Synthesis method of aminoacetaldehyde dimethyl acetal

Abstract

A synthesis method of aminoacetaldehyde dimethyl acetal relates to the technical field of fine chemical engineering, and comprises the following steps: chlorination reaction: uniformly mixing and stirring vinyl acetate and methanol; introducing chlorine gas and then carrying out heat preservation reaction; then adding a neutralizer to carry out neutralization reaction; after the neutralization reaction, standing for layering, removing a water phase, and carrying out primary rectification on an organic phase to obtain chloroacetaldehyde dimethyl acetal; ammonolysis reaction: introducing nitrogen and / or inert gas into the obtained chloroacetaldehyde dimethyl acetal for purging; dropwise adding a saturated methanol-ammonia mixed solution for reaction; after the reaction is completed, insoluble ammonium chloride is filtered out, filtrate is introduced into a rectifying tower for secondary rectification, and a finished product of aminoacetaldehyde dimethyl acetal is obtained. Wherein the neutralizer adopts calcium oxide, and the aminoacetaldehyde glycol is prepared by a solvent-free method, so that the generation of wastewater is greatly reduced in the preparation process, and the cost required by wastewater treatment is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of fine chemicals, in particular to a method for synthesizing aminoacetaldehyde dimethyl acetal. Background Art

[0002] Aminoacetaldehyde dimethyl acetal (C4H12NO2), also known as aminoacetaldehyde dimethyl acetal, is a colorless liquid and is often used as a pharmaceutical intermediate. For example, it is used in the effective synthesis of proline analogs from ascorbic acid through a three-step reaction. It is also used in the synthesis of the anti-AIDS raw material drug dolutegravir and the anthelmintic drug praziquantel.

[0003] In the prior art, the preparation method of aminoacetaldehyde acetal usually adopts a method of reacting a high-concentration aqueous solution of vinyl acetate as a raw material with chlorine to generate ethyl dichloroacetate, which is hydrolyzed at 50-60° C. to obtain chloroacetaldehyde acetal, and then reacting chloroacetaldehyde acetal and ammonia water as raw materials, followed by deamination, dehydration, neutralization, distillation, and rectification to obtain the product.

[0004] The steps of preparing aminoacetaldehyde diol by the above process are relatively complicated, and the use of high-concentration aqueous solution of vinyl acetate, ammonia water, etc. as raw materials will produce a large amount of wastewater, which requires a large amount of energy to treat the wastewater and causes environmental problems. Summary of the invention

[0005] The present invention aims to solve the shortcomings existing in the background technology and provides a method for synthesizing aminoacetaldehyde dimethyl acetal, which at least solves some technical problems in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions: A method for synthesizing aminoacetaldehyde dimethyl acetal comprises the following steps: Chlorination reaction: Vinyl acetate and methanol are mixed and stirred evenly; chlorine gas is introduced and the mixture is kept warm for reaction; then a neutralizing agent is added for neutralization reaction; After the neutralization reaction, the mixture is allowed to stand for stratification, the aqueous phase is removed, and the organic phase is subjected to a rectification step to obtain chloroacetaldehyde dimethyl acetal; Amination reaction: nitrogen and / or inert gas is passed into the obtained chloroacetaldehyde dimethyl acetal for purging; a saturated methanol-ammonia mixed solution is added dropwise for reaction; After the reaction is complete, the insoluble ammonium chloride is removed by filtration, and the filtrate is passed into a distillation tower for secondary distillation to obtain the finished product of aminoacetaldehyde dimethyl acetal; Wherein, the neutralizing agent is calcium oxide.

[0007] Furthermore, the neutralizing agent is calcium oxide powder; Preferably, the neutralizing agent is calcium oxide powder with a particle size range of 150-200 mesh.

[0008] Furthermore, the calcium oxide powder is added to the solution after the insulation reaction at a rate of 3-6 kg / min. After the calcium oxide powder is added, stirring is continued for 5-10 minutes. After the reaction is completed, the pH after neutralization is tested to be 7.

[0009] Further, nitrogen and / or an inert gas is introduced into the chloroacetaldehyde dimethyl acetal for bubbling and purging; Preferably, the introduction rate of the nitrogen and / or inert gas is 500-800 ml / min.

[0010] Further, nitrogen is introduced into the chloroacetaldehyde dimethyl acetal for bubbling and purging; The nitrogen is introduced for 48-76 minutes.

