Kinetic and mechanistic analysis of oxidation of 2-furoic hydrazide by hexachloroirradate(IV) in a wide pH range

Yao, Haiping; Tian, Hui Qiao; Xu, Liyao; Xia, Yaoyao; Zhou, Li; Liu, Chunli; Shi, Tiesheng

doi:10.1007/s11243-019-00347-x

Cited by 4 publications

(6 citation statements)

References 30 publications

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“…Moreover, for the aryl hydrazides, a linear correction of logk enolate = (0.16 ± 0.07)pK enol + (6.1 ± 0.8) is unraveled for the first time. Collectively, this work together with previous investigations [14,33] may pave a way for a rational design of new antioxidants based on aryl hydrazides. Additionally, the present work also offers the pK a values for BH and PAH at 25.0 • C and µ = 1.0 M.…”

Section: Discussionmentioning

confidence: 64%

“…Table 4 summarizes the main results acquired so far for the oxidations of hydrazides by [IrCl 6 ] 2− including a very recent one (2-furoic hydrazide (FH), cf. Figure S1 in SM) studied by the Shi group [33]. The pK a values for the deprotonation of R-CONHNH 3 + locate in a small region, only varying from 3.04 to 3.67 whereas the reactivity of the neutral forms of hydrazides changes from 157 to 1120…”

Section: Comparison Of the Rate Constantsmentioning

confidence: 99%

“…The same features were also observed for the oxidation of PAH by [IrCl6] 2− . 33,63,92,123,152,182,212,242,273,303,332,364,423, and 500 milliseconds after the start of the reaction.…”

Section: Spectral Analysis Of Reaction Coursementioning

confidence: 99%

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Oxidations of Benzhydrazide and Phenylacetic Hydrazide by Hexachloroiridate(IV): Reaction Mechanism and Structure–Reactivity Relationship

Zhang

2020

Molecules

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Benz(o)hydrazide (BH) is the basic aryl hydrazide; aryl hydrazides have been pursued in the course of drug discovery. Oxidations of BH and phenylacetic hydrazide (PAH) by hexachloroiridate(IV) ([IrCl6]2−) were investigated by use of stopped-flow spectral, rapid spectral scan, RP-HPLC and NMR spectroscopic techniques. The oxidation reactions followed well-defined second-order kinetics and the observed second-order rate constant k′ versus pH profiles were established over a wide pH range. Product analysis revealed that BH and PAH were cleanly oxidized to benzoic acid and phenylacetic acid, respectively. A reaction mechanism was proposed, resembling those suggested previously for the oxidations of isoniazid (INH) and nicotinic hydrazide (NH) by [IrCl6]2−. Rate constants of the rate-determining steps were evaluated, confirming a huge reactivity span of the protolysis species observed previously. The enolate species of BH is extremely reactive towards reduction of [IrCl6]2−. The determined middle-ranged negative values of activation entropies together with rapid scan spectra manifest that an outer-sphere electron transfer is probably taking place in the rate-determining steps. The reactivity of neutral species of hydrazides is clearly not correlated to the corresponding pKa values of the hydrazides. On the other hand, a linear correlation, logkenolate = (0.16 ± 0.07)pKenol + (6.1 ± 0.8), is found for the aryl hydrazides studied so far. The big intercept and the small slope of this correlation may pave a way for a rational design of new antioxidants based on aryl hydrazides. The present work also provides the pKa values for BH and PAH at 25.0 °C and 1.0 M ionic strength which were not reported before.

