14333-13-2Relevant academic research and scientific papers
Catalytic O2 evolution from water induced by adsorption of [(OH2)(Terpy)Mn(μ-O)2Mn(Terpy)(OH2)] 3+ complex onto clay compounds
Yagi, Masayuki,Narita, Komei
, p. 8084 - 8085 (2004)
Water oxidation to evolve O2 in photosynthesis is catalyzed by an enzyme whose active site contains a μ-oxo-bridged manganese core. Catalytic O2 evolution has been difficult to establish by manganese-oxo complexes in homogeneous aqueous solutions. The reaction of [(OH2)(terpy)MnIII(μ-O)2MnIV(terpy)(OH2)]3+ (terpy = 2,2′:6′,2″-terpyridine) (1) with a CeIV oxidant leads to the decomposition of 1 to the permanganate ion without O2 evolution in an aqueous solution but catalytically produces O2 from water when 1 is adsorbed on clay compounds. 18O-labeling experiments showed that the oxygen atoms in O2 originate exclusively from water. Catalysis of O2 evolution requires cooperation of 2 equiv of 1 adsorbed on clay compounds. Copyright
The oxidation of chlorine ions under the joint action of ozone and permanganate ions
Levanov,Kuskov,Antipenko,Lunin
, p. 557 - 561 (2006)
The oxidation of chlorine ions in the system O3 + MnO 4 - + H+ + Cl- with the formation of Cl2 in the gas phase was studied. The phenomenon of transfer catalysis of the reaction between O3 and Cl- by the MnO 4 - ion was observed (the products of the reduction of MnO 4 - by the chlorine ion are oxidized by ozone to recover MnO 4 - ). The rate of the formation of Cl2 in the O3 + MnO 4 - + H+ + Cl - system was higher than the sum of the corresponding rates in the oxidation of Cl- by O3 and MnO 4 - separately. A scheme explaining the trends observed experimentally for the formation of Cl2 and changes in MnO 4 - concentration was suggested. The formation of MnO 4 - in the oxidation of Mn3+ with ozone in acid media was studied. Pleiades Publishing, Inc., 2006.
The kinetics of the reaction between perruthenate(VII) and manganate(VI) in alkaline aqueous media
Luoma,Brubaker Jr.
, p. 1637 - 1641 (1966)
The rate of the reaction between perruthenate and manganate ions in aqueous alkali has been studied and it is found that the reaction is first order in each reactant and is reversible. The specific reaction rate constant at 20° is 5.7 × 102 Ms
Kinetics and Mechanism of the Permanganate Ion Oxidation of Sulfite in Alkaline Solutions. The Nature of Short-Lived Intermediates
Simandi, Laszlo I.,Jaky, Miklos,Savage, C. R.,Schelly, Z. A.
, p. 4220 - 4224 (1985)
The oxidation of sulfite by permanganate ion has been studied by the stopped-flow technique combined with rapid scan spectrophotometry.The overall reaction involves manganate(VI) as an intermediate, whose fate depends on the pH.The formation and disappearance of manganate(VI) represent two distinct phases: (1) reduction of permanganate to manganate(VI) via outersphere electron transfer; (2) slower disproportionation of manganate(VI) to permanganate and a soluble manganese(VI) product.The direct oxidation of sulfite by manganate(VI) is too slow to compete with the permanganate route.Manganate(V) has been detected for the first time by rapid scan spectrophotometry as an intermediate of manganate(VI) disproportionation.The first phase obeys overall second-order kinetics, the rate constant being pH-independent between 13 and 9.5.Disproportionation is second order in manganate, and the observed rate constant increases with decreasing pH.
