Beijing National Laboratory for Molecular Sciences, Key Laboratory of Colloid and Interface and Thermodynamics, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun North First Street 2, 100190, Beijing, P. R. China.
University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Angew Chem Int Ed Engl. 2019 Nov 25;58(48):17393-17398. doi: 10.1002/anie.201908788. Epub 2019 Oct 16.
Stable organic nitroxyl radicals are an important class of catalysts for oxidation reactions, but their wide applications are hindered by their steric hinderance, high cost, complex operation, and separation procedures. Herein, NO in DMSO is shown to effectively catalyze the aerobic oxidative cleavage of C(OH)-C bonds to form a carboxylic group, and NO was generated in situ by decomposition of nitrates. A diverse range of secondary alcohols were selectively converted into acids in excellent yields in this transition-metal-free system without any additives. Preliminary results also indicate its applicability to depolymerize recalcitrant macromolecular lignin. Detail studies revealed that NO from nitrates promoted the reaction, and NO served as hydrogen acceptor and radical initiator for the tandem oxidative reaction.
稳定的有机氮氧自由基是一类重要的用于氧化反应的催化剂，但因其空间位阻大、成本高、操作复杂、分离过程繁琐，其广泛应用受到了限制。本文表明，DMSO 中的 NO 可有效地催化 C(OH)-C 键的有氧氧化裂解，形成羧酸基团，而 NO 是由硝酸盐分解原位生成的。在这个无金属催化剂的体系中，无需任何添加剂，多种仲醇可被选择性地氧化成相应的酸，产率优异。初步结果还表明其适用于解聚难处理的高分子木质素。详细研究表明，来自硝酸盐的 NO 促进了反应，而 NO 则作为氢受体和自由基引发剂参与了串联氧化反应。
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