IB DP Chemistry: SL复习笔记10.1.4 Organic Families - Hydrocarbons

Alkanes

  • Hydrocarbons are compounds containing hydrogen and carbon only
  • There are four families of hydrocarbons you should know: alkanes, alkenes, alkynes and arenes
  • Alkanes have the general molecular formula CnH2n+2. They contain only single bonds and are said to be saturated
  • Alkanes are named using the nomenclature rule alk + ane
  • The alk depends on the number of carbons as outlined in the previous Section 10.1.2

10.1.4-Alkanes-First-6-members-110.1.4-Alkanes-First-6-members-2

The first six members of the alkane family

Alkenes

  • Alkenes have the general molecular formula CnH2n
  • They are said to be unsaturated
  • Alkenes are named using the nomenclature rule alk + ene
  • In molecules with a straight chain of 4 or more carbon atoms, the position of the C=C double bond must be specified
  • The carbon atoms on the straight chain must be numbered, starting with the end closest to the double bond
  • The lowest-numbered carbon atom participating in the double bond is indicated just before the -ene:

10.1.4-Alkenes-First-5-members-110.1.4-Alkenes-First-5-members-2

The first five members of the alkene family

  • There is a distinction to be made between the name of the functional group and the name of the family
  • The name of the family is alkene, but the name of the functional group is alkenyl

Alkynes

  • Alkynes have the general molecular formula CnH2n-2
  • The triple bond makes them unsaturated molecules
  • Alkynes are named using the nomenclature rule alk + yne
  • As with alkenes, in molecules with a straight chain of 4 or more carbon atoms, the position of the triple bond must be specified
  • The carbon atoms on the straight chain must be numbered, starting with the end closest to the triple bond
  • The lowest-numbered carbon atom participating in the triple bond is indicated just before the -yne:

10.1.4-Alkynes-First-5-members-110.1.4-Alkynes-First-5-members-2

The first five members of the alkyne family

  • The name of the functional group is alkynyl

Arenes

  • Arene is the collective name given to compounds with one or more rings with pi electrons that are delocalised throughout the ring(s)
  • Compounds with this feature are said to be aromatic
  • This doesn't mean they are necessarily smelly, although a lot of naturally occurring arenes do have distinctive smells!

10.1.4-Arenes-1

Arenes are present in many everyday chemicals and pharmaceuticals

  • BenzeneC6H6, is the only aromatic hydrocarbon that is covered in IB Chemistry and is dealt with in Section 10.1.12
  • The functional group in benzene is known as a phenyl group when attached to other molecules

 

 

 

 

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