Fast disproportionation of hexacyanomanganate(III) in acidic solution. Formation of hexacyanomanganate(IV) and kinetics of its decomposition

López-Cueto, Guillermo; Ubide, Carlos

doi:10.1139/v86-377

Cited by 14 publications

(14 citation statements)

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“…That is consistent with the following stoichiometry The manganese(1V) produced will remain in the form of cyano complex (Fig. l), while manganese(I1) will form the aquo complex (10,11). Though the remaining acidic solution of the Mn(1V) cyano complex decomposes, this reaction proceeds very slowly at low temperature (1 1) and therefore only quite slow changes are observed in the voltammogram after the disproportionation reaction has gone to completion.…”

Section: Current-potential Curvessupporting

confidence: 82%

“…is dissolved in acidic solution it rapidly disproportionates to yield ~n ( H 2 0 ) 6 ' + and (10,11) and this explains why a change in the uv-visible spectra of the fresh acidic solutions of M~( c N )~~-is observed. The manganese(1V) cyano complex formed decomposes to Mn(H20)6'+ and (CN)', but the reaction is auite slow at room temDerature (1 1) and thus ~, the M~( c N )~~-solution can be used for oxidizing purposes for a period of time (12).…”

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confidence: 99%

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A voltammetric study of the kinetics of the hexacyanomanganate(III) disproportionation in acidic medium

López-Cueto¹,

Ubide²

1991

Can. J. Chem.

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GUILLERMO LOPEZ-CUETO and CARLOS UBIDE. Can. J. Chem. 69, 21 12 (1991). The fast disproportionation of hexacyanomanganate(II1) in acidic medium yields Mn(CN)6'--and Mn(H20)6". The reaction has been studied by amperometry, with a rotating platinum-disk electrode, at a 1.0 V (vs. SCE) constant potential, in the acidity range 0.01-2.0 M and at temperatures between -5 and 15°C. A reversible one-electron process takes place with a 0.85 V (vs. SCE) half-wave potential that is not dependent on acidity. The reaction kinetics is pseudo-first order in s-' M-' , respectively. A mechanism is proposed where the three terms of kobs are assigned to pathways involving hexacyanomanganate(II1) in three different states of protonation. From the effect of temperature the activation parameters, AH# and AS#, for each pathway are also reported.

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Section: Current-potential Curvessupporting

confidence: 82%

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confidence: 99%

A voltammetric study of the kinetics of the hexacyanomanganate(III) disproportionation in acidic medium

López-Cueto¹,

Ubide²

1991

Can. J. Chem.

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“…In acidic solution, however, [Mn(CN) 6 ] 3− undergoes disproportionation and decomposition reactions producing hexacyanomanganate(IV), [Mn(CN) 6 ] 2− , as shown in reactions (5) and (6) [38]. …”

Section: Resultsmentioning

confidence: 99%

“…It was reported that the disproportionation reaction (5) was very fast and quantitative at room temperature [38] yielding [Mn(CN) 6 ] 2− ion. Although this complex is more stable in acidic medium, it was also found to slowly decompose producing Mn(II) (e.g., Mn(H 2 O) 6 2+ ) and cyanogen gas, (CN) 2 according to the reaction (6) [38].…”

Section: Resultsmentioning

confidence: 99%

Determination of lead by hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS): On-line generation of plumbane using potassium hexacyanomanganate(III)

Yılmaz

Arslan

Rose

2013

Analytica Chimica Acta

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A hydride generation (HG) procedure has been described for determination of Pb by ICP-MS using potassium hexacyanomanganate(III), K3Mn(CN)6, as an additive to facilitate the generation of plumbane (PbH4). Potassium hexacyanomanganate(III) was prepared in acidic medium as it was unstable in water. The stability of hexacyanomanganate(III) was examined in dilute solutions of HCl, HNO3 and H2SO4. The solutions prepared in 1% v/v/ H2SO4 were found to be stable for over a period of 24 h. The least suitable medium was 1% v/v HNO3. For generation of plumbane, acidic hexacyanomanganate(III) and sample solutions were mixed online along a 5-cm long tygon tubing (1.14 mm i.d.) and then reacted with 2% m/v sodium borohydride (NaBH4). A concentration of 0.5% m/v K3Mn(CN)6 facilitated the generation of PbH4 remarkably. In comparison to H2SO4, HCl provided broader working range for which optimum concentration was 1% v/v. No significant interferences were noted from transition metals and hydride forming elements, up to 0.5 μg mL−1 levels, except Cu which depressed the signals severely. The depressive effects in the presence of 0.1 μg mL−1 Cu were alleviated by increasing the concentration of K3Mn(CN)6 to 2% m/v. Under these conditions, the sensitivity was enhanced by a factor of at least 42 to 48. The detection limit (3s) was 0.008 μg L−1 for 208Pb isotope. Average signal-to-noise ratio (S/N) ranged between 18 and 20 for 1.0 μg mL−1 Pb solution. The accuracy of the method was verified by analysis of several certified reference materials, including Nearshore seawater (CASS-4), Bone ash (SRM 1400), and Mussel tissue (SRM 2976). The procedure was also successfully applied to the determination of Pb in coastal seawater samples by ICP-MS.

