Hydrochloric Acid → p-Toluenesulfinic acid

Participants

Reaction Steps

Treat a solution of p-toluenesulfinic acid sodium salt, (6.0 g, 33.7 mmol) in water (20 mL) and tert-butyl methyl ether (10 mL) dropwise with concentrated HCl (3 mL) and stir for 10 minutes. Separate the solution in a separatory funnel and wash the organic layer with saturated aqueous sodium chloride. Dry the organic over Na2SO4, filter, and remove the solvent to afford 5.2 g (quantitative) of p-toluenesulfinic acid. Combine the acid with benzaldehyde (2.4 g, 22.5 mmol), formamide (3.8 g, 84.2 mmol), and trimethylsilyl chloride (4.0 g, 37.0 mmol) in 30 mL of a 1:1 solution of toluene/acetonitrile. Heat the reaction to 50° C. and stir for 5 hours. Cool the reaction and dilute with water (100 mL) and tert-butyl methyl ether (30 mL). Cool the solution in an ice bath and filter to afford 4.5 g (70%) of desired product. Dry the solid under vacuum overnight to remove any residual water.

Provenance & Evidence