Characterization and activity analysis of catalytic water oxidation induced by hybridization of [(OH2)(terpy)Mn(μ-O)2Mn(terpy) (OH2)]3+ and clay compounds
Narita, Komei,Kuwabara, Takayuki,Sone, Koji,Shimizu, Ken-Ichi,Yagi, Masayuki
, p. 23107 - 23114 (2008/10/09)
Hybridization of [(OH2)(terpy)Mn(μ-O)2Mn(terpy) (OH2)]3+ (terpy = 2,2′:6′,2″- terpyridine) (1) and mica clay yielded catalytic dioxygen (O2) evolution from water using a CeIV oxidant. The reaction was characterized by various spectroscopic measurements and a kinetic analysis of O2 evolution. X-ray diffraction (XRD) data indicates the interlayer separation of mica changes upon intercalation of 1. The UV-vis diffuse reflectance (RD) and Mn K-edge X-ray absorption near-edge structure (XANES) data suggest that the oxidation state of the di-μ-oxo Mn2 core is MnIII-MnIV, but it is not intact. In aqueous solution, the reaction of 1 with a large excess CeIV oxidant led to decomposition of 1 to form MnO4- ion without O2 evolution, most possibly by its disproportionation. However, MnO4- formation is suppressed by adsorption of 1 on clay. The maximum turnover number for O2 evolution catalyzed by 1 adsorbed on mica and kaolin was 15 and 17, respectively, under the optimum conditions. The catalysis occurs in the interlayer space of mica or on the surface of kaolin, whereas MnO 4- formation occurs in the liquid phase, involving local adsorption equilibria of adsorbed 1 at the interface between the clay surface and the liquid phase. The analysis of O2 evolution activity showed that the catalysis requires cooperation of two equivalents of 1 adsorbed on clay. The second-order rate constant based on the concentration (mol g -1) of 1 per unit weight of clay was 2.7 ± 0.1 mol -1 s-1 g for mica, which is appreciably lower than that for kaolin (23.9 ± 0.4 mol-1 s-1 g). This difference can be explained by the localized adsorption of 1 on the surface for kaolin. However, the apparent turnover frequency ((kO2) app/s-1) of 1 on mica was 2.2 times greater than on kaolin when the same fractional loading is compared. The higher cation exchange capacity (CEC) of mica statistically affords a shorter distance between the anionic sites to which 1 is attracted electrostatically, making the cooperative interaction between adsorbed molecules of 1 easier than that on kaolin. The higher CEC is important not only for attaining a higher loading but also for the higher catalytic activity of adsorbed 1.
Estimation of One-Electron Oxidation Potentials of Some Donors Based on Data of Rate Constants for Their Interactions with Chlorine Dioxide
Kozlov, Yu. N.
, p. 218 - 220 (2007/10/02)
Reduction of ClO2. by various one- and two-electron donors is studied.The electron transfer rate constants (k) for the donors were measured directly, and their one-electron redox potential (φ) were either obtained by direct thermodynamic measurements or reliably established by various estimations and calculations with convergent results.An approximate linear dependence was found: log k = -12φ + 14.3, where k is in mol-1 s-1 and φ is in V.This dependence and the results of kinetic measurements are used to obtain the following one-electron redox potentials: φ(Sn3+/Sn2+) = 0.97 V, φ(PhO./PhO-) = 0.58 - 0.65 V, φ(SO3.-/SO32-) = 0.66 V, and φ(HCOO./HCOO-) = 1.45 V.
