Reactions of 1,2,3-Triazoles and Tetrazoles

When treated with heat or light nitrogen, can be eliminated from tetrazoles and 1,2,3-triazoles. Nitrile imides can be formed by photolysis or thermolysis of 2,5-disubstituted tetrazoles. The nitrile imides can then react 

The preparation of carbazoles involving the pyrolysis of 1-phenyl-1,2,3-benzotriazole prepared from ort/io-amino-diphenylamine and nitrous acid is known as the Graebe-Ullmann reaction. It is known that this reaction involves the cyclization of a diradical or iminocarbene intermediate, which isomerizes to carbazole via a [l,3]-hydrogen shift. 

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