Hydrochloric Acid → 3-Chloromandelic acid

A mixture of 158 g of 3-chlorobenzaldehyde, 111.6 g of trimethylsilylnitrile and a catalytic amount of zinc iodide was heated at 90° C. for 2 hours, with stirring. The reaction mixture was ice-cooled, and 350 ml of concentrated aqueous hydrochloric acid were added to it. The resulting mixture was then heated under reflux for 1 hour, after which it was mixed with water and with ethyl acetate. The ethyl acetate layer was separated and mixed with a 30% w/v aqueous solution of sodium hydroxide. The aqueous layer was separated, washed three times with ethyl acetate and then acidified with concentrated aqueous hydrochloric acid, after which it was extracted with ethyl acetate. The extract was washed with water and dried over anhydrous sodium sulfate. The solvent was then removed by distillation under reduced pressure, to give the title compound as crystals, melting at 110°-114° C.