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Section: Discussionmentioning

confidence: 64%

Section: Comparison Of the Rate Constantsmentioning

confidence: 99%

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Oxidations of Benzhydrazide and Phenylacetic Hydrazide by Hexachloroiridate(IV): Reaction Mechanism and Structure–Reactivity Relationship

Zhang

2020

Molecules

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“…Mesna. In order to further ascertain the pK a2 value of Mesna obtained by the above kinetic approach, we thus determined it by the spectrophotometric titration method [43][44][45]. A series of buffer solutions containing 0.12 mM Mesna at 1.0 M ionic strength were prepared covering a pH range from 6.77 to 11.97. ose solutions were flushed by nitrogen gas and concurrently thermoequilibated at 25.0°C for 10 min.…”

Section: Determination Of the Iol Dissociation Constant Ofmentioning

confidence: 99%

“…e measured absorption value as a function of pH is given in Figure 7 (data points). Equation 8is a standard correction between the measured absorbance and pK a2 [43][44][45] in which ε 2 and ε 3 are the molar absorptivities for HSCH 2 CH 2 SO 3 and -SCH 2 CH 2 SO 3 -, Abs(235 nm) �…”

Section: Determination Of the Iol Dissociation Constant Ofmentioning

confidence: 99%

Kinetic Analysis of the Reduction Processes of a Cisplatin Pt(IV) Prodrug by Mesna, Thioglycolic Acid, and Thiolactic Acid

Xia

Tian

et al. 2020

Journal of Chemistry

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Although Mesna is an FDA-approved chemotherapeutic adjuvant and an antioxidant based largely on its antioxidative properties, kinetic and mechanistic studies of its redox reactions are limited. A kinetic analysis of the reduction processes of cis-diamminetetrachloroplatinum(IV) (cis-[Pt(NH3)2Cl4], a cisplatin Pt(IV) prodrug) by thiol-containing compounds Mesna, thioglycolic acid (TGA), and DL-thiolactic acid (TLA) was carried out in this work at 25.0°C and 1.0 M ionic strength. The reduction processes were followed under pseudo-first-order conditions and were found to strictly obey overall second-order kinetics; the observed second-order rate constant k′ versus pH profiles were established in a wide pH range. A general reaction stoichiometry of Δ[Pt(IV)] : Δ[Thiol]tot = 1 : 2 was revealed for all the thiols; the thiols were oxidized to their corresponding disulfides which were identified by mass spectrometry. Reaction mechanisms are proposed which involves all the prololytic species of the thiols attacking the Pt(IV) prodrug in parallel, designating as the rate-determining steps. Transient species chlorothiol and/or chlorothiolate are formed in these steps; for each particular thiol, these transient species can be trapped rapidly by another thiol molecule which is in excess in the reaction mixture, giving rise to a disulfide as the oxidation product. The rate constants of the rate-determining steps were elucidated, revealing reactivity enhancements of (1.4–8.9) × 105 times when the thiols become thiolates. The species versus pH and reactivity of species versus pH distribution diagrams were constructed, demonstrating that the species ‒SCH2CH2SO3‒ of Mesna largely governs the total reactivity when pH > 5; in contrast, the form of Mesna per se (mainly as HSCH2CH2SO3‒) makes a negligible contribution. In addition, a well-determined dissociation constant for the Mesna thiol group (pKa2 = 8.85 ± 0.05 at 25.0°C and μ = 1.0 M) is offered in this work, which was determined by both kinetic approach and spectrophotometic titration method.

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Anti-oxidative reactivity and mechanism of formic hydrazide, acethydrazide and butyrohydrazide towards reduction of single electron oxidant iridium(IV)

Tian,

Fu,

Ren

et al. 2024

Journal of Molecular Liquids

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Kinetic and mechanistic analysis of oxidation of 2-furoic hydrazide by hexachloroirradate(IV) in a wide pH range

Cited by 4 publications

References 30 publications

Oxidations of Benzhydrazide and Phenylacetic Hydrazide by Hexachloroiridate(IV): Reaction Mechanism and Structure–Reactivity Relationship

Oxidations of Benzhydrazide and Phenylacetic Hydrazide by Hexachloroiridate(IV): Reaction Mechanism and Structure–Reactivity Relationship

Kinetic Analysis of the Reduction Processes of a Cisplatin Pt(IV) Prodrug by Mesna, Thioglycolic Acid, and Thiolactic Acid

Anti-oxidative reactivity and mechanism of formic hydrazide, acethydrazide and butyrohydrazide towards reduction of single electron oxidant iridium(IV)

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