Cobalt phthalocyanine with radicals

The soluble metalloporphyrin-containing polymers are formed by the copolymerization of MM A or 4-VP with macrocyclic MCM — an interaction product of acrylic acid chloride with tetra-p-aminophenylporphyrinate acetate manganese [96]. Copolymers obtained by the radical copolymerization of acryloyl derivatives of cobalt phthalocyanine with 9-vinylcarbazole [97] should also be mentioned. 

We have demonstrated a new class of effective, recoverable thermormorphic CCT catalysts capable of producing colorless methacrylate oligomers with narrow polydispersity and low molecular weight. For controlled radical polymerization of simple alkyl methacrylates, the use of multiple polyethylene tails of moderate molecular weight (700 Da) gave the best balance of color control and catalyst activity. Porphyrin-derived thermomorphic catalysts met the criteria of easy separation from product resin and low catalyst loss per batch, but were too expensive for commercial implementation. However, the polyethylene-supported cobalt phthalocyanine complex is more economically viable due to its greater ease of synthesis. 

It is clear that a core of four nitrogen atoms in the coordination center is crucial for active CCT. Replacement of two nitrogen atoms with oxygen (23— 26, 29—31) or sulfur (28) essentially shuts down the ability of LCo to abstract hydrogen from free radicals. Compound 28 is particularly interesting because of the similarity of molecular structure of this chelate to cobalt phthalocyanines, which are known to be good CCT catalysts. 

Cobalt phthalocyanines, PhtCo, can be readily reduced either with hydrazine,183 with sodium boro-hydride,184 or electrochemically.185 186 In the latter case, PhtCo can undergo five sequential reductions to the pentaanion. All of the negatively charged species have distinct visible spectra. The visible spectrum of PhtCo1 is independent of counterion or solvent. When radical polymerization of methacrylate is conducted in the presence of amides such as dimethylformamide, hexamethylphosphorus tria-... 

The diamagnetic cobalt(ii) corrin complex, iodo-cobalt(ii)-cobyrinic acid-heptamethylester (78), dissolves in benzene or toluene to give monomeric paramagnetic complexes which form 1 1 adducts with molecular oxygen in fast and reversible reactions. Reaction of [Co Pc] (Pc = phthalocyanine) with thionyl chloride or bromine yields C0PCX2 (X = Cl or Br). Physical and chemical measurements on the compounds indicate they contain a phthalocyanine radical and a cobalt(iii) ion. This is the first report of the isolation of a phthalocyanine radical in the solid state. Reduction of [Co"Pc] with sodium in THF or by electrochemical means leads to the formation of five... 

The interaction of cobalt(n) phthalocyanine with ammonia and dioxygen has been studied by ESR spectroscopy. Both 1 1 and 1 2 adducts with O2 are formed. The phthalocyanine ring is oxidized to a cation radical when the binunlear adduct is formed... 

For example, the cobalt(II) complex for phthalocyanine tetrasodium sulfonate (PcTs) catalyzes the autoxidation of thiols, such as 2-mercaptoethanol (Eq. 1) [4] and 2,6-di(t-butyl)phenol (Eq. 2) [5]. In the first example the substrate and product were water-soluble whereas the second reaction involved an aqueous suspension. In both cases the activity of the Co(PcTs) was enhanced by binding it to an insoluble polymer, e.g., polyvinylamine [4] or a styrene - divinylbenzene copolymer substituted with quaternary ammonium ions [5]. This enhancement of activity was attributed to inhibition of aggregation of the Co(PcTs) which is known to occur in water, by the polymer network. Hence, in the polymeric form more of the Co(PcTs) will exist in an active monomeric form. In Eq. (2) the polymer-bound Co(PcTs) gave the diphenoquinone (1) with 100% selectivity whereas with soluble Co(PcTs) small amounts of the benzoquinone (2) were also formed. Both reactions involve one-electron oxidations by Co(III) followed by dimerization of the intermediate radical (RS or ArO ). 

The mechanism of metal phthalocyanine catalysed oxidation by molecular oxygen -isobutyraldehyde system is not established at this stage. The iron[14], manganese[15] and cobalt tetrasulphonato-[16] phthalocyanines are known to form superoxo complexes with dioxygen and are known to catalyse autoxidation reactions[13]- The acyl radical formation thus can be initiated by interaction of metal phthalocyanine-dioxygen superoxo complex with isobutyraldehyde. The acyl radical in presence of oxygen can yield acylperoxy radical or peracid as the oxidising speceis[17]. 

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