Synthesis of 4,4′-diaminotriphenylmethane derivatives using H3PW12O40 and HZSM5 zeolite under solvent-free conditions

An efficient and very simple method for synthesis of 4,4′-diaminotriphenylmethane and its derivatives has been achieved via reaction of various substituted aromatic aldehydes containing both electron-donating and electron-withdrawing groups with various anilines having electron-withdrawing and electron-donating groups in the presence of catalytic amounts of HZSM5 zeolite and H3PW12O40 under solvent-free conditions. The reaction proceed with shorter reaction time and higher yield compared to the results obtained in different solvents. Anilines having electron-donating groups in comparison with those having electrondonating group performed this transformation in better yields. Also the results show that the steric hindrance plays an important role in this transformation. Reusability is an advantage of the HZSM5 zeolite, while it showed lesser activity than H3PW12O40. The one-pot reaction, simple work up, high yields, use of efficient catalytic amount and eco-friendly reagents are the advantages of the proposed method. All products were characterized using 1H NMR, 13C NMR and IR.