Operando X-ray absorption and EPR evidence for a single electron redox process in copper catalysis

• Published in: Chemical science (Cambridge) Vol. 6; no. 8; pp. 4851 - 4854
• Main Authors: Lu, Qingquan, Zhang, Jian, Peng, Pan, Zhang, Guanghui, Huang, Zhiliang, Yi, Hong, Miller, Jeffrey T, Lei, Aiwen
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 01.08.2015
• Subjects: INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c5sc00807g

An unprecedented single electron redox process in copper catalysis is confirmed using X-ray absorption and EPR spectroscopies. The oxidation state of the copper species in the interaction between Cu(ii) and a sulfinic acid at room temperature, and the accurate characterization of the formed Cu(i) are clearly shown using X-ray absorption and EPR evidence. Further investigation of anion effects on Cu(ii) discloses that bromine ions can dramatically increase the rate of the redox process. Moreover, it is proven that the sulfinic acids are converted into sulfonyl radicals, which can be trapped by 2-arylacrylic acids and various valuable β-keto sulfones are synthesized with good to excellent yields under mild conditions.