65095-13-8

Benzotriazole-1-carbonyl chloride tech is prepared by bubbling phosgene through a suspension of benzotriazole in toluene at 60 °C until  a clear solution is obtained. Evaporation at reduced pressure gives (1) (99% yield); this crude material has  mp 52-54 °C. Alternatively, an ethereal solution of benzotriazole may be added dropwise over 20 min to a  20% solution of phosgene in toluene (4 equiv); stirring until a clear solution is obtained followed by  evaporation at reduced pressure gives 98% yield of (1) with mp 52 °C.