Homolimonenol synthesis over Sn supported mesoporous materials

The synthesis of homolimonenol by Prins condensation of limonene and paraformaldehyde over heterogeneous tin-based catalysts is reported for the first time. The tin supported MCM-41, SBA-15, and KIT-6 materials were prepared by incipient wetness impregnation method, using SnCl2·2H2O as a tin precursor. The synthesized catalysts were characterized by N2-physisorption, X-ray diffraction (XRD), diffuse reflectance-infrared Fourier transform spectroscopy (DRIFTS), pyridine adsorption (Py-FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and chemical analysis. Sn4+ species were identified on the surface of the catalysts, and the materials showed mainly Lewis acid sites, which are responsible for the activity in the Prins reaction. Production of homolimonenol was confirmed by GC-MS and NMR analysis. Among the evaluated catalysts, the best conversion (26%), selectivity (90%) and TOF (12.7 h−1) were obtained over Sn-SBA-15, in the presence of ethyl acetate; Sn-SBA-15 catalyst was reused five times without loss of activity. The reaction was scaled up from 2 to 200 mL glass reactor with a local orange oil (93% wt/wt limonene) as a substrate, obtaining a 30% conversion of limonene and a 93% selectivity to homolimonenol.