Multicomponent Synthesis of Tetrahydrobenzo[a]xanthene and Tetrahydrobenzo[a]acridine Derivatives using Sulfonated Multi-Walled Carbon Nanotubes as Heterogeneous Nanocatalysts

Authors

• Shakir Mahmood Saied ¹
• Mohanad Yakdhan Saleh * ²
• Ahmed M. Hamdoon ³

1. Department of Medical Laboratory Techniques, Al-Noor University College, Iraq
2. Department of Chemistry, College of Education for pure Science, Mosul University, Ministry of High Education and Scientific Research, Mosul, Iraq
3. Branch of Basic Science, College of Agriculture and Forestry, University of Mosul, Iraq

Abstract

This study is the first report of the application of sulfonated multi-walled carbon nanotubes (MWCNTs-SO₃H) in the synthesis of tetrahydrobenzo[a]xanthene and tetrahydrobenzo[a]acridine derivatives. The catalyst was prepared via a chemical approach and the sulfonated groups were attached to the side-wall of MWCNTs with total density of 2.58 mmol.g^-1. In order to prove functionalization of the MWCNTs-SO₃H, the catalyst was characterized using FE-SEM, TEM, FT-IR, and Raman spectroscopy techniques. A three-component reaction including 2-naphthol, dimedone, and aromatic aldehydes were applied in the synthesis of tetrahydrobenzo[a]xanthene in the presence of 15.5 mol% of MWCNTs-SO₃H under solvent-free conditions. Also, a four-component reaction including 2-naphthol, dimedone, aromatic aldehydes, and ammonium chloride was used in the synthesis of tetrahydrobenzo[a]acridine in the presence of 12.9 mol% of MWCNTs-SO₃H under solvent-free conditions. All the derivatives of tetrahydrobenzo[a]xanthene and tetrahydrobenzo[a]acridine were obtained in good to excellent yields. The MWCNTs-SO₃H was reused in seven consequent catalytic cycles without loss of their catalytic activity.

Highlights

• An efficient and reusable sulfonated multi-walled carbon nanotubes were prepared.
• MWCNTs-SO₃H was used in the synthesis of tetrahydrobenzo[a]xanthene and tetrahydrobenzo[a]acridine.
• All of the reactions were performed under solvent-free conditions.
• The MWCNTs-SO3H was characterized using FE-SEM, TEM, FT-IR, and Raman spectroscopy.
• The catalyst could be reused for seven catalytic cycles.

Graphical Abstract

Keywords

• Multicomponent
• Carbon nanotubes
• Heterogeneous
• Xanthene. Acridine
• Catalyst