14.3
Nomenclature of Carboxylic Acid Derivatives: Amides and Nitriles
Naming Amides
The IUPAC and common names of amides are derived from the parent carboxylic acid, by replacing the suffix “oic acid” and “ic acid,” resp…
The IUPAC and common names of amides are derived from the parent acid by replacing the suffix "oic acid" and "ic acid," respectively, with "amide."
Amides, where the nitrogen atom bears alkyl groups, are named as N-alkyl or N,N-dialkyl substituents, with the groups listed in alphabetical order.
When the amide is attached to a ring, the suffix "carboxylic acid" is substituted with "carboxamide."
Cyclic analogues are named by replacing the suffix "oic acid" or "ic acid" with "olactam."
The names bear a prefix indicative of the ring size, denoted by a number for IUPAC names and a Greek letter for common names.
In nitriles, the IUPAC names are derived by adding the suffix "-nitrile" to the parent alkane.
For common names, the suffix "ic acid" of the parent acid is changed to "onitrile."
Lastly, a nitrile group bonded to a cycloalkane is named by citing the parent cycloalkane followed by the suffix "carbonitrile."
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Q1: How do you name amides using IUPAC nomenclature?
IUPAC amide names are derived from the parent carboxylic acid by replacing the suffix 'oic acid' with 'amide.' For example, ethanoic acid becomes ethanamide. When alkyl groups are bonded to the nitrogen atom, they are specified as N-alkyl or N,N-dialkyl substituents, listed in alphabetical order. For instance, N-methylethanamide contains a methyl group attached to nitrogen.
Q2: What is the difference between common and IUPAC names for amides?
Common amide names replace the suffix 'ic acid' of the parent acid with 'amide,' while IUPAC names replace 'oic acid' with 'amide.' For example, acetic acid becomes acetamide in common nomenclature, whereas ethanoic acid becomes ethanamide in IUPAC nomenclature. Both systems follow the same substitution rules for N-alkyl groups.
Q3: How are cyclic amides or lactams named?
Cyclic amides, called lactams, are named by replacing the suffix 'ic acid' of the parent acid with 'olactam.' The location of the oxygen atom on the ring is indicated by numbering carbons from the carbonyl carbon. For IUPAC names, a number prefix is used; for common names, a Greek letter replaces the number. For example, butyrolactam is the common name for γ-butyrolactam.
Q4: How do you name an amide group attached to a ring?
When an amide group is bonded to a ring, the suffix 'carboxylic acid' is replaced with 'carboxamide.' For example, cyclohexanecarboxylic acid becomes cyclohexanecarboxamide. This naming convention applies to both IUPAC and common nomenclature systems for ring-substituted amides. The parent ring structure remains unchanged.
Q5: What is the IUPAC naming rule for nitriles?
IUPAC nitrile names are derived by adding the suffix '-nitrile' to the parent alkane. For example, ethane becomes ethanenitrile. When a nitrile group is attached to a cycloalkane, the parent cycloalkane is named first, followed by the suffix 'carbonitrile,' such as cyclohexanecarbonitrile.
Q6: How do common names for nitriles differ from IUPAC names?
Common nitrile names are derived by replacing the suffix 'ic acid' of the parent carboxylic acid with 'onitrile.' For instance, acetic acid becomes acetonitrile. In contrast, IUPAC names use the parent alkane with the suffix '-nitrile,' so ethane becomes ethanenitrile. Both systems apply the same rules for cycloalkane-bonded nitriles.
Q7: What distinguishes N-alkyl amides from N,N-dialkyl amides in nomenclature?
N-alkyl amides have one alkyl group bonded to nitrogen, denoted as N-alkyl in the name, such as N-methylethanamide. N,N-dialkyl amides have two alkyl groups on nitrogen; if identical, they use the prefix N,N-di-, like N,N-dimethylethanamide. If different, both groups are listed alphabetically, such as N-ethyl-N-methylethanamide.