Coordination chemistry of higher oxidation states. 39. Structural and spectroscopic studies on manganese(IV) periodato complexes. Crystal structure of Na7[Mn(HIO6)2(H2IO 6)]·18H2O
Levason, William,Spicer, Mark D.,Webster, Michael
, p. 2575 - 2579 (2008/10/08)
The reaction of MIO4 (M = Na, K, Rb, or Cs) with a manganese(II) salt in acidic aqueous solution at 40°C produces insoluble dark red-brown manganese(IV) complexes MMnIO6·nH2O. In contrast NaOCl oxidation of a manganese(II) salt in alkaline solution in the presence of NaIO4 affords soluble red crystals of Na7[Mn(H2IO6)(HIO6) 2]·18H2O. This crystallizes in the orthorhombic system, space group Pnca (a = 10.281 (7) A?, b = 15.971 (2) A?, c = 19.564 (2) A?, Z = 4, V = 3212 A?3). The structure of the anion reveals octahedrally coordinated Mn, chelated by two O2IO3(OH)4- and one trans-O2IO2(OH)23- groups, and is the first structurally characterized example of a coordinated H2IO63- group. EXAFS (Mn K- and I LIII edge) studies on the MMnIO6·nH2O gave Mn-O = 1.89 A?, I-O = 1.92 A?, and Mn?I = 2.89 A?. UV-visible spectroscopy and magnetic data are reported and confirm all the complexes contain Mn(IV). Attempts to obtain periodate complexes of Mn(III) or of oxidation states Mn(≥5) have been unsuccesful. Spectroscopic and EXAFS data are also reported for the hexakis(iodate) complex K2[Mn(IO3)6].
REGENERATION OF PERMANGANATE FROM SPENT SOLUTION OF OXIDIZING AGENT USED FOR PURIFICATION OF GAS BLOWOUTS.
Dobryshin,Kirillov,Golovkina
, p. 1277 - 1278 (2008/10/08)
The purification of gas blowouts in food production and in other branches of industry is carried out by means of potassium permanganate in a slightly alkaline solution. KMnO//4 is thus reduced to MnO//2. Manganese dioxide is an ecologically harmful compound and is discharged with wastewaters to reservoirs. To allow for multiple use of KMnO//4 and to prevent dumping the manganese compounds into water reservoirs, it is proposed that the permanganate from manganese dioxide be regenerated by treating the latter with sodium (potassium or calcium) hypochlorite. Further studies show that the regeneration of permanganate from the dioxide by oxidation by hypochlorite can proceed only in the presence of catalysts - Cu(II), Ag(I), Co(II), and Fe(III) ions - at t equals 65-95 degree C, and the color of the solution passes from bright green to red-violet. The experimental data show that the rate of conversion of manganese dioxide into permanganate is determined by the temperature and amount of catalyst introduced. At t less than 50 degree C, the process practically ceases, even at a large content of the catalyst in the solution (more than 10% of the amount of MnO//2). The most vigorous formation of the permanganate takes place in the temperature range from 75 to 90 degree C. Higher temperature negatively affects the yield of permanganate.
Heteropolyvanadomanganates(IV) with Mn:V = 1:11 and 1:4
Flynn Jr.,Pope, Michael T.
, p. 2009 - 2014 (2008/10/08)
Two new vanadomanganate(IV) heteropoly complexes have been prepared by reaction of manganese(II), peroxydisulfate, and isopolyvanadate(V) ions. One complex, isolated as K5MnV11O32·10H2O, Cs4.5H0.5MnV11O32·7H 2O, and (NH4)4.5H0.5MnV11O 32·12H2O (all red to dark red crystals) is moderately stable in solutions of pH 2-3. In the pH range 4-6 it reacts to give high yields of 13-vanadomanganate(IV), accompanied by some amorphous precipitate and at least one other complex in low yields. The second complex, isolated as K5HMn3V12O39·10H2O and (NH4)5HMn3V12O 89·15H2O (black crystals), is also obtained in the pH range 2-3 and apparently exists up to a pH near 6. It is formulated as a trimeric species on the basis of the chemical analyses and single-crystal X-ray data. The 3:12 complex is unexpectedly inert to reaction with excess vanadium(V) to give 1:11 or 1:13 complexes. No visual evidence for heteropoly blue species was observed on reduction of the complexes. The 1:13 complex was found to be slightly photosensitive, the decomposition products apparently including the green reduced species. The acid decomposition of vanadomanganates(IV) leads to formation of small quantities of permanganate; similar behavior was noted for 12-niobomanganate(IV).
