Definition
Amides are organic compounds containing a carbonyl group (C=O) whose carbon atom is bonded to a nitrogen atom. They have the following general structure: R1, R2 and R3 can be aliphatic and aromatic radicals or hydrogen atoms. Amides can be synthesized with a carboxylic acid (or a carboxylic acid halide) and an amine using heat or a catalyst.
Nomenclature
Amides are named with the suffix -amide, for example ethanamide (trivial name acetamide) or propanamide. Amides can be aliphatic, aromatic, and cyclic. The cyclic amides are called lactams (see also under beta-lactam antibiotics). Anilides are amides derived from aniline.
Examples
- Benzamide
- Ethanamide
- Dipeptide
- Tripeptides
- Oligopeptides
- Peptides
- Proteins
Properties
- Amides can be hydrogen bond donors as well as acceptors. They are donors only when an NH or NH2 group is present.
- Unlike the amines, the amides are not basic. Acid-base reactions are only possible under extreme conditions.
- Amides are essential for life on Earth because amino acids, the building blocks of peptides and proteins, are linked with amide bonds. They are among the most important biomolecules.
Reactions
The amide bond is a strong bond. Its hydrolysis requires strong acids such as hydrochloric acid or strong bases such as sodium hydroxide in a high concentration.
In pharmaceuticals
Numerous active ingredients and excipients contain amides as a functional group. For example, therapeutic proteins, diazepam, thalidomide, capsaicin, barbiturates, and penicillins.
