697-91-6Relevant articles and documents
Kinetic study of the oxidative dehalogenation of 2,4,6-trichlorophenol catalyzed by chloroperoxidase
Diaz-Diaz, Goretti,Blanco-Lopez, M. Carmen,Lobo-Castanon, M. Jesus,Miranda-Ordieres, Arturo J.,Tunon-Blanco, Paulino
, p. 332 - 336 (2010)
A sigmoidal behaviour of chloroperoxidase for the oxidative dehalogenation of 2,4,6-trichlorophenol is reported for the first time. Kinetic data were adjusted to the Hill equation and the kinetic parameters were obtained: n = 1.7±0.2, vmax =(8.8±0.3) × 10 -5Mmin-1, the pseudo-Michaelis constant Ks * = (8.6±0.5) × 10-5 M, kcat = 677±84min-1 and the catalytic efficiency = (8.9 ±0.6) × 106M-1 min-1. The sigmoidal curve could be related to the cooperative binding of the substrate to the enzyme, so that the binding of the first substrate molecule may help the binding of the second one. Further, both substrate molecules could establish Π-Π interactions between them, which would confer more stability to the system.
Nonphotochemical base-catalyzed hydroxylation of 2,6-dichloroquinone by H2O2 occurs by a radical mechanism
Franzen, Stefan,Sasan, Koroush,Sturgeon, Bradley E.,Lyon, Blake J.,Battenburg, Benjamin J.,Gracz, Hanna,Dumariah, Rania,Ghiladi, Reza
, p. 1666 - 1676 (2012)
Kinetic and structural studies have shown that peroxidases are capable of the oxidation of 2,4,6-trichlorophenol (2,4,6-TCP) to 2,6-dichloro-1,4- benzoquinone (2,6-DCQ). Further reactions of 2,6-DCQ in the presence of H 2O2 and OH- yield 2,6-dichloro-3-hydroxy-1,4- benzoquinone (2,6-DCQOH). The reactions of 2,6-DCQ have been monitored spectroscopically [UV-visible and electron spin resonance (ESR)] and chromatographically. The hydroxylation product, 2,6-DCQOH, has been observed by UV-visible and characterized structurally by 1H and 13C NMR spectroscopy. The results are consistent with a nonphotochemical base-catalyzed oxidation of 2,6-DCQ at pH > 7. Because H2O 2 is present in peroxidase reaction mixtures, there is also a potential role for the hydrogen peroxide anion (HOO-). However, in agreement with previous work, we observe that the nonphotochemical epoxidation by H2O2 at pH 2O2 at low pH). Analysis of the kinetics using an Arrhenius model permits determination of the activation energy of hydroxylation (Ea = 36 kJ/mol), which is significantly lower than the activation energy of the peroxidase-catalyzed oxidation of 2,4,6-TCP (Ea = 56 kJ/mol). However, the reaction is second order in both 2,6-DCQ and OH - so that its rate becomes significant above 25 °C due to the increased rate of formation of 2,6-DCQ that feeds the second-order process. The peroxidase used in this study is the dehaloperoxidase-hemoglobin (DHP A) from Amphitrite ornata, which is used to study the effect of a catalyst on the reactions. The control experiments and precedents in studies of other peroxidases lead to the conclusion that hydroxylation will be observed following any process that leads to the formation of the 2,6-DCQ at pH > 7, regardless of the catalyst used in the 2,4,6-TCP oxidation reaction.
C. fumago chloroperoxidase is also a dehaloperoxidase: Oxidative dehalogenation of halophenols
Osborne, Robert L.,Raner, Gregory M.,Hager, Lowell P.,Dawson, John H.
, p. 1036 - 1037 (2006)
We have examined the H2O2-dependent oxidative dehalogenation of 2,4,6-trihalophenols and p-halophenols catalyzed by Caldariomyces fumago chloroperoxidase (CCPO). CCPO is significantly more robust than other peroxidases and can function under harsher reaction conditions, and so its ability to dehalogenate halophenols could lead to its use as a bioremediation catalyst for aromatic dehalogenation reactions. Optimal catalysis occurred under acidic conditions (100 mM potassium phosphate solution, pH 3.0). UV-visible absorption spectroscopy, high-performance liquid chromatography, and gas chromatography/mass spectrometry clearly identified the oxidized reaction product for CCPO-catalyzed dehalogenation of 2,4,6-trihalophenols as the corresponding 2,6-dihalo-1,4-benzoquinones. This reaction has previously been reported for two His-ligated heme-containing peroxidases (see Osborne, R. L.; Taylor, L. O.; Han, K. P.; Ely, B.; Dawson, J. H. Biochem. Biophys. Res. Commun. 2004, 324, 1194-1198), but this is the first example of a Cys-ligated heme-containing peroxidase functioning as a dehaloperoxidase. The relative catalytic efficiency (turnover number) of CCPO reported herein is comparable to that of horseradish peroxidase (Ferrari, R. P.; Laurenti, E.; Trotta, F. J. Biol. Inorg. Chem. 1965, 4, 232-237). The mechanism of dehalogenation has been probed using p-halophenols as substrates. Here the major product is a dimer with 1,4-benzoquinone as the minor product. An electron-transfer mechanism is proposed that accounts for the products formed from both the 2,4,6-trihalo- and p-halophenols. Finally, we note that this is the first case of a peroxidase known primarily for its halogenation ability being shown to also dehalogenate substrates. Copyright
Determination of separate inhibitor and substrate binding sites in the dehaloperoxidase-hemoglobin from Amphitrite ornata
Davis, Michael F.,Bobay, Benjamin G.,Franzen, Stefan
, p. 1199 - 1206 (2010)
Dehaloperoxidase-hemoglobin (DHP A) is a dual function protein found in the terrebellid polychaete Amphitrite ornata. A. ornata is an annelid, which inhabits estuary mudflats with other polychaetes that secrete a range of toxic brominated phenols. DHPA is capable of binding and oxidatively dehalogenating some of these compounds. DHP A possesses the ability to bind halophenols in a distinct, internal distal binding pocket. Since its discovery, the distal binding pocket has been reported as the sole binding location for halophenols; however, data herein suggest a distinction between inhibitor (monohalogenated phenol) and substrate (trihalogenated phenol) binding locations. Backbone 13Cα, 13Cβ, carbonyl 13C, amide 1H, and amide 15N resonance assignments have been made, and various halophenols were titrated into the protein. 1H- 15N HSQC experiments were collected at stoichiometric intervals during each titration, and binding locations specific for mono- and trihalogenated phenols have been identified. Titration of monohalogenated phenol induced primary changes around the distal binding pocket, while introduction of trihalogenated phenols created alterations of the distal histidine and the local area surrounding W120, a structural region that corresponds to a possible dimer interface region recently observed in X-ray crystal structures of DHP A. 2010 American Chemical Society.
