Synthesis and Identification of SO3H-functionalized Phthalimide (SFP) as an Efficient Catalyst for the Condensation of Dimedone with Arylaldehydes

A SO3 H-containing solid acid namely SO3 H-functionalized phthalimide (SFP) was synthesized from phthalimide and chlorosulfonic acid, and identified by studying its FT-IR, 1 H and 13C NMR, Mass, XRD, TG and DTG spectra. Afterward, its catalytic activity was examined for the solvent-free condensation of dimedone (5,5-dimethyl-1,3-cyclohexanedione) (2 eq.) with arylaldehydes (1 eq.). The results showed that SFP is a highly efficient catalyst to promote the title reaction for the preparation of 9-aryl-1,8-dioxo-octahydroxanthenes.