The proton NMR spectrum of valine methyl ester hydrochloride is summarized at the top of the next column.

Note that protons H^e are not split by H^d (and vice versa) because protons H^e are rapidly exchanging. Also, the chemical shifts of protons H^a and H^b could be reversed; the important point is that they are different.

(a) Explain why protons H^a and H^b have different chemical shifts and why the splitting of each is a doublet.

(b) Describe the splitting of proton H^c by constructing a splitting diagram. 

Transcribed Image Text:

8 1.15 (doublet, J = 7.0 Hz) - 8 1.16 (doublet, J = 7.0 Hz) HỌC CH H 8 2.49 OCH3 83.83 (singlet) Hd NH 88.85 (broad singlet) CIT 8 4.02 doublet (J= 4.3 Hz) valine methyl ester hydrochloride