N-Ethylmaleimide → 3-(3,4-dichlorophenyl)-1-ethyl-1H-pyrrole-2,5-dione

Participants

Reaction Conditions

Reaction Steps

A 260 g portion of 3,4-dichloroaniline was dissolved in a mixture of 400 ml of concentrated hydrochloric acid and 1.5 liters of water, cooled to 15° C. in an ice-salt bath. A solution of 111 g of sodium nitrite in 250 ml of water was added dropwise, with stirring, over a 90 minute period. Then 40 g of cupric chloride dihydrate was added followed by 200 g of N-ethylmaleimide in one liter of warm acetone. The reaction mixture was cooled to 10° C. and sodium bicarbonate was added in portions over 2 hours to adjust the pH to 3.5. The mixture was allowed to stand for 48 hours. The precipitate formed was collected, air dried, and taken up in 2.5 liters of isopropanol, then 185 ml of 2,6-lutidine was added and the mixture was heated to boiling, then poured into water and allowed to stand. The solid was collected and dried. Recrystallization from acetone gave 187.1 g of 3-(3,4-dichlorophenyl)-1-ethyl-1H-pyrrole-2,5-dione as a yellow solid, mp 138°-141° C.

Provenance & Evidence