Palladium oxide nanoparticles intercalated mesoporous silica for solvent free acceptorless dehydrogenation reactions of alcohols

Abstract

Aggregation-free well-dispersed palladium oxide nanoparticles intercalated into the walls of mesoporous silica (PdOMS) were prepared by using thioether groups during the sol-gel preparation of mesoporous silica. The PdOMS material was characterized by N2 adsorption-desorption, X-ray diffraction, scanning electron micro scopy, transmission electron microscopy and UV–Vis spectroscopy. The material retains mesoporous structure with narrow pore size distribution with an average pore diameter of 6.8 nm and possesses high surface area of 683 m2 g–1 . The PdOMS catalyst was employed as an efficient heterogeneous catalyst in the acceptor- and oxi dant-free dehydrogenation of neat alcohols to corresponding carbonyl compounds in very good to excellent yields (72–95%) at 80 °C under inert atmosphere. The catalytic efficacy of PdOMS has also been evaluated for the acceptorless dehydrogenative coupling reactions of alcohols with o-diamino benzene and o-amino phenol to yield azole-based heterocycles. The stability of PdOMS was assessed by investigating its recyclability and reu sability in the dehydrogenation of neat alcohol for up to five cycles