Organic Reactions

• Balancing Hydrocarbons


  carbon, hydrogen, oxygen
• thermal cracking


  hydrocarbons are heated until they vaporise

  vapour is passed over a hot catalyst

  thermal decomposition takes place

  products include alkanes and alkened
• steam cracking


  hydrocarbons are mixed with steam and heated to a high temperature
• Alkenes


  carbons have double bonds - unsaturated

  formula: CnH2n

  simplest: ethene, propene, butene, pentene
• alkene + hydrogen -> alkane
• alkene + steam -> ethanol
• alkenes are more reactive than alkanes
• alkenes react with bromine water, turning it from orange to colourless


  ethene reacts with bromine to form dibromoethane
• fermentation


  sugar -> ethanol + carbon dioxide

  temperatures of 25 - 50
• Alcohols


  dissolve in water to form neutral solutions

  react with sodium to produce hydrogen

  burn in air to produce carbon dioxide and water

  are used as fuels and solvents

  simplest: methanol, ethanol, propanol, butanol

  contain functional group -OH (hydroxyl)
• Carboxylic acids


  contain functional group -COOH (carboxyl)

  dissolve in water to form acidic solutions

  react with carbonates to produce carbon dioxide

  react with alcohols to form esters

  do not ionise fully in water - weak acids
• Esters


  functional group -COO

  volatile compounds (low boiling point)

  distinctive smells

  ethanol + ethanoic acid -> ethyl ethanoate
• Amino acids


  amine group -NH2

  carboxyl group -COOH
• DNA


  made from 2 polymer chains constructed from four different nucleuotides
• ethanol + sodium -> sodium ethoxide + hydrogen
• ethanol + oxidising agent -> ethanoic acid + water
• ethanoic acid + sodium carbonate -> sodium ethanoate + carbon dioxide + water
• carboxylic acid + alcohol -> ester + water
• production of esters requires a sulfuric acid catalyst