6.2/6.3 carbonyls, carboxylic acids and esters

• Carbonyl compounds


  Organic molecules containing a C=O group
• Examples of carbonyl compounds

  • Aldehydes
  • Ketones
  • Carboxylic acids
  • Esters
  • Amides
  • Acyl chlorides
  • Acid anhydrides
• Oxidation of alcohols


  1. Primary alcohol -> Aldehyde + H2O

  2. Secondary alcohol -> Ketone
• Oxidising agents


  • Acidified potassium dichromate (changes colour from orange to green)
  • Potassium permanganate (changes colour from purple to colourless)
• Distillation of aldehydes


  Prevent further oxidation
• Reflux


  Heating contents to high temperatures without losing any
• Nucleophilic addition


  With CN- to form hydroxynitrile
• Reduction of carbonyls


  Aldehyde to primary alcohol, Ketone to secondary alcohol
• Reducing agents


  NaBH4 (produces H-), Hydride ion
• Carbonyl compound reactions


  • Oxidation
  • Distillation
  • Reflux
  • 2,4-DNPH test
  • Tollens' test
  • Nucleophilic addition
  • Reduction
• Carboxylic acids


  Weak acids with general formula CnH2n+1COOH
• Properties of carboxylic acids


  • Water-soluble if less than 6 carbons due to hydrogen bonding
  • Form salts with metals, alkalis and carbonates
• Esters


  Carboxylic acid derivatives containing the ester group -COO-
• Esterification


  Condensation reaction between a carboxylic acid and an alcohol, catalysed by concentrated H2SO4
• Ester hydrolysis


  By dilute acid or dilute alkali
• Acyl chlorides


  Compounds with the COCl functional group, prepared from carboxylic acids and SOCl2
• Reactions of acyl chlorides


  Hydrolysis, reaction with alcohols to form esters, reaction with ammonia and amines to form amides