Question

Choose the molecule(s) that will only show two signals, with an integration ratio of 2:3, in their 1H NMR spectrum.

Answer 1

The question is missing the molecules in which the integration ratio of 2:3 will be observed. The complete question is given in the attachment.

Answer:

Molecule (a), (c), and (f) will show two peaks with the integration ratio of 2:3 in their 1H NMR spectrum

Explanation:

In the 1H NMR spectrum, the peak area is dependent on the number of hydrogen in a specific chemical environment. Hence, the ratio of the integration of these signals provides us with the relative number of hydrogen in two peaks. This rationale is used for the assignment of molecules that will give 2:3 integration ratio in the given problem.

• Molecule (a) have two CH₂ and three CH₃ groups. Hence, it will give two peaks and their integration ratio becomes 2:3 (Answer)
• Molecule (b) contains three chemical environments for its hydrogen atoms
• Molecule (c) have a single CH₂ and CH₃ group giving integration ratio of 2:3 (Answer)
• Molecule (d) will give two peaks but their ratio will be 1:3 because of two hydrogens of CH₂ and six hydrogens from two CH₃ groups
• Molecule (e) have three CH and three CH₃ groups, so their ratio will become 1:3
• Molecule (f) contains four CH and two CH₃ groups, giving two peaks. So, the integration ratio of their peaks is 2:3 (Answer)
• Molecules
• (g)
• and
• (h)
• both have two CH and two CH₃ groups giving two peaks with the integration ratio of 1:3