Green synthesis of 5-substituted-1H-1,2,3,4-tetrazoles and 1-sustituted-1H-1,2,3,4-tetrazoles via [3+2] cycloaddition by reusable immobilized AlCl₃on ã-Al₂O₃

We report the effectiveness of the surface modified γ-Al₂O₃which is reusable, efficient, catalytic, safe and environmentally acceptable procedure for the conversion of both alkyl and aryl nitriles into the corresponding 5-substituted-1H-1,2,3,4-tetrazoles via [3+2] cycloaddition with sodium azide in excellent yields at mild reaction conditions (50 ° C). The catalyst also afforded 1-substituted-1H-1,2,3,4-tetrazoles by the reaction of amines, sodium azide and triethyl orthoformate. The catalyst could be recycled and was reused eleven runs without losing its activity.