ALDEHYDES + KETONES

• Aldehydes


  Organic compounds recognised by the functional group -CHO containing a carbonyl group (C=O)
• Aldehydes


  • Produced from the initial oxidation and distillation of 1o alcohols
  • Readily oxidise further in the presence of acidified potassium dichromate to produce carboxylic acids
• Aldehydes


  • Tested for using Tollen's reagent or Fehling's solution as they produce a positive result in both tests if present
• Ketones


  Organic compounds recognised by the functional group -C=O, a carbonyl group
• Ketones


  • Produced from the oxidation of 2o alcohols with acidified potassium dichromate
  • No further oxidation and they produce no visible change with both Tollen's reagent and Fehling's solution
• Reduction of aldehydes and ketones

  1. Reducing agent of NaBH4 is used

  2. Example of nucleophilic addition
• Nucleophilic addition reactions with :CN- nucleophile

  1. Causes the carbon chain to be extended by one carbon atom

  2. Produces a hydroxy-nitrile
• Hydroxy-nitriles


  • Commonly contain a chiral carbon centre meaning optical isomers of the product exist
  • The :CN- nucleophile can attack from either above or below the double bond, causing different enantiomers to be produced
• Naming hydroxynitriles


  The carbon on the nitrile group is included in the carbon chain and is taken to be carbon number one
• Hydroxynitrile


  • 2-hydroxypropanenitrile