Sulfuric Acid → Ethyl 3-(2,4-difluorophenyl)prop-2-enoate

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Reaction Steps

51.6 g (0.40 mol) or 2,4-difluoroaniline are dissolved in 240 ml of glacial acetic acid. 45 ml (0.80 mol) of concentrated sulfuric acid are added slowly with cooling. The white suspension is diazotized at 12°-15° C. using a solution of 28.0 g (0.406 mol) of sodium nitrite in 70 ml of water. 1.2 g (0.0044 mol) of palladium bis(1,5-diphenyl-1,4-pentadien-3-one) (lit.: M. F. Rettig et al., Inorg. Synth. 17 (1977), 134) are added to the resultant yellow solution at 45° C. 40.5 g (0.405 mol) of ethyl acrylate are then added dropwise. The reaction is slightly exothermic, and the temperature slowly rises to about 60° C. The reaction mixture is stirred overnight with falling temperature and then poured into about 600 ml of ice-water. The waxy precipitate is extracted with 500 ml of diethyl ether. The ether phase is separated off, washed several times with ice-water and then dried using sodium sulfate. The ether is removed by distillation on a vacuum rotary evaporator. 51.2 g (60% of theory) of a waxy crystalline product which, after recrystallization from petroleum ether, melts at 40°-40.5° C. are obtained.

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