Couple of examples for judging 13C chemical shifts

Here are a couple of examples for judging ¹³C chemical shifts:

Remember that ¹³C shifts generally follow the pattern of ¹H shifts, but are much larger.
Thus, in (a)

• The peak at lowest field is the caarbon with the OH attached
• The peak at highest field is the CH₃ farthest from the OH
• Generally in both ¹³C and ¹H spectra, CH₂ groups fall to lower field than CH₃, which assigns the remaining peaks.

For (b):

• The peak at lowest field is the C=O carbon, shifted by electronegativity and "diamagnetic anisotropy"
• Assignment of the other two peaks follows from the CH₂ lower than CH₃ rule.

Now try predicting the splitting pattern to be found if the decoupler is turned off. 








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