Aldehyde NMR

2-methylbutyradehyde

R-COH: 9.0 - 10 ppm. Heavily deshielded by anisotropy and induction. This is an easy way to notice an aldehyde, since no other proton environments appear in this region.

R-CH-COH: 2.1 - 2.4 ppm. Same deshielding effects, just reduced by distance. All CH-C=O environments are in this region.

CH-CO-H coupling happens with J = 3 hz. This is why the aldehyde group on the spectrum above is a finely split doublet, though it would have to be expanded to observe.