Carbon kinetic isotope effects on the hydration of carbon dioxide and the dehydration of bicarbonate ion

Journal Article · Wed Sep 05 04:00:00 EDT 1984 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00330a003· OSTI ID:6199973

Marlier, J F; O'Leary, M H

/sup 13/C kinetic isotope effects on the hydration of CO/sub 2/ and the dehydration of HCO/sub 3//sup -/ in aqueous solution have been measured by rapid removal of the product and conversion to an isotopically stable form, followed by isotope-ratio analysis. The isotope effect on hydration is k/sup 12//k/sup 13/ = 1.0069 +/- 0.0003 at 24/sup 0/C. The isotope effect on dehydration is 1.0147 +/- 0.0007. The ratio of these two values gives an equilibrium isotope effect of K/sup 12//K/sup 13/ = 1.0077, in good agreement with previously measured values. The small magnitudes of the kinetic isotope effects indicate that the transition state for conversion of HCO/sub 3//sup -/ to CO/sub 2/ is very similar to that of HCO/sub 3//sup -/. This information together with previously measured solvent isotope effects indicates that the mechanism of HCO/sub 3//sup -/ dehydration probably involves general-acid-catalyzed donation of a proton from H/sub 3/O/sup +/ to the departing oxygen, rather than unimolecular decomposition of the zwitterion H/sub 2/O/sup +/-CO/sub 2//sup -/ in the rate-determining step. 21 references, 2 figures.

• Research Organization: Univ. of Wisconsin, Madison
• OSTI ID: 6199973
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 106:18; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
AQUEOUS SOLUTIONS
CARBON 13
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON ISOTOPES
CARBON OXIDES
CARBONATES
CHALCOGENIDES
DATA
DEHYDRATION
DISPERSIONS
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
HYDRATION
INFORMATION
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
MIXTURES
NUCLEI
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
SOLUTIONS
SOLVATION
STABLE ISOTOPES