Catalytic oxidation of α-pinene with methyltrioxorhenium immobilized onto polymeric resins

Abstract

The immobilization of methyltrioxorhenium (MTO) on vinylpyridine based resins synthesized by several procedures was investigated. Catalysts were characterized by IR and UV-VIS spectroscopy. Nitrogen and rhenium contents were determined by ICP-MS. The presence of ReO3 and ReO groups in the heterogenized catalysts was determined by FTIR analysis. New bands were observed in the UV-VIS spectra after treating the supports with MTO. The efficiency of incorporation of Rhenium was higher on PVP and CpPVP copolymers, and support oxidation decreased MTO incorporation on the support. Catalysts were tested for α-pinene oxidation with hydrogen peroxide. Low á-pinene (7%) conversions were obtained over PVP supported catalysts but, epoxide selectivity was high (92%). The highest á-pinene conversion, 50%, was obtained over MTO supported on copolymerized and oxidized supports. Epoxide rearrangement products, campholenic aldehyde and sobrerol, were the main products obtained with MeCN/DCM as solvent. In general, the oxidant efficiency was low, and it was favored in terbutanol and ethyl acetate as solvents.

Keywords

• methyltrioxorhenium
• polyvinylpyridine
• heterogenization
• α-pinene
• catalytic oxidation
• hydrogen peroxide