(532cm) Facile Activation of Mixed Light Alkanes with Ozone in Pressure-Tunable Condensed Phases

The selective activation of alkanes to liquid oxygenates with high C economy has been a grand challenge for decades. It is also crucial for efficient utilization of natural gas liquids as chemical feedstock to produce value-added chemicals. We demonstrate that mixtures of light alkanes including propane, n-butane, and isobutane can be efficiently oxidized by ozone in their liquid phases at ambient temperature and mild pressures, achieving up to 90% selectivity towards oxygenated compounds, such as alcohols and ketones. The liquid phase operation also inhibits carbon dioxide formation (to < 17%) drastically compared to gas phase reaction (> 50%). For example, isobutane ozonation yields tert-butyl alcohol (TBA) with 85% – 90% selectivity at temperatures as low as 16 °C and pressures around 0.6 MPa. These reaction conditions are significantly milder than those used for the conventional dioxygen-based isobutane oxidation. The key to achieving such high selectivities towards oxygenated compounds is the presence of protic additives and pressure-tuned ozone concentration in the condensed phase. These results and plausible mechanisms will be discussed.