NMR Spectroscopy

Correct Answer: C

Explanation: We see only two signals in the proton NMR spectrum. There are only two unique sets of hydrogens in molecule C: the hydrogens on the tert-butyl group (each of those nine hydrogens contributes to that signal near 1 ppm) and the hydrogens that are on the CH2 attached to the bromine (those two both contribute to the signal near 3 ppm). Molecule C is the only molecule shown above that has only two unique 1H NMR signals. In terms of spin-spin splitting, both types of protons in molecule C are expected to be singlets, since they don’t have any vicinal neighbors (ie. hydrogens that are 3 bonds apart from each other).