阅读说明：本技术 一种合成n-(2,6-二甲苯基)氨基丙酸甲酯的方法 (Method for synthesizing N- (2, 6-xylyl) methyl aminopropionate ) 是由 唐勇建 徐瑶 潘光飞 卢城炜 程希希 王进 曾挺 于 2020-06-16 设计创作，主要内容包括：本发明公开了一种合成N-(2,6-二甲苯基)氨基丙酸甲酯的方法,所述合成N-(2,6-二甲苯基)氨基丙酸甲酯的方法包括合成反应、分离粗提、蒸馏精制。本发明合成N-(2,6-二甲苯基)氨基丙酸甲酯的方法,2,6-二甲基苯胺和对甲苯磺酸丙酸甲酯反应过程中,不需要加入溶剂,既可以减少溶剂产生的污染,又可以减少成本投入,且反应温度低、副产物少、能耗较低,明显降低了生产成本,经济效益好。(The invention discloses a method for synthesizing N- (2, 6-xylyl) methyl aminopropionate, which comprises synthetic reaction, separation and crude extraction, and distillation and refining. According to the method for synthesizing the N- (2, 6-xylyl) methyl aminopropionate, no solvent is required to be added in the reaction process of the 2, 6-dimethylaniline and the methyl p-toluenesulfonate propionate, so that the pollution caused by the solvent can be reduced, the cost investment can be reduced, the reaction temperature is low, the byproducts are less, the energy consumption is lower, the production cost is obviously reduced, and the economic benefit is good.)

1. A method for synthesizing methyl N- (2, 6-xylyl) aminopropionate is characterized by comprising the following steps:

step one, synthetic reaction: pumping 2790 kg-2810 kg of 2, 6-dimethylaniline and 1490 kg-1510 kg of methyl p-toluenesulfonate into a reaction kettle, stirring, heating to 80-85 ℃, and carrying out heat preservation reaction for 20-36 hours under the condition that the temperature is 80-85 ℃ to obtain a product of N- (2, 6-xylyl) methyl aminopropionate;

step two, separating and crude extracting: transferring the product N- (2, 6-xylyl) methyl aminopropionate obtained in the step one to an alkaline hydrolysis kettle, cooling to 50-60 ℃, pumping 1190-1210 kg of toluene, dropwise adding 2290-2310 kg of sodium bicarbonate aqueous solution with the mass fraction of 30%, preserving heat for 55-65 minutes at the temperature of 50-60 ℃, standing for layering, collecting the toluene layer, returning the toluene layer to the reaction kettle, adding 1590-1610 kg of water for washing, standing for layering again, collecting the toluene layer, heating and decompressing to recover the solvent toluene, and obtaining a crude product of the N- (2, 6-xylyl) methyl aminopropionate after desolventizing is finished;

step three, distillation and refining: heating the oil furnace to 145-155 ℃, starting the screw vacuum unit, controlling the vacuum degree to 80-100 Pa, and when the temperature reaches 80-85 ℃, carrying out the N- (2,6-Xylyl) methyl aminopropionate crude product was pumped into the first stage 8m²Collecting dimethylaniline fraction in a molecular short-path rectifying still, pumping the high-content material without the dimethylaniline fraction into a second stage of 10m by a heat-insulating pipeline and a high-vacuum heat-insulating pump²Distilling in a molecular short-path rectifying still, and distilling to obtain refined N- (2, 6-xylyl) methyl aminopropionate.

2. The method of claim 1, wherein in step one, the stirring rate is 550 to 850 rpm.

3. The method according to claim 1, wherein the mass fraction of the 2, 6-dimethylaniline in the first step is 98.9-99.2%.

4. The method according to claim 1, wherein in the first step, the mass fraction of the methyl p-toluenesulfonate is 98.0% to 98.5%.

5. The method according to claim 1, wherein in the first step, the temperature increase rate is 3.5 ℃/min to 6.5 ℃/min.

6. The method according to claim 1, wherein in the second step, the cooling rate is 2.0 ℃/min to 4.0 ℃/min.

7. The method according to claim 1, wherein in the second step, after the standing and the separation, the aqueous layer is separated and extracted once with toluene.

8. The method according to claim 1, wherein in the second step, the temperature-rising and pressure-reducing solvent toluene recovery process is specifically as follows: under the condition that the pressure is-0.095 MPa to-0.055 MPa, the temperature is increased to 70-78 ℃ at the speed of 3.5 ℃/min to 6.5 ℃/min, and the solvent toluene is recovered by temperature increase and pressure reduction.

9. The method of claim 1, wherein in step three, the temperature of the molecular distillation is 110 ℃ to 118 ℃.

Technical Field

The invention relates to the technical field of organic synthesis, in particular to a method for synthesizing N- (2, 6-xylyl) methyl aminopropionate.

Background

The N-acyl alanine compounds are high-efficiency and low-toxicity systemic bactericides. Has better prevention and treatment effect on plant diseases caused by downy mildew, malpighia virens, glucose downy mildew and the like. The structural formula of the compound shows that the bactericide belongs to phenylamide compounds.

The skeleton is an active skeleton, contains a chiral carbon atom and has a pair of enantiomers, and the bactericidal activity of the R- (-) -isomer is higher than that of the S- (+) -isomer. Methyl N- (2, 6-xylyl) aminopropionate is the most important intermediate.

