1. 9.8 – NOTES Naming Branching Alkanes

2. Straight-chain alkanes
A.9 Alkanes Revisted
Straight-chain alkanes
Each carbon atom is linked to 1 or 2 carbons depending on location in the chain

3. Branched chain alkanes
One carbon is bonded to three or four other carbons
Need at least 4 carbons to be branched

4. Structural isomers
Molecules with identical formulas but different arrangements of atoms
Result in different boiling points and different properties
More branches result in lower boiling points

5. Examples:
C4H10
Draw and unbranched and branched.

6. C5H12
Draw and unbranched and branched.

7. Naming branched alkanes
Determine the name of the parent chain
Count the longest continuous chain of carbon atoms – it may not appear to be in a straight line
Determine the prefix based on the number of carbons in the longest chain
Add the ending –ane.

8. Determine the name of the branches
These names go in front of the parent chain.
Find the number of carbon that the branch is on, this needs to be the lowest numbered carbon atom.
Find the name of the group.
Find the root for the number of carbons in the chain (meth, eth, prop, etc.)
Add the suffix –yl
If there is more than on chain with the same number of carbons, use the following prefixes to indicate the number of that specific chain.
2 = di
3 = tri
4 = tetra
5 = penta
If more than one type of chain is present, list the chains in alphabetical order.

9. Examples
3-methylpentane

10. 2-methylpentane

11. 2,3-dimethylbutane