H. Higashimura et al., "Radical-controlled" oxidative polymerization of 4-phenoxyphenol catalyzedby a dicopper complex of a dinucleating ligand, J MOL CAT A, 161(1-2), 2000, pp. 233-237
The oxidative polymerization of 4-phenoxyphenol (PPL) catalyzed by a dicopp
er complex with a dinucleating ligand, 1,2-bis[2-(bis(2-pyridyl)methyl)-6-p
yridyl]ethane is described. The polymerization proceeded regioselectively t
o give crystalline unsubstituted poly(1,4-phenylene oxide) (PPO), in which
mu-eta(2):eta(2)-peroxo dicopper(II) species is probably involved as the ac
tive dioxygen intermediate. A copper complex with a mononucleating ligand o
f the similar structure, I,1,l-tris(6-methylpyrid-2-yl)ethane, also catalyz
ed the oxidative coupling of PPL. The coupling selectivity for the dicopper
/dinucleating ligand complex was close to that for the copper/mononucleatin
g ligand complex. However, the initial reaction rate for the former was ind
ependent on the catalyst amount in a certain range, whereas that for the la
tter decreased with the decrease of the catalyst amount. (C) 2000 Elsevier
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