Identify the major product formed in the following reaction sequence:

Step-by-step solution

The given reaction sequence is the Graebe-Ullmann synthesis of carbazole. The starting material, 2-aminodiphenylamine, reacts with NaNO ₂ and HCl at 0^ C . The primary amino group ( - NH ₂ ) undergoes diazotization to form a diazonium salt. The adjacent secondary amino group ( - NH - ) then attacks the diazonium group intramolecularly, leading to the formation of 1-phenyl-1H-benzotriazole. Upon heating ( ), 1-phenyl-1H-benzotriazole undergoes thermal decomposition. It loses a molecule of nitrogen gas ( N ₂ ) to for