Grafting of sulphamic acid on functionalized sawdust: A novel solid acid catalyst for the synthesis of 1,8-dioxo-octahydroxanthenes

Abstract

A solid acid catalyst bearing sulphamic acid on sawdust (SA@Sawdust) was designed as a novel heterogeneous catalyst. The structure of prepared catalyst was assessed by various spectroscopic techniques such as FT-IR, field emission scanning electron microscopy and energy dispersive X-ray, thermogravimetric analysis, solid-state CP/MAS 13C-NMR spectroscopy, and CHNS analysis. The efficiency of prepared catalyst was explored for synthesis of diverse 1,8-dioxo-octahydroxanthene derivatives. The mild reaction conditions are found to be more compatible with a wide range of functional groups. The obtained products could be conveniently separated from the reaction mixture by simple filtration, and the catalyst is recovered and reused for next cycle without significant loss in catalytic efficiency. The alluring features of this synthetic route are operational simplicity, shorter reaction time, high conversion, wide substrate scope, easy work-up procedure, and reusability of catalyst.