Chapter 15, Problem 15.51P

Interpretation Introduction

Interpretation:

Which compound $\text{C}$ or compound $\text{D}$ would you expect to have a higher $\text{C}-\text{O}$ stretch band in frequency is to be determined and explained.

Concept introduction:

IR spectroscopy enables us to identify 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 $\text{π}$ system is more stable in an aromatic compound than in regular conjugation. The stable $\text{π}$ system associates with stronger $\text{π}$ bond and stronger $\text{π}$ bond increases the vibrational frequency.