[0011] Furthermore, the aqueous phase after the neutralization reaction is allowed to stand and separate as waste water and is passed into an RTO furnace for incineration treatment; The rear fraction of the primary distillation of the organic phase is chloroacetaldehyde dimethyl acetal.

[0012] Further, the filtered ammonium chloride solid is added into water for washing to remove the oil phase therein, and the remaining water phase is the ammonium chloride solution; The ammonium chloride solution is sequentially subjected to crystallization and centrifugation to obtain high-purity ammonium chloride solid.

[0013] Furthermore, the filtrate is passed into a distillation tower for secondary distillation, in which the front fraction is methanol, and the obtained methanol is recovered and recycled; The filtrate is passed into a distillation tower for secondary distillation, and the rear fraction is aminoacetaldehyde dimethyl acetal finished product.

[0014] Further, the chlorination reaction is specifically: Add vinyl acetate and methanol into the reactor, stir evenly and control the temperature to below -5°C; At this temperature, chlorine gas is introduced to control the reaction temperature to -5°C-0°C; After the chlorine is passed, the temperature in the reactor is raised to 0-5°C and kept warm for 1.8-2.4 hours; Take samples for analysis. After the reaction is qualified, add calcium oxide powder at a rate of 3-6kg / min for neutralization reaction. The pH of the solution in the reactor is measured to be 7. The solution in the reaction kettle was allowed to stand, the aqueous phase was separated, and the organic phase was subjected to a rectification to obtain chloroacetaldehyde dimethyl acetal.

[0015] Beneficial effects of the present invention: The invention prepares aminoacetaldehyde diol by a solvent-free method, greatly reduces the generation of wastewater during the preparation process, and reduces the cost required for wastewater treatment.

[0016] The present invention can greatly increase the neutralization efficiency and effectively improve the working efficiency of the overall process by continuously adding calcium oxide powder of corresponding particle size.

[0017] The invention effectively removes volatile impurities and upper air in the chloroacetaldehyde dimethyl acetal by introducing nitrogen into the chloroacetaldehyde dimethyl acetal for bubbling and purging, avoids the influence of other impurities on the amination reaction, and improves the purity of aminoacetaldehyde dimethyl acetal to ≥99%. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0019] The disclosure below provides many different embodiments or examples for implementing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but a person of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0020] Aminoacetaldehyde dimethyl acetal is a colorless or light yellow liquid with a certain vapor pressure and boiling point. It has a very wide range of applications in the fields of chemistry, chemical engineering, and medicine, and is mainly used as an important intermediate for the synthesis of drugs such as ivabradine hydrochloride, proline analogs, and aminophosphoric acid esters. Aminoacetaldehyde dimethyl acetal is active and needs to be stored in a cool, dry place, away from fire.

[0021] In the prior art, the steps for preparing aminoacetaldehyde diacetal are relatively complicated and produce a large amount of wastewater, which requires a large amount of energy to treat and causes environmental problems.

[0022] In order to solve the above problems, the embodiment of the present invention provides a method for synthesizing aminoacetaldehyde dimethyl acetal, comprising the following steps: Chlorination reaction: Vinyl acetate and methanol are mixed and stirred evenly; chlorine gas is introduced and the mixture is kept warm for reaction; then a neutralizing agent is added for neutralization reaction; After the neutralization reaction, the mixture is allowed to stand for stratification, the aqueous phase is removed, and the organic phase is subjected to a rectification step to obtain chloroacetaldehyde dimethyl acetal; Amination reaction: nitrogen and / or inert gas is passed into the obtained chloroacetaldehyde dimethyl acetal for purging; a saturated methanol-ammonia mixed solution is added dropwise for reaction; After the reaction is complete, the insoluble ammonium chloride is removed by filtration, and the filtrate is passed into a distillation tower for secondary distillation to obtain the finished product of aminoacetaldehyde dimethyl acetal; Wherein, the neutralizing agent is calcium oxide.

[0023] It should be noted that the chlorination reaction is carried out by carrying out a chlorination reaction on vinyl acetate, methanol and chlorine as raw materials to prepare chloroacetaldehyde dimethyl acetal, acetic acid, hydrochloric acid and water, adding a neutralizing agent calcium oxide to neutralize the acetic acid and hydrochloric acid, so that the liquid components of the mixed solution are chloroacetaldehyde dimethyl acetal organic phase liquid and aqueous phase, and the aqueous phase is removed by allowing the mixed solution to stand for stratification to obtain the chloroacetaldehyde dimethyl acetal organic phase, and the chloroacetaldehyde dimethyl acetal organic phase is passed into a distillation tower for distillation to obtain high-purity chloroacetaldehyde dimethyl acetal.

