Selective oxidation of saturated hydrocarbons, alcohols and sulfur-containing compounds by transition metal complexes

Abstract

Oxidation reactions are interesting for functionalization of organic coumpounds and remain a reaction of considerable value in organic synthesis. This study focuses on the development of a catalytic system based on chromium catalysts. For this research, chromium(III) stearate and chromium(III) picolinate catalysts were utilized for the first time with tert-butyl hydroperoxide as an oxidant for the oxidation of alcohols. This reaction was achieved at 70℃ for 24 h and the corresponding carbonyl compounds were obtained in high yield with good selectivity especially for secondary alcohols without steric hindrance. The oxidation of primary alcohols afforded the corresponding carboxylic acids via aldehydes. Otherwise, the use of other oxidants such as hydrogenperoxide or sodium hypochorite afforded the unnecessary ability for the alcohol oxidations. After the optimized condition was established, this oxidation system was applied to the oxidation of various hydrocarbons. This catalytic oxidation also expressed good results for the oxidation at a benzylic position. Chromium(III) stearate and chromium(III) picolinate expressed comparable activity toward oxidation reaction, however chromium(III) picolinate was easy to separate from the reaction medium. This developed system was also appropriate for the oxidation of sulfur containing compounds. The outcome revealed that this system was suited to be employed as chemical remediation process in environmental viewpoint. These developed chromium(III) catalyst oxidation systems were believed to undergo via a free radical process.