Premium
THE ROLE OF DIOXYGEN SPECIES IN THE BASE‐ AND COBALT‐CATALYZED OXYGENATION OF HINDERED PHENOLS
Author(s) -
Nishinaga Akira,
Itahara Toshio,
Shimizu Tadashi,
Tomita Haruo,
Nishizawa Kanji,
Matsuura Teruo
Publication year - 1978
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1978.tb06999.x
Subject(s) - chemistry , cobalt , catalysis , stoichiometry , base (topology) , transition metal dioxygen complex , ionic bonding , medicinal chemistry , electron transfer , schiff base , phenols , radical , photochemistry , polymer chemistry , inorganic chemistry , organic chemistry , ion , mathematical analysis , mathematics
— The mechanisms by which 4‐substituted 2,6‐di‐ t ‐butylphenols are oxygenated by base‐ and Co(II) Schiff base complex‐catalysis into o ‐ or p ‐peroxyquinols and their Co(III) complexes, respectively, have been investigated. For the base‐catalyzed oxygenation, a one‐step ionic mechanism involving no radical species is suggested to be the most probable one. For the formation of the peroxycobalt(III) complexes, the following stoichiometry is concluded: ArOH + Co(II) + 5/4 O 2 → peroxycobalt(III) complex + 1/2 H 2 O. A mechanism involving an electron transfer between the phenols and the Co(II)‐O 2 complex followed by further electron transfer between the formed phenoxy radicals and the Co(II) complex to give the corresponding phenolate anions is proposed.