Transform one-group

Although there are relatively few groups we can attach to a benzene ring directly, we can often transform one group into another through chemical reactions. It is nitrobenzene that is the key to many of these transformations. Nitrobenzene itself is relatively unre-active, but the nitro group can be reduced in many ways to the amino group (Fig. 14.49). This transformation opens the way for the synthesis of a host of new molecules. 

Hemoglobin is not merely a passive carrier. The power of the iron inside hemoglobin can be redirected so that the transport protein becomes an enzyme that catalyzes a true chemical transformation. One group of chemists uses dissolved hemoglobin to make plastic polymers, because it s easy to make chemical links with the iron. 

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