Amide

An amide (/ˈæmaɪd/ or /ˈæmɪd/ or /ˈeɪmaɪd/), also known as an acid amide, is a compound with the functional group R_nE(O)_xNR'₂ (R and R' refer to H or organic groups). Most common are carboxamides (organic amides) (n = 1, E = C, x = 1), but many other important types of amides are known including phosphoramides (n = 2, E = P, x = 1 and many related formulas) and sulfonamides (E = S, x= 2). The term amide refers both to classes of compounds and to the functional group (R_nE(O)_xNR'₂) within those compounds.

Amide can also refer to the conjugate base of ammonia (the anion H₂N⁻) or of an organic amine (an anion R₂N⁻). For discussion of these "anionic amides", see Alkali metal amides.

The remainder of this article is about the carbonyl-nitrogen sense of amide.

Structure and bonding

The simplest amides are derivatives of ammonia wherein one hydrogen atom has been replaced by an acyl group. The ensemble is generally represented as RC(O)NH₂. Closely related and even more numerous are amides derived from primary amines (R'NH₂) with the formula RC(O)NHR'. Amides are also commonly derived from secondary amines (R'R''NH) with the formula RC(O)NR'R''. Amides are usually regarded as derivatives of carboxylic acids in which the hydroxyl group has been replaced by an amine or ammonia.