Potassium Hydroxide → 4-Chlorobenzo(b)thiophene-2-carboxylic Acid

Participants

Reaction Steps

A suspension of (Z)-3-(2,6-dichlorophenyl-2-mercapto-2-propenoic acid (72.4 g) and water (362 ml) was stirred at room temperature. Further, potassium hydroxide (40.8 g) was added, and the mixture was heated under reflux for 4 hours. After the mixture was allowed to cool, the mixture was stirred for 1 hour while cooling with ice. The precipitated crystals ((Z)-3-(2,6-dichlorophenyl-2-mercapto-2-propenoic acid potassium salt) were collected by filtration and washed with cold water. After the crystals were suspended in water, 35% concentrated hydrochloric acid (32 ml) was added (pH=1), and the mixture was stirred at room temperature for 1 hour. The precipitated crystals were collected by filtration and dried to obtain 2-carboxy-4-chlorobenzo[b]thiophene.

Provenance & Evidence