Synthesis and characterization of cetylpyridinium peroxyphosphotungstate and their catalytic properties for linalool oxidation.

In this study, cetylpyridinium peroxyphosphotungstate was synthesized as an environmentally benign phase transfer catalyst with high catalytic activity from cetylpyridinium chloride, phosphotungstic acid, and hydrogen peroxide. The chemical structure of the catalyst was identified by SEM, XRD, FT-IR, ICP, elemental analysis, XPS, and TGA/DTG, revealing its catalytic activity to be related to the regular and dense distribution of pores on its surface. High catalytic activity was demonstrated in the oxidation of linalool to furanoid and pyranoid linalool oxides using hydrogen peroxide in low toxicity organic solvents such as ethanol and ethyl acetate. The total yield and total selectivity of furanoid and pyranoid linalool oxides were optimized by varying parameters including the catalyst loading, hydrogen peroxide amount, reaction temperature, and reaction time. Optimized conditions providing furanoid and pyranoid linalool oxides with 80.1% total yield were 10 wt% catalyst and 1.16 mL/g 30% HO (vs. linalool) at 30 °C for 1.5 h. This procedure has the advantages of high yield, employing a green oxidant, and non-toxic reagents.