Hydrochloric Acid → 3-[4-(Trifluoromethyl)phenyl]-1H-pyrrole-2,5-dione

Participants

Reaction Steps

A mixture of hydrochloric acid (37%, 285 mL) and water (190 mL) was added to 4-(trifluoromethyl)aniline (150 g, 116 mL) at room temperature with vigorous stirring and the formed precipitate was allowed to stir for further 30 minutes. Temperature was reduced to 0° C. and sodium nitrite (70.6 g) in 180 mL of water was added dropwise to the stirred suspension. At the end of diazotisation, a clear yellow solution was obtained. Maleimide (180 g) in acetone (1.1 l) was added dropwise at 0° C. and then the pH of the solution was adjusted to 3-3.5 by adding sodium acetate. Copper (II) chloride (18.8 g) was added to the vigorously stirred mixture. After a few minutes a gas started to develop (conspicuous foaming). The reaction mixture was allowed to stir at 0° C. for 1 h and overnight at room temperature.

Provenance & Evidence