Question

Which of the following compounds has the most signals in the noise-decoupled \( ^{13}C \) NMR spectrum?

• A. \( \text{o-dibromobenzene} \)
• B. \( \text{m-dibromobenzene} \)
• C. \( \text{p-dibromobenzene} \)
• D. \( \text{1,3,5-tribromobenzene} \)

Hint:

Higher molecular symmetry results in fewer distinct NMR signals due to equivalent carbon environments.

Answer 1

The Correct Option is B

Meta-dibromobenzene has the highest number of distinct carbon environments, leading to more signals in \( ^{13}C \) NMR. The ortho and para isomers display fewer unique signals due to symmetry reducing chemical inequivalence. NMR spectroscopy helps in structural determination of organic molecules.