Chapter 15, Problem 15.29P

Interpretation Introduction

Interpretation:

Another molecule that is consistent with the IR spectrum in Figure $\text{15-26}$ is to be drawn.

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. For identifying correct structures from the given IR spectrum, the first step is to calculate the IHD from the given molecular formula of a compound. IHD accounts for the number of rings or multiple bonds the structure could possess. The C-H stretch on the terminal alkyne tends to appear as a strong, narrow band in the ${\text{3260-3330 cm}}^{\text{-1}}$ region while the triple bond shows a weak peak at ${\text{2100-2260 cm}}^{\text{-1}}$;N-H stretches appear as a small, sharp peak at $2100{\text{ cm}}^{\text{-1}}$.