CARBOXYLIC ACIDS + ESTERS

• Carboxylic acids


  Organic compounds recognised by the functional group -COOH containing a carbonyl group (C=O) and an -OH acid group
• Production of carboxylic acids

  Oxidation of 1o alcohols under reflux
• Carboxylic acids


  Weak acids that slightly dissociate when in solution, forming a H+ ion and a carboxylate ion, RCOO-
• Reaction of carboxylic acids with carbonates

  Produces a carboxylate salt, water and CO2
• Small chain carboxylic acids

  • Able to form hydrogen bonds with water molecules between the lone electron pair on an oxygen atom and a ∂+ hydrogen atom
  • Soluble in water
• Esterification


  Carboxylic acids can react with alcohols in the presence of a strong acid catalyst to form esters
• Esters


  • Sweet smelling compounds used in food flavourings and perfumes
  • Have low boiling points
  • Good solvents for other polar molecules
• Triglyceride esters


  Vegetable oils and fats are esters of naturally occurring glycerol (propane-1,2,3-triol)
• Biodiesel


  An ester produced from vegetable oils and methanol in the presence of a strong acid catalyst
• Ester hydrolysis


  Reverse reaction to esterification, converting esters back into alcohols and carboxylic acids by adding water
• Ester hydrolysis under acidic conditions


  Simple reverse reaction back to an alcohol and a carboxylic acid
• Ester hydrolysis under alkaline conditions

  1. Carboxylic acid produced reacts further with the base to form a salt

  2. Production of this salt is called saponification

  3. Salts have hydrophilic and hydrophobic properties, commonly used as soaps
• Carboxylic acid derivatives


  Acid anhydrides, acyl chlorides, amides
• Reactions of carboxylic acid derivatives

  Nucleophilic addition-elimination reactions where the addition of a nucleophile leads to the elimination of a product under aqueous conditions
• Reactions of acyl chlorides

  • With water = Carboxylic acid
  • With alcohol = Ester
  • With ammonia = Amide
  • With amines = N-substituted amide
• Aspirin


  An ester produced from salicylic acid and ethanoic anhydride
• Ethanoyl chloride can also be used to produce aspirin but is not used in industry as it is expensive and produces harmful HCl fumes as part of the reaction. Ethanoic anhydride is much safer for industrial use.
• Elimination reaction


  A type of reaction where two substituents are removed from a molecule, resulting in the formation of a double bond. This can be represented by the general equation: RX + Y^- -> RY + X^-
• Substitution reaction


  A type of reaction where one functional group is replaced by another functional group. This can be represented by the general equation: RX + Y -> RY + X
• Carboxylic acid derivatives elimination reactions

  Typically involve the removal of a leaving group (X) and a proton (H) from the alpha carbon, resulting in the formation of a double bond between the alpha and beta carbons.
• Carboxylic acid derivatives substitution reactions

  Typically involve the replacement of a leaving group (X) with a nucleophile (Y).