Silica-Immobilized Chromium Colloids for Cyclohexane Autoxidation

The Formation of Byproducts in the Autoxidation of Cyclohexane

In this work, a complementary experimental and theoretical approach is used to unravel the formation of byproducts in the autoxidation of cyclohexane. The widely accepted vision that cyclohexanone would be the most important precursor of undesired products was found inconsistent with several experimental observations. However, the propagation reaction of cyclohexyl hydroperoxide, which we recently put forward as the missing source of cyclohexanol and cyclohexanone, is now unambiguously identified also as the dominant path leading to byproducts. Indeed, this overlooked reaction produces large amounts of cyclohexoxy radicals, able to ring-open via a beta-C--C cleavage to omega-formyl radicals. The pathway by which these radicals are converted into the observed and quantified byproducts is derived in this work. In this liquid-phase reaction, solvent cages were found very important, steering the fate of nascent species.