Basics concepts of organic chemistry

• Organic chemistry


  Originally defined by the Swedish chemist Jacob Berzelius as the chemistry of compounds derived from living systems
• Today about sixteen million organic compounds are known
• Before 1828, scientists did not believe it was possible to make organic compounds from inorganic compounds
• In 1828, the German chemist Friedrich Wöhler accidentally synthesised urea whilst attempting to prepare ammonium cyanate from silver cyanide and ammonium chloride
• This was the first organic synthesis carried out from inorganic compounds, dispelling the myth that only living organisms could produce organic compounds
• Modern organic chemistry


  Studies the structure, properties, composition, reactions, and preparation of carbon-containing compounds
• Organic compounds are vital in every area of modern life: pharmaceutical, detergents, dyes and pigments, cosmetics, plastics, and agricultural chemicals
• Today, the vast majority of the organic materials used are produced from fractions of crude oil
• Carbon


  In Group 14(4) of the periodic table, with four electrons in its outer shell
• Each carbon atom can form four covalent bonds to other atoms
• Carbon atoms can bond to other carbon atoms to form long chains
• Hydrocarbon


  A compound containing carbon and hydrogen only
• Hydrocarbons


  • methane
  • but-2-ene
  • propyne
• Saturated hydrocarbon


  Has single bonds only
• Unsaturated hydrocarbon


  Contains carbon-to-carbon multiple bonds
• Homologous series


  A family of compounds with similar chemical structures and properties, where successive members differ by the addition of a -CH2- group
• Alkanes homologous series


  • methane
  • ethane
  • propane
• Functional group


  The part of the organic molecule that is largely responsible for the molecule's chemical properties
• Functional groups


  • alcohol-OH
  • amine-NH2
• The bond angles around carbon in an alkane is 109.5°, not 90° as suggested by displayed formula
• Aliphatic


  Carbon atoms are joined to each other in unbranched (straight) or branched chains, or non-aromatic rings
• Alicyclic


  Carbon atoms are joined to each other in ring (cyclic) structures, with or without branches
• Aromatic


  Some or all of the carbon atoms are found in a benzene ring
• Homologous series of aliphatic hydrocarbons

  • Alkanes
  • Alkenes
  • Alkynes
• Stem


  Indicates the number of carbon atoms in the longest continuous chain in the molecule
• Prefix


  Can be added before the stem, often to indicate the presence of side chains or a functional groups
• Suffix


  Added after the stem to indicate functional groups
• Steps for naming aliphatic alkanes

  • Identify the longest continuous chain of carbon atoms (the 'parent' chain) and name it
  • Identify any side chains attached to the parent chain (alkyl groups)
  • Add numbers before any alkyl groups to show the position on the parent chain
• When two or more side chains are the same, the prefixes di-, tri-, or tetra- are used, corresponding to two, three, or four of the same side chain respectively
• Cyclic alkanes


  The prefix cyclo- is used in front of the stem to show the carbon atoms are arranged in a ring structure
• Alkenes


  Named using the same rules as for alkanes, except the suffix is -ene. The position of the C-C bond in the chain must be stated for alkenes that have four or more carbon atoms in the longest chain.
• Common functional groups


  • Alkene (-C=C-)
  • Alcohol (-OH)
  • Haloalkane (-X)
  • Aldehyde (-CHO)
  • Ketone (-C(=O)-)
  • Carboxylic acid (-COOH)
  • Ester (-COO-)
  • Acyl chloride (-COCl)
  • Amine (-NH2)
  • Nitrile (-CN)
• Common functional groups


  • Alcohol
  • Halogen
  • Aldehyde
  • Carboxylic acid
  • Ester
  • Acyl chloride
  • Amine
  • Nitrile
• Alkanes


  Longest unbranched chain of carbon atoms
• Naming alkanes


  1. Identify the longest unbranched chain of carbon atoms

  2. The stem is the name of the corresponding alkane

  3. Identify any functional groups and alkyl side chains

  4. Use appropriate prefixes or suffixes

  5. Number any alkyl groups and functional groups to indicate their position on the longest unbranched chain
• Molecular formula


  Shows the number and type of atoms of each element present in a molecule
• Empirical formula


  The simplest whole-number ratio of the atoms of each element present in a compound
• General formula


  The simplest algebraic formula for any member of a homologous series
• Displayed formula


  Shows the relative positioning of all of the atoms in a molecule and the bonds between them
• Structural formula


  Uses the smallest amount of detail necessary to show the arrangement of the atoms in a molecule