CN111393387B - Method for synthesizing imidacloprid intermediate morpholinyl propylene by using microchannel reactor - Google Patents
Method for synthesizing imidacloprid intermediate morpholinyl propylene by using microchannel reactor Download PDFInfo
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- CN111393387B CN111393387B CN202010304027.5A CN202010304027A CN111393387B CN 111393387 B CN111393387 B CN 111393387B CN 202010304027 A CN202010304027 A CN 202010304027A CN 111393387 B CN111393387 B CN 111393387B
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- C07D295/00—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms
- C07D295/02—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms containing only hydrogen and carbon atoms in addition to the ring hetero elements
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- C07D—HETEROCYCLIC COMPOUNDS
- C07D295/00—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms
- C07D295/02—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms containing only hydrogen and carbon atoms in addition to the ring hetero elements
- C07D295/027—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms containing only hydrogen and carbon atoms in addition to the ring hetero elements containing only one hetero ring
- C07D295/03—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms containing only hydrogen and carbon atoms in addition to the ring hetero elements containing only one hetero ring with the ring nitrogen atoms directly attached to acyclic carbon atoms
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Abstract
The invention adopts a method for synthesizing enamine by a microchannel reactor, morpholine and n-propionaldehyde are pumped into the microchannel reactor at the same time according to the molar ratio of (2.0-10.0): 1, and react under certain reaction temperature, reaction pressure and reaction time; then the enamine finished product is obtained by heat preservation, negative pressure dehydration and negative pressure rectification. The invention also provides a production method of imidacloprid, which comprises the following steps: cyclizing enamine to prepare ring Ding Wu, and aminolysis ring Ding Wu to prepare pyridone; preparing 2-chloro-5-methylpyridine by performing chlorine addition and phosgene chlorination on pyridone; 2-chloro-5-methylpyridine is chloridized by chlorine to synthesize 2-chloro-5-chloromethylpyridine; and (3) synthesizing imidacloprid from the 2-chloro-5-chloromethylpyridine/N, N-dimethylformamide solution and imidazolidine.
Description
Technical Field
The invention belongs to the technical field of organic chemical industry, and relates to a method for synthesizing imidacloprid intermediate morpholinyl propylene by a microchannel reactor.
Background
Imidacloprid (chemical name: 1- (6-chloropyridine-3-pyridylmethyl) -N-nitroimidazolidine-2-ylamine) is a neonicotinoid insecticide with the largest global dosage, has excellent insecticidal activity and low mammalian toxicity, is rapidly developed due to high efficiency, broad spectrum and good environmental compatibility, and can be used for crops such as rice, wheat, corn, fruit trees and the like. At present, the main production processes of imidacloprid in China include a benzylamine-n-propionaldehyde method, a cyclopentadiene-acrolein method and a morpholine-n-propionaldehyde method.
Benzylamine-n-propanal process: benzylamine is used as raw material to synthesize N-benzyl-N-propenyl acetamide with N-propionaldehyde and acetic anhydride, then the N-benzyl-N-propenyl acetamide is further chloridized and cyclized to obtain 2-chloro-5-methylpyridine (short for CMP), and then side chain methyl chlorination is carried out to prepare 2-chloro-5-chloromethylpyridine (short for CCMP). The boiling point of the byproduct benzyl chloride and the product 2-chloro-5-methylpyridine is close, and the separation is difficult; the ammonolysis synthesis of benzylamine by a large amount of byproduct benzyl chloride is complex in process and high in cost; the phosphorus oxychloride generates a large amount of phosphorus-containing wastewater which is difficult to treat. At present, the domestic manufacturer for producing imidacloprid by the route is in a semi-stop state.
Cyclopentadiene-acrolein method: the method has the characteristics of easily obtained raw materials, low technical threshold and the like, is the method which is most applied to domestic production of imidacloprid at present and accounts for more than 70 percent of the production method of imidacloprid. Firstly, depolymerizing dicyclopentadiene into cyclopentadiene, then performing addition reaction with acrolein, and then performing secondary addition reaction with acrylonitrile to generate [2,2,1] cyclohepta-alpha-aldehyde-beta-propionitrile-5-ene, cracking the intermediate at high temperature and high vacuum to generate 4-aldehyde pentenenitrile, wherein cyclopentadiene with low boiling point is difficult to recover due to high vacuum, chlorinating the 4-aldehyde pentenenitrile to generate 2-chloro-3-chloromethyl-4-cyanobutanal, and cyclizing to generate CCMP under the action of phosphorus oxychloride. The main disadvantages of this method are: cyclopentadiene has low boiling point and is difficult to recover, and acrolein and acrylonitrile are listed in catalog of highly toxic chemicals, so that safety and environmental risk are high; phosphorus oxychloride is used as a chlorinating reagent, so that the three wastes generated by the generation of phosphate are difficult to treat, and the generation amount of hazardous wastes is large.
