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

Abstract

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 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 radicals, which significantly enhanced the αH 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.

Water‐Promoted Metal‐Free Aerobic Oxidative Annulation for the Multicomponent Synthesis of Acridine‐1,8‐Diones Derivatives and Their Photophysical Studies

“…Based on the above experimental results, control experiments, and previous literature works, a plausible mechanism is proposed (Scheme 3). In the remark of Frank Robinowitch solvent‐cage reaction, [13] a similar type of mechanism is expected to be initiated. The usual radical chain initiation was built up by TBHP, after self‐decomposition to hydroxyl radical.…”

Electrocatalytic Lignin Valorization into Aromatic Products via Oxidative Cleavage of C α −C β Bonds

“…We experimentally verified that the C α −C β bond cleavage goes through 2 pathways at once by forming different key intermediates. For the route 1, O 2 from air participated in the formation of 1a′OO· with 1a′ which extracted C β –H from 1a by t BuO · [ 53 – 58 ]. Next, the intermediate 1a′OO· bind with the H of t BuOH to form 1a′OOH and then decomposed into 1a′OH and [O] .…”

Recent advances in TBHP‐promoted heterocyclic ring construction via annulation/cyclization

“…It plays an important role for the introduction of peroxy groups in organic synthesis. While, TBHP can act as an oxidizing agent in the presence of I 2 , TBAI, metal promoters, thermal or photocatalysis, as a radical initiator as well as an efficient methylating agent, various mechanistic attributes were mentioned in Figure 1 [3][4][5][6][7][8][9][10][11].…”