HOMOGENEOUS CATALYSIS BY TETRA-T-BUTYLPHTHALOCYANINE IRON - INTERMEDIATES IN THE OXIDATIVE DIMERIZATION OF 2,6-DI-T-BUTYLPHENOL

The oxygen-bridged dinuclear complex derived from tetra-t-butylphthalo cyaninato-iron efficiently catalyses the oxidative dimerization of o,o '-disubstituted phenols such as 2,6-di-t-butylphenol to yield 3,3',5,5 '-tetra-t-butyl-p-bisphenoquinone. UV and NMR spectroscopy, as well as an independent synthesis of the product, clearly indicate that the in termediate 3,3',5,5'-tetra-t-butylbiphenyl-4,4'-diol (3) is accumulate d at high substrate to catalyst ratios, i.e. about 1550, whereas at ra tios of about 100 the bisphenoquinone 4 is exclusively formed. (C) 199 8 Elsevier Science S.A. All rights reserved.