9.8: Functional Group introduction

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Learning Objectives
• to describe functional groups and explain why they are useful in the study of organic chemistry.

Previously, we considered several kinds of hydrocarbons. Now we examine some of the many organic compounds that contain functional groups. We first introduced the idea of the functional group, a specific structural arrangement of atoms or bonds that imparts a characteristic chemical reactivity to the molecule. If you understand the behavior of a particular functional group, you will know a great deal about the general properties of that class of compounds. In this chapter, we make a brief yet systematic study of some of organic compound families. Each family is based on a common, simple functional group that contains an oxygen atom or a nitrogen atom. Some common functional groups are listed in Table 7.8.1.

Table 7.8.1 Selected Organic Functional Groups
Name of Family General Formula Functional Group Suffix*
alkane RH none -ane
alkene R2C=CR2 -ene
alkyne RC≡CR –C≡C– -yne
alcohol ROH –OH -ol
thiol RSH –SH -thiol
ether ROR –O– ether
aldehyde -al
ketone -one
carboxylic acid -oic acid
*Ethers do not have a suffix in their common name; all ethers end with the word ether.

Concept Review Exercises

1. What is the functional group of an alkene? An alkyne?

2. Does CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3 have a functional group? Explain.

1. carbon-to-carbon double bond; carbon-to-carbon triple bond

2. No; it has nothing but carbon and hydrogen atoms and all single bonds.

Key Takeaway

• The functional group, a structural arrangement of atoms and/or bonds, is largely responsible for the properties of organic compound families.

Exercises

1. What is the functional group of 1-butanol (CH3CH2CH2CH2OH)?

2. What is the functional group of butyl bromide, CH3CH2CH2CH2Br?