Chapter 10.22, Problem 32P

Interpretation Introduction

Interpretation:

${}^{\text{1}}\text{H NMR}$ spectra of the given compound has to be distinguised.

Concept introduction:

The number of signals in ${}^{\text{1}}\text{H NMR}$ is equal to the number of chemically non-equivalent protons. The protons in the different chemical environment are called chemically non-equivalent protons and the protons in the same chemical environment are called chemically equivalent protons.

For each set of chemically equivalent protons, there will be one signal.  For example, the ${}^{\text{1}}\text{H NMR}$ spectrum of ethanol $\left(\text{C}\underset{\text{a}}{{\text{H}}_{\text{3}}}-\text{C}\underset{\text{b}}{{\text{H}}_{\text{2}}}-\text{O}\underset{\text{c}}{\text{H}}\right)$ will show 3 signals because there are 3 set of chemically equivalent protons labelled as a, b and c.

Different compounds give a different number of signals corresponding to the number of chemically non-equivalent proton it has and thus can be distinguished from one another.