ISOXADIFEN-ETHYL

Uses

Isoxadifen-ethyl is a particularly useful pesticide.

Definition

ChEBI: Isoxadifen-ethyl is an isoxazoline that is the ethyl ester of isoxadifen. It is used as a herbicide safener, especially in conjunction with the herbicides fenoxaprop-P-ethyl and iodosulfuron-methyl-sodium. It is not approved for use within the European Union. It has a role as a herbicide safener and an agrochemical. It is an ethyl ester and an isoxazoline. It is functionally related to an isoxadifen.

Preparation

Isoxadifen-ethyl is prepared by reacting 1, 1-diphenyl ethylene and ethyl 2-chloro-2-(hydroxyimino)acetate under the action of alkali metal compounds. The reaction process is as follows:

Flammability and Explosibility

Non flammable

Synthesis

Ethyl 2,2-diphenylcyclopropanecarboxylate (0.97 g, 3.7 mmol) was dissolved in 3.7 mL of trifluoroacetic acid (CF3CO2H). Sodium nitrite (NaNO2, 0.28 g, 4.0 mmol, 1.1 eq.) was added to the solution in batches under controlled reaction temperature not exceeding 40 °C. After addition, the reaction mixture was stirred at room temperature (about 18 °C) for 30 minutes. Subsequently, the reaction mixture was poured into ice water and extracted with ether (2 x 20 mL). The organic phases were combined and washed sequentially with saturated aqueous sodium bicarbonate (NaHCO3) (2 x 20 mL), water (20 mL) and brine (20 mL). The washed organic phase was dried with anhydrous sodium sulfate (Na2SO4). After filtration to remove the desiccant, the organic phase was concentrated under reduced pressure to give a light brown oily crude product. 1H NMR analysis of the crude product showed complete reaction with 100% yield. The crude product was further purified by silica gel column chromatography (Rf: 0.45, eluent: petroleum ether solution of 20% ethyl acetate) to afford ethyl 5,5-diphenyl-4,5-dihydroisoxazole-3-carboxylate (0.958 g, 89% yield) as a white solid.1H NMR (400 MHz, CDCl3): δ 7.41-7.26 (m, 10H), δ 4.34 (q, J = 7.1 Hz, 2H), 3.86 (s, 2H), 1.36 (t, J = 7.1 Hz, 3H). 13C NMR (400 MHz, CDCl3): δ 160.54, 151.09, 142.99, 128.54, 128.02, 125.95, 94.79, 62.15, 46.78 14.12.

References

[1] Patent: US2016/60223, 2016, A1. Location in patent: Paragraph 0022