Outer-sphere hexacyanoferrate(III) oxidation of organic substrates

Leal, José M.; García, Begoña; Domingo, Pedro L.

doi:10.1016/s0010-8545(97)00068-4

Cited by 51 publications

(49 citation statements)

References 167 publications

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“…The first recorded UVVis spectrum of the reaction mixture corresponded to Fe(CN) 6 3− , whereas the spectrum measured after the reaction was completed corresponded to Fe(CN) 6 4− ( Figure S1). Since on that time-scale [Fe(CN) 6 ] 3− does not undergo the observable aquation reaction, 33 the observed colour fading can be attributed to the reduction of Fe(CN) 6 3− with hydroxyureas. A single exponential decay Eq.…”

Section: General Observationsmentioning

confidence: 99%

Kinetics and Mechanism of Oxidation of Hydroxyurea Derivatives with Hexacyanoferrate(III) in Aqueous Solution

Budimir¹,

Weitner²,

Kos³

et al. 2011

Croat. Chem. Acta

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Abstract. Kinetics and mechanisms of the oxidation of methoxyurea and N-methylhydroxyurea were studied in neutral and basic aqueous solutions. The obtained pH dependences of the oxidation rates indicate that for both hydroxyureas the reactive species are the deprotonated ones. The second order rate constants, the activation enthalpies and the activation entropies for the reactions of methoxyurea (O-methylhydroxyurea) and N-methylhydroxyurea anions with Fe(CN) 6 3− at 25 o C, I = 2 mol dm −3 (NaClO 4 ) were determined as (5.06 ± 0.01)  10 2 mol −1 dm 3 s −1 , (1.92 ± 0.02)  10 4 mol −1 dm 3 s −1 , 27 ± 1 kJ mol, and 107 ± 4 J mol −1 K −1 , respectively. The pK a value of methoxyurea at 25 o C and 2 mol dm −3 ionic strength was determined kinetically as 12.7 ± 0.1 and the thermodynamic parameters for the deprotonation reaction were determined as Δ a H = 43 ± 1 kJ mol, and. When the kinetic results are compared with the data reported for hydroxyurea, an inverse dependence of the rate constants on the pK a of the hydroxyurea derivatives at 25 o C is observed. Such unexpected behaviour has been explained by the ab initio calculations and NBO analysis of HOMOs for all three hydroxyureates. (doi: 10.5562/cca1799)

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Section: General Observationsmentioning

confidence: 99%

Kinetics and Mechanism of Oxidation of Hydroxyurea Derivatives with Hexacyanoferrate(III) in Aqueous Solution

Budimir¹,

Weitner²,

Kos³

et al. 2011

Croat. Chem. Acta

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“…These values are low enough to enable hydrogen peroxide to reduce efficiently an oxidant even as mild as the [Fe(CN) 6 ] 3-anion, E o = 0.355 V [5]. Hexacyanoferrate(III) is an attractive model for a one electron oxidant due to (i) its constant standard potential above pH 4, (ii) exceptional inertness of both the d 5 and d 6 low spin redox forms and (iii) a large difference in electronic absorption spectra between [Fe(CN) 6 ] 3-and [Fe(CN) 6 ] 4- [6].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen peroxide as a reductant of hexacyanoferrate(III) in alkaline solutions: kinetic studies

Katafias

Impert

Kita

2008

Transition Met Chem

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The kinetics of hexacyanoferrate(III) reduction by hydrogen peroxide in strongly alkaline media leading to hexacyanoferrate(II) ion have been studied spectrophotometrically within the wavelength range 300-500 nm. The reaction obeys a simple pseudo-first-order rate expression under the applied conditions, namely, a large excess of the reductant and OH -anion concentrations, and a low oxidant concentration. The linear dependences of the pseudo-firstorder rate constant on OH -and H 2 O 2 concentrations are consistent with the rate law of the form: À d½Fe III dt ¼ ðk II HO 2 À þ k III O 2 2À ½OH À Þ½HO 2 À ½Fe III where k II HO 2 À and k III O 22À are the second-and the pseudo-third-order rate constants for the electron transfer from HO 2 -and O 2 2-to [Fe(CN) 6 ] 3-, respectively. The apparent activation parameters determined at 0.4 M NaOH are as follows: DH # = (18.0 ± 1.0) kJ mol -1 and DS # = (-155 ± 3.5) J K -1 mol -1 . The possible mechanism of the reaction is discussed.

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“…Transition metal ions such as Ru(III), Ru(IV), Ru(VI), Os(VIII), and Ir(III), in conjunction with co-oxidants, oxidize several organic compounds in acidic as well as in alkaline media [1][2][3][4][5][6][7][8][9]. Recently, the use of oxocomplexes of ruthenium (RuO 4 2− , RuO 4 − , and RuO 4 ) as homogeneous catalysts for the oxidation of alcohols has become increasingly important because of the necessity of finding economical and environmentally sound conditions for these reactions.…”

Section: Introductionmentioning

confidence: 99%

Kinetic study of the ruthenium(VI)‐catalyzed oxidation of benzyl alcohol by alkaline hexacyanoferrate(III)

Mucientes¹,

Santiago²,

Almena³

et al. 2002

Int J of Chemical Kinetics

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The kinetics of the Ru(VI)-catalyzed oxidation of benzyl alcohol by hexacyanoferrate(III), in an alkaline medium, has been studied using a spectrophotometric technique. The initial rates method was used for the kinetic analysis. The reaction is first order in [Ru(VI)], while the order changes from one to zero for both hexacyanoferrate(III) and benzyl alcohol upon increasing their concentrations. The rate data suggest a reaction mechanism based on a catalytic cycle in which ruthenate oxidizes the substrate through formation of an intermediate complex. This complex decomposes in a reversible step to produce ruthenium(IV), which is reoxidized by hexacyanoferrate(III) in a slow step. The theoretical rate law obtained is in complete agreement with all the experimental observations.

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Outer-sphere hexacyanoferrate(III) oxidation of organic substrates

Cited by 51 publications

References 167 publications

Kinetics and Mechanism of Oxidation of Hydroxyurea Derivatives with Hexacyanoferrate(III) in Aqueous Solution

Kinetics and Mechanism of Oxidation of Hydroxyurea Derivatives with Hexacyanoferrate(III) in Aqueous Solution

Hydrogen peroxide as a reductant of hexacyanoferrate(III) in alkaline solutions: kinetic studies

Kinetic study of the ruthenium(VI)‐catalyzed oxidation of benzyl alcohol by alkaline hexacyanoferrate(III)

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