Oxidation of 2,4-Di-t-butylphenol with Hydrogen Peroxide Catalyzed by Bis(ethylenediamine)copper(II) Complexes

• Published in: Bulletin of the Chemical Society of Japan Vol. 62; no. 4; pp. 1147 - 1153
• Main Authors: Kushioka, Keiko, Tanimoto, Iwao, Maruyama, Kazuhiro
• Format: Journal Article
• Language: English
• Published: Tokyo The Chemical Society of Japan 01.04.1989; Chemical Society of Japan
• Subjects: Chemistry; Exact sciences and technology; Kinetics and mechanisms; Organic chemistry; Reactivity and mechanisms; Phenols; Catalytic reaction; Oxidation; Kinetics; Copper II Complexes; Radical mechanism
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.62.1147

2,4-Di-t-butylphenol (1) was efficiently oxidized with H2O2 in methanol in the presence of bis(ethylenediamine)copper(II) (Cu(II)(en)2) complexes. Activity of the Cu(II) complexes was strongly dependent on the structure of the en ligands, as in the cases of the O2 oxidation of phenol 1. In the H2O2 oxidation of 1, ens having none of N-alkyl substituent were of the most efficient. By addition of H2O2, stable Cu(II)(en)2 complexes exhibited a new absorption at 340 nm, which was assigned to Cu(II)–en–H2O2 (1:2:1) complexes. Furthermore, the rapid-scanning spectrophotometry proved that quadruple Cu(II)–en–phenol 1–H2O2 (1:1:1:1) complexes were the key intermediate for the oxidation of 1. The initial velocity can be summarized in the equation v=k[H2O2]1[phenol 1]1[Cu(II)(en)2]1. The oxidation mechanism of phenol 1 with H2O2 is proposed.