Temperature and pressure effects on the kinetics of the Bromate ion‐iodide ion‐L‐ascorbic acid clock reaction

I. Fábián, Rudi Van Eldik

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8 Citations (Scopus)

Abstract

The kinetics of the bromate ion‐iodide ion‐L‐ascorbic acid clock reaction was investigated as a function of temperature and pressure using stopped‐flow techniques. Kinetic results were obtained for the uncatalyzed as well as for the Mo(VI) and V(V) catalyzed reactions. While molybdenum catalyzes the BrO 3−‐I reaction, vanadium catalyzes the direct oxidation of ascorbic acid by bromate ion. The corresponding rate laws and kinetic parameters are as follows. Uncatalyzed reaction: r2 = k2[BrO 3−] [I][H+]2, k2 = 38.6 ± 2.0 dm9 mol−3 s−1, ΔH‡ = 41.3 ± 4.2 kJmol−1, ΔS‡ = −75.9 ± 11.4 Jmol−1 K−1, ΔV‡ = −14.2 ± 2.9 cm3 mol−1. Molybdenum‐catalyzed reaction: r′2 = k2[BrO 3−] [I] [H+]2 + kMo[BrO 3−] [I] [ H+]2[M0(VI)], kMo = (2.9 ± 0.3)106 dm12 mol−4 s−1, ΔH‡ = 27.2 ± 2.5 kJmol−1, ΔS‡ = −30.1 ± 4.5 Jmol−1K−1, ΔV‡ = 14.2 ± 2.1 cm3 mol−1. Vanadium‐catalyzed reaction: r′1 = kV[BrO 3−] [V(V)], kV = 9.1 ± 0.6 dm3 mol−1 s−1, ΔH‡ = 61.4 ± 5.4 kJmol−1, ΔS‡ = −20.7 ± 3.1 Jmol−1K−1, ΔV‡ = 5.2 ± 1.5 cm3 mol−1. On the basis of the results, mechanistic details of the BrO 3−‐I reaction and the catalytic oxidation of ascorbic acid by BrO 3− are elaborated. © 1995 John Wiley & Sons, Inc.

Original languageEnglish
Pages (from-to)491-498
Number of pages8
JournalInternational Journal of Chemical Kinetics
Volume27
Issue number5
DOIs
Publication statusPublished - 1995

Fingerprint

Bromates
bromates
Pressure effects
pressure effects
Thermal effects
clocks
Ascorbic Acid
temperature effects
Clocks
Pressure
Vanadium
acids
Kinetics
Temperature
Acids
Molybdenum
Catalytic oxidation
kinetics
Kinetic parameters
Ions

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

Cite this

@article{456c475fddc74eb3ae702f4add2cd99f,
title = "Temperature and pressure effects on the kinetics of the Bromate ion‐iodide ion‐L‐ascorbic acid clock reaction",
abstract = "The kinetics of the bromate ion‐iodide ion‐L‐ascorbic acid clock reaction was investigated as a function of temperature and pressure using stopped‐flow techniques. Kinetic results were obtained for the uncatalyzed as well as for the Mo(VI) and V(V) catalyzed reactions. While molybdenum catalyzes the BrO 3−‐I− reaction, vanadium catalyzes the direct oxidation of ascorbic acid by bromate ion. The corresponding rate laws and kinetic parameters are as follows. Uncatalyzed reaction: r2 = k2[BrO 3−] [I−][H+]2, k2 = 38.6 ± 2.0 dm9 mol−3 s−1, ΔH‡ = 41.3 ± 4.2 kJmol−1, ΔS‡ = −75.9 ± 11.4 Jmol−1 K−1, ΔV‡ = −14.2 ± 2.9 cm3 mol−1. Molybdenum‐catalyzed reaction: r′2 = k2[BrO 3−] [I−] [H+]2 + kMo[BrO 3−] [I−] [ H+]2[M0(VI)], kMo = (2.9 ± 0.3)106 dm12 mol−4 s−1, ΔH‡ = 27.2 ± 2.5 kJmol−1, ΔS‡ = −30.1 ± 4.5 Jmol−1K−1, ΔV‡ = 14.2 ± 2.1 cm3 mol−1. Vanadium‐catalyzed reaction: r′1 = kV[BrO 3−] [V(V)], kV = 9.1 ± 0.6 dm3 mol−1 s−1, ΔH‡ = 61.4 ± 5.4 kJmol−1, ΔS‡ = −20.7 ± 3.1 Jmol−1K−1, ΔV‡ = 5.2 ± 1.5 cm3 mol−1. On the basis of the results, mechanistic details of the BrO 3−‐I− reaction and the catalytic oxidation of ascorbic acid by BrO 3− are elaborated. {\circledC} 1995 John Wiley & Sons, Inc.",
author = "I. F{\'a}bi{\'a}n and {Van Eldik}, Rudi",
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TY - JOUR

T1 - Temperature and pressure effects on the kinetics of the Bromate ion‐iodide ion‐L‐ascorbic acid clock reaction

AU - Fábián, I.

