An environmentally friendly method is described for the synthesis of various isoindoline-1,3-dione derivatives from the reaction of phthalic anhydride with aromatic/aliphatic amines in ethanol at 80 C by phthalimide-N-sulfonic acid as an efficient heterogeneous acid catalyst. Some advantages include the metal-free and environmentally friendly protocol, simple operation and reusable processes, easy recovery, short reaction times, and high yields.