Sodium azide, 0.79 g (12.1 mmol), and 1.65 g (12.1 mmol) of ZnCl2 were added to 30 mL of MeCN. The mixture was heated with stirring until boiling (80 °C), and then 1 g (10.1 mmol) of allyl isothiocyanate was added. The reaction mixture was stirred for 1 h at 80 °C, and the solvent was then removed in a vacuum. The residue was treated with 5% aqueous NaOH (50 mL) with stirring for 20 min. The suspension was filtered, and the filtrate was treated with chloroform (2×10 mL) to remove impurities. The aqueous layer was acidified with conc. HCl to pH 1. The formed precipitate was filtered off, washed with water, and dried in air to afford 1-Phenyltetrazole-5-thiol. Yield 1.31 g(99%), colorless crystals.
