反应详情

温度

10 °C

Into a solution of 4-trifluoromethyl benzaldehyde (400.0 g, 2.3 mol) and 2,3-butanedione monoxime (212 g, 2.055 mol) in 800 mL of glacial acetic acid at 2–5° C., hydrogenchloride gas (250 g) is slowly bubbled for 1.5 hours. The mixture is stirred at the same temperature for 1 hour further. 3.75 L of t-butyl methyl ether are added while maintaining the temperature between 5–25° C. (first 400 mL addition is exothermic). The resulting suspension is stirred for 30 minutes, then cooled to 10° C. and the solids are collected by filtration. The filter cake is washed with 500 mL of t-butylmethyl ether, and dried at 55–60° C. (20 mbar) for 18 hours to afford 550 g (91% yield) of 4,5-dimethyl-2-[4-(trifluoromethyl)phenyl]-oxazole 3-oxide, hydrochloride salt: m.p. 182–184° C. (with decomposition).

1. temperaturewhile maintaining the temperature between 5–25° C.
2. addition(first 400 mL addition is exothermic)
3. stirringThe resulting suspension is stirred for 30 minutes
4. filtrationthe solids are collected by filtration
5. washThe filter cake is washed with 500 mL of t-butylmethyl ether
6. customdried at 55–60° C. (20 mbar) for 18 hours