Question

Label the protons in each highlighted CH₂ group as enantiotopic, diastereotopic, or homotopic.

a.

b.

c.

Short answer

a. Enantiotopic

b. Neither

c. Diastereotopic

Step-by-step solution

Homotopic, enantiotopic, and diastereotopic protons

• Homotopic protons are formed when the same product is formed by the substitution of two H by Z.

• Enantiotopic protons are formed when two H are equivalent and occur at the same NMR signal.

• Diastereotopic protons are formed when two H are not equivalent and occur at two different signals.

Explanation for highlighted proton

a.

The replacement of H with X is shown below.

Enantiotopic proton

b.

The replacement of H with X is shown below.

Neither enantiotopic nor diastereotopic

c.

The replacement of H with X is shown below.

Diastereotopic proton