[0024] During the amination reaction, the prepared chloroacetaldehyde dimethyl acetal and methanol-ammonia saturated solution are used as raw materials for amination reaction to obtain aminoacetaldehyde diacetal and ammonium chloride, the ammonium chloride is filtered to obtain a crude aminoacetaldehyde diacetal, and the crude aminoacetaldehyde diacetal is passed into a distillation tower for distillation to obtain high-purity aminoacetaldehyde diacetal.

[0025] Among them, the structural reaction formula of the chlorination reaction is:

[0026] The structural reaction formula of the amination reaction is:

[0027] The solvent-free method is used to prepare aminoacetaldehyde diacetal in the overall process, which greatly reduces the wastewater generated in the production process, thereby reducing the energy consumption required for wastewater treatment and reducing the impact on the environment.

[0028] In a further embodiment of this example, the neutralizing agent is calcium oxide powder; Preferably, the neutralizing agent is calcium oxide powder with a particle size range of 150-200 mesh.

[0029] It should be noted that calcium oxide powder in different particle size ranges will affect the reaction rate and neutralization effect during the neutralization process.

[0030] When the particle size of the calcium oxide powder is too coarse, the reaction rate of the calcium oxide powder during the neutralization process will be low, the time required for neutralization will be long, and there may be a waste of raw materials; on the other hand, when the particle size of the calcium oxide powder is too fine, although it can effectively increase the reaction rate of the neutralization reaction and reduce the time required for neutralization, it will also increase the cost of raw materials.

[0031] Therefore, it is necessary to use calcium oxide powder with moderate particle size for neutralization reaction. When the particle size of calcium oxide is in the range of 150-200 mesh, the reaction rate can be effectively increased, and there will be no incomplete reaction inside the calcium oxide particles, thus avoiding the waste of raw materials and the overall raw material cost of the powder is low.

[0032] In a further implementation of this example, the calcium oxide powder is added to the solution after the insulation reaction at a rate of 3-6 kg / min. After the calcium oxide powder is added, stirring is continued for 5-10 minutes. After the reaction is completed, the pH after neutralization is tested to be 7.

[0033] It should be noted that calcium oxide will undergo a neutralization reaction with acetic acid and hydrochloric acid in the mixed solution, and violent heat release will occur during the reaction. Therefore, if calcium oxide is added too quickly, the temperature in the reactor may rise sharply, making it difficult to control the reaction in the reactor in a heat-insulating state, resulting in side reactions that affect the yield of the product, waste of raw materials, and even possible safety accidents.

[0034] On the other hand, if the calcium oxide is added too slowly, the neutralization rate will be slow, resulting in a decrease in overall production efficiency. Therefore, when the calcium oxide addition rate is 3-6 kg / min, it is easier to control the temperature in the reactor and ensure the reaction rate of the neutralization reaction.

[0035] After the calcium oxide powder is introduced, there will still be a certain amount of calcium oxide in the mixed liquid that has not reacted completely. Therefore, continuing to stir for 5-10 minutes can make the reaction more complete and improve the utilization rate of the raw materials.

[0036] Calcium oxide will react with acetic acid and hydrochloric acid in the mixed liquid to produce neutral calcium salt and water, and the calcium salt will dissolve in water to form a calcium salt solution. When the pH of the overall mixed liquid is 7, it means that the neutralization reaction has been completed.

[0037] In a further implementation of this embodiment, nitrogen and / or an inert gas is introduced into the chloroacetaldehyde dimethyl acetal for bubbling and purging; Preferably, the introduction rate of the nitrogen and / or inert gas is 500-800 ml / min.

[0038] It should be noted that although the chloroacetaldehyde acetal has been purified during the distillation process, some volatile impurities are still inevitably present. Therefore, bubbling with nitrogen and / or inert gas can effectively remove the impurities in the chloroacetaldehyde acetal and further purify it.

[0039] By purging with nitrogen and / or inert gas, air components can be effectively removed to avoid side reactions caused by the presence of other substances in the air above the reaction liquid during the amination reaction, thereby improving the purity of the product.

