A practical multigram-scale method for the green synthesis of 5-substituted-1H-tetrazoles in deep eutectic solvent

A series of 5-substituted-1H-tetrazoles have been efficiently synthesized in moderate to excellent yields (68–90%) under mild reaction conditions by combining aryl aldehydes, hydroxylamine hydrochloride with sodium azide in the presence of catalytic amount of Cu(OAc)₂ in deep eutectic solvent (DES). The new synthetic method has many advantages, such as high conversion, green reaction medium, easy work-up, low cost, and environment friendly.