aromatics

• Sun - source of fossil fuels and hydrocarbons

  Hydrocarbons: aliphatics and aromatics

  Aliphatics: alkanes, alkenes, alkynes

  Aromatics: benzene-parent compounds
• aromatic compounds:

  • compounds containing the benzene (C6H6) ring
  • Benzene is unreactive and more stable than alkenes and alkynes
  • reacts like alkanes - it does not undergo addition reactions
  • Benzene is not considered saturated or unsaturated
• Benzene has 3 double C-C bonds and 3 single C-C bonds. Structure was not understood until Kekule had a dream about a snake chasing his tail
• benzene had delocalized bonds; it is a resonance structure
• • benzene is a non-polar liquid that is colourless and flammable, with a sweet distinctive odour
  • it is carcinogenic and used in industrial processes (plastics, lubricants, rubbers, glue, paints, dyes, etc.)
  • VOC - volatile organic compound
• when benzene is a branch, it is called phenyl
• Bromine Test:

  • Ethene (ethylene) will react with bromine in an addition reaction
  • Brown -> colourless = positive result -> unsaturated sample (bonds present; alkene or alkyne)
  • Benzene will NOT undergo an addition rxn with bromine
• KMNO4 Test (Baeyer's Reagent)

  • Ethene (ethylene) will undergo an addition rxn with KMNO4
  • positive: pink would disappear; dark brown ppt = unsaturated sample
  • negative: pink would stay; no ppt = saturated sample
  • Benzene will NOT undergo a rxn
• Uses

  • Alkanes - fuel
  • Alkenes and alkynes - make stuff
  • Aromatics - glues, solvents, paints