carbonyl compounds

• oxidation of carbonyl compounds


  • only aldehydes oxidised - oxidised to carboxylic acids
  • oxidising agent is a acidified potassium dichromate
  • carried out under reflux
  • colour change orange -> green
• oxidation of aldehyde to carboxylic acid

  
• nucleophilic addition reactions of carbonyls


  • reduction using NaBH4 followed by addition of water
  • NaBH4 is a source of hydride ions, H+

  
• mechanism for nucleophilic addition

  
• reaction with HCN


  • HCN toxic so carbonyl reacted with mixture of H2SO4/NaCN
  • product is a hydroxynitrile
  • e.g propanal with HCN

  
• mechanism for reaction with HCN

  
• identifying aldehydes to ketones 


  • testing for C=O
  • brady's reagent
  • orange precipitate confirms presence of C=O
  • purify precipitate by recrystallisation
  • measure melting point of purified derivative
  • compare melting point to known data values