Brief introduction

Imidacloprid is an insecticide, especially a proinsecticide (meaning it is metabolized into an active insecticide after entering the host), derived from a compound produced by a class of microorganisms called halogenated pyrrole. The US Environmental Protection Agency initially refused registration for use on cotton in 2000, mainly due to concerns about the toxicity of this insecticide to birds and the availability of effective alternatives. However, it was registered by the EPA in January 2001 for use in non food crops in greenhouses. In 2005, the US Environmental Protection Agency (EPA) established tolerance levels for imidacloprid residues in or on all foods. Carfenapyr works by disrupting the production of adenosine triphosphate, particularly through the oxidation of the N-ethoxymethyl group of Carfenapyr by mixed functional oxidases, forming compound CL 303268. CL 303268 breaks down mitochondrial oxidative phosphorylation, leading to the interruption of ATP production, cell death, and ultimately the death of the organism. Imidacloprid is also used as a wool insecticide and has been introduced as a substitute for synthetic pyrethroids due to its low toxicity to mammals and aquatic organisms.

Basic information

Numbering system

Physical and Chemical Properties

• Appearance and characteristics:

• Grey white to light brown powder with a halide odor

• Density:

• 1.53 g/cm3

• Boiling point:

• 443.5ºC at 760 mmHg

• Melting point:

• 100.5ºC

• Flash point:

• 222ºC

• Refractive index:

• 1.559

• Storage conditions:

• 0-6ºC

• Steam pressure:

• 4.6E-08mmHg at 25°C

Security information

• Safety instructions:

• S13-S36/37-S45-S60-S61

• Hazard category code:

• R22; R23; R50/53

• Dangerous goods transportation code:

• UN 2811

• Dangerous goods signs:

