Organic Chemistry: Concepts and Applications - Headley Allan D. 2020

Carbon Functional Groups and Organic Nomenclature
2.2 Functional Groups

The functional groups shown in Figure 2.1 all have basically the same heteroatoms, but for each functional group, the atomic arrangements are different. A functional group can be defined also as a specific arrangement of a particular set of atoms in regions of molecules. In later chapters, we will see that reactions of organic molecules take place at the functional groups. Thus, it is important to be able to recognize functional groups. The heteroatoms that comprise functional groups are mostly oxygen, nitrogen, and halogens, but many contain other heteroatoms, such as phosphorous, sulfur, and silicon. There are few functional groups, however, that contain only carbon atoms that are either sp² or sp hybridized; specifically, the carbon—carbon double bond and the carbon—carbon triple bond. Table 2.1 lists the common functional groups that we will encounter in organic chemistry.

Figure 2.1 Examples of common compounds that have different functional groups, functional groups are highlighted in red.

Table 2.1 Common functional groups of organic molecules.

R represents a group of atoms, typically alkyl groups, bonded to the functional group.

In Figure 2.2, the functional groups of some of the molecules shown in Figure 2.1 are identified.

Figure 2.2 Commonly known compounds with functional groups identified.

Problem 2.1

i. Give the name of the functional group in each of the following molecules.

ii. Utilizing structures similar to those shown in part (i) of this question, give structural formulas for different compounds that contain no more than four carbons and contain the following functional groups.