Chapter 15, Problem 15.68P

Interpretation Introduction

Interpretation:

Between cyclohexanone or cyclobutanone, which compound has greater $s$ character in the $\text{σ}$ bond between $\text{C}$ and $\text{O}$ is to be explained based on their respective absorption frequency in IR spectrum and $\text{C=O}$ bond strength.

Concept introduction:

IR spectroscopy helps in identifying 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 $\text{C=O}$ absorption for a ketone appears at $\text{~1710}-{\text{1730 cm}}^{\text{-1}}$. The bond with more $s$ character is stronger and tends to have higher vibrational frequency.