alkanes

• Termination


  The step at the end of a radical substitution when two radicals combine to form a molecule.
• Propagation


  The steps that continue a free radical reaction, in which a radical reacts with a reactant molecule to form a new molecule and another radical, causing a chain reaction.
• Radical

  A species with an unpaired electron.
• Saturated


  Containing single bonds only.
• Saturated hydrocarbon


  A hydrocarbon with single bonds only.
• Alkanes


  The hydrocarbon homologous series with the general formula CnH2n+2
• Chain reaction

  A reaction in which the propagation steps release new radicals that continue the reaction
• Initiation

  The first stage in a radical reaction in which radicals starts when a covalent bond is broken by homolytic fission
• homolytic fission

  breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals
• Alkanes lack reactivity because

  • C-C and C-H sigma bonds are strong
  • C-C bonds are non-polar
  • the electronegativity of carbon and hydrogen is so similar that the C-H bond can be considered non-polar
• Alkanes are used as fuels because...

  • they are readily available
  • easy to transport
  • burn in a plentiful supply of oxygen without releasing toxic products
• State two limitations of using radical substitution in organic synthesis

  1. further substitutions
  2. substitution at different positions along chain
• Alkanes are used as fuels because: readily available, easy to transport, burn to release no toxic products