1.11: Amines and Amides

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Rebekah O'Donnell
Boston University via OpenStax CNX

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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.