Nomenclature of Carboxylic Acid Derivatives: Amides and Nitriles

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.

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.

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.

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.

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.

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.

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.