Correlation of oxygen‐17 substituent‐induced chemical shifts: Meta‐ and para‐substituted methyl benzoates

Oxygen‐17 NMR spectra of 45 substituted methyl benzoates in acetonitrile were measured at natural abundance. The substituent‐induced chemical shifts (SCS) of the carbonyl oxygen correlate well with the σm and σ substituent constants in two separate correlations for meta and para derivatives; principal component analysis (PCA) is only slightly better [particularly for the N(CH3)2 substituent]. The 17O SCS generally depend on the same factors as the 13C SCS of the β‐carbon of alkenes, provided comparison is made between compounds of similar polarity. SCS of the methoxyl oxygen depend less precisely on σm or σp, with some unexplained deviations.