ALCOHOLS

Cards (10)

  • Alcohols contain an -OH group and follow the general formula CnH2n+1OH
  • Alcohols can be produced via two main methods: hydration and fermentation
  • Hydration method:
    • Alcohols are produced from alkenes in the presence of an acid catalyst
    • Phosphoric acid is commonly used as the catalyst under aqueous conditions at 300°C and high pressures
    • Very high percentage yield as ethanol is the only product, favored as an industrial process
  • Fermentation method:
    • Enzymes break down starch from crops into sugars which can be fermented to form alcohol
    • Cheaper than hydration, can be carried out at a lower temperature
    • Fermented in batches, slower process with a lower percentage yield
    • Ethanol is a common biofuel produced in this way, considered carbon neutral
  • Alcohols can be primary (1o), secondary (2o), or tertiary (3o)
    • 1o and 2o alcohols can be oxidised to produce various products
    • 3o alcohols are not easily oxidised
  • 1o alcohols can be heated in the presence of acidified potassium dichromate and distilled to produce aldehydes
    • When heated further under reflux conditions, 1o alcohols oxidise further to produce carboxylic acids
  • 2o alcohols can be oxidised when heated in the presence of acidified potassium dichromate to produce ketones
  • Potassium Dichromate (K2Cr2O7) is used in the oxidation of alcohols as the oxidising agent
    • It is reduced as the alcohol is oxidised, observed as a colour change from orange to green
  • Alkenes can be formed from the dehydration of alcohols, where a molecule of water is removed from the molecule
    • Excess of hot sulfuric acid is added and aluminium oxide is used as a catalyst
  • H+ acidic ions are reformed in the reaction showing how they act as a catalyst
    • Addition polymers can be produced from fermentation without the need for crude oil, a nonrenewable resource
    • Fermentation produces the primary alcohol which is then dehydrated to produce an alkene used in the production of addition polymers