mod 5

• unsaturated aliphatics

  -carbon atoms form multiple bonds

  -more reactive than saturated
• alkenes

  -contain at least one double bond
• alkynes

  • contain at least one triple bond
• alkenes

  • olefins (oil making)
  • CnH2n
  • contain two hydrogen less than the corresponding alkanes
  • useful products like plastics and rubber
• ethylene

  • first member of this homologous series
• Alkynes

  • unsaturated aliphatic hydrocarbons characterized by a triple covalent bond between two carbon atoms
  • CnH2n-2
  • contain four hydrogen less than the corresponding alkanes
  • two hydrogen less than the alkenes
  • acetylene series
• acetylene

  CH =-CH

  • first member of the acetylene series
• ethyne

  C2H2

  • commonly known as acetylene, is a linear molecule with all four atoms in a line
  • bond angles in the molecule are 180º
• alkene : thylene

  product : polythylene

  structure CH2-CH2

  use : films, pipes, containers
• alkene : Tetrafluoroethylene

  product : teflon

  structure (CF2-CF2 )n

  use : gaskets, valves, insulation
• alkene : chloroprene

  product : neoprene

  use : rubber substitute
• alkenes

  • slightly smaller molar masses, their boiling points are slightly lower than the corresponding alkanes.
• C1 to C5 : gas alkenes room temp.

  C5 to C17 : liquid alkenes

  above C17 : solid alkenes
• alkene

  • non polar
  • soluble in organic solvents
  • insoluble in water
• alkene

  • less dense than water
• alkene

  • burn in air with luminous flame.
  • Ethylene burns with yellow flame forming carbon dioxide and water as products of combustion
• most common alkene reaction is the addition of two new groups to the double-bonded carbons
• Markovnikov’s rule

  • states that when a hydrogen containing unsymmetric molecule (HX) adds to a double bond, the hydrogen will add to the carbon with the greatest number of hydrogens.
• Another typical alkene reaction is oxidation; this reaction impacts many biological materials.
• Acetylene

  • is a colorless, odorless gas (at room temperature and pressure) that is partially water soluble
• Acetylene reacts with oxygen to yield a very hot flame – a property used in oxyacetylene cutting and welding.