rate is improved (the N-alkyl amino propionic acid is quickly transferred from an organic phase to the alkali metal hydroxide aqueous solution while the alkali metal hydroxide aqueous solution is added, so that the residual raw materials in the organic phase can be continuously reacted). More optimally, the alkali metal hydroxide is strong alkaline sodium hydroxide or potassium hydroxide, so that the hydrolysis speed can be accelerated, and the conversion efficiency can be improved.

3. The yield of the N-alkyl amino dipropionate is improved by adding pure water before the reduced pressure distillation. The product N-alkyl amino dipropionate after the hydrolysis process has stronger hydrophilicity but also has hydrophobic groups, so that the product N-alkyl amino dipropionate can be distributed in a water phase and an organic phase, and the N-alkyl amino dipropionate is completely separated from the organic phase by adding pure water with the mass 5-20 times of that of alkyl primary amine, so that the entrainment of an organic reagent is reduced, the product loss in the subsequent reduced pressure distillation process is reduced, the yield is effectively improved, and the purity of the product is not influenced.

4. The invention can obtain high-purity N-alkyl amino dipropionate, and the impurity content can be reduced to below 5 percent; and does not need high temperature and high pressure and complicated crystallization purification steps, thus being simple and easy to operate; the used raw materials and the solvent can be recycled, so that the energy is saved and the environment is protected.

Detailed Description

The present invention will be further described with reference to the following specific examples.