Nomenclature of aromatic compounds

Because aromatic chemistry developed in a haphazard fashion many years before systematic methods of nomenclature were developed, common names have acquired historic respectability and are accepted by lUPAC. Examples include  

Solution One hydrogen in the formula for benzene is replaced by the aldehyde group. 

PROBLEM 4.5 Write the formulas for benzyl alcohol, toluene, and benzoic acid (eq. 4.1). 

Monosubstituted benzenes that do not have common names accepted by lUPAC are named as derivatives of benzene. 

When two substituents are present, three isomeric structures are possible. They are designated by the prefixes ortho-, meta-, and para-, which are usually abbreviated as 0-, m-, andp-, respectively. If substituent X is attached (by convention) to carbon 1, then o-groups are on carbons 2 and 6, m-groups are on carbons 3 and 5, and p-groups are on carbon 4.  

Names are derived using prefixes from Table B and Table C, followed by the name 

Names are derived using prefixes (including commonly accepted names) and numbers or words. 

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Arenes, including reaction mechanisms and nature of the bonding in terms of pi-electron distribution. Video clips on this site about nomenclature of aromatic compounds and electrophilic substitution in benzene. 

Two systems (246,247) will be discussed in this subsection. The nomenclature of these compounds, as of other borazaromatics, has been a point of controversy. Whereas the authors in this field generally followed the procedure of naming these compounds after the isoconjugate parent aromatic hydrocarbon with prefixes like bora and aza indicating the replacement of a methine group by these atoms, in Chemical Abstracts the principal names are derived by reference to the azaborine system. In this Section and in Section... 

To those unfamiliar with the complexities of chemical nomenclature, this lesson may all sound thoroughly confusing, but with a little practice it can be quite easily learned and applied to all types of aromatic compounds. 

Solution To draw these structures, it will be necessary to consider the nomenclature of arenes (compounds that contain both aromatic and aliphatic units). 

Before we discuss the monomers that are used in PPAs, it is in order to talk briefly about the nomenclature of these types of polymers. In nylons, there is common nomenclature to identify the types by a number code. The numbers refer to the chain lengths of the diamine and the diacid. In the case of aromatic compounds, for IPA, I is used and for TPA, T is used. In PPA, a similar nomenclature is used. Examples are given in Table 12.1. However, for fully aromatic PAs the nomenclature is not extended for practical use. 

Chapter 21 introduces aromatic hydrocarbons and their unique chemistry. In another class of aromatic compounds, heteroatoms replace one or more of the ring carbons. These compounds are collectively known as heterocycles or heterocyclic aromatic compounds, and they comprise a class of compounds so large that an entire course is easily built around their chemistry. Heterocycles are seen in several places in this book, including a brief introduction to their nomenclature in Chapter 5 (Section 5.6) and in Chapter 8 (Section 8.9). The most common heterocycles include five- and six-membered monocyclic derivatives that contain nitrogen, oxygen, or sulfur. Several important bicyclic derivatives contain nitrogen. The use of heterocycles in medicine and industry is extensive. This chapter will expand the aromatic chemistry from Chapter 21 and introduce the world of heterocyclic chemistry. 

Chapter 21 discusses the concept of aromaticity as well as the nomenclature and the specialized chemical reactions of aromatic compounds such as benzene and its derivatives. This chapter comes late in the book, with the notion that the chemistry of aliphatic compounds is simply used more often. The acid-base theme is continued with the recognition that the fundamental substitution chemistry associated with benzene derivatives may be explained by the reaction of aromatic rings as Lewis bases or nucleophiles with electrophilic reagents. The reactions of benzene derivatives with strong bases and good nucleophiles are also presented. 

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