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“…radicals and complex species of Fez+ would be generated. Although this kind of rupture is unusual, a few references were found in the literature involving complexes of cobalt, chromium, and others (28)(29)(30)(31)(32)(33)(34); it was also found in the decomposition of hexacyanomanganate(II1) and hexacyanomanganato(1V) ions in aqueous acid media (35,36). However, the best proof was recently supplied (37): potassium ferricyanide is slowly reduced under dry air atmosphere, forming cyanogen and ferricyanide in small amounts, according to reactions [8] Rhodes' test (38) for the detection of cyanogen was negative,' which means that CN.…”

Section: 13mentioning

confidence: 93%

Acid–base behaviour of the ferricyanide ion in perchloric acid media. Spectrophotometric and kinetic study

Domingo¹,

Garcı́a²,

Leal³

1990

Can. J. Chem.

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A wide study was carried out of the acid-base behaviour of ferricyanide ions in aqueous perchloric acid media in the range 0.1-1 1.5 M. 'This study shows that protonation and decomposition of the ferricyanide ions occur simultaneously. The three successive protonation equilibria were found in the acidity ranges 0.1-4.0, 3.5-8.5, and 7.0-11.5 M HC104, respectively. A kinetic study was also made of the decomposition reaction at 60°C. The kinetic data are explained by considering a reaction mechanism involving homolytic and heterolytic dissociation steps. The homolytic and heterolytic rate constants corresponding to each of the four protonated species were determined, along with the acid-base protonation constants, pK1 = -6.25 + 0.10; pK2 = -3.23 * 0.03; and pK3 = -0.60 2 0.02. Mots clis : comportement acide-base, espkces protonks, dtcomposition, dissociation homolytique, dissociation hCtCrolytique.[Traduit par la revue] Introduction In a previous paper, the acid-base behaviour of the ferrocyanide ion in perchloric acid media was studied by potentiometry and spectrophotometry ( 1). In this paper, the corresponding acid-base investigation of the ferricyanide ion is undertaken; this study, however, involves also kinetic measurements, since femcyanide ions decompose at high acid concentrations.The potentiometric titration of a sample of 0.01 N K3Fe(CN)6 with aqueous HCl shows no evidence of protonation; the curve coincides with that obtained in the titration of a blank solution containing pure water, this fact indicating that the three ionization constants of ferricyanic acid, H3Fe(CN)6, are higher than 0.1 (2,3). On the other hand, the titration curves of a sample of 0.01 M H3Fe(CN)6 with NaOH, obtained by potentiometric and conductimetric techniques, are identical to those achieved titrating 0.03 M HC1. Thus the three constants must be quite high (4). None of the three pK values was found in the literature; however, to be able to explain the effect of acidity on the rate constant, several contributions on the oxidation of organic substrates by femcyanide in acid media (5-1 1) suggest that the first protonation occurs in the range 0.1-3.8 M HC104.

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Fast disproportionation of hexacyanomanganate(III) in acidic solution. Formation of hexacyanomanganate(IV) and kinetics of its decomposition

Cited by 14 publications

References 4 publications

A voltammetric study of the kinetics of the hexacyanomanganate(III) disproportionation in acidic medium

A voltammetric study of the kinetics of the hexacyanomanganate(III) disproportionation in acidic medium

Determination of lead by hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS): On-line generation of plumbane using potassium hexacyanomanganate(III)

Acid–base behaviour of the ferricyanide ion in perchloric acid media. Spectrophotometric and kinetic study

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