Mechanistic insights into liquid-phase autoxidation of cyclohexene in acetonitrile

Concepts of Heterogeneously Catalyzed Liquid‐Phase Oxidation of Cyclohexene with tert‐Butyl Hydroperoxide, Hydrogen Peroxide and Molecular Oxygen

“…This assumption can also be supported by several studies on Cocontaining oxide nanocatalysts by Peng and coworkers, [10a,19,20,26] in which Co 3 + species were found to be the active sites for O 2 activation, [26] whereas Co 2 + cations were essential for the catalytic decomposition of 2-cyclohexene-1-hydroperoxide. [9] These Co-based catalysts enabled moderate to high cyclohexene conversions between 62 and 79 % with moderate product selectivities of 27 to 47 % to the main product 2cyclohexene-1-one (Figure 1, green columns) and leaching of the active Co species was excluded by ICP-MS measurements identifying the reaction to occur heterogeneously. [9] On the contrary, CuO nanoparticles provided a much higher cyclohexene conversion of 90 % but failed to decompose the formed hydroperoxide due to their lower redox potential.…”

“…[9] These Co-based catalysts enabled moderate to high cyclohexene conversions between 62 and 79 % with moderate product selectivities of 27 to 47 % to the main product 2cyclohexene-1-one (Figure 1, green columns) and leaching of the active Co species was excluded by ICP-MS measurements identifying the reaction to occur heterogeneously. [9] On the contrary, CuO nanoparticles provided a much higher cyclohexene conversion of 90 % but failed to decompose the formed hydroperoxide due to their lower redox potential. [18] Studies on the aerobic cyclohexene oxidation over MOFs only showed a low catalytic activity below 20 % (Figure 1, purple columns), which can also be assigned to the low availability of redox pairs.…”

“…[8] However, the epoxidation and allylic pathways are branched so that they cannot clearly be differentiated and usually, reaction products of both pathways are formed (Scheme 1). [9] In addition, cyclohexene oxidation is known to partially proceed autocatalytically involving radical chain reactions, which strongly complicates the production of a desired single product due to their low selectivity. [9,10] Hence, due to its complex reaction network and the involvement of radicals, the selective cyclohexene oxidation is a rather challenging reaction that requires the development of highly active, selective and stable catalysts.…”

“…[9] In addition, cyclohexene oxidation is known to partially proceed autocatalytically involving radical chain reactions, which strongly complicates the production of a desired single product due to their low selectivity. [9,10] Hence, due to its complex reaction network and the involvement of radicals, the selective cyclohexene oxidation is a rather challenging reaction that requires the development of highly active, selective and stable catalysts. Moreover, the reaction is strongly influenced by the choice of the oxidant.…”

“…However, the epoxidation and allylic pathways are branched so that they cannot clearly be differentiated and usually, reaction products of both pathways are formed (Scheme 1). [9] In addition, cyclohexene oxidation is known to partially proceed autocatalytically involving radical chain reactions, which strongly complicates the production of a desired single product due to their low selectivity [9,10] …”