The C NMR spectrum of 2-ethylbutanal consists of the following absorptions: 11.5, 21.7, 55.2,

Question:

The C NMR spectrum of 2-ethylbutanal consists of the following absorptions: δ 11.5, δ 21.7, δ 55.2, and δ 204.7. Draw the structure of this aldehyde, label each chemically non-equivalent set of carbons, and assign each absorption to the appropriate carbon(s).