New Function and Preparation of Diflubenzuron

Diflubenzuron is a white to yellowish crystalline solid with a melting point of 210-230°C (decomposition) and a vapor pressure of <0.013 millipascals. It is insoluble in water but slightly soluble in most organic solvents. As a urea insecticide, it exhibits stomach poison and contact killing effects without systemic activity. Its aqueous solution is effective against various leaf-eating larvae and concealed pests. The acute oral LD50 for rats and mice is >4640 milligrams/kilogram.

Mechanism of action of diflubenzuron:

Diflubenzuron is highly effective against lepidopteran pests and is safe for use, having no adverse effects on fish, bees, or natural enemies. Its mode of action is distinct from conventional insecticides as it is neither a neurotoxin nor an acetylcholinesterase inhibitor. Its primary action is the inhibition of chitin synthesis in the insect’s exoskeleton. It also damages the endocrine and glandular systems such as the fat body and midgut, disrupting the insect’s normal molting process.

Application of diflubenzuron

Diflubenzuron has a wide range of applications and can be used on various plants such as apples, pears, peach, citrus fruit trees, corn, wheat, rice, cotton, peanuts, cruciferous vegetables, solanaceous vegetables, melons, tea trees, and forests. It is primarily used to control lepidopteran pests, including cabbage worms, armyworms, diamondback moths, oriental fruit moths, oblique-banded leaf rollers, oblique-lined leaf moths, citrus leaf miners, whiteflies, tea leaf rollers, cotton bollworms, gypsy moths, pine caterpillars, leaf rollers, and leaf miners.

Preparation method of diflubenzuron

A method for preparing the insecticide diflubenzuron is described as follows:

(1) In a reaction vessel equipped with a tail gas treatment system, stirring, a condensation tube, an air vent, and a thermometer, an appropriate amount of aromatic compound solvent is added and cooled to -15 to -30°C. Dichloroarylurea is slowly dropped in and the temperature is gradually increased to 20°C over a period of 0.5 to 2.0 hours. After completion of the dropwise addition, the mixture is stirred at 20-50°C for 0.4-1.0 hours. Triethyleneamine and aromatic compound solvent are added, and the mixture is heated slowly to 90-100°C and maintained at this temperature for 2-4.0 hours. The residual phosgene and hydrochloric acid gas are removed by purging with nitrogen, and the temperature is lowered to 30-60°C. After filtering off the insoluble material, a solution of dichloroaryl isocyanate and the aromatic compound solvent is obtained by removing some solvent under a vacuum of -0.098 MPa or higher.

(2) In a reaction vessel equipped with a condensation tube and a thermometer, the aromatic compound solvent is added and 2,6-difluoro benzamide is added with stirring. The temperature is raised to 110-140°C, and the solution obtained in step (1) is slowly dropped in over a period of 0.5-3.0 hours. After completion of the dropwise addition, the mixture is maintained at 110-140°C for 4.0-8.0 hours. The temperature is lowered to below 10°C, and the mixture is filtered. The filter cake is washed with an appropriate amount of aromatic compound solvent and dried to obtain diflubenzuron.

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