page_title: Amide
section_title: Bonding
hierarchical_section_title: Amide / Properties / Bonding
context_page_description: In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula RCNR′R″, where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it is part of the main chain of a protein, and isopeptide bond when it occurs in a side chain, such as in the amino acids asparagine and glutamine. It can be viewed as a derivative of a carboxylic acid RCOH with the hydroxyl group –OH replaced by an amine group –NR′R″; or, equivalently, an acyl group RC– joined to an amine group.
  Common examples of amides are acetamide H₃C–CONH2, benzamide C₆H₅–CONH2, and dimethylformamide HCON(–CH₃)₂.
  Amides are qualified as primary, secondary, and tertiary according to whether the amine subgroup has the form –NH₂, –NHR, or –NRR', where R and R' are groups other than hydrogen.
  The core –CN= of amides is called the amide group.
  Amides are pervasive in nature and technology. Proteins and important plastics like Nylons, Aramid, Twaron, and Kevlar are polymers whose units are connected by amide groups; these linkages are easily formed, confer structural rigidity, and resist hydrolysis.
context_section_description: The lone pair of electrons on the nitrogen atom is delocalized into the carbonyl group, thus forming a partial double bond between nitrogen and carbon.  In fact the O, C and N atoms have molecular orbitals occupied by delocalized electrons, forming a conjugated system.  Consequently, the three bonds of the nitrogen in amides is not pyramidal (as in the amines) but planar.
  The structure of an amide can be described also as a resonance between two alternative structures:
  It is estimated that for acetamide, structure A makes a 62% contribution to the structure, while structure B makes a 28% contribution.  (These figures do not sum to 100% because there are additional less-important resonance forms that are not depicted above). There is also a hydrogen bond present between the active groups hydrogen and nitrogen atoms. Resonance is largely prevented in the very strained quinuclidone.
caption: Ball-and-stick model of the formamide molecule, showing the π molecular orbitals (gray).
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