Tetrasulfophthalocyanine

We have developed an efficient and practical method for clean oxidation of starch (21-23) resulting in the oxidation of primary alcohol function in Ce position and the cleavage of vicinal diols in C2 and C3 position (Figure 30.2). We used small amounts of cheap iron tetrasulfophthalocyanine catalyst, pure water as reaction medium and H2O2 as clean oxidant to achieve a one-pot conversion of starch resulting in the introduction of aldehyde and carboxyl functions in polymer chains. The iron content... 

The heterogeneous catalytic system iron phthalocyanine (7) immobilized on silica and tert-butyl hydroperoxide, TBHP, has been proposed for allylic oxidation reactions (10). This catalytic system has shown good activity in the oxidation of 2,3,6-trimethylphenol for the production of 1,4-trimethylbenzoquinone (yield > 80%), a vitamin E precursor (11), and in the oxidation of alkynes and propargylic alcohols to a,p-acetylenic ketones (yields > 60%) (12). A 43% yield of 2-cyclohexen-l-one was obtained (10) over the p-oxo dimeric form of iron tetrasulfophthalocyanine (7a) immobilized on silica using TBHP as oxidant and CH3CN as solvent however, the catalyst deactivated under reaction conditions. 

The water-soluble iron tetrasulfophthalocyanine (FePcS) complex, which is cheap and available on an industrial scale, was also a very active and selective catalyst for the oxidation reaction. Starches of different origin (potatoes, rice, wheat, com) were oxidized by H202 following two operating modes, viz. oxidation in aqueous suspension and oxidation by incipient wetness. 

ESR measurements of aqueous solutions of the V02+ complex of 4,4 4,, 4 "-tetrasulfophthalocyanine (tspc) show that it is polymeric.890 In dilute solutions (10 5M), the dimeric form predominates and higher polymers increase with concentration.891 The formation of adducts prevents polymerization and in solutions containing DMF most of the chelate is dimeric with a V—V distance of —4.5 A. 

Ukrainczyk, L., Chibwe, M., Pinnavaia, T.J. Boyd, S. A. (1994). ESR study of cobalt(II) tetrakis(N-methyl-4-pyridiniumyl)porphyrin and cobalt(II) tetrasulfophthalocyanine intercalated in layered aluminosilicates and a layered double hydroxide. Journal of Physical Chemistry, 98, 2668-76. 

Zinc tetrasulfophthalocyanine is an attractive choice for the chromophore in multi-component systems for the photoreduction of water, but recent studies have shown that only low yields of photoproducts are obtained, and that porphyrin-based chromophores are more efficient.1181 1182... 

The strong preference towards enone formation, which was realized by Gonzalez et al. employing iron(III) tetrasulfophthalocyanine and tBuOOH (Scheme 3.28, method B) [120], could be further improved by immobilization of the phthalocyanine complex on silica (method C). Under these conditions, p.-oxo dimeric species are suggested to be the active catalysts. 

Oekermann, T., Yoshida, T., Schlettwein, D., Sugiura, T. and Minoura, H. (2001). Photo-electrochemical properties of ZnO/tetrasulfophthalocyanine hybrid thin films prepared by electrochemical self-assembly. Phys. Chem. Chem. Phys. 3(16), 3387-3392. 

In order to increase the solubility of porphyrin and phthalocyanine complexes, several structural modifications have been made, a, jS, y, 6-Tetra-(4-pyridyl)-porphin complexes of copper(II), nickel(II), and zinc(II) have been synthesized (35) and their ultraviolet spectra determined in chloroform and in acid solution. By utilizing sulfonic acid groups to increase solubility, complexes of 4,4, 4",4" -tetrasulfophthalocyanine complexes of many metals were prepared (94j 95). This chelating agent was found to have a ligand field strength comparable to cyanide (94y 95). 

The most important t5q)es of homogeneous catalysis in water are performed by acids, bases and trace metals. A wide variety of mechanisms have been outlined for acid/base catalysis and are presented in kinetics texts (e.g. Moore and Pearson, 1981 Laidler, 1965). A number of bases have been observed to catalyze the hydration of carbon dioxide (Moore and Pearson, 1981 Dennard and Williams, 1966). Examples are listed in Table 9.7 for OH and the base Co(NH3)gOH2. The most dramatic effect is the catalysis of HS-oxidation by cobalt-4,4, 4",4"-tetrasulfophthalocyanine (Co-TSP ). At concentrations of 0.1 nM Co-TSP the reaction rate was catalyzed from a mean life of roughly 50 h to about 5 min. The investigators attributed the reason for historically inconsistent experimentally determined reaction rates for the H2S-O2 system by different researchers partly to contamination by metals. Clearly, catalysis by metal concentrations that are present in less than nanomolar concentrations is likely to be effective in aquatic systems. We shall see that similar arguments apply to catalysis by surfaces and enzymes. 

