617-43-6Relevant articles and documents
Degradation of chlorinated phenols in water in the presence of H 2O2 and water-soluble μ-nitrido diiron phthalocyanine
Colomban, Cédric,Kudrik, Evgeny V.,Afanasiev, Pavel,Sorokin, Alexander B.
, p. 14 - 19 (2014/08/18)
Efficient disposal of pollutants is a key problem in the environmental context. In particular, chlorinated aromatic compounds are recalcitrant to biodegradation and conventional treatment methods. Iron phthalocyanines were previously shown to be efficient catalysts for the oxidative degradation of chlorinated phenols considered as priority pollutants. We have recently discovered μ-nitrido diiron phthalocyanines as powerful oxidation catalysts. Herein, we evaluate these emerging catalysts in the oxidation of chlorinated phenols in comparison with conventional mononuclear complex. Catalytic performance of iron tetrasulfophthalocyanine (FePcS) and corresponding μ-nitrido dimer [(FePcS)2N] have been compared in the oxidation of chlorinated phenols by hydrogen peroxide in water. The oxidative degradation of 2,6-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) has been studied. The (FePcS)2N exhibited better catalytic properties than mononuclear FePcS in terms of conversion and mineralization (transformation of organic chlorine to Cl- and decrease of total organic carbon due to the formation of CO2). Kinetics of the DCP oxidation indicated that different reaction mechanisms are involved in the presence of FePcS and (FePcS)2N. The high catalytic activity of (FePcS)2N in the degradation and mineralization of chlorinated phenols make μ-nitrido diiron phthalocyanines promising catalyst to apply also in environmental remediation.
Key role of the phosphate buffer in the H2O2 oxidation of aromatic pollutants catalyzed by iron tetrasulfophthalocyanine
Sanchez, Muriel,Hadasch, Anke,Fell, Rainer T.,Meunier, Bernard
, p. 177 - 186 (2007/10/03)
The non-innocent role of the phosphate buffer has been established in the H2O2 oxidative decomposition of 2,4,6-trichlorophenol (TCP), a benchmark pollutant, catalyzed by iron(III) tetrasulfophthalocyanine (FePcS). The catalytic oxidation of several other substrates (3,5-dichloroaniline, tetrachlorocatechol, di-tert-butylcatechol and catechol itself) has been carried out, also demonstrating a crucial influence of the phosphate buffer in the decomposition of the chlorinated substrates. Three hypotheses have been studied: modification of the ionic strength, formation of a peroxyphosphate species, or catalysis by a peroxyphosphate-FePcS complex. Supports for the latter proposal have been obtained from several experimental results and attempts have been made to characterize this putative catalytic intermediate. This intermediate derivative has also been generated from the reaction of FePcS with peroxymonophosphoric acid (PMPA) and its catalytic activity has been checked on the decomposition of TCP in different reaction mixture. A short mechanistic study has allowed different reaction pathways to be proposed, dependent on the active species implicated.
Regioselectivity of metal hydride reductions of unsymmetrically substituted cyclic anhydrides. Systems where "steric hindrance along the preferred reaction path" rationalization is not applicable
Kayser, Margaret M.,Morand, Peter
, p. 2484 - 2490 (2007/10/02)
Metal hydride reductions of planar cyclic anhydrides such as methylmaleic or 3-substituted phthalic anhydrides occur preferentially at the sterically more hindered carbonyl function.This regioselectivity cannot be rationalized in terms of "the most favourable pathway for non-perpendicular attack by a nucleophile" since both carbonyl groups present are equally accessible to non-perpendicular approach.A study which takes into account the alkaline cation and inductive, mesomeric, and steric effects has been conducted for the reduction of several conjugated and aromatic anhydrides.A qualitative interpretation for the regioselectivities observed in these reductions (as well as in reductions already reported in the literature) is suggested.An early transition state for the catalyzed versus late transition state for the non-catalyzed process is proposed.
