Thionyl Chloride → 2-Methoxy-4-methylbenzene-1-sulfonyl chloride

Participants

Reaction Steps

Thionyl chloride (350 ml, 2.5 ml/g) was cautiously added to 2-methoxy-4-methylbenzenesulfonic acid (from (b), 140 g, 0.587 moles) over a period of 30 minutes. The mixture was stirred and heated to reflux for 1 hour and at room temperature for 16 hours. The excess thionyl chloride was removed by evaporation under reduced pressure and the residue was partitioned between deionised water (300 ml) and dichloromethane (400 ml). The phases were separated and the organic phase dried (MgSO4), filtered and concentrated to give the crude product (70 g, 54% yield). The crude product was partially dissolved in hexane (490 ml) at reflux, hot filtered to remove insoluble material and allowed to cool. The precipitated product was collected to give the title compound (41.3 g, 59% recovery) as a white crystalline solid (m.p.=81-84° C.).

Provenance & Evidence