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“Radical‐controlled” oxidative polymerization of phenols. Substituent effect of phenol monomers on the reaction rate
Author(s) -
Higashimura Hideyuki,
Fujisawa Kiyoshi,
Morooka Yoshihiko,
Namekawa Shuhei,
Kubota Masaaki,
Shiga Akinobu,
Uyama Hiroshi,
Kobayashi Shiro
Publication year - 2000
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/1099-1581(200008/12)11:8/12<733::aid-pat51>3.0.co;2-h
Subject(s) - polymerization , substituent , chemistry , polymer chemistry , cobalt mediated radical polymerization , steric effects , photochemistry , radical polymerization , monomer , phenol , organic chemistry , polymer
A “radical‐controlled” oxidative polymerization of phenols catalyzed by a tyrosinase model complex, (1,4,7‐triisopropyl‐1,4,7‐triazacyclononane)copper(II) dichloride, has been achieved. The polymerization of 4‐phenoxyphenol regioselectively proceeded to give poly(1,4‐phenylene oxide) showing heat‐reversible crystallinity with a melting point. For this polymerization, as the steric hindrance of substituent of the catalyst ligands increased, the selectivity for coupling at the p‐position became higher. In this work, the substituent effect of phenol monomers on the reaction rate in the “radical‐controlled” oxidative polymerization was examined. It was found that the steric factors of the phenol substituents, especially those at the o‐positions, influenced the reaction rates more greatly than the electronic ones. These data strongly support the reaction mechanism of “radical‐controlled” oxidative polymerization, in which the coupling of phenoxy radical species takes place from phenoxo–copper(II) complex and/or phenoxy radical–copper(I) complex. Copyright © 2000 John Wiley & Sons, Ltd.