Targeted development of sustainable green catalysts for regioselective acylation of aromatic ethers with carboxylic acids via chlorosulfonic acid coated on poly(guanidine–triazine–sulfonamide) grafted quartz–γ-Fe2O3

Abstract

Friedel–Crafts (FC) acylation of aromatic compounds is considered one of the essential and valuable reactions in organic synthesis. The present study offers a recyclable eco-friendly catalyst for FC acylation of anisole with benzoic acid derivatives. For this purpose, poly(guanidine–triazine–sulfonamide) (PGTSA), as a new group of sulfonamides, was immobilized on a magnetic quartz (quartz–γ-Fe₂O₃) surface. Afterward, it was functionalized using chlorosulfonic acid. The prepared quartz–γ-Fe₂O₃–PGTSA–SO₃H was used as a novel recoverable nanocatalyst for the FC acylation of aromatic compounds such as anisole. Both aromatic and aliphatic carboxylic acids reacted smoothly under specific conditions and provided the desired aromatic ketones with good to very good yields. The synthesized quartz–γ-Fe₂O₃–PGTSA–SO₃H shows a great catalytic activity because of the combined effect of Brønsted acidity and high functional group density. This nanocatalyst is reusable for several cycles and can be easily segregated from the reaction mixture.