(Solved): #4 - NMR Spectroscopy 4 5 points The structures of ethyl butanoate and propyl butanoate are shown be ...

4 5 points The structures of ethyl butanoate and propyl butanoate are shown below. Note how each has an ethyl group and a propyl group; the only difference is how they are oriented around the ester functional group. The way to distinguish between the carbons on either side of the ester group is by chemical shift: the protons on the carbon next to the oxygen will usually have a shift of 3-4 ppm, while the protons on the carbon next to the carbonyl will usually have a shift of 2- 3 ppm. Note also that the further away from a functional group the end of a chain is, the lower its chemical shift is likely to be (this will help in assigning the methyl groups at the ends of both molecules). B ci D F H A G Ethyl butanoate Propyl propanoate Match each proton from these two structures with the corresponding peak in one of these spectra. 3H 3H 2H 2H Spectrum 1: 3H 3H 2H 1.0 PPM 3H 2H Spectrum 2: 2H 3.5 3.0 2H 2H 2H 2H 2H 2H 2H 1.5 3H 1.0 PPM 3H 1.0 PPM Proton A Proton B Proton C Proton D Proton E Proton F Proton G Proton H Proton I Proton J > > > > > >