Kinetics of oxidation of l-histidine by tetrachloroaurate(III) ion in perchloric acid solution

Soni, Vimal; Sindal, R. S.; Mehrotra, Raj N.

doi:10.1016/j.poly.2005.03.057

Cited by 30 publications

(22 citation statements)

References 46 publications

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“…The reaction mechanism described in Equations (7)(8)(9)(10)(11) is similar to that proposed earlier for the Ag(III)-triethanolamine reaction [9]. Results of this study give convincing support to the earlier literature that silver(III) periodato oxidizes ethanolamine(bidentate with N,O two coordination atoms) via a one-step two-electron transfer.…”

Section: Discussionsupporting

confidence: 88%

“…Based on the observed kinetic results and analysis, a straightforward reaction mechanism is proposed in Equations (7)- (11), in which the pre-equilibrium is incorporated. …”

Section: Protolytic Equilibriamentioning

confidence: 99%

“…Oxidation of biological molecules and some functional molecules by hypervalent metal ions have received considerable attention recently [11][12][13][14][15]. N-phenyldiethanolamine(PEA), a derivative of aniline, is used as an intermediate for dyes (red or orange colors of disperse) and other organic compounds.…”

Section: Introductionmentioning

confidence: 99%

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Mechanistic study of the oxidation of N-phenyldiethanolamine by bis(hydrogen periodato)argentate(III) complex anion

Shen

Shi

Sun

et al. 2007

Transition Met Chem

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The kinetics of oxidation of phenyldiethanolamine (PEA) by a silver(III) complex anion, [Ag(HIO 6 ) 2 ] 5) , has been studied in an aqueous alkaline medium by conventional spectrophotometry. The main oxidation product of PEA has been identified as formaldehyde. In the temperature range 20.0-40.0°C , through analyzing influences of [OH ) ] and [IO 4 ) ] tot on the reaction, it is pseudo-first-order in Ag(III) disappearance with a rate expression:where k 1 = (0.61 ± 0.02) Â 10 )2 s )1 , k 2 = (0.049 ± 0.002) M )1 s )1 at 25.0°C and ionic strength of 0.30 M. Activation parameters associated with k 1 and k 2 have also been derived. A reaction mechanism is proposed involving two preequilibria, leading to formation of an Ag(III)-periodato-PEA ternary complex. The ternary complex undergoes a two-electron transfer from the coordination PEA to the metal center via two parallel pathways: one pathway is spontaneous and the other is assisted by a hydroxide ion.

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Section: Discussionsupporting

confidence: 88%

“…Based on the observed kinetic results and analysis, a straightforward reaction mechanism is proposed in Equations (7)- (11), in which the pre-equilibrium is incorporated. …”

Section: Protolytic Equilibriamentioning

confidence: 99%

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Mechanistic study of the oxidation of N-phenyldiethanolamine by bis(hydrogen periodato)argentate(III) complex anion

Shen

Shi

Sun

et al. 2007

Transition Met Chem

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“…Such coordination has been proposed in the oxidations of hypophosphate [42], iodide [43] and mandelate [44] by the square planar Ag(OH) 4 -complex. The formation of a similar axial intermediate complex has been proposed in the oxidation of histidine [20], SO 3 2-ion [45] and oxalic acid [18] by AuCl 4 -ion. This possibility is most likely considering that AuCl 3 (OH) -ion is also square-planar like Ag(OH) 4 -ion and that Au III and Ag III are…”

Section: Mechanism and Discussionmentioning

confidence: 53%

“…Concerted efforts have been made to understand the oxidations of organic and inorganic substrates, such as oxalic acid [18], hydroxylamine [19], histidine [20], glycine [21], Pt(CN) 4 2- [22], I -[23], 4-thio-2 0 -deoxyuridine and 4-thiouridine 5 0 -monophosphate [24], dimethyl sulphide [25], thiocyanate [26], HNO 2 [27], HSO 3 - [28] and As(III) [29] by various gold(III) complexes. It is suggested that Au(III) complexes are reduced to the corresponding Au(I) complexes by soft nucleophiles [30] either by a direct two-electron transfer without observable intermediates [23] or by rapid and/or consecutive substitutions followed by reductive elimination through attack on the complex by the reducing agent [31].…”

