Amidebased

Amide-based compounds are chemical species that contain one or more amide functional groups, defined by a carbonyl group (C=O) directly bonded to a nitrogen atom (R-CO-NR'R''). The amide bond exhibits resonance that gives the C–N bond partial double-bond character, resulting in planarity and high polarity. This stabilizes amide-containing structures and reduces reactivity compared with many carbonyl compounds. Amide-based materials encompass small molecules, polymers, and ligands in coordination chemistry.

Amides are categorized by the substitution on nitrogen: primary amides (R-CO-NH2), secondary amides (R-CO-NHR'), and tertiary amides (R-CO-NR'R''). N-substituted amides include a wide range of structures, including aromatic (benzamide) and aliphatic derivatives. Their synthesis commonly involves condensation of carboxylic acids (or derivatives) with amines, often promoted by coupling reagents or dehydrating conditions. Peptide bonds between amino acids are biologically important amide linkages, formed by enzyme-catalyzed ligation in living organisms.

Amide groups confer characteristic properties such as high resonance stabilization, relatively high boiling points for simple amides, and strong hydrogen-bonding capabilities, influencing solubility and thermal properties. Amide bonds are relatively resistant to hydrolysis but can be cleaved under strong acid or base or by specific enzymes (amidases, proteases). Applications span pharmaceuticals, where many drugs contain amide moieties, and polymers, notably polyamides like nylon, where amide linkages give mechanical strength and stability. Amide-based chemistry thus plays a central role in biology, materials science, and chemical synthesis.