Pc2a M4.1

• Hydrocarbons are organic compounds containing only carbon and hydrogen.
• TYPES OF HYDROCARBONS

  SATURATED

  UNSATURATED

  CYCLOALKANES

  AROMATIC
• SATURATED

  • Composed entirely of single bonds and are saturated with hydrogen.
• UNSATURATED

  • Contain one or more double or triple bonds between carbon atoms, resulting in fewer hydrogen atoms than saturated hydrocarbons
• CYCLOALKANES

  • Saturated hydrocarbon containing one or more carbon rings to which hydrogen atoms are attached.
• AROMATIC

  • Table unsaturated cyclic compounds containing one or more six-carbon atom ring.
• ALIPHATIC HYDROCARBONS

  • Open-chain compounds contain no rings of any type and thus are termed aliphatic (straight chain HC).
  • “non-aromatic hydrocarbons”
  • Mostly are flammable.
• Aliphatic Hydrocarbons can be classified further by the type of bonds they contain:

  ALKANES

  ALKENES

  ALKYNES
• ALKANES

  • Presence of single bond (CnH2n+2)
  • Called paraffins (low affinity compounds), they do not react as most chemicals do
  • Saturated hydrocarbons (single covalent bonds) can be:

  1. LINEAR - carbon atoms are joined in a snake-like structure.
  2. BRANCHED - the carbon backbone splits off in one or more directions.
  3. CYCLIC - the carbon backbone is linked so as to form a loop.
• ALKENES

  • Presence of double bond (CnH2n)
  • Called olefins
• ALKYNES

  • Presence of triple bond (CnH2n-2)
  • TERMINAL ALKYNES - have triple bond at the end of the chain.
  • INTERNAL ALKYNES - have a carbon atom bonded to each carbon atom of the triple bond.
• PHYSICAL PROPERTIES OF ALIPHATIC CARBONS

  • All alkanes are colorless.
  • Alkanes with the lowest molecular weights are gasses and the heaviest are waxy solids.
  • Alkenes are lighter than water and are insoluble in water due to their non-polar characteristics.
• PHYSICAL STATES OF ALIPHATIC CARBONS

  • Gases (Fewer than 5 carbon atoms)
  • Liquid (5-15 carbon atoms)
  • solid (more than 15 carbon atoms)
• VOLATILITY

  • Hydrocarbons, in general, are volatile.
  • Higher molecular mass of hydrocarbons has low volatility.
• SOLUBILITY (Alkanes and cycloalkanes)

  • Soluble in organic solvents
  • Insoluble in water
• DENSITY

  Hydrocarbons are less dense than water.
• BOILING/MELTING POINT

  • Boiling point decreases as branching increases.
  • Melting point increases as branching increases.
  • Linear hydrocarbons have higher boiling than branched hydrocarbons.
  • Within the branched series, increased symmetry leads to higher melting point and lower boiling point
  • Increased molar mass, increased boiling point
• BOILING POINT OF SPECIFIED HYDROCARBONS

  • Alkane (-84C)
  • Alkene (-103.7C)
  • Alkyne (-88C)
• CHEMICAL REACTIONS OF ALIPHATIC HYDROCARBONS

  (CHEMICAL REACTIVITY)

  Increase Reactivity ->

  Alkane -> Alkene -> Alkyne