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Rates and Mechanism of Carbonyl Sulfide Oxidation by Peroxides in Concentrated Sulfuric Acid

Dalleska, N. F. and Colussi, A. J. and Hyldahl, A. M. and Hoffmann, M. R. (2000) Rates and Mechanism of Carbonyl Sulfide Oxidation by Peroxides in Concentrated Sulfuric Acid. Journal of Physical Chemistry A, 104 (46). pp. 10794-10796. ISSN 1089-5639. doi:10.1021/jp002333o.

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We measured the rates of carbonyl sulfide (OCS) oxidation by hydrogen peroxide H_2O_2 (HP) and peroxymonosulfuric acid HOOSO_2OH (PSA) in 13.5−18.0 M (76−96 wt %) sulfuric acid (SA) between 290 and 306 K. The reaction is first order in both [OCS] and [peroxide], having nearly identical second-order rate constants k_1 for HP or PSA as oxidants. k_1 increases exponentially with Hammett acidity Ho in the range investigated:  log(k_1/M^(-1) s^(-1)) = − (9.57 ± 0.41) − (0.80 ± 0.05) H_o, (H_o < 0), at 306 K. OCS is, however, inert toward HP in concentrated perchloric acid at equivalent H_o values. We infer that OCS oxidation by HP in SA proceeds by an acid-catalyzed process involving the intermediacy of PSA rather than H_3O^(2+). k_1 depends on temperature according to log(k_1/M^(-1) s^(-1)) = (6.64 ± 1.58) − (2606 ± 472)/T, in 18 M SA. The observed kinetic behavior and parameters are typical of sulfide oxidations by PSA in very acidic media. Present data, in conjunction with data on ambient HP and sulfate aerosol levels in the lower stratosphere, lead to reaction lifetimes that are many orders of magnitude longer than the currently estimated OCS atmospheric residence time of about 4 years.

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Dalleska, N. F.0000-0002-2059-1587
Colussi, A. J.0000-0002-3400-4101
Hoffmann, M. R.0000-0001-6495-1946
Additional Information:© 2000 American Chemical Society. Received: July 3, 2000; In Final Form: September 12, 2000. This work was supported by the National Science Foundation under Grant ATM-9711923.
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Issue or Number:46
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Official Citation:Rates and Mechanism of Carbonyl Sulfide Oxidation by Peroxides in Concentrated Sulfuric Acid N. F. Dalleska, A. J. Colussi, A. M. Hyldahl, and M. R. Hoffmann The Journal of Physical Chemistry A 2000 104 (46), 10794-10796 DOI: 10.1021/jp002333o
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58487
Deposited By: George Porter
Deposited On:28 Jul 2015 20:07
Last Modified:10 Nov 2021 22:05

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