Halloysite Nanoclay containing Ionic-liquid and Cuprous Sulfite: Efficient Catalyst for Click Reaction

A novel heterogeneous catalyst, Hal-IMI-SO3Cu, was designed and synthesized based on functionalization of Halloysite nanotubes with ionic liquid. It was prepared and fully characterized by applying TEM, BET, SEM/EDS, ICP-AES, XRD, TGA, and FTIR spectroscopy. Hal-IMI-SO3Cu exhibited excellent catalytic activity for Click reaction under mild and eco-friendly condition. The comparison of the catalytic activities the catalyst without sulfur(Hal-IMI-Cu), the catalyst without IL(Hal-SO3HCu), the catalyst in which –SH was not oxidized to –SO3H(Hal-IMI-SCu) , the catalyst without copper(Hal-IMI-SO3H), with that of the catalyst confirmed that copper played the dominant role in the catalysis. Moreover, the contribution of sulfur species and IL, to the catalysis was confirmed. It was also proved that the presence of –SO3H was more favorable than –SH. Notably, the catalyst could be recovered and reused for ten reaction runs with slight loss of the catalytic activity and copper leaching.