Figure 11.4. 1 H–NMR Spectrum of Dichloromethyl Methyl Ether
Peak a: Dichloromethyl proton; Peak b: Methyl protons.MCAT EXPERTISE
To determine how many peaks will be in the spectrum, see if you can describe protons
differently using words. In the dichloromethyl methyl ether shown in Figure 11.4, one could
call Ha the hydrogen on the carbon with two chlorides and all three Hb hydrogens the ones in
the methyl group. It would not be possible to describe each of these three hydrogens as
distinct from each other because they rotate freely in space.The peak on the left (a) is from the single dichloromethyl proton, and the taller middle peak is from
the three methyl protons (b). The height of each peak is proportional to the number of protons it
contains. Specifically, if we were to analyze the area under the peaks, called the integration, we
would find that the ratio of (a) to (b) is 1:3, corresponding exactly to the ratio of protons that
produced each peak.
Now that we know which peak is which, let’s talk about their respective positions on the spectrum.
We can see that the peak for the single proton (a) is fairly far downfield compared with the other
protons. This is because it is attached to a carbon with two electronegative chlorine atoms and an