Selective regulation of oxygen transfer over Mn porphyrin-based organic polymers enables the mild aerobic epoxidation of isobutylene

Background Oxygen activation is a critical step in oxidation reactions for energy conversion and fine chemical synthesis, with its efficiency directly determining catalytic performance and industrial applicability. The main challenges are the high activation energy barriers and low target product selectivity caused by the inherent inertness of molecular oxygen. To address these issues, this study draws on the advantages of biomimetic catalysis using metal porphyrins and synthesizes a series of porphyrin-based organic polymers (Metal-Por-POPs) to achieve efficient aerobic epoxidation of olefins. Method A series of metalloporphyrin-based organic polymers were synthesized and thoroughly characterized using techniques such as SEM, XRD, and XPS. The catalytic performance was systematically evaluated under various conditions, including catalyst types, oxidant amount, reaction time, and temperature. Significant finding Using Mn-Por-POP as a catalyst, isobutylene was converted to the corresponding epoxide within 1 h at room temperature with a selectivity of up to 96.4 %. The catalyst also demonstrated excellent recyclability and broad substrate adaptability, maintaining over 96 % epoxide selectivity after five consecutive reaction cycles. Mechanistic studies via EPR and HRMS revealed that Mn-Por-POP promoted the generation of acyl radicals from isobutyraldehyde under aerobic conditions. These radicals subsequently reacted with molecular oxygen to form acylperoxy radicals, which facilitate the highly selective epoxidation of alkenes.