9.8 – NOTES Naming Branching Alkanes

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

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

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

Examples: C4H10 Draw and unbranched and branched.

C5H12 Draw and unbranched and branched.

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.

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.

Examples 3-methylpentane

2-methylpentane

2,3-dimethylbutane