CN110818686B - Synthetic method of imidacloprid - Google Patents
Synthetic method of imidacloprid Download PDFInfo
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- CN110818686B CN110818686B CN201911117368.5A CN201911117368A CN110818686B CN 110818686 B CN110818686 B CN 110818686B CN 201911117368 A CN201911117368 A CN 201911117368A CN 110818686 B CN110818686 B CN 110818686B
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- C07D401/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom
- C07D401/02—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings
- C07D401/06—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings linked by a carbon chain containing only aliphatic carbon atoms
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Abstract
The invention provides a method for synthesizing imidacloprid, which takes 2-chloro-5-chloromethyl pyridine, ethylenediamine and guanidine nitrate as raw materials and synthesizes the imidacloprid through the steps of amination, cyclization, dehydration and the like. The method avoids the safety problem caused by the generation of unstable nitroguanidine in the reaction process, has high production process safety, good product purity and high yield, and is easy to realize industrialization.
Description
Technical Field
The invention belongs to the technical field of petrochemical industry, and relates to a method for synthesizing imidacloprid, in particular to a method for synthesizing imidacloprid by taking 2-chloro-5-chloromethyl pyridine, ethylenediamine and guanidine nitrate as raw materials.
Background
The imidacloprid has the chemical name of 1- (6-chloropyridine-3-pyridylmethyl) -N-nitroimidazolidine, is a nicotine ultra-high-efficiency pesticide, has broad spectrum, high efficiency, low toxicity and low residue, is not easy to generate resistance to pests, and is widely applied to pest control in crops such as rice, potatoes, cotton, corn, beet and the like.
The traditional synthetic method of imidacloprid is an imidazolidine method, which comprises the following two steps: 1) taking nitroguanidine and ethylenediamine as raw materials, and reacting and crystallizing in water to obtain imidazolidine solid; 2) reacting 2-chloro-5-chloromethylpyridine with the imidazolidine obtained in the step 1) in an organic solvent, and crystallizing to obtain light yellow imidacloprid. The process uses nitroguanidine with poor stability as a raw material, is easy to explode and poor in safety, and the nitroguanidine is produced by generally using guanidine nitrate as the raw material in factory production through sulfuric acid dehydration, so that the safety risk still exists in the storage process. Patent CN 107445897A uses nitroguanidine to react with ethylenediamine to synthesize imidazolidine, and the yield is only 90%. Therefore, there is a need to develop a method for producing imidacloprid with higher yield.
Disclosure of Invention
The invention provides a synthetic method of imidacloprid. The imidacloprid is synthesized by taking 2-chloro-5-chloromethylpyridine, ethylenediamine and guanidine nitrate as raw materials through the steps of amination, cyclization, dehydration and the like. The method avoids the safety problem caused by the generation of unstable nitroguanidine in the reaction process, and has the advantages of high process safety, good product purity, high yield and easy realization of industrialization. The reaction equation is as follows:
a synthetic method of imidacloprid comprises the following steps:
(1) 2-chloro-5-chloromethyl pyridine and ethylenediamine are subjected to amination reaction in the presence of a solvent under the condition of an alkaline substance, and are subjected to crystallization or layering treatment to obtain N1- ((6-chloropyridin-3-yl)) Methyl) ethane-1, 2-diamine imine, compound 1;
(2) carrying out cyclization reaction on the compound 1 in the step (1) and guanidine nitrate in the presence of a solvent, and washing to obtain 1- ((6-chloropyridin-3-yl) methyl) imidazolidine-2-imine as a compound 2;
(3) and (3) carrying out nitration reaction on the compound 2 in the step (2) in the presence of strong acid, and carrying out hydrolysis and crystallization on reaction liquid to obtain the target product imidacloprid.