Section: Introductionmentioning

confidence: 99%

Mechanism of the oxidation of hydrazoic acid by tetrachloroaurate(III) ion

Soni

Mehrotra

2008

Transition Met Chem

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The oxidation of hydrazoic acid in perchloric acid in the absence of added chloride under pseudo first-order conditions ([HN 3 ] » [AuCl 4 -]) is first order in [Au(III)]. Michaelis-Menten type of dependence (linear plots of k obs -1 vs [HN 3 ] -1 ) is observed with respect to [HN 3 ]. The k obs is independent of ionic strength and the plot between k obs -1 and [H + ] is linear. The inner-sphere mechanism is consistent with the formation of an axial complex (K = 25 dm 3 mol -1 ) between AuCl 3 (HO) -ion and HN 3 prior to its rate determining decomposition (k = 0.0182 s -1 ). It is inferred that the free radicals N 3• do not oxidise Au(II). The reaction becomes outer-sphere in the presence of added Cl -ions which are inferred to form a cage around the hydronium ion surrounding the AuCl 4 -ions. The penetration of N 3 -through the cage is rate controlling and within the cage, the electron transfer from N 3 -ion to AuCl 4 -is fast. The value of the rate determining constant k 2 is 0.547 dm 3 mol -1 s -1 and the equilibrium constant K Cl for the cage formation is 5 dm 3 mol -1 at 25°C. It is calculated that the minimum HN 3 concentration required before the reaction exhibits zeroorder dependence in HN 3 is 0.31 mol dm -3 when [H + ] = 0.18 mol dm -3 at 25°C.

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A Computational Mechanistic Investigation into Reduction of Gold(III) Complexes by Amino Acid Glycine: A New Variant for Amine Oxidation

Chipman

Gouranourimi

Farshadfar

et al. 2018

Chemistry A European J

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Density functional theory (DFT) was utilized to explore the reduction of gold(III) complexes by the amino acid glycine (Gly). Interestingly, when the nitrogen atom of Gly coordinates to the gold(III) center, its C -hydrogen atom becomes so acidic that it can be easily deprotonated by a mild base like water. The deprotonation converts the amino acid into a potent reductant by which gold(III) is reduced to gold(I) with a moderate activation energy. To our knowledge, this is the first contribution suggesting that primary amines are oxidized to imines via direct α-carbon deprotonation. This finding may provide new insights into the mechanistic interpretation of amine oxidations catalyzed/mediated by a center with high cathodic reduction potential. This work also provides a rationalization behind why gold(III) complexes with amine-based polydentate ligands are reluctant to undergo a redox process. Gold(III) reduction occurs most efficiently if the C proton leaves in the plane of the C , N and Au atoms. Chelation prevents this alignment, resulting in the gold(III) complex being unreactive toward reduction. It has been experimentally found that gold(III) is capable of oxidizing Gly to glyoxylic acid (GA) as the initial product. The latter, in the presence of another gold(III) complex, has been reported to undergo oxidative decarboxylation to afford CO and HCOOH. This process is found to be mediated by formation of a geminal diol intermediate produced by reaction of water with the aldehyde functional group of the coordinated GA.

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Kinetics of oxidation of l-histidine by tetrachloroaurate(III) ion in perchloric acid solution

Cited by 30 publications

References 46 publications

Mechanistic study of the oxidation of N-phenyldiethanolamine by bis(hydrogen periodato)argentate(III) complex anion

Mechanistic study of the oxidation of N-phenyldiethanolamine by bis(hydrogen periodato)argentate(III) complex anion

Mechanism of the oxidation of hydrazoic acid by tetrachloroaurate(III) ion

A Computational Mechanistic Investigation into Reduction of Gold(III) Complexes by Amino Acid Glycine: A New Variant for Amine Oxidation

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