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1.11: Amines and Amides

  • Page ID
    222815
  • Learning Objective

    • How to name amines and amides.

    An amino group consists of a nitrogen atom bonded to two hydrogen atoms, written as -NH2. If the hydrogens are replaced by R groups, the group is referred to as a substituted amino group. Amines and amides are two compounds which contain amino or substituted amino groups.

    Amines are designated as primary, secondary, or tertiary amines based upon the degree of substitution of the amino group. For example, an amine in which all three of the potential nitrogen bonds are with R groups instead of hydrogens is called a tertiary amine (see the right-most molecule below).

    Figure \(\PageIndex{1}\).svg
    Figure \(\PageIndex{1}\): primary, secondary, and tertiary amines

    Despite the complexity of the below molecule, because the nitrogen is directly bound to two hydrogens and only one R group, it is a primary amine.

    Figure \(\PageIndex{2}\).svg
    Figure \(\PageIndex{2}\): an enormous primary amine

    There are multiple substitutive nomenclatures for naming amines, with the two most common being IUPAC and Chemical Abstract Service. Both will be described below.

    This molecule is named 2-pentanamine (CAS) or 2-aminopentane (IUPAC).

    Figure \(\PageIndex{3}\).svg
    Figure \(\PageIndex{3}\): 2-pentanamine (CAS) / 2-aminopentane (IUPAC)

    Practice Questions

    1. What are the names of Molecule A?

    Molecule A

    Figure \(\PageIndex{4}\).svg

    Figure \(\PageIndex{4}\).

    2. This molecule is named 1,6-hexanediamine (CAS) or 1,6-diaminohexane (IUPAC).

    Figure \(\PageIndex{5}\).svg
    Figure \(\PageIndex{5}\): 1,6-hexanediamine (CAS) / 1,6-diaminohexane (IUPAC)

    What are the names of Molecule B?

    Figure \(\PageIndex{6}\).svg
    Figure \(\PageIndex{6}\): Molecule B

    3. This molecule is named N,N-dimethylethanamine (CAS) or dimethylaminoethane (IUPAC).

    N,N-dimethylethanamine (CAS) / dimethylaminoethane (IUPAC)

    Figure \(\PageIndex{7}\).svg

    Figure \(\PageIndex{7}\).

    What are the names of Molecule C?

    Figure \(\PageIndex{8}\).svg
    Figure \(\PageIndex{8}\): Molecule C

    4. This molecule is named 4-amino-2-pentanone (CAS) or 4-aminopentan-2-one (IUPAC). Number the carbons.

    Figure \(\PageIndex{9}\).svg
    Figure \(\PageIndex{9}\): 4-amino-2-pentanone (CAS) / 4-aminopentane-2-one (IUPAC)

    5. Number the carbons. What are the names of Molecule D?

    Figure \(\PageIndex{10}\).svg
    Figure \(\PageIndex{10}\): Molecule D

    6. This molecule is named 2-(N-methylamino)ethanol (CAS) or 2-methylaminoethanol (IUPAC). Number the carbons.

    Figure \(\PageIndex{11}\).svg
    Figure \(\PageIndex{11}\): 2-(N-methylamino)ethanol (CAS) / 2-methylaminoethanol (IUPAC)

    7. Number the carbons. What are the names of Molecule E?

    Figure \(\PageIndex{12}\).svg
    Figure \(\PageIndex{12}\): Molecule E

    An amide is a carboxylic acid derivative in which the carboxyl -OH has been replaced with an amino or substituted amino group. Amides are also described as primary, secondary, or tertiary depending on the number of R groups bound directly to the nitrogen.

    Figure \(\PageIndex{13}\).svg
    Figure \(\PageIndex{13}\): primary, secondary, and tertiary amides

    The naming of simple amides is based on the carboxylic acid nomenclature, and keeps the same name in the CAS and IUPAC systems.

    The name of this molecule is 3-methylbutanamide.

    Figure \(\PageIndex{14}\).svg
    Figure \(\PageIndex{14}\): 3-methylbutanamide

    Practice Questions

    1. What is the name of Molecule F?

    Molecule F

    Figure \(\PageIndex{15}\).svg

    Figure \(\PageIndex{15}\).

    2. The name of this molecule is N-methylbenzamide.

    Figure \(\PageIndex{16}\).svg
    Figure \(\PageIndex{16}\): N-methylbenzamide

    What is the name of Molecule G?

    Figure \(\PageIndex{17}\).svg
    Figure \(\PageIndex{17}\): Molecule G

    3. What additions do we make to our existing naming rules to name amines and amides, in the substitutive naming system that you use?

    4. Write the steps that you use to name an amine in order, as instructions for a student who doesn't know how to do it.

    5. Draw any amine and go through the steps in naming your molecule.

    6. Write the steps that you use to name an amide in order, as instructions for a student who doesn't know how to do it.

    7. Draw any amide and go through the steps in naming your molecule.

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