Alkenes &

Alkynes

Alkenes Hydrocarbons containing double

bonds. General Formula: CnH2n

They are unsaturated – the double bond is a reactive site for other atoms to bond to the carbon atom.

Naming Alkenes Alkenes # of C

AtomsPrefix Alkene

2 Eth- Ethene3 Prop- Propene4 But- Butene5 Pent- Pentene6 Hex- Hexene7 Hept- Heptene8 Oct- Octene9 Non- Nonene10 Dec- Decene

Naming Alkenes1. The parent chain must contain the

double bond. (even if it is not the longest chain)

Naming Alkenes2. The parent chain carbon atoms are

numbered starting at the end closest to the double bond.

Naming Alkenes2. The position of the double bond is

indicated in the name by stating the number of the carbon atom in the parent chain that the double bond follows.

3. 1-pentene

Naming Alkenes3. Name the branches.

Naming Alkenes4. Name the compound.

2-ethyl-1-pentene

Naming Alkenes1. Parent Chain.2. Number the parent

chain.3. Name the

branches.4. Name the

compound

2-hexene

Naming Alkenes1. Parent Chain.2. Number the parent

chain.3. Name the

branches.4. Name the

compound

1,3-pentadiene

Alkynes Hydrocarbons containing triple

bonds. General Formula: CnH2n-2

They are unsaturated – the double bond is a reactive site for other atoms to bond to the carbon atom.

Naming Alkynes The same rules for naming an alkene

apply; however the ending is “yne” instead of “ene.”

Naming Alkynes Alkynes # of C

AtomsPrefix Alkyne

2 Eth- Ethyne3 Prop- Propyne4 But- Butyne5 Pent- Pentyne6 Hex- Hexyne7 Hept- Heptyne8 Oct- Octyne9 Non- Nonyne10 Dec- Decyne

Naming Alkynes1. Parent Chain.2. Number the parent

chain.3. Name the

branches.4. Name the

compound3-methyl-1-pentyne

Naming Alkynes1. Parent Chain.2. Number the parent

chain.3. Name the

branches.4. Name the

compound3-ethyl-4-methyl-1-hexyne