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11.
Ranendu Sekhar Das Bula Singh Arabinda Mandal Rupendranath Banerjee Subrata Mukhopadhyay 《国际化学动力学杂志》2014,46(12):746-758
In alkaline media, well‐characterized gelatin‐stabilized palladium (GPd) nanoparticles catalyze the reduction of the azo group containing pollutant dye, Acid Orange 7 (AO7) by sodium borohydride (NaBH4) to 1‐amino‐2‐napthol and sulfanilic acid. Kinetic observations and detailed FTIR studies suggests that the reaction follows Langmuir–Hinshelwood kinetic model, where during the reaction both AO7 and borohydride are adsorbed on the GPd surface. Plots of lnko versus ln[AO7] or ln[NaBH4] show that the order of reaction with respect to AO7 and NaBH4 remains almost same over different molar ratios of [NaBH4]/[AO7]. The catalyzed reaction shows an initial induction period (t0) due to a surface‐restructuring process of GPd nanoparticles, and (1/t0) can be defined as the rate of surface restructuring. The activation energy of the catalyzed reaction and energy of the surface‐restructuring process of GPd are estimated as 22 ± 3 and 25 ± 7 kJ M?1, respectively. 相似文献
12.
Ritu Mishra Rupendranath Banerjee Subrata Mukhopadhyay 《Journal of Physical Organic Chemistry》2012,25(12):1193-1197
Copper(II) dramatically catalyzes the oxidation of thiols by a superoxide bridging two CoIII ions. The catalyzed path overwhelmingly dominates over the uncatalysed path and is first order in the superoxo complex concentration. The first‐order rate constants show a first‐order dependence in [Cu2+], a second‐order dependence in [thiol] and linearly varies with [H+]?3. On the basis of observed kinetics reported here, it is proposed that Cu(II) reacts with two thiol molecules to form a CuII(thiol)2 complex, an electron is transferred from one ligated thiol to the CuII center to form CuI(thiol) and a thiyl radical. The copper(I)‐thiol complex is oxidized by the conjugate base of the title complex to regenerate CuII(thiol). A CuII/I catalytic cycle is thus believed to be responsible for the observed catalysis. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
13.
The complex ion [FeIII2(μ‐O)(phen)4(H2O)2]4+ ( 1 ) (phen = 1,10‐phenanthroline) and its hydrolytic derivatives [FeIII2(μ‐O)(phen)4(H2O)(OH)]3+ ( 1a ) and [FeIII2(μ‐O)(phen)4‐ (OH)2]2+ ( 2a ) coexist in rapid equilibria in the range pH 4.23–5.35 in the presence of excess phenanthroline (pKa1 = 3.71±0.03, pKa2 = 5.28± 0.07). The solution reacts quantitatively with I− to produce [Fe(phen)3]2+ and I2. Only 1 but none of its hydrolytic derivatives is kinetically active. Both inner and outer sphere pathways operate. The observed rate constants show second‐order dependence on the concentration of iodide, while the dependence on [H+] is complex in nature. Added Cl− inhibits the formation of adduct with I− and thus retards the rate of inner sphere path, leading to a rate saturation at high [Cl−], where only the outer sphere mechanism is active. Kinetic data indicate that simultaneous presence of two I− in the vicinity of diiron core is necessary for the reduction of 1 . © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 737–743, 2005 相似文献
14.
Kinetics and mechanism of reaction between zirconium‐lactate and pentane‐2,4‐dione in excess lactate
The kinetics of the reaction of pentane‐2,4‐dione (HA) with ZrIV has been studied at 25.0°C in an excess lactate (L?) media. The equilibrium reaction was found to be: Zr2L6+HA?HL+Zr2AL5. The equilibrium was approached from either direction and a plausible mechanism has been proposed with kinetic constants, but individual reactivities of the keto and the enol tautomers of pentane‐2,4‐dione could not be apportioned. However, it was found that both the uncatalyzed and acid‐catalyzed paths contribute to the reverse reaction. But 2‐thenoyltrifluoroacetone (HT) forms a stronger chelate with ZrIV, so its reaction with less reactive Zr2L5(OH2) could not be detected; reactivity of the more reactive Zr2L5(OH2)(OH) could be found. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 725–729, 2011 相似文献
15.
