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4.7: Amides

  • Page ID
    340353
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    Learning Objectives

    • Identify the general structure for an amide.
    • Identify the functional group for an amide.
    • Names amides with common names.
    • Name amides according to the IUPAC system.

     

    Amides are carboxylic acid derivatives that contain a functional group has an nitrogen atom attached to a carbonyl carbon atom. If the two remaining bonds on the nitrogen atom are attached to hydrogen atoms, the compound is a simple amide. If one or both of the two remaining bonds on the atom are attached to alkyl or aryl groups, the compound is a substituted amide.

    general structure of an amide
     

    Figure \(\PageIndex{1}\): General structure of an amide. If R' and R'' are both hydrogen atoms, the compound is a simple amide. If not, it is a substituted amide.

     

    The carbonyl carbon-nitrogen bond is called an amide linkage. This bond is quite stable and is found in the repeating units of protein molecules, where it is called a peptide linkage.

     

    Naming Amides

    Simple amides are named as derivatives of carboxylic acids. The -ic acid ending of the common name or the -oic acid ending of the International Union of Pure and Applied Chemistry (IUPAC) name of the carboxylic acid is replaced with the suffix -amide.

    naming.jpg

     Figure \(\PageIndex{2}\): Structures of a carboxylic acid (left) and amide (right) along with common (top) and IUPAC (bottom) names.

     

    The names of substituted amides, include the identity of the R' or R'' (of N–R) substituents.  Instead of locator numbers, N– is used to indicate the location of these groups (Figure \(\PageIndex{3}\)). 

    structure of a substituted amide

     Figure \(\PageIndex{3}\): Skeletal structure of N,N-diethylpentanamide.

     

    Example \(\PageIndex{1}\)

    Name each compound with the common name, the IUPAC name, or both.

    1.   clipboard_e058ba88ac7fd31b4c53e349c494beba8.png

       
    2.   structure of a substituted amide

       

    Solution

    1. This amide has two carbon atoms and is thus derived from acetic acid. The OH of acetic acid is replaced by an NH2 group. The -ic acid from acetic acid (or -oic acid from ethanoic acid) is dropped, and -amide is added to give acetamide (or ethanamide in the IUPAC system).

    2. This is a substituted amide since there is a methyl group bonded to the nitrogen. The parent portion of the molecule is derived from butanoic acid. The -oic acid is dropped, and -amide is added to give butanamide. The methyl group is attached to the nitrogen (N) of the functional group, so the location is indicated as N-methyl. Therefore the name of the molecule is N-methylbutanamide.

     

    Exercise \(\PageIndex{1}\)

    Name each compound with the common name, the IUPAC name, or both.

    1.   clipboard_e034f0f4ad2aa384c02ef17a1457a3aa5.png
       
    2.   clipboard_ea72761843b67752dc441426669d9cc0b.png

     

    Key Takeaways

    • Amides have a general structure in which a nitrogen atom is bonded to a carbonyl carbon atom.
    • The functional group for an amide is as follows:
      KT.jpg
    • In names for amides, the -ic acid of the common name or the -oic acid ending of the IUPAC for the corresponding carboxylic acid is replaced by -amide.

     


    4.7: Amides is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.