In the step (1), the amination reaction conditions are as follows: the reaction temperature is-10-50 ℃, and the reaction molar ratio is 2-chloro-5-chloromethyl pyridine: ethylenediamine is 1:1.0 to 1: 1.5; the alkaline substance is one or a mixture of more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and calcium hydroxide, and the dosage of the alkaline substance is 0.9-1.5 times of the mole number of the 2-chloro-5-chloromethylpyridine; the reaction solvent is one or a mixture of more of water, acetonitrile, methanol, ethanol, ethylene glycol, acetone, dichloromethane, trichloromethane, dichloroethane, chlorobenzene and dichlorobenzene, and the dosage of the reaction solvent is 0.5-10 times of the weight of the 2-chloro-5-chloromethylpyridine; the reaction time is 10-200 min;
in the step (1), when the amination reaction solvent has strong water solubility, the compound 1 is precipitated by adopting a crystallization method; when the water solubility of the solvent is weak, the compound 1 is obtained from an oil layer through layering treatment and directly put into the next reaction;
in the step (2), the cyclization reaction conditions are as follows: the reaction temperature is 0-50 ℃, the reaction solvent is one or a mixture of more of water, acetonitrile, methanol, ethanol, ethylene glycol, acetone, dichloromethane, trichloromethane, dichloroethane, chlorobenzene and dichlorobenzene, the dosage of the solvent is 0.5-20 times of the weight of the compound 1, the dosage of the guanidine nitrate is 1.0-1.5 times of the mole number of the compound 1, and the reaction time is 10-300 min;
in the step (2), when the cyclization reaction solvent is highly water-soluble, the compound 2 is precipitated by a crystallization method; when the water solubility of the solvent is weak, the compound 2 is obtained from an oil layer through layering treatment;
in the step (3), the nitration reaction conditions are as follows: the reaction temperature is-10-50 ℃, and the reaction molar ratio is as follows: and 2, the nitric acid is 1: 1.0-1: 1.2, the strong acid is sulfuric acid, the dosage of the strong acid is 1-10 times of the weight of the compound 2, the reaction time is 10-200 min, the dosage of the water for hydrolysis is 2-5 times of the weight of the sulfuric acid, and the hydrolysis temperature is-10-50 ℃.
The invention has the following advantages: the production process has high safety, good product purity and high yield, and is easy to realize industrialization.
Detailed Description
The following examples are intended to illustrate the invention in more detail, but are not intended to limit the invention further. In the above description, "%" is "% by mass" unless otherwise specified.
Example 1
Amination: 30.0g of 50% NaOH, 112.0g of ethylenediamine and 200mL of acetonitrile are put into a 1000mL four-mouth bottle; 95.88% 2-chloro-5-chloromethylpyridine 63.0g was dissolved in 100mL of acetonitrile and placed in a 250mL dropping funnel. And placing the 1000mL four-neck flask in an ice-water bath, controlling the temperature of the system at 8-10 ℃, and controlling the dropping time at about 1 h. After the dropwise addition of the acetonitrile solution of 2-chloro-5-chloromethylpyridine, the temperature of the system starts to rise, and after the temperature of the system rises to 30 ℃, the temperature is kept for 3 hours, and the reaction process is finished. After the reaction is finished, desolventizing to recover the solvent, cooling, leaching, and desolventizing at negative pressure to obtain the residue N169.51g of ((6-chloropyridin-3-yl) methyl) ethane-1, 2-diamine imine, the product purity was 97.98% and the yield was 98.4%.
Cyclization: into a 500mL reaction flask, 456g of an aqueous solution containing 10% guanidine nitrate was charged, cooled to 20 ℃ and N was added169.51g of ((6-chloropyridin-3-yl) methyl) ethane-1, 2-diamine imine, which was incubated for 3 hours, whereupon the reaction was terminated. After filtration and drying, 74.64g of 1- ((6-chloropyridin-3-yl) methyl) imidazolidine-2-imine was obtained as a brown yellow solid with a purity of 98.25% and a yield of 94.9%.
Nitration: 74.64g of 1- ((6-chloropyridin-3-yl) methyl) imidazolidine-2-imine solid is dissolved in 300g of concentrated sulfuric acid, the temperature is reduced to-10 ℃, 24.7g of 98% fuming nitric acid is dropwise added, the dropwise addition is finished within about 30min, and the temperature is kept at 0 ℃ for 30 min. After the reaction is finished, quickly adding ice water, precipitating light yellow solid powder, washing and drying to obtain 85.8g of imidacloprid without recrystallization, wherein the purity of the product is 97.6 percent, and the yield is 94.0 percent. The total yield of imidacloprid in the whole process is 88 percent.
