ZnS nanoparticles as an efficient and reusable heterogeneous catalyst for synthesis of 1-substituted-1H-tetrazoles under solvent-free conditions

An efficient and green protocol for the synthesis of 1-substituted-1H-tetrazoles through cyclization reaction of various primary amines, sodium azide, and triethyl orthoformate was described. In this method, a series of tetrazole derivatives was synthesized by using ZnS nanoparticles as an effective, recoverable, and reusable catalyst under solvent-free conditions. This strategy is a magnificent improvement for the synthesis of these heterocycles due to the non-acidic, clean, and solvent-free conditions via a solid recyclable catalyst. The catalyst was separated by simple filtration and reused seven times without significant loss of activity. The ZnS nanoparticles with high surface area and fine monodisperse particles were prepared using the simple microwave-assisted method without using any surfactant. The ZnS nanoparticle catalyst is a good candidate to replace bronsted acids and metal salts or other catalyst for the preparation of 1-substituted-1H-tetrazoles in high yields and has potential values for industrial applications.