Oxygen‐17 and Carbon‐13 Nuclear Magnetic Resonance. Chemical shifts of unsaturated carbonyl compounds and acyl derivatives

The 17O and 13C chemical shifts (δ) of 14 α,β-unsaturated aldehydes and ketones and 33 acyl derivatives RXC = O (X = Cl, OH, OMe, OEt, NH2 and R = H or alkyl) have been measured. In the unsaturated carbonyl series, a correlation exists between δ 17O and the π electron density at the β-carbon atom. From this correlation, an δ 17O of 530 ppm was extrapolated for the loss of one electron at the oxygen atom. In the acyl series, the δr 17O were also sensitive to changes in the polarity of the carbon-oxygen bond. A partial correlation between 17O-NMR. chemical shifts and the nuclear quadrupole coupling constants exists for aldehydes, ketones, esters and amides but not for acyl chlorides.