Radical Propagation Facilitating Aerobic Oxidation of Substituted Aromatics Promoted by Tert-Butyl Hydroperoxide

摘要

The selective oxidation of aromatics to synthesize valuedadded products is of great significance for chemical industry. Molecule oxygen as oxidant is the priority for this process, however, low efficiency was usually obtained. In this work, a new strategy for aromatics oxidation using O2 and Tert-butyl hydroperoxide (TBHP) as dual oxidants without catalyst was proposed. Typical radical process was observed when Toluene was used as the substrate. As high as 47.1% conversion and 87.6% selectivity of benzol acid were obtained, while a negligible or low activity were observed under O2 or TBHP oxidative systems. Detailed investigation shows that the distribution of products was almost the same between TBHP+ N2 and TBHP+O2 processes, in which the very close active energies were obtained (46.0 and 46.3 kJ/mol). These results indicated that TBHP+N2 or TBHP+O2 involved reactions underwent the same reaction process. The mechanism study demonstrated that the decomposition of TBHP could produce abundance of t-BuO~· and ~·OH radicals, which significantly enhanced the αH abstraction from toluene and formed alkyl radicals. The alkyl radicals then react with O2 to produce peroxides, which started the radical propagation cycle. The overall rate would be enhanced subsequently. Furthermore, an extension application of other aromatic substrates was investigated and displayed a great promising future to produce aromatic products.