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17 O NMR of L ‐Ascorbic Acid. New Spectroscopy of an Old Molecule
Author(s) -
Ruchmann A.,
Lauterwein J.,
Bäcker T.,
Klessinger M.
Publication year - 1996
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199602)34:2<116::aid-omr854>3.0.co;2-l
Subject(s) - chemistry , ascorbic acid , titration , aqueous solution , molecule , solvent , nuclear magnetic resonance spectroscopy , chemical shift , nmr spectra database , analytical chemistry (journal) , inorganic chemistry , spectral line , stereochemistry , organic chemistry , astronomy , physics , food science
Natural abundance 17 O NMR spectra of L ‐ascorbic acid were recorded in aqueous solution as a function of pH. The water solvent peak was suppressed through the use of 17 O‐depleted water and inversion–recovery. The 17 O NMR resonances were assigned from chemical shift comparison and pH titration behaviour. The resonance of the β‐enol oxygen could also be located because of its isotopic exchange with water. Charge densities and bond orders were calculated for α‐hydroxytetronic acid at the 6–31G** SCF level. Their variations with pH related well with the 17 O titration shifts in L ‐ascorbic acid.