Ultrasound and microwave irradiated sustainable synthesis of 5- and 1-substituted tetrazoles in TAIm[I] ionic liquid

TAIm[I] ionic liquid was used as a suitable medium for microwave- and ultrasound-assisted preparation of 1-substituted-1H-1,2,3,4-tetrazoles as well as 5-substituted 1H-tetrazoles under environmentally friendly conditions. In the presence of N₃⁻ ion, TAIm[N₃] active species, were responsible for the progress of the reactions under microwave as well as ultrasonic irradiation. High to excellent yields were obtained for a variety of aldehyde and nitrile substrates toward the synthesis of 5-substituted 1H-tetazole. Also, 1-substituted 1H-1,2,3,4-tetrazoles were prepared from amine precursor under these conditions with high to excellent efficiencies. The TAIm[I] ionic liquid could be recycled from the homogenous mixture for at least six consecutive cycles without any activity loss. The present method suggests a catalyst-free, solvent-free, cost-effective and environmentally friendly protocol for the synthesis of a wide variety of tetrazole derivatives. Graphical Abstract: TAIm[I] ionic liquid was utilized for the efficient preparation of 5- and 1-substituted tetrazoles under ultrasonic and microwave via a catalyst-free and solvent-free method [Figure not available: see fulltext.]