Thermal and catalytic formation of radicals during autoxidation

The aerobic autoxidation of hydrocarbons proceeds through a complicated reaction mechanism, mediated by free radicals. Most reported autoxidation catalysts enhance the radical formation rate via homolytic activation of hydroperoxide products. Whereas our knowledge of the product formation mechanisms has significantly improved over the last couple of years, the chain-initiation is still poorly understood. In this contribution, the thermal and catalytic initiation rate for the oxidation of the renewable olefin α-pinene is quantified, thereby providing evidence for a substrate-assisted thermal initiation. The kinetics of the catalytic initiation is in good agreement with previous studies under model conditions.

Graphical abstractQuantitative insight was obtained in the formation of radicals during the autoxidation of the renewable olefin α-pinene, decoupling thermal and catalytic contributions to the chain-initation.Figure optionsDownload full-size imageDownload high-quality image (86 K)Download as PowerPoint slideHighlights► Quantification of thermal and catalytic radical formation. ► In situ determination of rate constants of elementary reaction steps under autoxidation conditions. ► Experimental evidence for substrate assisted homolytic initiation. ► Determination of the relative contribution of the catalytic initiation to the overall radical formation mechanisms.