[0040] During the bubbling and purging process, the ventilation rate should not be too high, as a high rate will lead to the loss of raw materials and increase costs. Similarly, the ventilation rate should not be too low, as a low rate will lead to reduced efficiency. Therefore, setting the ventilation rate at 500-800ml / min can ensure efficiency while avoiding the loss of raw materials.

[0041] In a further implementation of this embodiment, nitrogen is introduced into the chloroacetaldehyde dimethyl acetal for bubbling and purging; The nitrogen is introduced for 48-76 minutes.

[0042] It should be noted that nitrogen is selected as the bubbling and purging gas because nitrogen is easier to prepare and has a lower cost.

[0043] In a further embodiment of this embodiment, the aqueous phase of the static stratification after the neutralization reaction is passed into an RTO furnace as waste water for incineration treatment; The rear fraction of the primary distillation of the organic phase is chloroacetaldehyde dimethyl acetal.

[0044] It should be noted that the RTO furnace can efficiently remove organic matter from wastewater, with a purification rate of more than 99%. Through the heat recovery of the regeneration bed, it can significantly reduce energy consumption and improve energy utilization efficiency. The products after combustion are mainly carbon dioxide and water, reducing the risk of secondary pollution. Therefore, incineration treatment of wastewater through the RTO furnace is an efficient and environmentally friendly method.

[0045] In a further embodiment of this embodiment, the filtered ammonium chloride solid is added to water for washing to remove the oil phase, and the remaining water phase is an ammonium chloride solution; The ammonium chloride solution is sequentially subjected to crystallization and centrifugation to obtain high-purity ammonium chloride solid.

[0046] It should be noted that the filtered ammonium chloride solid will inevitably adhere to some chloroacetaldehyde dimethyl acetal and other impurities, so the chloroacetaldehyde dimethyl acetal and some oil phase impurities can be washed out by water washing, and the washed ammonium chloride aqueous solution can be crystallized and centrifuged to obtain a high-purity ammonium chloride product.

[0047] Ammonium chloride has many uses and is widely used in industry, agriculture, medicine, laboratories and other fields. Specifically: In the agricultural field, ammonium chloride can be used as a nitrogen fertilizer to provide the nitrogen elements needed by plants, promote plant growth, and regulate the pH value of the soil. It can improve the structure of acidic soil. Appropriate application can increase the water retention capacity and air permeability of the soil.

[0048] In the industrial field, ammonium chloride is one of the main components of dry battery electrolytes, used to improve the conductivity and stability of the battery. It can be used as a metal surface treatment agent, such as pickling, rust removal and pretreatment before galvanizing. It can remove oxides and dirt on the metal surface and improve the cleanliness of the metal surface.

[0049] In the medical field, it can be used as a raw material or excipient for drugs, such as the preparation of certain antibiotics and vitamins. It can also be used as a buffer and stabilizer to adjust the pH value of drugs. It can also be used as a nitrogen supplement to supplement the nitrogen element needed by the human body, and as an electrolyte supplement to maintain electrolyte balance in the body.

[0050] In the laboratory field, it can be used as a common chemical reagent in the laboratory, participate in a variety of chemical reactions, can be used as a component of the buffer solution to adjust the pH value of the solution, and in biochemical experiments, it can be used as a component of the culture medium.

[0051] In a further implementation of this embodiment, the filtrate is passed into a distillation tower for secondary distillation, in which the front fraction is methanol, and the obtained methanol is recycled; The filtrate is passed into a distillation tower for secondary distillation, and the rear fraction is aminoacetaldehyde dimethyl acetal finished product.

[0052] It should be noted that secondary distillation through a distillation tower can effectively improve the purity of aminoacetaldehyde dimethyl acetal to more than 99%. The front fraction of the secondary distillation can separate methanol and recycle the methanol, effectively increasing the utilization rate of raw materials.

[0053] In a further implementation of this embodiment, the chlorination reaction is specifically: Add vinyl acetate and methanol into the reactor, stir evenly and control the temperature to below -5°C; At this temperature, chlorine gas is introduced to control the reaction temperature to -5°C-0°C; After the chlorine is passed, the temperature in the reactor is raised to 0-5°C and kept warm for 1.8-2.4 hours; Take samples for analysis. After the reaction is qualified, add calcium oxide powder at a rate of 3-6kg / min for neutralization reaction. The pH of the solution in the reactor is measured to be 7. The solution in the reaction kettle was allowed to stand, the aqueous phase was separated, and the organic phase was subjected to a rectification to obtain chloroacetaldehyde dimethyl acetal.

