Experimental study of a closed system in the chlorine dioxide–iodine–ethyl acetoacetate–sulfuric acid oscillation reaction by UV–vis and online FTIR spectrophotometric methods

Experimental study of a closed system in the chlorine dioxide–iodine–ethyl... The appearance of oscillations depends critically on the pH for a closed system of ClO2–I2–ethyl acetoacetate in the absence of sulfuric acid, and was investigated by determining the absorbance of I 3 − with reaction time at 280 nm. The pH should be 2.2–3.8. The initial concentration of ethyl acetoacetate, chlorine dioxide, iodine, and sulfuric acid has great influence on the oscillation at 581 nm for I 3 − –starch complex (SI 3 − ). The oscillation occurs as long as the reactants are mixed at 280 nm. There is no pre-oscillatory period. However, at 581 nm, there is an induction period. The curve’s shape at 581 nm is very different from that at 280 nm. The oscillation becomes more obvious by adding starch at 581 nm for I 3 − –starch complex (SI 3 − ) than that observed without adding starch at 280 nm. The oscillation curve is more regular and smooth by adding starch at 581 nm than that without adding starch at 280 nm. The amplitude and the number of oscillations are associated with the initial concentration of reactants. The higher the initial concentration of ethyl acetoacetate, the bigger the amplitude. Also, the number of oscillations becomes small. An opposite influence exists for chlorine dioxide and iodine. The higher the initial concentration of sulfuric acid, the bigger the amplitude. Also, the number of oscillations becomes large. The equations for the triiodide ion reaction rate changing with reaction time and the initial concentrations on the oscillation stage were obtained. The intermediates were detected by the online FTIR analysis. Based upon the experimental data in this work and in the literature, a plausible reaction mechanism was proposed for the oscillation reaction. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Research on Chemical Intermediates Springer Journals

Experimental study of a closed system in the chlorine dioxide–iodine–ethyl acetoacetate–sulfuric acid oscillation reaction by UV–vis and online FTIR spectrophotometric methods

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Publisher
Springer Netherlands
Copyright
Copyright © 2010 by Springer Science+Business Media B.V.
Subject
Chemistry; Inorganic Chemistry ; Physical Chemistry ; Catalysis
ISSN
0922-6168
eISSN
1568-5675
D.O.I.
10.1007/s11164-010-0164-z
Publisher site
See Article on Publisher Site

Abstract

The appearance of oscillations depends critically on the pH for a closed system of ClO2–I2–ethyl acetoacetate in the absence of sulfuric acid, and was investigated by determining the absorbance of I 3 − with reaction time at 280 nm. The pH should be 2.2–3.8. The initial concentration of ethyl acetoacetate, chlorine dioxide, iodine, and sulfuric acid has great influence on the oscillation at 581 nm for I 3 − –starch complex (SI 3 − ). The oscillation occurs as long as the reactants are mixed at 280 nm. There is no pre-oscillatory period. However, at 581 nm, there is an induction period. The curve’s shape at 581 nm is very different from that at 280 nm. The oscillation becomes more obvious by adding starch at 581 nm for I 3 − –starch complex (SI 3 − ) than that observed without adding starch at 280 nm. The oscillation curve is more regular and smooth by adding starch at 581 nm than that without adding starch at 280 nm. The amplitude and the number of oscillations are associated with the initial concentration of reactants. The higher the initial concentration of ethyl acetoacetate, the bigger the amplitude. Also, the number of oscillations becomes small. An opposite influence exists for chlorine dioxide and iodine. The higher the initial concentration of sulfuric acid, the bigger the amplitude. Also, the number of oscillations becomes large. The equations for the triiodide ion reaction rate changing with reaction time and the initial concentrations on the oscillation stage were obtained. The intermediates were detected by the online FTIR analysis. Based upon the experimental data in this work and in the literature, a plausible reaction mechanism was proposed for the oscillation reaction.

Journal

Research on Chemical IntermediatesSpringer Journals

Published: Aug 18, 2010

References

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