Chapter 16, Problem 16.9P

Interpretation Introduction

Interpretation:

A compound gives rise to two signals in its $\text{H}$ NMR spectrum. Which of compounds D-G, can it be, is to be identified and explained.

Concept introduction:

Sometimes, it is not immediately obvious whether certain hydrogen atoms in a molecule are chemically distinct. In such cases, the chemical distinction test is used.

Chemical distinction test: The complete structure of the molecule is to be drawn in which only the hydrogen atom is replaced by an imaginary “X” atom. There should be one X-substituted molecule for each hydrogen atom being tested.

If the chemical distinction test yields enantiomers, then the corresponding hydrogen atoms are said to be enantiotopic. If the test yields diastereomers, then the corresponding hydrogen atoms are said to be diastereotopic.

Enantiotopic and diastereotopic hydrogen are distinct in $\text{H}$ NMR spectrum.