CHAPTER 15: Hydrocarbons

• Introduction to Alkanes
• Reactions of Alkanes
• Introduction to Alkenes
• Reactions of Alkenes
• Uses of Hydrocarbons

Learning outcomes:

• show awareness of the general unreactivity of alkanes, including towards polar reagents
• describe the chemistry of alkanes as exemplified by the following reactions of ethane:
  • combustion
  • substitution by chlorine and by bromine
• describe the mechanism of free-radical substitution at methyl groups with particular reference to the initiation, propagation and termination reactions
• describe the chemistry of alkenes as exemplified, where relevant, by the following reactions of ethene and propene (including the Markovnikov addition of asymmetric electrophiles to propene):
  • addition of hydrogen, steam, hydrogen halides and halogens
  • oxidation by cold, dilute, acidified manganate(VII) ions to form the diol
  • oxidation by hot, concentrated, acidified manganate(VII) ions leading to the rupture of the carbon-to-carbon double bond in order to determine the position of alkene linkages in larger molecules
  • polymerisation
• describe the mechanism of electrophilic addition in alkenes, using bromine/ethene and hydrogen bromide/propene as examples
• explain the use of crude oil as a source of both aliphatic and aromatic hydrocarbons
• suggest how ‘cracking’ can be used to obtain more useful alkanes and alkenes of lower Mr from larger hydrocarbon molecules
• describe and explain how the combustion reactions of alkanes led to their use as fuels in industry, in the home and in transport
• recognise the environmental consequences of:
  • carbon monoxide, oxides of nitrogen and unburnt hydrocarbons arising from the internal combustion engine and of their catalytic removal
  • gases that contribute to the enhanced greenhouse effect