Nanocrystalline titania-based sulfonic acid (TiO2-Pr-SO3H) as a new, highly efficient and recyclable solid acid catalyst for the N-Boc protection of amines at room temperature

Sulfonic acid-functionalized nanoporous titania (TiO2-Pr-SO3H) was prepared from the reaction of (3-mercaptopropyl) trimethoxysilane and TiO2, then by oxidation of thiols group with hydrogen peroxide. The morphology and acidity of synthesized catalyst was characterized by FT-IR, SEM, TEM, TGA and XRD techniques and Hammett acidity test. The catalytic performance of TiO2-Pr-SO3H was investigated in the N-tert-butoxycarbonylation of amines under solvent-free conditions at room temperature. Our novel method is mild, chemoselective and has the advantages such as heterogeneous catalysis, low cost and the recyclability of the catalyst.