Selective functionalization of polymers derived from branched alkane monomers is extremely challenging due to the low reactivity of CH bonds and uncontrolled depolymerization. In this work, the chemoselective and regioselective catalytic oxygenation mechanism of hydrocarbons with ruthenium porphyrin complexes and aromatic N-oxides was investigated by density functional theory (DFT) calculations. The results revealed that the oxoruthenium porphyrin species with remarkable reactivity as oxygen transfer agents is responsible for the hydrogen abstraction from CH bonds followed by fast hydroxyl radical rebound. Details regarding the calculations of various oxidation processes show that the regioselectivity is related to the intrinsic strength of different CH bonds in branched alkanes and the charge transfer of the hydrogen atom transfer (HAT) step. Comparing the oxidations of branched alkanes to alcohols and ketones, the chemoselectivity is attributed to the relative barriers of HAT pathways in the two-step oxidation stage. Finally, the substituent effects of fluorine in the porphyrin ligand are elucidated and a stronger electron-withdrawing group is predicted to promote the HAT process and regulate hydroxyl radical rebound, ultimately enabling more efficient oxidation. These findings provide relevant information for understanding the selective oxidation of polyolefins through transition metal catalysis and enzymatic catalysis.

中文翻译：

---

钌卟啉催化C[sbnd]H键氧化的化学和区域选择性的机制和起源

由于CH键的低反应性和不受控制的解聚，衍生自支化烷烃单体的聚合物的选择性官能化极具挑战性。在这项工作中，通过密度泛函理论（DFT）计算研究了钌卟啉配合物和芳香族氮氧化物对碳氢化合物的化学选择性和区域选择性催化氧化机理。结果表明，作为氧转移剂具有显着反应活性的氧钌卟啉物种负责从CH键上夺氢，随后羟基自由基快速反弹。有关各种氧化过程计算的详细信息表明，区域选择性与支链烷烃中不同CH键的固有强度以及氢原子转移（HAT）步骤的电荷转移有关。比较支链烷烃与醇和酮的氧化，化学选择性归因于两步氧化阶段 HAT 途径的相对障碍。最后，阐明了卟啉配体中氟的取代效应，并预测更强的吸电子基团可以促进 HAT 过程并调节羟基自由基反弹，最终实现更有效的氧化。这些发现为理解通过过渡金属催化和酶催化的聚烯烃选择性氧化提供了相关信息。