Carboxylic Acids

• Carboxylic acids


  Organic compounds with the functional group -COOH
• Formation of carboxylic acids from alcohols and aldehydes


  1. Primary alcohols are oxidised to aldehydes

  2. Aldehydes are further oxidised to carboxylic acids

  
• Oxidising agent


  Acidified potassium dichromate(VI)
• Oxidation of alcohols and aldehydes

  Potassium dichromate(VI) changes colour from orange to green
• Oxidation of primary alcohols

  RCH2OH + [O] → RCHO + H2O

  
• Oxidation of aldehydes


  RCHO + [O] → RCOOH + H2O

  
• Full oxidation of alcohols

  RCH2OH + 2[O] → RCOOH + 2H2O

  
• Formation of carboxylic acids from nitriles

  1. Acid hydrolysis: Nitrile is heated under reflux with dilute acid, producing carboxylic acid and salt

  2. Alkaline hydrolysis: Nitrile is heated under reflux with alkali, producing carboxylic acid and ammonia

  
• Formation of salts from carboxylic acids

  1. Reaction with metals: Carboxylic acid + metal → salt + hydrogen

  2. Reaction with alkalis: Carboxylic acid + alkali → salt + water

  3. Reaction with carbonates: Carboxylic acid + carbonate → salt + carbon dioxide + water

  
• Formation of alkyl esters

  Carboxylic acid + alcohol, heated with acid catalyst → ester

  
• Reduction of carboxylic acids to alcohols

  RCOOH + 4[H] → RCH2OH + H2O

  
• Acid hydrolysis of esters


  Ester + water ⇌ carboxylic acid + alcohol

  
• Alkaline hydrolysis of esters


  Ester + alkali → carboxylate salt + alcohol

  
• Commercial uses of esters


  Solvents, perfumes, flavourings