Morpholine-n-propanal process: the global Yannong group only adopts the process route to produce 2-chloro-5-methylpyridine and 2-chloro-5-chloromethylpyridine, morpholine and n-propionaldehyde are added under alkaline conditions to obtain morpholinyl propylene (enamine for short), then the morpholinyl propylene and the n-propionaldehyde are subjected to secondary addition reaction to obtain 3-methyl-4-morpholinyl cyclobutane carboxylic acid methyl ester (ring Ding Wu for short), the cyclobutane is subjected to pressure catalytic ammonolysis to synthesize 5-methyl-3,4 dihydropyridine-2 (1H) -ketone (pyridone for short), pyridone and chlorine are subjected to addition dehydrochlorination and aromatization to obtain 2-chloro-5-methylpyridine, and then the side chain chlorination is further carried out to generate 2-chloro-5-chloromethylpyridine. The specific byproduct 2,3-dichloro-5-methylpyridine of the process can be used for producing 2,3-dichloro-5-trifluoromethylpyridine, is a main raw material for producing important pesticide varieties such as fluazinam, chlorfluazuron and high-efficiency Gelidonium, and greatly improves the comprehensive utilization level in the production process
In the last 90 s, yannong group established 200 ton/year morpholine-n-propionaldehyde method imidacloprid production equipment, and through continuous production technical improvement, product yield and quality are greatly improved. However, the synthesis of enamine, an important intermediate, still has the following problems: the kettle type reactor is adopted, the reaction temperature is-5 to-10 ℃, the retention time is 10 hours, and because the reaction is strong in heat release, cryogenic brine at-20 ℃ is needed as a cooling medium, so that the energy consumption is high, the production efficiency is low, and the essential safety is poor.
The micro chemical technology is a new technology for realizing green synthesis for preparing chemical intermediates such as pesticides, medicines and the like, which is developed in recent years, and the reaction process is strengthened by changing the mass transfer, heat transfer and flow characteristics of fluid. The performance of the micro-reactor has great advantages in temperature control, time control and safety control. The microchannel reactor has the characteristics of small volume, green safety, less side reaction, increased number and the like, namely, the mass production is realized by adding the micro reaction unit, and the amplification effect is basically not generated.
The invention provides a novel synthetic method for synthesizing imidacloprid intermediate enamine by a microchannel reactor, which aims to overcome the defects in an enamine synthesis process.
Disclosure of Invention
Compared with the prior art, the method has the advantages of mild reaction temperature, continuous production, reaction completion in extremely short time, low production cost, high raw material utilization rate, high product selectivity and the like. The main reaction equations involved are as follows:
a method for synthesizing enamine by using a microchannel reactor comprises the following steps:
(1) Morpholine and n-propionaldehyde are pumped into a microchannel reactor for reaction at the same time according to the molar ratio of (2.0-10.0): 1, the reaction temperature is 20-80 ℃, the reaction pressure is 0.2-2.0 Mpa, the reaction residence time is 5-300 s, and the flow rate of a mixed solution of morpholine and n-propionaldehyde is 0.08-5 ml/s;
(2) Conveying the reaction product obtained in the step (1) into a product collecting tank after heat preservation; keeping the temperature at 20-80 ℃ for 1-5 hr;
(3) Dehydrating the product obtained in the step (2) under negative pressure to obtain a dehydrated product, wherein the vacuum degree is 0.1-3kPa, and the end point liquid temperature is 40-80 ℃;
(4) And (4) carrying out negative pressure rectification on the dehydrated product obtained in the step (3) to obtain an enamine finished product, wherein the vacuum degree is 0.5-2.5kPa, and the end point liquid temperature is 90-130 ℃.
The invention also provides a method for producing imidacloprid, which is characterized by comprising the following steps:
the first step is as follows: taking n-propionaldehyde and morpholine as raw materials, continuously synthesizing enamine by adopting a microchannel reactor, and carrying out post-treatment on reaction liquid to prepare an enamine finished product;
the second step is that: cyclizing enamine to prepare ring Ding Wu, and aminolysis ring Ding Wu to prepare pyridone;
the third step: preparing 2-chloro-5-methylpyridine by performing chlorine addition and phosgene chlorination on pyridone;
the third step: 2-chloro-5-methylpyridine is chloridized by chlorine to synthesize 2-chloro-5-chloromethylpyridine;
the fourth step: and (3) synthesizing imidacloprid from the 2-chloro-5-chloromethylpyridine/N, N-dimethylformamide solution and imidazolidine.
The content of the imidacloprid finished product synthesized by the steps is more than 98.5 percent and exceeds the quality index requirement of the national imidacloprid standard GB/T28126-2011.
