Hydrochloric Acid → 5-(methylthio)-1H-indole-2,3-dione

Participants

Reaction Conditions

Reaction Steps

A mixture of 4-(methylthio)aniline (13.92 g, 100 mmol) and diethyl ethanedioate (17.42 g, 100 mmol) in acetic acid (50 mL) was stirred at 90° C. for 8 h. The mixture was cooled to room temperature and allowed to stand overnight, at which time the product had crystallized. The crystals were collected by filtration and washed with minimal acetic acid. The crystals were dissolved in 5% sodium hydroxide (150 mL), and the solution was heated to 90° C. Air was bubbled through the solution continuously, forming a yellow solution. After 8 hours, the solution was cooled and acidified with concentrated HCl. The precipitate was collected by filtration and was washed with water and dried to afford 5-(methylthio)-1H-indole-2,3-dione (1.9 g, 10% yield). MS (m/z) 194.0 (M+H+).

Provenance & Evidence