H NMR Position of Signals

When substitution of two H atoms by Z forms enantiomers, the two H atoms are equivalent and give a single NMR signal. These two H atoms are called enantiotopic protons. 

In contrast, the two H atoms of the CH2 group in (/ )-2-chlorobutane, which contains one stereo-genic center, are not equivalent to each other. Substitution of each H by Z forms two diastereo-mers, and thus, these two H atoms give different NMR signals. 

Problem 14.6 How many different types of protons does 2-chlorobutane contain  

Problem 14.7 Label the indicated protons in each CH2 group as enantiotopic, diastereotopic, or neither. 

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