The invention has the following advantages: (1) the yield of enamine synthesized by the reaction of morpholine and n-propionaldehyde is more than 99 percent; (2) By using the microchannel reactor, backmixing is eliminated, and continuous production can be realized; (3) The micro-channel continuous flow reactor is adopted, the reaction time is shortened from the traditional hours to dozens of seconds to several minutes, and the reaction efficiency is obviously improved; (4) The raw materials are mixed well in the micro-channel, the temperature is controlled accurately, the local overheating phenomenon is eliminated, the side reaction is inhibited, and the reaction selectivity is improved.
Drawings
FIG. 1 is a flow chart of the production process of imidacloprid.
Detailed Description
Example 1
Morpholine and n-propionaldehyde are mixed according to a molar ratio of 10.0:1 is pumped into a microchannel reactor to react at the reaction temperature of 20 ℃ and the reaction pressure of 0.2MPa, the retention time of the reaction materials is controlled to be 200s by adjusting the flow of a feed pump, and the flow rate of the mixed liquid is 0.12ml/s. The product is maintained at 20 deg.C for 1.5hr, and vacuum dehydration is carried out under vacuum degree of 3kPa after the temperature is maintained, and the final liquid temperature is 80 deg.C. And then carrying out negative pressure rectification on the dehydrated product under the vacuum degree of 2.5kPa, and obtaining an enamine finished product for the next reaction at the end point liquid temperature of 130 ℃. The enamine yield, based on n-propionaldehyde, was 89.3% by analysis of the finished enamine.
Example 2
Morpholine and n-propionaldehyde are mixed according to a molar ratio of 4.0:1 is pumped into a microchannel reactor to react at the reaction temperature of 40 ℃ and the reaction pressure of 2.0MPa, the residence time of the reaction materials is controlled to be 10s by adjusting the flow of a feed pump, and the flow rate of the mixed liquid is 2.4ml/s. The product is kept at 40 deg.C for 3hr, and vacuum dehydration is carried out under vacuum degree of 0.1kPa after the temperature is kept, and the final liquid temperature is 40 deg.C. And performing negative pressure rectification on the dehydrated product at the vacuum degree of 2.1kPa, wherein the final liquid temperature is 120 ℃, and thus an enamine finished product is obtained for the next reaction. The enamine yield, based on n-propionaldehyde, was 97.6% by analysis of the finished enamine.
Example 3
Morpholine and n-propionaldehyde are mixed according to a molar ratio of 2.4:1 is pumped into a microchannel reactor to react at the reaction temperature of 50 ℃ and the reaction pressure of 0.8MPa, the residence time of the reaction materials is controlled to be 15s by adjusting the flow of a feed pump, and the flow rate of the mixed liquid is 1.5ml/s. Keeping the temperature of the product at 50 deg.C for 2hr, and vacuum dehydrating at 0.3kPa to obtain final liquid temperature of 45 deg.C. And then carrying out negative pressure rectification on the dehydrated product under the vacuum degree of 1.3kPa, and obtaining an enamine finished product for the next reaction at the final liquid temperature of 105 ℃. The enamine product obtained by analysis showed an enamine yield of 99.3% based on n-propionaldehyde.
Example 4
Morpholine and n-propionaldehyde are mixed according to a molar ratio of 2.1:1 is pumped into a microchannel reactor to react at the reaction temperature of 80 ℃ and the reaction pressure of 1.2 MPa. The residence time of the reaction material was controlled to 50s by adjusting the flow rate of the feed pump, and the flow rate of the mixed liquid was 0.48ml/s. Keeping the temperature of the product at 80 ℃ for 1hr, performing negative pressure dehydration at the vacuum degree of 2.5kPa after the temperature is kept, performing negative pressure rectification on the dehydrated product at the end point liquid temperature of 70 ℃ at the vacuum degree of 0.5kPa, and obtaining an enamine finished product for the next reaction at the end point liquid temperature of 90 ℃. The enamine product was analyzed and the enamine yield was 90.6% based on n-propionaldehyde.
Example 5
Morpholine and n-propionaldehyde are mixed according to a molar ratio of 3.0:1 is pumped into a microchannel reactor to react at the reaction temperature of 50 ℃ and the reaction pressure of 1.0 MPa. The residence time of the reaction material was controlled to 5s by adjusting the flow rate of the feed pump, and the flow rate of the mixed liquid was 4.8ml/s. The product is kept at 50 deg.C for 4.5hr, and vacuum dehydration is carried out under vacuum degree of 2kPa after the temperature is kept, and the final liquid temperature is 65 deg.C. And then carrying out negative pressure rectification on the dehydrated product at the vacuum degree of 1.9kPa, wherein the final liquid temperature is 115 ℃, and an enamine finished product is obtained and used for the next reaction. When the obtained enamine product was analyzed, the enamine yield based on n-propionaldehyde was 88.1%.
