Olson, Terese M. and Hoffmann, Michael R. (1988) Formation kinetics, mechanism, and thermodynamics of glyoxylic acid-sulfur(IV) adducts. Journal of Physical Chemistry, 92 (14). pp. 4246-4253. ISSN 0022-3654. https://resolver.caltech.edu/CaltechAUTHORS:20150814-140636633
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Abstract
A spectrophotometric study of the reversible addition of glyoxylic acid and S(IV) was conducted over the pH range of 0.7-2.9. Formation rates of the adduct, 2-hydroxy-2-sulfcethanoiacc id (HSEA), and its conjugate base were consistent with the following rate expression: -d[S(IV)]/dt = (k_1α_1β_1+ k_3α_2β_1)[C_2H_2O_3][S(IV)], where [C_2H_2O_3]= [CHOCO_2H]+ [CHOCO_2^-] + [CH(OH)_2CO_2H] + [CH(OH)_2CO_2^-], [S(IV)] = [H_2O•SO_2] + [HSO_3^-] + [SO_3^(2-)]ɑ_1 = [HSO_3^-]/[S(IV)], α_2 = [SO_3^(2-)]/[S(IV)], and β_1 = [CHOCO_2H]/[C_2H_2O_3]. The rate constants k_1 and k_3 correspond to the respective addition steps of HSO_3^- and SO_3^(2-) with CHOCO_2H. A study of the pH dependence gave k_1 = 443 (±21.2) M^(-1) s^(-1) and k_3 = 1.98 x 10^7 M^(-1) s^(-1). Temperature studies of the reaction showed that the ΔS^* for the addition of bisulfite and glyoxylic acid is significantly more negative than activation entropies for other low molecular weight aldehydes. A transition state was proposed that involves intramolecular hydrogen bonding. Adduct stability constants were determined as ^cK_1 = [HO_2CCH(OH)- SO_3^-]/([CHOCO_2H][HSO_3^-]) 7.09 X l0^7 M^(-1) and ^cK_2 = [^-O_2CCH(OH)SO_3^_]/([CHOCO_2^-][HSO_3^_]) = 5.27 x 10^6 M^(-1) at 25 ºC and µ = 0.2 M. Correlations of these and other α-hydroxyalkanesulfonate stability constants with the Taft σ^* parameter and with carbonyl hydration constants are presented. The acid dissociation constant for the HSEA carboxyl group was estimated by potentiometric titration to be p^cK_(a5) = 2.99. The importance of glyoxylic acid as a reservoir for S(IV) in atmospheric water droplets was evaluated on the basis of these thermodynamic constants.
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Additional Information: | © 1988 American Chemical Society. Received: December 2, 1987. We thank Eric Betterton for his helpful advice, and we gratefully acknowledge the Electric Power Research Institute (RP1630-47), the Environmental Protection Agency (R811496-01-1), and the Public Health Service (ES04635-01) for their financial support. | |||||||||
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Issue or Number: | 14 | |||||||||
Record Number: | CaltechAUTHORS:20150814-140636633 | |||||||||
Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20150814-140636633 | |||||||||
Official Citation: | Formation kinetics, mechanism, and thermodynamics of glyoxylic acid-sulfur(IV) adducts Terese M. Olson and Michael R. Hoffmann The Journal of Physical Chemistry 1988 92 (14), 4246-4253 DOI: 10.1021/j100325a050 | |||||||||
Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
ID Code: | 59552 | |||||||||
Collection: | CaltechAUTHORS | |||||||||
Deposited By: | Ruth Sustaita | |||||||||
Deposited On: | 17 Aug 2015 17:38 | |||||||||
Last Modified: | 03 Mar 2020 13:01 |
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