The synthesis of N- (2, 6-xylyl) methyl aminopropionate generally takes alpha-chloropropionic acid as a raw material, the preparation is carried out by two steps of reactions, the synthesis yield is respectively 90 percent and 92 percent, and the product purity is more than or equal to 95 percent; moreover, the N- (2, 6-xylyl) amino methyl propionate is synthesized by reacting 2, 6-dimethylaniline and 2-methyl chloropropionate under the condition that AM is used as a solvent, and the method has the characteristics of short reaction time, less by-products, less consumption of 2-methyl chloropropionate and low production cost, but has the defects of large solvent pollution, high reaction temperature, lower product yield and only 82 percent of product yield.

Therefore, the invention provides a method for synthesizing N- (2, 6-xylyl) methyl aminopropionate, aiming at the problems of incomplete solvent recovery, high reaction temperature, high energy consumption, low product yield and the like in the conventional synthesis of N- (2, 6-xylyl) methyl aminopropionate.

Disclosure of Invention

The invention aims at the problems and provides a method for synthesizing N- (2, 6-xylyl) amino methyl propionate.

The technical scheme adopted by the invention for solving the problems is as follows: a method for synthesizing N- (2, 6-xylyl) amino methyl propionate comprises the following steps:

step one, synthetic reaction: pumping 2790 kg-2810 kg of 2, 6-dimethylaniline and 1490 kg-1510 kg of methyl p-toluenesulfonate into a reaction kettle, stirring, heating to 80-85 ℃, and carrying out heat preservation reaction for 20-36 hours at the temperature of 80-85 ℃ to obtain a product of N- (2, 6-xylyl) methyl aminopropionate;

the reaction process of the synthesis reaction comprises the following steps:

step two, separating and crude extracting: transferring the product N- (2, 6-xylyl) methyl aminopropionate obtained in the step one to an alkaline hydrolysis kettle, when the temperature is reduced to 50-60 ℃, pumping 1190-1210 kg of toluene, dropwise adding 2290-2310 kg of sodium bicarbonate aqueous solution with the mass fraction of 30%, and preserving the heat for 55-65 minutes at the temperature of 50-60 ℃ to convert p-toluenesulfonic acid into sodium p-toluenesulfonate and simultaneously generate CO₂Mixing with water, standing for layering, collecting the toluene layer, returning the toluene layer to the reaction kettle, adding 1590 kg-1610 kg of water for washing, standing for layering again, heating the collected toluene layer, reducing the pressure to recover the toluene solvent, recycling the toluene for a water washing section, and obtaining a crude product of the N- (2, 6-xylyl) methyl aminopropionate after desolventizing is finished; and (5) conveying the wastewater collected by standing and layering to a wastewater station for treatment.

Step three, distillation and refining: heating the oil furnace to 145-155 ℃, starting a screw vacuum unit, controlling the vacuum degree to be 80-100 Pa, and pumping the crude product of the N- (2, 6-xylyl) methyl aminopropionate obtained in the second step into the first stage of 8m when the temperature reaches 80-85 DEG C²Collecting dimethylaniline fraction in a molecular short-path rectifying still, pumping the high-content material without the dimethylaniline fraction into a second stage of 10m by a heat-insulating pipeline and a high-vacuum heat-insulating pump²Distilling in a molecular short-path rectifying still, and distilling to obtain refined N- (2, 6-xylyl) methyl aminopropionate.

Further, in the first step, the stirring speed is 550 rpm-850 rpm.

Further, in the step one, the mass fraction of the 2, 6-dimethylaniline is 98.9-99.2%.

Further, in the step one, the mass fraction of the methyl p-toluenesulfonate propionate is 98.0-98.5%.

Further, in the step one, the heating rate is 3.5 ℃/min to 6.5 ℃/min.

Further, in the second step, the cooling rate is 2.0 ℃/min to 4.0 ℃/min.

Further, in the second step, after standing and layering, the water layer is separated and extracted once with toluene.

Further, in the second step, the process of recovering the solvent toluene by heating and reducing pressure specifically comprises the following steps: under the condition that the pressure is-0.095 MPa to-0.055 MPa, the temperature is increased to 70-78 ℃ at the speed of 3.5 ℃/min to 6.5 ℃/min, and the solvent toluene is recovered by temperature increase and pressure reduction.

Further, in the third step, the temperature of molecular distillation is 110-118 ℃.

The invention has the advantages that:

(1) according to the method for synthesizing the methyl N- (2, 6-xylyl) aminopropionate, no solvent is required to be added in the reaction process of the 2, 6-dimethylaniline and the methyl p-toluenesulfonate propionate, so that the pollution caused by the solvent can be reduced, the cost investment can be reduced, the reaction temperature is low, the byproducts are less, the energy consumption is lower, the production cost is obviously reduced, and the economic benefit is good;

(2) the invention discloses a method for synthesizing N- (2, 6-xylyl) methyl aminopropionate, which adopts molecular short-range rectification in the refining process of N- (2, 6-xylyl) methyl aminopropionate, can reduce the rectification temperature, shorten the rectification time, reduce the rectification cost, improve the yield and realize the high yield of 95.0 to 97.0 percent;

(3) the method for synthesizing the N- (2, 6-xylyl) methyl aminopropionate disclosed by the invention has the advantages of rich raw material sources, simple synthesis reaction steps, strong controllability, good reaction environmental friendliness and suitability for popularization.

Detailed Description

The following detailed description of embodiments of the invention, but the invention can be practiced in many different ways, as defined and covered by the claims.