Heteropolyacid-Based Ionic Liquids/Schiff Base Metal Catalyzed ?-Pinene Oxidation Reaction

This paper designed and synthesized 24 kinds of heteropoly acids salts ionic liquids,11 kinds of heteropoly acid ionic liquids,9 kinds of metal-doped tungstophoric salt,6 kinds of schiff base metal catalyst (ML). These compounds were characterized by nuclear magnetic resonance (1H NMR), infrared analysis (FT-IR), and micro-beam analysis-quantitative analysis spectroscopy (EDS). Thermal gravimetric analysis (TG-DTG) was used to analyze the stability of these compounds.The catalysts were used to catalyze the reaction of a-pinene oxidation, the best catalyst was selected and the preferred reaction conditions were optimized. [MIMPS]CoPW12O40 was the optimal catalyst for the catalytic oxidation of ?-pinene with O2 to prepare verbenone. The best reaction conditions were as follows:?-pinene 12 mmol, the amount of catalyst 0.06 mmol, the amount of acetonitrile 0.02 mol, the oxygen pressure of 2 MPa, the reaction temperature 85?, and reaction time 3 h. Under the above conditons, ?-pinene conversion was 98.78%, and the selectivity of target produc verbenone was 63.26%. The catalyst was recycled 5 times, the catalytic activity was not changed.[BMIM]MnPW12O40 was the better catalyst for the catalytic oxidation of ?-pinene with H2O2 to prepare of 2,3-epoxypinane. The optimization of conditions was as follows:?-pinene 12.5 mmol, the amount of catalyst 0.125 mmol H2O2 dosage of 50 mmol, NaHCO3 5 mmol, acetonitrile 0.15 mmol, tert-butanol as solvent, reaction temperature 0?, and reaction time 4 h. The conversion of ?-pinene was 97.44% and the selectivity of 2,3-epoxypinane of 80.38%. Under the above conditions, the catalyst was reused three times, the catalytic activity was essentially unchanged.Double o-phenylenediamine salicylaldehyde Schiff base (MnL1) for the better catalyst was used to the catalytic oxidation of H2O2 a-pinene to prepare of 2,3-epoxypinane. The optimization of conditions was as follows:a-pinene 12 mmol, the catalyst 0.05 g, the amount of acetonitrile 0.18 mol, H2O2 36 mmol, reaction temperature 0 ?, and reaction time 4 h. The conversion of a-pinene was 65.74%, and the selective of 2,3-epoxypinane was 75.91%.In this paper, heteropoly acids ionic liquids and Schiff base metal catalyst were used for the catalytic oxidation of a-pinene. The better catalytic results were given, and the recycle of the catalyst was studied. It has provided a new thinking for a-pinene oxidation reaction.