alcohol

• primrary alcohols are oxidised to aldehydes and can be further oxidised to carboxylic acids
• secondary alcohols are oxidised to ketones and cant be oxidised further
• tertiary alcohols are not easily oxidised as oxidation would need a c-c bond to break rather than a C-H
• most ketones and aldehydes have a pleasant smell
• experimental details of oxidation

  • a solution of potassiumdichromate , acidified with sulfuric acid is used to oxidise alcohols
  • the orange dichromate (VI) ions are reduced to green chromium (III) ions
• to oxidise primary ethanol to aldehyde

  • use dilute sulfuric acid and less pottassiumdichromate (VI) than is need for carboxcylic acid
  • the mixture is heated with the receiver cooled to reduce evaporation
  • ethanal vapourises as soon as its formed and distills off before becoming a carboxylic acid
• to oxidise primary ethanol to carboxylic acid

  • concentrated sulfuric acid and more than enough potassiumdichromate (in excess)
  • the mixture is refluxed so any ethanol or ethanal vapour will condense and drip back into the flask until its oxidised to acid
  • after refluxing for around 2o mintues you can distill off ethanoic acid
• reflux means the vapour condenses and drips back into the reaction flask