NMR Spectra  for Carbonyl Compounds

Hydrogens attached to carbon adjacent to the sp² hybridized carbon in aldehydes and ketones usually show up 2.0-2.5 ppm.

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Aldehyde hydrogens are highly deshielded and appear far downfield as 9-10 ppm.

Chemical shift of each protons is predicted by ¹H chemical shift ranges (H_a): chemical shift of methyl groups (1.1 ppm). (H_b) The chemical shift of the -CH- group move downfield due to effect an adjacent aldehyde group: (2.4 ppm). The chemical shift of aldehyde hydrogen is highly deshielded (9.6 ppm).

4) Splitting pattern is determined by (N+1) rule: Ha is split into two peaks by H_b(#of proton=1). H_b has the septet pattern by H_a (#of proton=6). H_c has one peak.(Note that H_c has doublet pattern by H_b due to vicinal proton-proton coupling.)