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Chemistry LibreTexts

1.1: Functional Groups in Organic Compounds

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  • Learning Objectives

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

    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. Some common functional groups are listed in Table \(\PageIndex{1}\).

    Last semester, we studied alkanes, alkenes, alkynes, aromatic, alcohols, thiols, ethers, and phenols. This semester, we will begin with aldehydes and ketones as our first functional groups

    Table \(\PageIndex{1}\): Selected Organic Functional Groups
    Name of Family General Formula Functional Group Suffix*
    alkane RH none -ane
    alkene R2C=CR2 alkene.jpg -ene
    alkyne RC≡CR –C≡C– -yne
    alcohol ROH –OH -ol
    thiol RSH –SH -thiol
    ether ROR –O– ether
    aldehyde aldehyde formula.jpg aldehyde functional group.jpg -al
    ketone ketone formula.jpg ketone functional group.jpg -one
    carboxylic acid carboxylic acid formula.jpg carboxylic acid functional group.jpg -oic acid
    *Ethers do not have a suffix in their common name; all ethers end with the word ether.


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

    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.


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

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


    1. OH

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