Amines, Amides & Amino acids

• Amines = derived from ammonia in which one or more hydrogen are replaced by a carbon chain (aliphatic) or ring (aromatic).

  They can be primary, secondary or tertiary based on now many carbons are attached to the N.

  
• Amides = derived from carboxylic acids in which the OH group is replaced by an amine group.
• because of their lone pair amines act as bases

  • the lone pair will form a dative bond & will accept H+.
  • CH3NH2 + HCl = CH3NH3+Cl-
• ammonia and amines can act as nucleophiles

  • 2NH3CH3CH2Cl = CH3CH2NH2 + NH4+Cl-
• a nucleophile is a species that donates a pair of electrons to form a covalent bond.
• how do you make an aliphatic amine?

  react ammonia and a haloalkane

  • CH3CH2Cl + NH3 --> CH3CH2NH3+Cl-
  • because a salt is made NaOH is used to neutralise it
  • CH3CH2NH3+Cl- + NaOH --> CH3CH2NH2 + NaCl + H2O
• how do you make an aromatic amine?

  by reduction of nitrobenzene using Sn (tin), conc HCl and NaOH

  
• When making aliphatic amines an excess of NH3 is used to prevent further substitution.

  • ethanol is used as a solvent because if water was used it would react with the haloalkane --> alcohol.
• benzene with an amine group is called phenylamine
• amino acids contain both a carboxylic acid group and an amine group.

  
• what group of an amino acid does an acid (HCl) react with?

  amino group, forming NH3+
• what group of an amino acid does an alkali (NaOH) react with?

  carboxylic acid group, forming a CO-Na+
• what group of an amino acid does an alcohol react with?

  • both amine and carboxyl group, esterification due to ester bond forming with COOH group.
  • amine group becomes NH3+.