Chapter 15, Problem 15.23P

Interpretation Introduction

Interpretation:

The isomers $\text{C}$ and $\text{D}$ are to be matched with the correct IR spectrum.

Concept introduction:

IR spectroscopy enables to identify different functional groups in the given molecule.

One of the greatest advantages of IR spectroscopy is that the frequency of a particular type of vibration is typically found within a characteristic range of frequencies, regardless of the functional group with which the vibration is associated. The fact that absorptions by certain vibrations appear with characteristic frequency ranges enables us to use IR spectroscopy to obtain structural information about a molecule. The absorption band for alkene $\text{C=C}$ bond appears as a single peak in the range of $1620–1680{\text{ cm}}^{-1}$ and for aromatic $\text{C=C}$ bond appears as two or three peaks in the range of $\text{1450}-{\text{1600 cm}}^{-1}$.