Chapter 15, Problem 15.49P

Interpretation Introduction

Interpretation:

Why in an IR spectrum the $\text{C}-\text{O}$ stretch for an alcohol or ether appears near ${\text{1050 cm}}^{-1}$ whereas for carboxylic acid or an ester it appears near ${\text{1250 cm}}^{-1}$ is to be explained.

Concept introduction:

IR spectroscopy enables us to identify the different functional groups in the 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 resonance effect alters the bond absorption frequency in IR spectrum.