Preparation, characterization and the use of sulfonic acid-functionalized phthalimide (SFP) as a highly efficient and green catalyst for the condensation of arylaldehydes with 2-naphthol

Phthalimide was reacted with chlorosulfonic acid to give sulfonic acid-functionalized phthalimide (SFP), which characterized by 1H NMR, 13C NMR, FT-IR, XRD (X-ray diffraction), SEM (scanning electron microscopy), EDX (energy-dispersive X-ray), mass and DTG (derivative thermal gravimetry) spectra. Afterward, its catalytic activity was examined for the condensation of arylaldehydes with 2-naphthol under solvent-free conditions to afford 14-aryl-14H-dibenzo[a,j]xanthenes. The results showed that SFP was highly efficient catalyst to promote the reaction. The advantages of this work include generality, efficiency, short reaction times, excellent yields, synthesis of the catalyst using available and inexpensive reactants, performing the reaction in milder conditions relative to most of the reported catalysts, and good agreement with the green chemistry protocol