Chapter 15, Problem 15.61P

Interpretation Introduction

Interpretation:

The reasonable structure of the compound having a molecular formula ${\text{C}}_8{\text{H}}_8\text{O}$ is to be suggested based on the given IR spectrum.

Concept introduction:

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. The IHD accounts for the number of rings or multiple bonds the structure could possess. A benzene ring has an IHD of 4, which accounts for the three double bonds plus a ring. The next step would be analyzing the given IR spectrum for:

1) The number of stretching modes (above ${\text{1400 cm}}^{-1}$) that are evident in the spectrum, 2) Look especially for the presence or absence of peaks for $\text{O-H, N-H, C=O, C=C, C}\equiv \text{C, and C-H}$. 3) For the evident peaks, determine if it is possible that the corresponding bonds that are consistent with a particular class of compound. 4) The next step is to look for the specific frequencies of the stretching absorptions that give you additional insight into the structure of the unknown compound. 5) Look for the bending vibrations in the fingerprint region and determine if you have monosubstituted benzene, or an ortho-, meta-, or para- disubstituted benzene ring.