aldehydes and ketones

• have a carbonyl functional group (C=O)
• aldehydes have a carbonyl group at the end carbon

  there suffix is -al
• ketones have a carbonyl group on an inner carbon

  suffix is -one
• aldehydes and ketones have lower boiling points compared to alcohols

  this is because they have London forces and induced dipole dipole forces

  they do not have hydrogen bonding
• aldehydes and ketones can form hydrogen bonds with water therefore are soluble

  however as the carbon chain increases the solubility decreases
• why does the solubility decreases as the ketone or aldehyde chain increases

  they have larger hydrocarbon components which are nonpolar and cant form hydrogen bonds

  only the oxygen in the C=O bond can form hydrogen bonds with water
• testing for aldehydes and ketones

  using acidified potassium dichromate

  aldehydes: will be oxidised. will turn the solution from orange to green

  ketones: will not be oxidised
• testing for aldehydes and ketones

  tollens reagent

  aldehydes: tollens reagent is reduced and forms silver which coats inside of flask

  ketone: no silver precipitate formed
• how is tollens reagent made

  react silver nitrate with ammonia
• testing for aldehydes and ketones

  Fehling's solution

  aldehydes: blue solution to brick red precipitate

  ketone: no reaction
• testing for aldehydes and ketones

  benedict's solution

  aldehydes: blue solution to brick red precipitate

  ketone: no reaction
• aldehydes and ketones can be reduced to form primary and secondary alcohols
• potassium cyanide reacts with the carbonyl group to form hydroxynitriles
• potassium cyanide reacts with carbonyl group via nucleophilic addition
• hydroxynitriles

  substances that contain a OH and CN group
• testing for carbonyl groups using Brady's reagent

  it is first dissolved in sulfuric acid and methanol before being added to the substance.

  if carbonyl group is present, a bright orange precipitate forms
• carbonyl reaction with iodine (methyl carbonyl groups)

  heat iodine in the presence of a methyl carbonyl group

  forms a yellow precipitate (triiodomethane)
• methyl carbonyl groups are only found in the following circumstances

  in ethanal

  in ketones with methyl group