A compound with a molecular formula C₉H₁₂ has the following ¹H NMR spectrum.Which of the following structures is consistent with this spectrum?

Question

Quizplus · Accepted Answer

The peak at 2.1 ppm corresponds to the two protons attached to the carbon atom adjacent to the sulfur atom, which is consistent with the chemical shift for a carbon atom with a sulfur atom in its vicinity. This indicates that there must be a CS group in the molecule.

The peak at 2.8 ppm corresponds to the proton attached to the carbon atom that is two carbons away from the sulfur atom, which indicates that there must be a CH2 group in the molecule.

The broad peak between 6-7 ppm corresponds to the aromatic protons, and there are 11 of them. This indicates that there must be an aromatic ring with 11 protons in the molecule.

Putting together these pieces of information, we can come up with the structure in choice C, where there is a CS group and a CH2 group attached to an aromatic ring with 11 protons.

A Compound with a Molecular Formula C9H12 Has the Following

A Compound with a Molecular Formula C₉H₁₂ Has the Following