1.1 Alkanes

Organic Chemistry

  • Organic Chemistry is the study of carbon-based compounds.
    • Except CO, CO2, HCN. These are inorganic compounds.
    • Organic compounds all contain: CHNOPS
    • ^^Carbon^^
    • ^^Hydrogen^^
    • Nitrogen
    • Oxygen
    • Phosphorus
    • Sulfure

Alkanes

  • Called saturated hydrocarbons - they cannot fit any more hydrogens
  • All bonds are single bonds
  • General formula is CnH2n + 2
    • An alkane with 4 carbons: C4H10 (Butane)

Representation of Molecules

  • Structural diagram

    • Complete/Extended: shows all bonds
    • Condensed: show only the bonds between carbon atoms, all atoms bonded to any particular are written directly behind it

  • Space-filled model

  • Ball-and-stick model

  • Lined diagram

  • Molecular formula

  • Expended molecular formula

Naming Straight Chain Alkanes

  • The “root” of the name describes the number of carbons in the chain.

Cyclic Alkanes

  • The chain is linked to form a closed loop.
  • Add “cycle” as a prefix.
  • Example: cyclobutane

Structural Isomers

  • compounds that have the same molecular formula, but different structure

  • A straight butane has the same molecular formula as a propane carbon branch

Substituent & Alkyl Groups

  • Substituent group: an atom or group of atoms that replaces a hydrogen in an organic compound.

  • Alkyl group: one or more carbon atoms that form a branch off the main chain of a hydrocarbon.

    • If the group is attached to the main chain via a middle carbon, a number is inserted:

How to name alkanes

  1. Find the longest carbon chain (called the parent chain)
  2. Identify the substituent groups
  3. Number the parent chain so that the substituents are attached to the carbon atom with the smallest number. In case of a tie, the group that comes first alphabetically gets the lowest number
  4. If the same substituent is present more than once, use a prefix (di, tri, tetra) and include the number to indicate the substituent’s location
  5. List the substituents in alpha order (NOT including the di, tri tetra). Separate words by hyphens, numbers by commas.

Prefix + Root + Suffix

  • Prefix: name and location of substituents
  • Root: # of carbons in parent chain
  • Suffix: type of hydrocarbon