Question

How many NMR signals does each compound give?

a.

b.

c.

d.

Short answer

a. 3

b. 4

c. 5

d. 3

Step-by-step solution

NMR spectroscopy

The chemical shift’s value of a proton depends on the type of atom attached to it. If it is attached to an electronegative atom, the value of the chemical shift increases.

 1H NMR signals in a and b

a.

The given compound has a plane of symmetry, as shown below.

Structure of a

Thus, the given compound has three types of protons, and it will give three signals.

b.

The given compound has four types of protons, and it will give four signals, as shown below.

Structure of b

 1H NMR signals in c and d

c.

The given compound has five types of protons, and it will give five signals, as shown below.

Structure of c

d.

The given compound has a plane of symmetry, as shown below.

Structure of d

Thus, the given compound has three types of protons, and it will give three signals.