Functional Groups and Nomenclature II

This chapter begins where Chapter 5 left off and considers the nomenclature, physical properties, natural occurrences, and uses of the principal functional groups that were not discussed in Chapter 5. The nomenclature rules are extensions of those in Chapter 5, with different suffixes for the new functional groups. We will also see how compounds that have more than one functional group are named. 

A complete definition of aromatic compounds must wait until Chapter 16. For the present we will define them as benzene and its substituted derivatives. They are also called arenes. These aromatic compounds have a six-membered ring with three conjugated doable bonds. It is this cycle of conjugated double bonds that makes arenes special. Examples include the following  

If you have spent much time in an organic laboratory, you are well aware that many organic compounds have rather strong (and sometimes disagreeable) odors. Aromatic compounds, however, tend to have more fragrant odors than other compounds. If you have a chance, compare the odor of toluene, for example, with that of cyclohexene. In fact, the term aromatic was originally given to 

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When several substituents are present on a benzene ring, the ring is numbered in the same manner as the rings of cycloalkanes—that is, so that the numbers for the substituents are as low as possible. In addition, some special terms are used with disuhsti-tuted benzenes only. Two substituents on adjacent carbons (positions I and 2) are said to be ortho, or o-. Two substituents on positions 1 and 3 are meta, or m-. And two substituents on positions 1 and 4 are para, or p-. Finally, if an alkyl group with six or more carbons is attached to a benzene ring, the compound is named as an alkane with a phenyl substituent. Some examples are as follows  

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The Constitutional Repeat Unit the repeat urrit of a polymer, is described in the section on polymer nomenclature in Appendix II. It is the chemical functional group which is named to rrame the polymer by enclosing the name of the Constitutional Repeat Urrit in parentheses and placing the word poly" in fiont of it. 

The first section of this chapter is devoted to a statement of the problem of total synthesis and to a historical review. In the second section, the synthetic aspects of the formation, of the steroid skeleton and the introduction of functional groupings are considered. The third section is devoted to an analysis of certain problems connected with the formation of centers of asymmetry during total synthesis. Since the experimental material is summarized in detail in Chapters II-IV, in these sections, essentially, we give only references to the appropriate schemes of synthesis. Finally, in the fourth section of this chapter, the main features of the nomenclature of the synthetic steroids obtained by total synthesis are briefly discussed. 

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