[0054] Example 1 Chlorination reaction: put the measured vinyl acetate and methanol into the reactor, stir evenly and control the temperature to below -5°C; At this temperature, chlorine gas is introduced to control the reaction temperature to -5°C-0°C; After the chlorine is passed, the temperature in the reactor is raised to 0-5°C and kept warm for 1.8-2.4 hours; Take samples for analysis. After the reaction is qualified, add calcium oxide powder at a rate of 3-6kg / min for neutralization reaction. The pH of the solution in the reactor is measured to be 7. The solution in the reaction kettle was allowed to stand, the aqueous phase was separated, and the organic phase was subjected to a rectification to obtain chloroacetaldehyde dimethyl acetal.

[0055] Amination reaction: The obtained chloroacetaldehyde dimethyl acetal is purged with nitrogen for 1 hour, and a saturated methanol-ammonia mixture is added dropwise (about 28% solution can be obtained by passing methanol into ammonia). After the reaction is completed, insoluble ammonium chloride is removed by filtration, and the filtrate enters a distillation tower for vacuum distillation to obtain the finished aminoacetaldehyde dimethyl acetal.

[0056] After testing, the mass ratio of the separated water phase to the raw material is 10%, the mass ratio of the obtained aminoacetaldehyde dimethyl acetal to the raw material ratio is more than 85%, the purity is 99.1%-99.5%, and the time of the neutralization reaction is recorded as M.

[0057] Example 2 Chlorination reaction: put the measured vinyl acetate and methanol into the reactor, stir evenly and control the temperature to below -5°C; At this temperature, chlorine gas is introduced to control the reaction temperature to -5°C-0°C; After the chlorine is passed, the temperature in the reactor is raised to 0-5°C and kept warm for 1.8-2.4 hours; Sampling analysis, after the reaction is qualified, calcium oxide solid particles are added in batches for neutralization reaction, and the pH of the solution in the reactor is measured to be 7; The solution in the reaction kettle was allowed to stand, the aqueous phase was separated, and the organic phase was subjected to a rectification to obtain chloroacetaldehyde dimethyl acetal.

[0058] Amination reaction: The obtained chloroacetaldehyde dimethyl acetal is purged with nitrogen for 1 hour, and a saturated methanol-ammonia mixture is added dropwise (about 28% solution can be obtained by passing methanol into ammonia). After the reaction is completed, insoluble ammonium chloride is removed by filtration, and the filtrate enters a distillation tower for vacuum distillation to obtain the finished aminoacetaldehyde dimethyl acetal.

[0059] After testing, the mass ratio of the separated water phase to the raw material was 10%, the mass ratio of the obtained aminoacetaldehyde dimethyl acetal to the raw material ratio was more than 85%, the purity was 99.1%-99.5%, and the time of the neutralization reaction was recorded as N. After comparison, N=1.2M was obtained.

[0060] Example 3 Chlorination reaction: put the measured vinyl acetate and methanol into the reactor, stir evenly and control the temperature to below -5°C; At this temperature, chlorine gas is introduced to control the reaction temperature to -5°C-0°C; After the chlorine is passed, the temperature in the reactor is raised to 0-5°C and kept warm for 1.8-2.4 hours; Take samples for analysis. After the reaction is qualified, add calcium oxide powder at a rate of 3-6kg / min for neutralization reaction. The pH of the solution in the reactor is measured to be 7. The solution in the reaction kettle is allowed to stand, the aqueous phase is separated, and the organic phase is distilled once to obtain chloroacetaldehyde dimethyl acetal.

[0061] Amination reaction: add the obtained chloroacetaldehyde dimethyl acetal to a saturated methanol-ammonia mixture (about 28% solution can be obtained by passing methanol into ammonia). After the reaction is completed, filter to remove insoluble ammonium chloride, and the filtrate enters the distillation tower for vacuum distillation to obtain the finished aminoacetaldehyde dimethyl acetal.

[0062] After testing, the mass ratio of the separated water phase to the raw material was 10%, the mass ratio of the obtained aminoacetaldehyde dimethyl acetal to the raw material ratio was more than 84%, the purity was 98.2%-98.7%, and the time of the neutralization reaction was recorded as M.

