Physical and Chemical Properties of Aldehydes & Ketones

• aldehydes & ketones have a carbonyl group- which is a carbon double bonded to an oxygen atom (C=O)
• aldehyde- when the carbonyl group is at the end of the chain
• ketone- when the carbonyl group is in the middle of the chain or in a ring
• some common ketones are: propanone (acetone) & cyclohexanone
• some common aldehydes are: methanal (formaldehyde), ethanal (acetaldehyde), benzaldehyde
• the carbonyl group is very polar
  • this makes aldehydes & ketones up to 3-4 carbons in length miscible in water
• they are less soluble in water and have lower boiling points than alcohols
  • more soluble in water and have higher boiling points than ethers & hydrocarbons
• aldehydes & ketones undergo addition reactions at the carbon-oxygen double bond called nucleophilic addition
  • this is different from alkene addition because the carbonyl double bond is polar while alkenes have a non-polar pi bond
• ketones can’t be further oxidized but aldehydes can be oxidized to carboxylic acids

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