• A?base?is a species that can?donate?its lone pair of electrons to form a?dative covalent bond?with another species
• Amines?are basic as the?nitrogen?atom has a lone pair of electrons which can form a dative covalent bond with anelectron-deficient species (such as an H⁺?ion)
• The?basicity?of the amine depends on the availability of this lone pair of electrons
  • The?more readily?available the lone pair of electrons is for dative covalent bonding, the?stronger the base
  • The?less readily?available the lone pair of electrons is, the?weaker the base
• Electron-donating?groups such as alkyl groups?increase?the electron density on the nitrogen atom causing the lone pair to become more available
• Electron-withdrawing?groups such as aromatic benzene rings, cause?delocalisation?of the lone pair of electrons which become less readily available
• This is why?phenylamine?(which contains an electron-withdrawing benzene ring) is a?weaker base?than?propylamine?(which contains an electron-donating alkyl group)

Basicity of amides

• Amides also contain a nitrogen atom with a lone pair of electrons
• Again, the?basicity?of the amide depends on the availability of this lone pair for dative covalent bonding
• Due to the presence of the?electron-withdrawing?oxygen atom in the amide group, electron density is?removed?from the nitrogen atom
• The lone pair on the nitrogen atom, therefore, becomes?less readily?available and is not available to donate to an electron-deficient species
• Since this electron-withdrawing oxygen is characteristic of amides and is?not?present in amines, amides are?much weaker bases?than amines