11. Basic concepts of Organic Chemistry

• organic chemistry - the chemistry of carbon-containing compounds
• Carbon:

  • has 4 valence shell electrons and forms 4 covalent bonds
  • Electronic configuration: 1s2 2s2 2p2
  • forms giant covalent structures such as diamond and graphite, as well as simple covalent molecules like fullerene (C60)
• hydrocarbon - compound containing only hydrogen and carbon

  • saturated: only single C-C bonds
  • unsaturated: contains double and triple C=C bonds
• Functional group - group of atoms which give an organic compound its characteristic properties and reactions
• homologous series:

  • families of similar chemical properties e.g. alkene, alkane
  • they have:
  • similar chemical properties
  • a trend in physical properties
  • differ by CH2
  • same functional group
  • same general formula
• Rules for naming compounds:

  1. find longest unbranched chain (end of name)
  2. identify an alkyl groups attached
  3. number the carbons in the main chain (aim for lower numbers)
  4. attach the numbered alkyl group as a prefix to the name
  5. side groups should be arranged alphabetically; adding di, tri or tetra doesn't change order
• substituted alkanes have a halo- prefix added e.g. fluoro, bromo, chloro, iodo. Nitrogen substitution is nitro
• cycloalkanes are named normally, with cyclo added before the suffix
• empirical formula - simplest whole number ratio of atoms of each element in a compound
• molecular formula - number of atoms of each element in a molecule
• structural formula - shows in minimal detail which atoms, or groups, are attached to each other in one molecule
• displayed formula - shows all the atoms and all the bonds between them in a molecule of a compound
• skeletal formula - shows the functional group fully but the hydrocarbon part of the molecule simply as lines between carbon atoms
• isomer - same molecular formula, different structural formula
• structural isomer - same molecular formula but different structural formula. 3 types: chain, position, functional group
• chain isomer - linear vs branched
• position isomer - moving functional group
• functional group isomer - OH vs O-C-H (alcohol vs ester)
• Homolytic fission:

  • each bonded atom takes one of the shared pairs of electrons from the bond
  • each atom contains one unpaired electron and is known as a radical
• Heterolytic fission:

  • one of the bonded atoms takes both bonded pairs of electrons
  • a cation and anion are formed
• curly arrows:

  • show the movement of a pair of electrons
  • homolytic - one headed arrow
  • heterolytic - double headed arrow
• addition reaction: the addition of two or more reactants to form a single product with 100% atom economy
• addition polymerisation: small molecules with double bonds add to each other and join up in long chains with 100% atom economy
• elimination: produces an unsaturated product by loss of atoms or groups from adjacent carbons
• substitution: one atom or group is replaced by another atom or group