Oxidation of l‐Methionine by Bisperoxo(1,10‐phenanthroline)oxovanadate(V): A Mechanistic Study
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In phosphate buffer media (pH 5.8–8.0), bisperoxo(1,10‐phenanthroline)oxovanadate(V) ( 1 ) oxidizes l ‐methionine to methionine sulfoxide. The stoichiometry of the reaction is 1:1. The reaction occurs in two subsequent first‐order steps. In the first step, one of the peroxo ligands of 1 gets substituted by l ‐methionine. The observed first‐order rate constants for both steps increase linearly with increasing [H+] as well as with increasing [l ‐methionine]. The EPR spectra prove that the reaction involves a cysteinyl radical‐type intermediate and that VV gets reduced to a VIV species. 相似文献
16.
17.
Amit Mondal Piyali De Subrata Mukhopadhyay Rupendranath Banerjee Prasenjit Kar Amilan D. Jose Amitava Das 《Polyhedron》2009,28(13):2655-2660
18.
Choudhury Utpal Roy Banerjee Saumen Banerjee Rupendranath 《Transition Metal Chemistry》2002,27(1):42-46
In aqueous acid, hydrazine reduces [MnIV
3(-O)4(bipy)4(H2O)2]4+, (1), quantitatively to [MnIII,IV
2(-O)2(bipy)4]3+, (2), and Mn2+ if [N2H+
5] 2 × (stoichiometric amount). At higher [N2H+
5], reduction proceeds up to Mn2+. The reduction of (1) to (2) is strongly catalysed by Mn2+ and the absorbance (A
t
) versus time (t) graphs have sigmoidal shapes. The graphs become steeper with increasing amounts of added Mn2+ and N2H+
5, but remain unchanged when [H+] is changed. The A
t
– t graphs, under various experimental conditions, can all be simulated with a single set of second order rate constants, estimated for the individual steps in a proposed reaction scheme, in which the catalytic action of Mn2+ involves a one-electron and a two-electron reduced form of (1), but not (1) itself. The absence of any proton-dependence of the reaction rate refutes an electroprotic mechanism and an inner-sphere mechanism appears to be most likely for the reduction of (1) by N2H+
5 相似文献
19.
Synthesis of solid [Cr(nta)(H2O)2] 1, kinetics and equilibrium of ots reaction with pentane-2,4-dione (Hpd) to form [Cr(nta)(pd)]− 2 (H3nta is nitrilotriacetic acid), aquation of 2 into 1, and some related reactions have been described. Parallel proton-independent and inverse proton-dependent paths lead from 1 to 2. The [H+]−1 path arises from metal assisted deprotonation of HE, the enol form of Hpd. Aquation of 2 into 1 involves [Cr(Hnta)(pd)(H2O]+ 2H (Hnta is tridentate nta) in addition to 2. The nta comples 1 is considerably more labile and a weaker acid than [Cr(H2O)6]3+. 相似文献
20.
The trinuclear complex ion [MnIV
3(-O)4(phen)4(H2O)2]4+
(1) is quantitatively reduced by an excess of S2O3
2– to MnII, but the binuclear complex [MnIIIMnIV(-O)2(phen)4]3+, (2) is the only manganese product when [S2O3
2–] = 1.5 [(1)]. With an excess of S2O3
2– biphasic kinetics, (1) k
1
0
(2) k
2
0 MnII is observed, while the reaction with S2O3
2– = 1.5 [(1)], follows one-step second order kinetics with the second order rate constant k = k
0
1/[S2O3
2–]. The rate constant k
0
1 is independent of c
phen ( = [phen] + [Hphen+]) but directly proportional to [H+] and [S2O2–
3]. Rapid formation of an adduct between (1) and S2O2–
3, followed by rate-determining one-electron, one-proton reduction of the adduct, appears logical. A comproportionation reaction in one of the subsequent rapid steps leads to (2) without any MnII co-product. Kinetic dependences for the second step are same to those for an authentic complex of (2), and further support the assigned reaction sequence. 相似文献