• T

Production method and purpose

Production method

1. Preparation of 2- (2-chlorophenyl) sarcosine: 88g of methylamine hydrochloride aqueous solution and 53g of NaCN aqueous solution were added to 153g of 2-chlorobenzaldehyde in tetrahydrofuran solution. Stir at room temperature for 16 hours. Extract with toluene, add 10mL of pyridine to the toluene layer, and then add 50mL of acetic anhydride. Stir at room temperature and concentrate under vacuum to obtain an oily substance, which is then added to a 1:1 mixture of water and hydrochloric acid. Heat and reflux for 2 hours, cool, dilute with water, neutralize with 50% sodium hydroxide solution to pH 2, and solid precipitate. Filter and air dry to obtain 180g of white solid. m. P.208-213 ℃. Preparation of 2- (2-chlorophenyl) - N - (trifluoroacetyl) sarcosine: Dissolve 27g of 2- (2-chlorophenyl) sarcosine in anhydrous toluene, treat with 20mL of trifluoroacetic anhydride, stir for 1 hour, and concentrate under vacuum to obtain a solid residue. Repeat the vaporization of the residue with toluene several times to obtain 38.7g of red solid. m. P.117-118 ℃. The preparation of 2- (2-chlorophenyl) -1-methyl-5- (trifluoromethyl) -2-pyrroline-3-nitrile was carried out by adding 5.1g of acetic anhydride, 1.6g of acrylonitrile, and 10 drops of triethylamine to a 7.4g solution of 2- (2-chlorophenyl) - N - (trifluoromethyl) sarcosine in acetonitrile. The reaction was heated under reflux for 5.5 hours, cooled, and concentrated in vacuum to obtain a red oily residue. Filter with a silica gel column, first wash with a mixture of n-hexane/ethyl acetate, then wash with a mixture of dichloromethane and ethyl acetate. Combine the filtrate, concentrate under vacuum, and recrystallize from dichloromethane to obtain a light yellow needle shaped solid. m. P.158-160 ℃. The preparation of 2- (2-chlorophenyl) -1-methyl-5- (trifluoromethyl) pyrrole-3-nitrile was carried out by adding 1.76g of bromine in a chlorobenzene solution of 2.87g of 2- (2-chlorophenyl) -1-methyl-5- (trifluoromethyl) -2-pyrroline-3-nitrile, heating to 100 ℃, and reacting for 4-5 hours. Cool to room temperature, dilute with water, and extract with ethyl acetate. Combine the extracts, wash with water, sodium metabisulfite, and water sequentially, dry with anhydrous magnesium sulfate, and concentrate under vacuum to obtain a light yellow solid residue. Recrystallized from n-pentane/ethyl acetate to obtain 2.4g of light yellow crystals, with a temperature range of 129.5-130 ℃. The preparation of 4-bromo-2- (p-chlorophenyl) -1-methyl-5- (trifluoromethyl) pyrrole-3-nitrile was carried out in a chlorobenzene solution of 2- (p-chlorophenyl) -1-methyl-5- (trifluoromethyl) pyrrole-3-nitrile (5.70g). 3.52g of bromine was added and heated to 80 ℃ for 20 hours. After cooling, add 3.52g of bromine and heat to 100 ℃. Cool the reaction mixture and extract with ethyl acetate. Combine the extraction solutions, wash them successively with water and sodium metabisulfite solution, dry them with anhydrous magnesium sulfate, and concentrate them under vacuum to obtain a solid residue. The residue was crystallized using a mixed solvent of ethyl acetate and n-hexane to obtain 6.50g of white solid. m. P.126-129 ℃. Preparation of 4-bromo-2- (2-chlorophenyl) -1- (bromomethyl) -5- (trifluoromethyl) pyrrole-3-nitrile: Under stirring, 7.27g of 4-bromo-2- (2-chlorophenyl) -1-methyl-5- (trifluoromethyl) pyrrole-3-nitrile was dissolved in carbon tetrachloride, 3.52g of bromine was added, heated to a certain temperature, irradiated with light for 2-4 days, then cooled to room temperature, washed with sodium metabisulfite aqueous solution, and the organic phase was vacuum concentrated. The residue was recrystallized from n-hexane to obtain a white solid product. m. P.131-131.5 ℃. The preparation of imidacloprid nitrile involves mixing 4.42g of 4-bromo-2- (4-chlorophenyl) -1- (bromomethyl) -5- (trifluoromethyl) pyrrole-3-nitrile with anhydrous ethanol, treating with a 0.715g ethanol solution of 21% sodium ethoxide, heating to 80 ℃, and maintaining for 15-25min. Cool, dilute with water and ether, separate the organic layer, and dry over anhydrous magnesium sulfate. Vacuum concentration and n-hexane recrystallization resulted in 3.45g of white solid imidacloprid. m. P.91-92 ℃.
2. Preparation method two involves the reaction of trifluoroacetamido-4-chlorobenzoic acid with aldehyde anhydride to obtain 2- (4-chlorophenyl) -5-trifluoromethyl oxazole-3, which is then reacted with alpha chloroacrylonitrile to obtain 2- (4-chlorophenyl) -5-trifluoromethyl pyrrole-3-nitrile. Subsequently, it is reacted with bromine and chloroethyl ether to obtain imidacloprid. The synthesis route of imidacloprid is detailed in "Pesticides", 2003, 42
(2)。

use to

1. New structured pyrrole insecticides and acaricides. It has excellent control effect on boring, sucking, chewing pests and mites. More effective than cypermethrin and cyhalothrin, its acaricidal activity is stronger than that of trichlorfon and tricyclic tin. This drug has the following characteristics: broad-spectrum insecticidal and acaricidal agents; It has both stomach toxicity and contact killing effects; No cross resistance with other insecticides; Moderate residual activity on crops; Selective internalization activity through root absorption in nutrient solution; Moderate oral toxicity to mammals, low dermal toxicity; Low effective application rate (100g of active ingredient/h
m2). Its significant insecticidal and acaricidal activities, as well as unique chemical structure, have received widespread attention and concern.