[0063] In summary, by continuously adding calcium oxide powder of corresponding particle size, the neutralization efficiency can be greatly increased and the overall process efficiency can be effectively improved.

[0064] By introducing nitrogen into chloroacetaldehyde dimethyl acetal for bubbling and purging, the volatile impurities and upper air in the chloroacetaldehyde dimethyl acetal are effectively removed, the amination reaction is prevented from being affected by other impurities, and the purity of aminoacetaldehyde dimethyl acetal is improved to ≥99%.

[0065] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of the above disclosed technical contents without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for synthesizing aminoacetaldehyde dimethyl acetal, characterized in that: The following steps are involved: Chlorination reaction: Vinyl acetate and methanol are mixed and stirred evenly; chlorine gas is introduced and the mixture is kept warm for reaction; then a neutralizing agent is added for neutralization reaction; After the neutralization reaction, the mixture is allowed to stand for stratification, the aqueous phase is removed, and the organic phase is subjected to a rectification step to obtain chloroacetaldehyde dimethyl acetal; Amination reaction: nitrogen and / or inert gas is passed into the obtained chloroacetaldehyde dimethyl acetal for purging; a saturated methanol-ammonia mixed solution is added dropwise for reaction; After the reaction is complete, the insoluble ammonium chloride is removed by filtration, and the filtrate is passed into a distillation tower for secondary distillation to obtain the finished product of aminoacetaldehyde dimethyl acetal; Wherein, the neutralizing agent is calcium oxide.

2. The synthetic method of aminoacetaldehyde dimethyl acetal according to claim 1, characterized in that: The neutralizing agent is calcium oxide powder; Preferably, the neutralizing agent is calcium oxide powder with a particle size range of 150-200 mesh.

3. The synthetic method of aminoacetaldehyde dimethyl acetal according to claim 2, characterized in that, The calcium oxide powder is added into the solution after the insulation reaction at a rate of 3-6 kg / min. After the calcium oxide powder is added, stirring is continued for 5-10 minutes. After the reaction is completed, the pH after neutralization is tested to be 7.

4. The synthetic method of aminoacetaldehyde dimethyl acetal according to claim 1, characterized in that: Passing nitrogen and / or an inert gas into the chloroacetaldehyde dimethyl acetal for bubbling and purging; Preferably, the introduction rate of the nitrogen and / or inert gas is 500-800 ml / min.

5. The method for synthesizing aminoacetaldehyde dimethyl acetal according to claim 1, characterized in that: Passing nitrogen into the chloroacetaldehyde dimethyl acetal for bubbling and purging; The nitrogen is introduced for 48-76 minutes.

6. The method for synthesizing aminoacetaldehyde dimethyl acetal according to claim 1, characterized in that: The aqueous phase after the neutralization reaction is allowed to stand and stratify is passed into an RTO furnace as waste water for incineration treatment; The rear fraction of the primary distillation of the organic phase is chloroacetaldehyde dimethyl acetal.

7. The method for synthesizing aminoacetaldehyde dimethyl acetal according to claim 1, characterized in that: The filtered ammonium chloride solid is added into water for washing to remove the oil phase, and the remaining water phase is the ammonium chloride solution; The ammonium chloride solution is sequentially crystallized and centrifuged to obtain high-purity ammonium chloride solid.

8. The method for synthesizing aminoacetaldehyde dimethyl acetal according to claim 1, characterized in that: The filtrate is passed into a distillation tower for secondary distillation, wherein the first fraction is methanol, and the obtained methanol is recovered and recycled; The filtrate is passed into a distillation tower for secondary distillation, and the rear fraction is aminoacetaldehyde dimethyl acetal finished product.

9. The method for synthesizing aminoacetaldehyde dimethyl acetal according to claim 1, characterized in that: The chlorination reaction is specifically: Add vinyl acetate and methanol into the reactor, stir evenly and control the temperature to below -5°C; At this temperature, chlorine gas is introduced to control the reaction temperature to -5°C-0°C; After the chlorine is passed, the temperature in the reactor is raised to 0-5°C and kept warm for 1.8-2.4 hours; Take samples for analysis. After the reaction is qualified, add calcium oxide powder at a rate of 3-6kg / min for neutralization reaction. The pH of the solution in the reactor is measured to be 7. The solution in the reaction kettle is allowed to stand, the aqueous phase is separated, and the organic phase is distilled once to obtain chloroacetaldehyde dimethyl acetal.

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