Abstract
Abstract The 200 MHz H NMR spectra of the herbicide, fenoxaprop-ethyl, 1, have been studied in CDCl3 solution at ambient temperatures as the racemic ester free base with the added chiral lanthanide shift reagent (LSR), tris [3 - (heptafluoropropylhydroxymethylene) - (+) - camphorato]europium(III), Eu(HFC)3, 2, with some additional runs using the achiral LSR, tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato) europium(III), Eu(FOD)3, 3, for supplemental spectral simplification. With 2, definite enantiomeric shift differences (ΔΔδ) were observed only for the CH3CH2O resonance. Although increased spectral complexity for the CH2O signal was seen with added 2, this could have resulted from anisochrony of the diastereotopic protons, Ha and Hb, of this methylene group rather than true ΔΔδ, since the achiral 3 led to near-baseline separation between the CHaHbO signals. Lanthanide-induced shift (LIS) magnitudes were interpreted as consistent with predominant LSR binding at the ester carbonyl.
Published Version
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