Kinetics and Mechanisms of the Oxidation of Hydrazine by Aqueous Iodine

Liu, Rongming; Margerum, Dale W.

doi:10.1021/ic970753v

Cited by 14 publications

(12 citation statements)

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“…There seems to be a little information available on the oxidation kinetics of INH or azo compounds in general by haloamines. Liu and Margerum [11] have studied the kinetics of oxidation of hydrazine by aqueous iodine over a wide range of acidity from pH 0.35 to 8.00, using stopped-flow and pulsed-acceleratedflow methods. A multistep mechanism is proposed where iodine reacts rapidly with N 2 H 4 to form the adduct I 2 N 2 H 4 , which undergoes general base-assisted deprotonation with loss of I Ϫ ion in the rate-limiting step.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of isoniazid by N-haloarenesulfonamidates in alkaline medium: A kinetic and mechanistic study

Puttaswamy

Anuradha

Ramachandrappa

et al. 2000

Int. J. Chem. Kinet.

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The kinetics of oxidation of Isoniazid (INH) by sodium N‐haloarenesulfonamidates, chloramine‐T (CAT), bromamine‐T (BAT), chloramine‐B (CAB), and bromamine‐B (BAB), has been studied in alkaline medium at 303 K. The oxidation reaction follows identical kinetics with a first‐order dependence on each [oxidant] and [INH] and an inverse fractional‐order on [OH−:]. Addition of the reaction product (p‐toluenesulfonamide or benzenesulfonamide) had no significant effect on the reaction rate. Variation of ionic strength and addition of halide ions have no influence on the rate. There is a negative effect of dielectric constant of the solvent. Studies of solvent isotope effects using D2O showed a retardation of rate in the heavier medium. The reaction was studied at different temperatures, and activation parameters have been computed from the Arrhenius and Eyring plots. Isonicotinic acid was identified as the oxidation product by GC‐MS. A two‐pathway mechanism is pro‐posed in which RNHX and the anion RNX− interact with the substrate in the rate‐limiting steps. The mechanism proposed and the derived rate laws are consistent with the observed kinetics. The rate of oxidation of INH increases in the order: BAT > BAB > CAT > CAB. This effect is mainly due to electronic factors. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 221–230, 2000

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Section: Introductionmentioning

confidence: 99%

Oxidation of isoniazid by N-haloarenesulfonamidates in alkaline medium: A kinetic and mechanistic study

Puttaswamy

Anuradha

Ramachandrappa

et al. 2000

Int. J. Chem. Kinet.

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“…In all cases, the reactions proceed to equilibrium extremely rapidly, as we have also found for MSA. A reaction to form an I 2 addition species (I 2 Nu – ) instead of NuI is also reported as in eq for various nucleophiles, , but the linear dependence on 1/[I – ] 2 in Figure shows that formal net I + transfer as in eq is the observed process with MSA. …”

Section: Resultsmentioning

confidence: 90%

Methanesulfonyl Iodide

2019

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Methanesulfonyl iodide is produced in aqueous solutions from the reaction of triiodide with methanesulfinate. Dichroic crystals of (CH 3 SO 2 I) 4 •KI 3 •2I 2 are formed from KI/I 2 solutions with high concentrations of CH 3 SO 2 − , while dichroic crystals of (CH 3 SO 2 I) 2 • RbI 3 are formed from RbI/I 2 solutions. X-ray crystallography of these two compounds shows that the CH 3 SO 2 I molecules coordinate through their oxygen atoms to the metal cations and that the S−I bond length is 2.44 Å. At low concentrations of CH 3 SO 2 − , the solutions remain homogeneous and the sulfonyl iodide is formed in a rapid equilibrium: CH 3 SO 2 − + I 3 − ⇌ CH 3 SO 2 I + 2I − , K MSI = 1.07 ± 0.01 M at 25 °C (μ = 0.1 M, NaClO 4 ). The sulfonyl iodide solutions display an absorbance maximum at 309 nm with a molar absorptivity of 667 M −1 cm −1 . Stopped-flow studies reveal that the equilibrium is established within the dead time of the instrument (∼2 ms). Solutions of CH 3 SO 2 I decompose slowly to form the sulfonate: CH 3 SO 2 I + H 2 O → CH 3 SO 3 − + I − + 2H + , k hyd . In dilute phosphate buffer, this decomposition occurs with k hyd = 2.0 × 10 −4 s −1 ; the decomposition rate shows an inverse-squared dependence on [I − ] because of the K MSI equilibrium.

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“…To get an observable effect, a relatively high concentration of ascorbic acid had to be added to the sample solution (5×10 −3 –5.6×10 −2 M), which resulted in a long zone migrating in the same direction as the analyte thereby decreasing the sample loadability. Therefore, we tested another agent, hydrazine, which is positively charged in the tested pH range and migrates to the cathode ( pK a =8.1 56). A 5×10 −3 M hydrazine in the sample solution was proven to ensure satisfying prevention of 5‐MTHF decomposition for several days.…”

Section: Resultsmentioning

confidence: 99%

Analysis of 5‐methyltetrahydrofolate in human blood, serum and urine by on‐line coupling of capillary isotachophoresis and zone electrophoresis

Pantůčková

Křivánková

2010

Electrophoresis

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A novel biocatalytic process for production of L‐homoalanine from L‐threonine has been developed using coupled enzyme reactions consisting of a threonine deaminase (TD) and an ω‐transaminase (ω‐TA). TD catalyzes the dehydration/deamination of L‐threonine, leading to the generation of 2‐oxobutyrate which is asymmetrically converted to L‐homoalanine via transamination with benzylamine executed by ω‐TA. To make up the coupled reaction system, we cloned and overexpressed a TD from Escherichia coli and an (S)‐specific ω‐TA from Paracoccus denitrificans. In the coupled reactions, L‐threonine serves as a precursor of 2‐oxobutyrate for the ω‐TA reaction, eliminating the need for employing the expensive oxo acid as a starting reactant. In contrast to α‐transaminase reactions in which use of amino acids as an exclusive amino donor limits complete conversion, amines are exploited in the ω‐TA reaction and thus maximum conversion could reach 100%. The ω‐TA‐only reaction with 10 mM 2‐oxobutyrate and 20 mM benzylamine resulted in 94% yield of optically pure L‐homoalanine (ee>99%). However, the ω‐TA‐only reaction did not produce any detectable amount of L‐homoalanine from 10 mM L‐threonine and 20 mM benzylamine, whereas the ω‐TA reaction coupled with TD led to 91% conversion of L‐threonine to L‐homoalanine.

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Kinetics and Mechanisms of the Oxidation of Hydrazine by Aqueous Iodine

Cited by 14 publications

References 50 publications

Oxidation of isoniazid by N-haloarenesulfonamidates in alkaline medium: A kinetic and mechanistic study

Oxidation of isoniazid by N-haloarenesulfonamidates in alkaline medium: A kinetic and mechanistic study

Methanesulfonyl Iodide

Analysis of 5‐methyltetrahydrofolate in human blood, serum and urine by on‐line coupling of capillary isotachophoresis and zone electrophoresis

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