Beta-Naphthol: Caustic Soda Fusion of the Sulphonate

Beta-naphthol is the coupling half of Para Red and many other azo colours. Gattermann (1914): melt three parts of caustic soda at 280 °C, stir in one part of sodium beta-naphthalenesulphonate, hold at 310 to 320 °C until the melt runs thin, pour it out, dissolve and free the naphthol with hydrochloric acid. Yield half the weight of the sulphonate. Molten caustic spatters: gloves, goggles and face shield. The picture: our own drawing.