Organic Chemistry

NMR Spectroscopy

Figure 188

Disubstituted Rings

The sum of integrated intensity values for the entire aromatic region shows how many
substituents are attached to the ring, so a total value of 4 indicates that the ring has 2
substituents. When a benzene ring has two substituent groups, each exerts an influence
on following substitution reactions. The site at which a new substituent is introduced
depends on the orientation of the existing groups and their individual directing effects. For
a disubstituted benzene ring, there are three possible NMR patterns.