Examples 2 to 6
On the basis of example 1, the amination temperature and time are changed, other conditions are not changed, and the reaction results are as follows:
examples 7 to 9
On the basis of example 1, the concentration and molar ratio of the guanidine nitrate solution in the cyclization reaction are changed, and the result of the cyclization reaction is as follows:
examples 10 to 12
On the basis of example 1, the cyclization reaction temperature and time are changed, and the result of the cyclization reaction is as follows:
| example numbering | Cyclization reaction temperature/. degree.C | Cyclization reaction time/h | Compound 2 purity/%) | Cyclization yield/%) |
| Example 1 | 20 | 3 | 98.25 | 94.9 |
| Example 10 | 0 | 5 | 98.12 | 94.6 |
| Example 11 | 30 | 2 | 98.21 | 94.3 |
| Example 12 | 50 | 1 | 98.08 | 93.5 |
Examples 13 to 16
On the basis of example 1, the compound 2 obtained in example 2 is used as a raw material, the dosage of sulfuric acid, the concentration of nitric acid and the reaction temperature in the nitration reaction are changed, and the nitration reaction results are as follows:
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 (5)
1. A synthetic method of imidacloprid comprises the following steps:
(1) 2-chloro-5-chloromethyl pyridine and ethylenediamine are subjected to amination reaction in the presence of a solvent under the condition of an alkaline substance, and are subjected to crystallization or layering treatment to obtain N1- ((6-chloropyridin-3-yl) methyl) ethane-1, 2-diamine imine as compound 1;
(2) carrying out cyclization reaction on the compound 1 in the step (1) and guanidine nitrate in the presence of a solvent, and washing with water to obtain 1- ((6-chloropyridin-3-yl) methyl) imidazolidine-2-imine as a compound 2; the cyclization reaction conditions are as follows: the reaction temperature is 0-50 ℃, the reaction solvent is water, the dosage of the solvent is 0.5-20 times of the weight of the compound 1, the dosage of guanidine nitrate is 1.0-1.5 times of the mole number of the compound 1, and the reaction time is 10-300 min;
(3) and (3) carrying out nitration reaction on the compound 2 in the step (2) in the presence of strong acid, and carrying out hydrolysis and crystallization on reaction liquid to obtain the target product imidacloprid.
2. The method for synthesizing imidacloprid as claimed in claim 1, wherein in the step (1), the amination reaction conditions are as follows: the reaction temperature is-10-50 ℃, and the reaction molar ratio is 2-chloro-5-chloromethyl pyridine: ethylenediamine =1:1.0 to 1: 1.5; the alkaline substance is one or a mixture of more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and calcium hydroxide, and the dosage of the alkaline substance is 0.9-1.5 times of the mole number of the 2-chloro-5-chloromethylpyridine; the reaction solvent is one or a mixture of more of water, acetonitrile, methanol, ethanol, ethylene glycol, acetone, dichloromethane, trichloromethane, dichloroethane, chlorobenzene and dichlorobenzene, and the dosage of the reaction solvent is 0.5-10 times of the weight of the 2-chloro-5-chloromethylpyridine; the reaction time is 10-200 min.
3. The method for synthesizing imidacloprid according to claim 2, wherein in the step (1), when the amination reaction solvent has strong water solubility, the compound 1 is precipitated by a crystallization method; when the solvent is poorly water-soluble, compound 1 is obtained from the oil layer by a layer separation treatment.
4. The method for synthesizing imidacloprid according to claim 1, wherein in the step (3), the nitration reaction conditions are as follows: the reaction temperature is-10-50 ℃, and the reaction molar ratio is as follows: and 2, nitric acid =1: 1.0-1: 1.2, the strong acid is sulfuric acid, the dosage of the strong acid is 1-10 times of the weight of the compound 2, and the reaction time is 10-200 min.
5. The method for synthesizing imidacloprid as claimed in claim 4, wherein in the step (3), the amount of water added for hydrolysis is 2-5 times of the weight of sulfuric acid, and the hydrolysis temperature is-10-50 ℃.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6022967A (en) * | 1985-02-04 | 2000-02-08 | Nihon Bayer Agrochem K.K. | Heterocyclic compounds |
| CN203207045U (en) * | 2013-04-22 | 2013-09-25 | 新沂市景腾园林有限公司 | Novel device for producing special insecticide for ligustrun lucidum |
| CN104672212A (en) * | 2013-11-26 | 2015-06-03 | 嘉兴学院 | Method for synthesizing imidacloprid employing cascade reaction |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6022967A (en) * | 1985-02-04 | 2000-02-08 | Nihon Bayer Agrochem K.K. | Heterocyclic compounds |
| CN203207045U (en) * | 2013-04-22 | 2013-09-25 | 新沂市景腾园林有限公司 | Novel device for producing special insecticide for ligustrun lucidum |
| CN104672212A (en) * | 2013-11-26 | 2015-06-03 | 嘉兴学院 | Method for synthesizing imidacloprid employing cascade reaction |
Non-Patent Citations (3)
| Title |
|---|
| 吡虫啉的合成方法研究;陆阳等;《化工技术与开发》;20081115(第11期);第20-21页 * |
| 吡虫啉的合成研究;高仁君等;《农药》;19970525(第05期);第13页 * |
| 硝基胍法制备吡虫啉工艺;郑亚清等;《农药》;20140110(第01期);第17-18页 * |
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