Photophysical and photocatalytic properties of β-sulfonatoporphycenes
Baba, Tatsushi,Shimakoshi, Hisashi,Endo, Ayataka,Adachi, Chihaya,Hisaeda, Yoshio
, p. 264 - 265 (2008)
The photophysical properties and photooxidation ability of the β-sulfonatoporphycenes are reported. The photophysical parameters depend on the number of substitutions. The disulfonated porphycene 2 is expected to be a new photosensitizer due to its high catalytic activity and photostability. Copyright
Polyoxometalate-based supramolecular porous frameworks with dual-active centers towards highly efficient synthesis of functionalized: P -benzoquinones
An, Haiyan,Chang, Shenzhen,Chen, Yanhong,Huang, Yaohui,Luo, Huiyun,Zhu, Qingshan
, p. 8591 - 8603 (2021/11/17)
Selective oxidation of substituted phenols is an ideal method for preparing functionalized p-benzoquinones (p-BQs), which serve as versatile raw materials for the synthesis of a variety of biologically active compounds. Herein, two new polyoxometalate-based supramolecular porous frameworks, K3(H2O)4[Cu(tza)2(H2O)]2[Cu(Htza)2(H2O)2][BW12O40]·6H2O (1) and H3K3(H2O)3[Cu(Htza)2(H2O)]3[SiW12O44]·14H2O (2) (Htza = tetrazol-1-ylacetic acid), were synthesized and structurally characterized by elemental analysis, infrared spectroscopy, thermal analysis, UV-vis diffuse reflectance spectroscopy, and single-crystal X-ray and powder diffraction. The single-crystal X-ray diffraction analysis indicates that both compounds possess unique petal-like twelve-nucleated Cu-organic units composed of triangular and hexagonal metal-organic loops. In 1, the Cu-organic units are isolated and [BW12O40]5- polyoxoanions are sandwiched between staggered adjacent triangular channels in the structure. However in 2, the Cu-organic units extend into a two-dimensional layered structure, and the [SiW12O44]12- polyoxoanions occupy the larger hexagonal channels in the stacked structure. Both compounds as heterogeneous catalysts can catalyze the selective oxidation of substituted phenols to high value-added p-BQs under mild conditions (60 °C) with TBHP as the oxidant, particularly in the oxidation of 2,3,6-trimethylphenol to 2,3,5-trimethyl-p-benzoquinone (TMBQ, key intermediate in vitamin E production). Within 8-10 min, the yield of TMBQ is close to 100%, and oxidant utilization efficiency is up to 94.2% for 1 and 90.9% for 2. The turnover frequencies of 1 and 2 are as high as 5000 and 4000 h-1, respectively. No obvious decrease in the yield of TMBQ was observed after five cycles, which indicates the excellent sustainability of both compounds. Our study of the catalytic mechanism suggests that there is a two-site synergetic effect: (i) the copper ion acts as the catalytic site of the homolytic radical pathway; and (ii) the polyoxoanion acts as the active center of the heterolytic oxygen atom transfer pathway. This journal is
Oxidative degradation of toxic organic pollutants by water soluble nonheme iron(iv)-oxo complexes of polydentate nitrogen donor ligands
Jana, Rahul Dev,Munshi, Sandip,Paine, Tapan Kanti
, p. 5590 - 5597 (2021/05/04)
The ability of four mononuclear nonheme iron(iv)-oxo complexes supported by polydentate nitrogen donor ligands to degrade organic pollutants has been investigated. The water soluble iron(ii) complexes upon treatment with ceric ammonium nitrate (CAN) in aqueous solution are converted into the corresponding iron(iv)-oxo complexes. The hydrogen atom transfer (HAT) ability of iron(iv)-oxo species has been exploited for the oxidation of halogenated phenols and other toxic pollutants with weak X-H (X = C, O, S,etc.) bonds. The iron-oxo oxidants can oxidize chloro- and fluorophenols with moderate to high yields under stoichiometric as well as catalytic conditions. Furthermore, these oxidants perform selective oxidative degradation of several persistent organic pollutants (POPs) such as bisphenol A, nonylphenol, 2,4-D (2,4-dichlorophenoxyacetic acid) and gammaxene. This work demonstrates the utility of water soluble iron(iv)-oxo complexes as potential catalysts for the oxidative degradation of a wide range of toxic pollutants, and these oxidants could be considered as an alternative to conventional oxidation methods.
