Examples of aromatic compounds

Many compounds in addition to benzene are aromatic. Several examples are presented in Section 17.8. 

Probl6m 17.9 Estimate where the protons bonded to sp hybridized carbons will absorb in the H NMR spectrum of each compound. 

In Section 17.8 we look at many different types of aromatic compounds. 

Benzene is the most common aromatic compound having a single ring. Completely conju ted rings larger than benzene are also aromatic if they are planar and have 4 + 2 jc electrons. 

To name an annulene, indicate the number of atoms in the ring in brackets and add the word annulene. Thus, benzene is [6]-annulene. Both [14]-annulene and [18]-annulene are cyclic, planar, completely conjugated molecules that follow Hiickel s rule, and so they are aromatic. 

The molecule puckers to keep these H s farther away from each other. 

Problem 17.11 Would [16]-, [20]- or [22]-annulene be aromatic If each ring Is planar  

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FIGURE 4.32 Some examples of aromatic compounds as dienophiles. 

Figure 17.6 Examples of aromatic compounds found in some metabolic pathways...

Two additional examples of aromatic compounds containing heteroatoms eire shown in Figure 6-14. In both compounds, the heteroatom has two lone pairs. However, only one of the pairs is in a p-orbital perpendiculcir to the plane of the ring. The other electron pair is in the plane of the ring. 

The following are a few examples of aromatic compounds, including benzene itself. In these formulas we foreshadow our discussion of the special properties of the benzene ring by using a circle in a hexagon to depict the six tt electrons and six-membered ring of these compounds, whereas up to now we have shown benzene rings only as indicated in the left-hand formula for benzene below. 

In addition to those that we have seen so far, there are many other examples of aromatic compounds. Representatives of one broad class of benzenoid aromatic compounds, called polycyclic aromatic hydrocarbons (PAH), are illustrated in Fig. 14.14. 

Toluene is a representative example of aromatic compounds investigated due to its extensive use in industrial processes as solvent or as feedstock for the production of polymers or adhesives, but also due to its existence in petroleum-derived fuels. In a close relation, catalytic total oxidation takes into consideration the serious environmental concern generated by its perilous health effects but also by its contribution to global warming smog processes as a result of the emission of toluene from both stationary and mobile sources. 

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