Selective aerobic oxidation of alcohols catalyzed by iron chloride hexahydrate/TEMPO in the presence of silica gel

• Published in: Applied organometallic chemistry Vol. 26; no. 1; pp. 37 - 43
• Main Authors: Wang, Lianyue, Li, Jun, Lv, Ying, Zhao, Gongda, Gao, Shuang
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.01.2012; Wiley
• Subjects: 2,2,6,6‐tetramethylpiperidine N‐oxyl (TEMPO); 6-tetramethylpiperidine N-oxyl (TEMPO); aerobic alcohol oxidation; Chemistry; Chemistry, Applied; Chemistry, Inorganic & Nuclear; iron chloride; molecular oxygen; Physical Sciences; Science & Technology; silica gel; iron chloride; 6-tetramethylpiperidine N-oxyl (TEMPO); SYSTEM; aerobic alcohol oxidation; COMPLEX; ALDEHYDES; silica gel; SALTS; OXYGEN; KETONES; 2; MILD CONDITIONS; 6; RADICALS; EFFICIENT; molecular oxygen
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.1862

An environmentally friendly and efficient process whereby FeCl3•6H2O/2,2,6,6‐tetramethylpiperidine N‐oxyl (TEMPO)‐catalyzed oxidation of alcohols to the corresponding aldehydes and ketones is accomplished in the presence of silica gel using molecular oxygen or air as the terminal oxidant. The electron‐deficient benzyl alcohol was smoothly oxidized to the corresponding aldehydes with up to 99% isolated yield. It was found that silica gel not only could enhance the catalytic reaction rate but also increase the selectivity for the product. The high performance of FeCl3•6H2O/TEMPO catalyst system in the presence of silica gel might be attributed to the surface silanol groups. UV–visible spectra analysis showed that the Fe (III)–TEMPO complex could serve as the active intermediate species in the present catalytic system. A plausible mechanism of the catalytic system is proposed. Copyright © 2012 John Wiley & Sons, Ltd. An efficient FeCl3·6H2O/TEMPO catalyst system for alcohol oxidation in the presence of silica gel using molecular oxygen or air as terminal oxidant has been developed. The UV/Vis spectra analysis showed that the Fe (III)‐TEMPO complex could serve as the active intermediate species. A plausible mechanism of the catalytic system is proposed.