Abstract It has been shown that amino derivatives of sulfanilamide, and also some functionally substituted primary arylamines and cycloalkylamines, undergo heterocyclization with triethyl orthoformate and sodium azide with the formation of 1-monosubstituted tetrazoles. Primary amines of the azole series, 5-aminotetrazole, 5-amino-1-methyltetrazole, 4-amino-1, 2, 4-triazole, and also less basic arylamines (4-fluoro-3-nitroaniline, 2, 6- ...