Carboxylic Acids

• Carboxylic acids

  • are organic compounds having hydroxyl group attached to the acyl group.
  • The hydroxyl group of carboxylic acid may be substituted with other functional groups resulting in the formation of carboxylic acid derivatives.
• Carboxylic acids: Physical Properties

  • can be in liquid form or wax
  • have high boiling points due to hydrogen bonds between the molecules
  • colorless and have a particular odor
• Carboxylic acids: Physical Properties

  Carboxylic acid derivatives

  • also form hydrogen bonds with water molecules which makes them soluble in water
• Carboxylic acids

  • have much higher boiling points than hydrocarbons, alcohols, ethers, aldehydes, or ketones of similar molecular weight.
• Carboxylic acids: Boiling Point

  • The factors that influence the relative boiling points and water solubilities of various types of compounds.
  • In general, dipolar attractive forces between molecules act to increase the boiling point of a given compound, with hydrogen bonds being an extreme example.
  • Hydrogen bonding is also a major factor in the water solubility of covalent compounds.
• Carboxylic acids: Solubility

  • solubility of carboxylic acids in water is similar to that of alcohols, aldehydes, and ketones.
  • Acids with fewer than about five carbons dissolve in water.
  • The solubility decreases with increasing number of carbon atoms due to the increased hydrophobic interaction of hydrocarbon part.
  • Carboxylic acids are also soluble in less polar organic solvents like benzene, ether, alcohol, chloroform, etc.
• Carboxylic acids: Physical Phase

  Liquid Form

  • with less than ten number of carbon atoms are colorless liquids at room temperature.

  Wax

  • more than 10 carbon atoms are wax like solids.
  • The higher acids are wax like solids due to their low volatility.
• Carboxylic acids: Odor

  • colorless liquids with disagreeable odors.
  • 5 to 10 carbon atoms all have “goaty” odors.
  • more than 10 carbon atoms are waxlike solids, and their odor diminishes with increasing molar mass and resultant decreasing volatility.
  • These acids are also produced by the action of skin bacteria on human sebum (skin oils), which accounts for the odor of poorly ventilated locker rooms.
• Carboxylic acids: Chemical Properties

  • more acidic than other organic compounds containing hydroxyl groups but are generally weaker than the familiar mineral acids (e.g., hydrochloric acid, HCl, sulfuric acid, H2SO4, etc.).