Sodium sulfide has been photooxidised using Zn and A1 complexes and the metal-free derivatives of tetrasulfophthalocyanine in oxygen-saturated alkaline solutions to give the sulfate. Irradiation of self-assembled n-dodecanethiol... 

Cobalt(II) 4,4, 4",4" -tetrasulfophthalocyanine, covalently linked to the surface of titanium dioxide particles, Ti02-CoTSP, was shown [207] to be an effective photocatalyst for the oxidation of sulfur (IV) to sulfur (VI) in aqueous suspensions. Upon bandgap illumination of the semiconductor, conduction-band electrons and valence-band holes are separated the electrons are channeled to the bound CoTSP complex resulting in the reduction of dioxygen, while the holes react with adsorbed S(IV) to produce S(VI) in the form of sulfate. 

Chlorinated aromatic compounds such as 2,4,6-trichlorophenol (278) are well known recalcitrant pollutants because of their slow biodegradation by microorganisms. Hydrogen peroxide oxidation of (U- C)-278 catalyzed by FePcS (iron tetrasulfophthalocyanine) was... 

Recently, controlled procedures for the covalent anchoring of iron tetrasul-fophthalocyanine onto amino-modified silicas have been developed to fix the complex either in a monomer or dimer form.80 Remarkably, the normally inactive dimeric oxo iron tetrasulfophthalocyanine is an active and selective... 

The reactions of a-hydroxyalkyl radicals with Co P also took place via addition to the metal but, unlike the case of Fe P, the adducts were found to undergo heterolysis leading to reduction of the porphyrin to Co P. Another difference between the iron and cobalt porphyrins is in the stability of the methyl adduct CH3Co P was found to be stable even in the presence of O2. Related studies were carried out on the reactions of alkyl radicals with Co -tetrasulfophthalocyanine (tspc) and with Bi2r. Several cobalt-carbon adducts have been observed and in many cases they were found to decompose to yield the oxidized Co -complex. However, in the reaction of Co tspc with the radical derived from t-BuOH, the oxidized product was formed in neutral solutions but the reduced product, Co tspc, was formed in alkaline solutions. 

Y. Soreq, H. Cohen, W.A. Mulac, K.H. Schmidt, and D. Meyerstein, Reaction of CH2C(CH3)20H Radicals with Cobalt(Il) Tetrasulfophthalocyanine in Aqueous Solutions. A Pulse Radiolytic Study, Inorg. Chem., 22 (1983) 3040. 

Anionic metal complexes, such as tetrasulfophthalocyanine or disulfoferrocene, can be incorporated from solution during the oxidative eleetro-chemical polymerization of pyrrole [24-27]. After re-reduction of the polypyrrole film the phthalocyanine derivative remains in the film, and the observed electrochemical conductivity is explained by ion transport of small electrolyte cations [26]. 

The results reported by Geiger et al. (1985) in a study of Ce(IV) oxidation of Co(II)-, Co(III)- and Ni(II)-tetrasulfophthalocyanine complexes provide evidence that the primary step is the formation of a ligand radical, rather than participation of the metal ion in the redox reaction. The combination of stopped-flow spectrophotometric and ESR data demonstrated that the Co(III)- and Ni(II)-phthalocyanine radicals disproportionate with regeneration of the original compound and ligand degradation products. In contrast, the Co(II) complex reaction proceeds via the formation of a radical and subsequent rapid reaction to produce the parent compound. 

The kinetics and mechanism have been elucidated for the reduction of cobalt(II) 4,4, 4",4" -tetrasulfophthalocyanine by 2-mercaptoethanol. A rate constant of 228 3.8 s was obtained for the rate-limiting electron transfer in the formation of the 2-hydroxyethyl disulfide. The reduction of Cr(VI) by glutathione has been examined by visible spectroscopy (A ax = nm) and by... 

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