CN110746397B - Method for synthesizing imidacloprid with high yield - Google Patents
Method for synthesizing imidacloprid with high yield Download PDFInfo
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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 with high yield, which takes 2-chloro-5-chloromethyl pyridine, ethylenediamine and cyanogen halide as raw materials to synthesize the imidacloprid through the steps of amination, cyclization, nitration and the like. The method has the advantages of high safety in production process, good product purity, high yield and easy realization of industrialization.
Description
Technical Field
The invention belongs to the technical field of petrochemical industry, relates to a method for synthesizing imidacloprid, and more particularly relates to a method for synthesizing imidacloprid by taking 2-chloro-5-chloromethyl pyridine, ethylenediamine and cyanogen halide 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 method for synthesizing imidacloprid with high yield. Specifically, the imidacloprid is synthesized by taking 2-chloro-5-chloromethylpyridine, ethylenediamine and cyanogen halide as raw materials through the steps of amination, cyclization, nitration and the like. The method has the advantages of high safety in production process, 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, designated compound 1;
(2) performing cyclization reaction on the compound 1 in the step (1) and cyanogen halide in the presence of a solvent to obtain 1- ((6-chloropyridin-3-yl) methyl) imidazolidine-2-imine, namely 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 then carrying out hydrolysis, crystallization and other steps 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: the preparation method comprises the following steps of (1: 1.0) - (1: 1.5) preparing ethylenediamine, wherein a reaction solvent is one or a mixture of water, acetonitrile, methanol, ethanol, ethylene glycol, acetone, dichloromethane, trichloromethane, dichloroethane, chlorobenzene and dichlorobenzene, the dosage of the solvent is 0.5-10 times of the weight of 2-chloro-5-chloromethyl pyridine, and 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 cyanogen halide is one or a mixture of more of cyanogen fluoride, cyanogen bromide, cyanogen chloride and cyanogen iodide, and the molar ratio of the reaction is compound 1: cyanogen halide is 1: 1.0-1: 1.5, and the content of the hydrogen halide solution is 1-15%;
in the step (2), the cyclization reaction conditions are as follows: the reaction temperature is-10-50 ℃, 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 0.5-10 times of the weight of the compound 1, and the reaction time is 10-200 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 ℃, the molar ratio of nitric acid to compound 2 is 1: 1.0-1: 1.2, the strong acid is sulfuric acid, the use amount of the strong acid is 1-10 times of the weight of the compound 2, the reaction time is 10-200 min, the use amount of 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: has the advantages of high process safety, good product purity, high yield and easy realization of 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: 400g of an aqueous solution containing 10% cyanogen bromide was put into a 1000mL reaction flask, 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, 74.90g of 1- ((6-chloropyridin-3-yl) methyl) imidazolidine-2-imine was obtained as a brown yellow solid with a purity of 98.12% and a yield of 95.1%.
Nitration: 77.26g 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 ℃, 46.6g 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, the mixture is quickly added into ice water, light yellow solid powder is separated out, 85.9g of imidacloprid is obtained after washing and drying, recrystallization is not needed, the product purity is 97.7 percent, and the yield is 94.1 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 compound 1 obtained by amination was used as a raw material, and the cyclized raw material cyanogen bromide was changed to other cyanogen halides, and the results were as follows, except that the conditions were not changed:
examples 10 to 14
Based on example 1, the compound 1 obtained in example 1 was used as a starting material, and the concentration of the cyanogen bromide solution for the cyclization reaction, the type of the solvent, the temperature and the time were varied, so that the results of the cyclization reaction were as follows:
examples 15 to 18
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 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 several 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 present invention.
Claims (6)
1. A method of synthesizing imidacloprid comprising the steps of:
(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, designated compound 1;
(2) performing cyclization reaction on the compound 1 in the step (1) and cyanogen halide in the presence of a solvent to obtain 1- ((6-chloropyridin-3-yl) methyl) imidazolidine-2-imine, namely a compound 2; the cyclization reaction conditions are as follows: the reaction temperature is-10-50 ℃, the reaction solvent is water, the dosage of the solvent is 0.5-10 times of the weight of the compound 1, and the reaction time is 10-200 min;
(3) and (3) carrying out nitration reaction on the compound 2 in the step (2) in the presence of strong acid, and then 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: the reaction solvent is one or a mixture of water, acetonitrile, methanol, ethanol, ethylene glycol, acetone, dichloromethane, trichloromethane, dichloroethane, chlorobenzene and dichlorobenzene, the dosage of the solvent is 0.5-10 times of the weight of 2-chloro-5-chloromethylpyridine, and 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 is highly water-soluble, 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 according to claim 1, wherein in the step (2), the cyanogen halide is one or more of cyanogen fluoride, cyanogen bromide, cyanogen chloride and cyanogen iodide, and the molar ratio of the compound 1: cyanogen halide =1: 1.0-1: 1.5, and the content of the hydrogen halide solution is 1-15 wt%.
5. The method for synthesizing imidacloprid as claimed in claim 1, wherein in the step (3), the nitration reaction conditions are as follows: the reaction temperature is-10-50 ℃, the molar ratio of the compound 2 to the nitric acid is =1: 1.0-1: 1.2, the strong acid is sulfuric acid, the use amount of the strong acid is 1-10 times of the weight of the compound 2, and the reaction time is 10-200 min.
6. The method for synthesizing imidacloprid as claimed in claim 5, 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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