Example 6
Morpholine and n-propionaldehyde are mixed according to a molar ratio of 8.0:1 is pumped into a microchannel reactor to react at the reaction temperature of 50 ℃ and the reaction pressure of 0.8 MPa. Controlling the residence time of the reaction materials to 300s by adjusting the flow rate of the feeding pump, controlling the flow rate of the mixed liquid to 0.08ml/s, keeping the temperature of the product at 70 ℃ for 5hr, and carrying out negative pressure dehydration under the vacuum degree of 1.5kPa after the temperature is kept, wherein the end point liquid temperature is 60 ℃. And then carrying out negative pressure rectification on the dehydrated product at the vacuum degree of 1.6kPa, and obtaining an enamine finished product for the next reaction, wherein the end point liquid temperature is 110 ℃. The enamine yield, based on n-propionaldehyde, was 86.0% by analysis of the finished enamine.
Example 7
Morpholine and n-propionaldehyde are mixed according to a molar ratio of 6.0:1 is pumped into a microchannel reactor to react at the reaction temperature of 50 ℃ and the reaction pressure of 1.6 MPa. The residence time of the reaction material was controlled to 25s by adjusting the flow rate of the feed pump, and the flow rate of the mixed liquid was 0.96ml/s. The product is kept at 30 deg.C for 4hr, and vacuum dehydration is carried out under vacuum degree of 1kPa after the temperature is kept, and the final liquid temperature is 55 deg.C. And then carrying out negative pressure rectification on the dehydrated product at the vacuum degree of 0.8kPa, wherein the final liquid temperature is 95 ℃, and an enamine finished product is obtained and used for the next reaction. The enamine yield, based on n-propionaldehyde, was 94.4% when the final enamine product was analyzed.
Example 8
Morpholine and n-propionaldehyde are mixed according to a molar ratio of 2.0:1 is pumped into a microchannel reactor to react at the reaction temperature of 50 ℃ and the reaction pressure of 0.5 MPa. The residence time of the reaction material was controlled to 100s by adjusting the flow rate of the feed pump, and the flow rate of the mixed liquid was 0.24ml/s. Keeping the temperature of the product at 60 deg.C for 2.5hr, and vacuum dehydrating at 0.5kPa to obtain final liquid temperature of 50 deg.C. And then carrying out negative pressure rectification on the dehydrated product at the vacuum degree of 1.1kPa, and obtaining an enamine finished product for the next reaction at the final liquid temperature of 100 ℃. The enamine product was analyzed and the enamine yield was 92.8% based on n-propionaldehyde.
Comparative example
An enamine kettle type synthesis process: morpholine is put into a reaction kettle, a dehydrating agent is added, the temperature of reaction liquid is firstly reduced to-10 ℃ to-5 ℃, 0.35 to 0.5 equivalent of frozen propionaldehyde is slowly pumped, the reaction temperature is controlled to be lower than-5 ℃, and the reaction pressure is normal pressure. The propionaldehyde is dripped for 3-4 hr at the dripping speed of 0.25-0.5 ml/min. After the reaction is finished, the product is kept at 30 ℃ for 2hr, and after the temperature is kept, negative pressure dehydration is carried out under the vacuum degree of 0.3kPa, and the end liquid temperature is 45 ℃. And then carrying out negative pressure rectification on the dehydrated product under the vacuum degree of 1.3kPa, and obtaining an enamine finished product for the next reaction at the final liquid temperature of 105 ℃. The enamine product obtained by analysis showed 83% enamine yield based on n-propionaldehyde.
The invention is not limited to the embodiments of the invention described.
The structure and the implementation of the present invention are described herein by using specific examples, and the above description of the examples is only used to help understand the core idea of the present invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (1)
1. A method for synthesizing enamine by a microchannel reactor comprises the following steps:
(1) Morpholine and n-propionaldehyde are pumped into a microchannel reactor at the same time according to the molar ratio of (2.0-6.0) to 1, and react under certain reaction temperature, reaction pressure and reaction time; the reaction temperature is 40-50 ℃, and the reaction pressure is 0.8-2.0 Mpa; the flow rate of the mixed liquid of morpholine and n-propionaldehyde is 0.24 ml/s-2.4 ml/s; the reaction residence time is 10 to 100s;
(2) Conveying the reaction product obtained in the step (1) into a product collecting tank after heat preservation; keeping the temperature at 30-60 ℃ for 2-4 hr;
(3) Dehydrating the product obtained in the step (2) under negative pressure to obtain a dehydrated product, wherein the vacuum degree is 0.1-1kPa, and the end point liquid temperature is 40-55 ℃;
(4) And (4) carrying out negative pressure rectification on the dehydrated product obtained in the step (3) to obtain an enamine finished product, wherein the vacuum degree is 0.8-2.1kPa, and the end point liquid temperature is 95-120 ℃.
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