Imidacloprid is an important insecticide widely used in agriculture, horticulture and home control. Its chemical structure is azacyclic methylpyrimidine, and it is a new type of nitrogen chloride insecticide. This article will describe in detail all the synthetic methods of Imidacloprid. It is a broad-spectrum insecticide belonging to the group of chlorinated nitrobenzimidazoles. Known for its broad-spectrum insecticidal action, the drug is often used in agriculture, horticulture and lawns. Below is a breakdown of the uses for Imidacloprid.
1. Agriculture:
Imidacloprid is widely used on crops to control a variety of pests, such as aphids, migratory locusts, beet armyworms, planthoppers, thrips, cocoon aphids, etc. It can be applied to a variety of crops, including corn, rice, wheat, rapeseed, cotton, potatoes, tomatoes, beans, figs, tobacco, etc. Imidacloprid acts on insects by interfering with the nervous system, blocking the nerve conduction of the insects, reducing the activity of the insects, and finally achieving the purpose of killing insects.
2. Gardening:
Imidacloprid is commonly used in the insecticide and treatment of horticultural plants, such as spraying treatment for the control of beetles, aphids and other pests. In addition, it is also used to kill insects and fertilize the lawn to increase the aesthetics of the lawn.
3. Household and public places:
As an indoor agent, Imidacloprid can be used in homes or public places to control various pests such as ants, spiders, mosquitos and flies, and improve indoor hygiene.
4. Neuropharmacology:
In addition to insecticides, imidacloprid also shows certain neuropharmacological effects. It is a new type of benzimidazole compound, which can interact with the acetylcholine receptor in the insect brain and block its signal transduction, thereby interfering with the insect's appetite, taste, vision and motor ability. At the same time, it can also affect higher neurological functions such as behavior, cognition and sensation by interfering with acylcholine-mediated synaptic transmission in the spinal cord and brain.
5. Paddy fields:
During the rice planting process, the water in the paddy field cannot be renewed in time. Therefore, the use of imidacloprid in paddy fields can effectively control rice planthoppers. This pest has a short lifespan and is difficult to control with traditional pesticides, but imidacloprid can be handled inexperienced.
6. Fruits and vegetables:
The application of imidacloprid is not limited to crops, but can also be used in fruits and vegetables. For example, during the maintenance of figs, it can be sprayed to survey areas where pests have occurred. At the same time, it can also protect bees during beekeeping.
7. The Swiss Army Knife:
Imidacloprid can also be used as a Swiss Army knife. Due to its physical and chemical stability, it can be used in the manufacture of numerous everyday products such as leather, fiber products, glue, paper, etc.
8. Other:
Imidacloprid is also widely used in other fields, such as gardening, forest protection, wild animal protection, western medicine and so on. In forest protection, it can be used to deal with plant root pests. In the medical field, imidacloprid has also been used as a β-agonist in in vitro studies of the β-cell phosphorylase pathway, and in the interaction of animal cells with the estrogen receptor environment.
In general, imidacloprid is used widely and usually with good results. However, it should also be noted that its wide application also brings certain risks to insects and the environment, so measures should be taken to ensure safety in use. For example, follow the recommended Dosages to control the amount and frequency of application; at the same time, a certain number of non-pest organisms should be tolerated to maintain the balance of the ecosystem.
1. Pyridazine:
The pyridazine method is one of the earliest synthetic methods of imidacloprid. The specific synthetic process of pyridazine role method is as follows:
Step 1: The precursor compound 2-amino-5-chloropyridine of imidacloprid is condensed with 4,5-diethylamino-1H-pyridin-2-one to obtain the intermediate N-(2-amino-5-chloro pyridine)-N'-(4,5-diethylamino-1H-pyridin-2-one).
Step 2: Carry out nucleophilic substitution reaction on 1 with sodium hypochlorite, remove an ethylamino group in the intermediate, and generate N-(2-amino-5-chloropyridine)-N'-(4-methyl-5-chloro-2 -pyridyl)-1,2-dihydropyridin-6-one.
Step 3: Acylation reaction of 2 with chloropropionitrile to obtain Imidacloprid.
The advantage of the pyridazine method to synthesize imidacloprid is that the raw materials are easy to obtain, but the disadvantage is that the reaction conditions are harsh and the purity of the product is low.
2. Polyboric acid method:
The polyboronic acid method is another common synthesis method of imidacloprid. The synthesis process of polyboric acid method is as follows:
The first step: react 2-amino-5-chloropyridine with dipropyl carbonate under basic conditions to obtain the intermediate N-(2-amino-5-chloropyridine)-2-propionylaminopropionate .
The second step: in the presence of polyboric acid, carry out the ethylation reaction of 4 to obtain the intermediate N-(2-amino-5-chloropyridine)-N'-(2-ethoxycarbonyl-2-ethoxycyanide base)-1,2-dihydropyridin-6-one.
The third step: hydrogenation reaction of 5 with deacetamidase to remove ethoxycarbonyl and ethoxycyano groups to generate Imidacloprid.
The advantage of polyboric acid method to synthesize imidacloprid is that the reaction conditions are mild, the product has good crystallinity, and can be directly used in industrial production. However, polyboric acid is easily affected by moisture in the air and requires strict control of moisture conditions.
3. Pyridine method:
The pyridine method is another synthetic method of imidacloprid, which is obtained by condensation reaction using the electrophilic group of pyridine. The specific synthetic process of pyridine method is as follows:
The oxazoline propellants were reacted with 2,3,5-collidine to obtain the intermediate N-benzidine-2,3,5-collidine-4-amine (7). Then 7 is condensed with cyanomethylbenzene, cyanomethylhexane and chloroacetonitrile to obtain the intermediate N-(2,6-dimethylpyridin-4-yl)-N′-methylnitro- 1,2-Dihydropyridin-6-one (8). Finally, epoxidation of 8 with ethylene oxide yielded imidacloprid (9).
The advantage of the pyridine synthesis of Imidacloprid is that the reaction conditions are relatively mild and the product has a high purity. However, the pyridine method requires the use of aniline ammonium catalyst, and the selection of the catalyst quantity will affect the yield and product purity.
The above three methods are the main synthetic methods of Imidacloprid, among which the polyboric acid method is the most commonly used industrial synthetic method at present. Through the understanding of the synthesis method of imidacloprid, the structure and preparation process of the compound can be better understood, which will help to better apply and develop this important insecticide.