Sevelamer (polyallyamine resin)-supported sulfonic acid (S-SO3H) has been prepared from the reaction of sevelamer with chlorosulfonic acid and characterized using FT-IR spectroscopy, scanning electronmicroscopy (SEM) and ther‑ mogravimetric analysis (TGA). | Sulfonic acid-functionalized polyallylamine sevelamer as an efficient reusable strong solid acid catalyst for the synthesis of xanthenes derivatives