Correlations between structure and nuclear magnetic resonance (N.M.R.) spectra for aliphatic esters

The n.m.r. chemical shift for 18 acetate esters, CH₃COOR', and 16 methyl esters, RCOOCH₃, have been measured neat and in carbon tetrachloride solution. The n.m.r. chemical shifts of acetate esters, CH₃COOR', are controlled largely by polar effects and six carbon effects of the R' group while the n.m.r. chemical shifts of methyl esters, RCOOCH₃, are partially controlled by polar and hyperconjugation effects of the R group. All these correlations and the factors responsible for deviations are discussed