Chapter 14, Problem 34P

Interpretation Introduction

Interpretation:

The structure of compound $\text{L}$ is to be proposed and the assignment for the peaks in $\text{IR}$ spectrum is to be done.

Concept introduction:

IR spectroscopy is used to determine the presence of functional groups in the compounds.

NMR spectroscopy is used to determine the presence of equivalent protons in the structure of the compound.

In the $\text{IR}$ spectra, benzene shows absorption at $\text{3030 cm}$ for the $\text{C}-\text{H}$ stretching. Monosubstituted benzene gives peaks between $\text{690}$ and $\text{770 cm}$.

Para di-substituted benzene gives a strong peak between $\text{800}$ and $\text{860 cm}$.

Aromatic rings show absorption at ${\text{3030 cm}}^{\text{-1}}$ due to $\text{C}-\text{H}$ stretching and between ${\text{1600-1400 cm}}^{\text{-1}}$ due to $\text{C=C}$ stretching vibrations.

Alkyl groups show absorption between ${\text{2950 and 2850 cm}}^{\text{-1}}$ due to $\text{C}-\text{H}$ stretching.