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

摘要

The selective oxidation of aromatics to synthesize valued-added 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 O-2 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 O-2 or TBHP oxidative systems. Detailed investigation shows that the distribution of products was almost the same between TBHP+N-2 and TBHP+O-2 processes, in which the very close active energies were obtained (46.0 and 46.3 kJ/mol). These results indicated that TBHP+N-2 or TBHP+O-2 involved reactions underwent the same reaction process. The mechanism study demonstrated that the decomposition of TBHP could produce abundance of t-BuO. and (OH)-O-. radicals, which significantly enhanced the alpha H abstraction from toluene and formed alkyl radicals. The alkyl radicals then react with O-2 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.