Aerobic oxidation of 2,4,6-tri-tert-butylphenol to quinones catalyzed by copper(II) complexes of an N-octylated bis-benzimidazolyl ligand

作者：Yadav Anjana; Mathur Pavan

来源：Inorganica Chimica Acta, 2015, 435: 206-214.

DOI：10.1016/j.ica.2015.06.026

• Homogeneous catalysis
• Kinetic study
• Oxidative dealkylation
• 2,4,6-Tri-tert-butylphenol
• Phenoxyl radical
• Reactive copper(II)/O-2 species

Copper(II) complexes of a N-octylated bisbenzimidazolyl ligand are synthesized and characterized. These complexes carry out the oxidative dealkylation of 2,4,6-tri-tertbutylphenol (TTBP) using molecular oxygen to 2,6-ditertbutylbenzoquinone and 4,6-di-tertbutylbenzoquinone. The oxidation proceeds via a phenoxyl radical species detected spectrophotometrically, and by EPR. A reactive copper(II)-dioxygen species is involved that carries out the oxidation reaction. A comparison of the rates of formation of the 4,6-di-tert-butylbenzoquinone versus 2,6-di-tert-butylbenzoquinone suggests that alternative pathway may exist for the formation of the para-quinone derivative. Isolation of an intermediate 4,4'-peroxybis(2,4,6-tri-tert-butylcyclohexa-2,5-dienone species and its structural characterization supports the above contention.

• 出版日期2015-8-24