Question

For each compound, first label each different type of proton and then rank the protons in order of increasing chemical shift.

a.

b.

c.

Short answer

a.

b.

c.

Step-by-step solution

NMR spectroscopy

The chemical shift of the proton depends upon the atoms attached to it. The proton near the electronegative goes downshield or has more value of the chemical shift.

Explanation

a.

The given compound has three types of proton, as shown below:

Given compound in a

Cl is more electronegative than Br. Thus, the proton near Cl is more downshield as compared to the proton near Br.

The order of the chemical shft is shown below:

${\text{H}}_{\text{b}}<{\text{H}}_{\text{c}}<{\text{H}}_{\text{a}}$

b.

The given compound has three types of proton, as shown below:

Given compound in b

The proton between the oxygen atoms will go more downshield as compared to the proton near the oxygen atom at the extreme left.

The order of the chemical shft is shown below:

${\text{H}}_{\text{c}}<{\text{H}}_{\text{a}}<{\text{H}}_{\text{b}}$

c.

The given compound has three types of proton, as shown below:

Given compound in c

Proton near the oxygen atom will go more downshield as compared to the proton away from the oxygen atom.

The order of chemical shft is shown below:

${\text{H}}_{\text{c}}<{\text{H}}_{\text{a}}<{\text{H}}_{\text{b}}$