The amide functional group is:
Amides are commonly formed from the reaction of a carboxylic acids with an amine:
This is the reaction that forms peptide bonds between amino acids. These amides can participate in hydrogen bonding as hydrogen bond acceptors and donors, but do not ionize in aqueous solution, wheras their parent acids and amines are slightly ionised in solution.
An amide linkage is kinetically stable to hydrolysis. Amide linkages in a biochemical context are called peptide linkages. Amide linkages constitute a defining molecular feature of proteins, the secondary structure of which is due in part to the hydrogen bonding abilities of amides.
Amides play a large part in condensation polymers, see for instance nylon and polyacrylamide[?].
Sulfonamides are amides in which the atom double bonded to oxygen is sulfur rather than carbon.
Amides can be broken down in amide hydrolysis.
Compounds in which a hydrogen atom on nitrogen from ammonia or an amine is replaced by a metal cation are also known as amides, or azanides.
References
- IUPAC Compendium of Chemical Terminology, http://www.chemsoc.org/chembytes/goldbook/