Oxygen-17 magnetic resonance study of oxygen exchange between arsenite ion and solvent water

Oxygen-17 magnetic resonance spectra of aqueous solutions of sodium arsenite were measured for 0.6 < (As(III)) < 4.1 m, 10 < t < 90/sup 0/C. Line broadening of the water resonance in the 40 to 90/sup 0/C range gives the rate of oxygen exchange between AsO(OH)/sub 2//sup -/ and solvent wa...

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Veröffentlicht in:J. Am. Chem. Soc.; (United States) 1978-06, Vol.100 (12), p.3776-3780
Hauptverfasser: Copenhafer, William C, Rieger, Philip H
Format: Artikel
Sprache:eng
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Zusammenfassung:Oxygen-17 magnetic resonance spectra of aqueous solutions of sodium arsenite were measured for 0.6 < (As(III)) < 4.1 m, 10 < t < 90/sup 0/C. Line broadening of the water resonance in the 40 to 90/sup 0/C range gives the rate of oxygen exchange between AsO(OH)/sub 2//sup -/ and solvent water. Exchange takes place via a first-order pathway, ..delta..S/sub 1//sup 2+/ = -120 +- 3 J K/sup -1/ mol/sup -1/, ..delta..H/sub 1//sup 2+/ = 25 +- 1 kJ mol/sup -1/, and a pathway second-order in arsenite, ..delta..S/sub 2//sup 2+/ = -102 +- J K/sup -1/ mol/sup -1/, ..delta..H/sub 2//sup 2+/ = 33 +- 4 kJ mol/sup -1/. Rates were measured using solutions of pH approximately 10.2; exchange appears to be only slightly faster in solutions of lower pH.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja00480a020