Ester

• Ester

  molecules are polar but have no hydrogen atom attached directly to an oxygen atom.
• Ester: Water Solubility

  • Esters of low molar mass are somewhat soluble in water.
  • Borderline solubility occurs in those molecules that have three to five carbon atoms.
• Ester: Water Solubility

  • longer alkyl group decrease solubility
• Boiling Point and Melting Point

  • Esters are polar molecules, but their boiling points are lower than those of carboxylic acids and alcohols of similar molecular weight because there is no intermolecular hydrogen bonding between ester molecules.
• Ester Hydrolysis

  • Acidic hydrolysis is simply the reverse of esterification.
  • Easter is heated with a large excess of water containing a strong-acid catalyst.
• Ester Hydrolysis

  • When a base (such as sodium hydroxide [NaOH] or potassium chromate hydroxide [KOH]) is used to hydrolyze an ester, the products are a carboxylate salt and an alcohol.
  • Soaps are prepared by the alkaline hydrolysis of fats and oils, alkaline hydrolysis of esters is called saponification.
• Chemical Test: RCOOR + Hydroxylamine

  Esters with hydroxylamine produce hydroxamic acids, which form intense, colored complex (often dark maroon) with Fe3+
• Drugs with ester substituents

  Clopidogrel

  • Anticoagulant

  Enalapril

  • Diuretic
• Esters as Anesthethics

  Coccaine

  Benzocaine

  Chloroprocaine