Thionyl Chloride → 5-Chlorothiophene-2-carbonyl Chloride

Participants

Reaction Conditions

Reaction Steps

3.00 kg of 5-chlorothiophene-2-carboxylic acid (commercially available) are suspended in 8.48 kg of toluene and heated to 75 to 80° C. At this temperature, 2.63 kg of thionyl chloride are added dropwise over a period of 85 minutes, followed by stirring at 75 to 80° C. for 30 minutes and then at the reflux temperature until gas evolution ceases. After cooling, the reaction mixture is distilled under reduced pressure with gradually increasing internal temperature (up to a maximum of 60° C.) to remove excess thionyl chloride and toluene until an approximately 30% strength solution of the acid chloride in toluene is produced.

Provenance & Evidence