AU - Van Eldik, Rudi

PY - 1995

Y1 - 1995

N2 - The kinetics of the bromate ion‐iodide ion‐L‐ascorbic acid clock reaction was investigated as a function of temperature and pressure using stopped‐flow techniques. Kinetic results were obtained for the uncatalyzed as well as for the Mo(VI) and V(V) catalyzed reactions. While molybdenum catalyzes the BrO 3−‐I− reaction, vanadium catalyzes the direct oxidation of ascorbic acid by bromate ion. The corresponding rate laws and kinetic parameters are as follows. Uncatalyzed reaction: r2 = k2[BrO 3−] [I−][H+]2, k2 = 38.6 ± 2.0 dm9 mol−3 s−1, ΔH‡ = 41.3 ± 4.2 kJmol−1, ΔS‡ = −75.9 ± 11.4 Jmol−1 K−1, ΔV‡ = −14.2 ± 2.9 cm3 mol−1. Molybdenum‐catalyzed reaction: r′2 = k2[BrO 3−] [I−] [H+]2 + kMo[BrO 3−] [I−] [ H+]2[M0(VI)], kMo = (2.9 ± 0.3)106 dm12 mol−4 s−1, ΔH‡ = 27.2 ± 2.5 kJmol−1, ΔS‡ = −30.1 ± 4.5 Jmol−1K−1, ΔV‡ = 14.2 ± 2.1 cm3 mol−1. Vanadium‐catalyzed reaction: r′1 = kV[BrO 3−] [V(V)], kV = 9.1 ± 0.6 dm3 mol−1 s−1, ΔH‡ = 61.4 ± 5.4 kJmol−1, ΔS‡ = −20.7 ± 3.1 Jmol−1K−1, ΔV‡ = 5.2 ± 1.5 cm3 mol−1. On the basis of the results, mechanistic details of the BrO 3−‐I− reaction and the catalytic oxidation of ascorbic acid by BrO 3− are elaborated. © 1995 John Wiley & Sons, Inc.

AB - The kinetics of the bromate ion‐iodide ion‐L‐ascorbic acid clock reaction was investigated as a function of temperature and pressure using stopped‐flow techniques. Kinetic results were obtained for the uncatalyzed as well as for the Mo(VI) and V(V) catalyzed reactions. While molybdenum catalyzes the BrO 3−‐I− reaction, vanadium catalyzes the direct oxidation of ascorbic acid by bromate ion. The corresponding rate laws and kinetic parameters are as follows. Uncatalyzed reaction: r2 = k2[BrO 3−] [I−][H+]2, k2 = 38.6 ± 2.0 dm9 mol−3 s−1, ΔH‡ = 41.3 ± 4.2 kJmol−1, ΔS‡ = −75.9 ± 11.4 Jmol−1 K−1, ΔV‡ = −14.2 ± 2.9 cm3 mol−1. Molybdenum‐catalyzed reaction: r′2 = k2[BrO 3−] [I−] [H+]2 + kMo[BrO 3−] [I−] [ H+]2[M0(VI)], kMo = (2.9 ± 0.3)106 dm12 mol−4 s−1, ΔH‡ = 27.2 ± 2.5 kJmol−1, ΔS‡ = −30.1 ± 4.5 Jmol−1K−1, ΔV‡ = 14.2 ± 2.1 cm3 mol−1. Vanadium‐catalyzed reaction: r′1 = kV[BrO 3−] [V(V)], kV = 9.1 ± 0.6 dm3 mol−1 s−1, ΔH‡ = 61.4 ± 5.4 kJmol−1, ΔS‡ = −20.7 ± 3.1 Jmol−1K−1, ΔV‡ = 5.2 ± 1.5 cm3 mol−1. On the basis of the results, mechanistic details of the BrO 3−‐I− reaction and the catalytic oxidation of ascorbic acid by BrO 3− are elaborated. © 1995 John Wiley & Sons, Inc.

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SN - 0538-8066

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