反应详情

Sodium nitrite (9.6 g) was warmed in concentrated sulfuric acid (40 ml) to form a homogeneous mixture. The solution was allowed to cool to room temperature and a solution of 2,6-dichloro-4-trifluoromethylaniline (described in European Patent Publication 23,100:30.0 g) in glacial acetic acid (230 ml) was added dropwise, with stirring and efficient external cooling to keep the temperature below 30° C. The reaction mixture was heated at 55°-60° C. for 45 minutes, allowed to cool to room temperature, and added dropwise to a stirred solution of ethyl 4-chloroacetoacetate 21.6 g) in glacial acetic acid (100 ml) and water (200 ml). Sodium acetate (122 g) and a further 200 ml of water were added. The resultant precipitate was filtered and the filter cake was washed thoroughly with water, sucked dry and dried in a vacuum desiccator to give ethyl 2-(2,6-dichloro-4-trifluoromethylphenylazo)-4-chloroacetoacetate as a light brow solid (52.7 g), m.p. 62°-67° C.

1. customto form a homogeneous mixture
2. temperatureefficient external cooling
3. customthe temperature below 30° C
4. temperatureThe reaction mixture was heated at 55°-60° C. for 45 minutes
5. temperatureto cool to room temperature
6. filtrationThe resultant precipitate was filtered
7. washthe filter cake was washed thoroughly with water
8. customsucked dry
9. customdried in a vacuum desiccator