IUPAC naming system

Naming Branched Alkanes

1. Find Parent Chain: Longest continuous chain of carbons (if two equal chains exist, pick the one with more substituents).

2. Number Parent Chain: Start from the end closer to a substituent.

3. Name Substituents: Alkyl groups end in -yl (e.g., methyl, ethyl).

4. Assemble Name: List substituents alphabetically with locator numbers (e.g., 3-ethyl-2-methylhexane). Use multipliers (di-, tri-) for identical groups.

Naming Substituted Cycloalkanes

• 1 Substituent: No locator number needed (e.g., methylcyclopentane).

• 2+ Substituents: Number ring to give the lowest possible set of locator numbers for the first two groups, counting clockwise or counterclockwise. List groups alphabetically.

Naming Substituted Alkenes and Alkynes

1. Parent chain must contain both carbons of the double/triple bond.

2. Change suffix to -ene (alkene) or -yne (alkyne).

3. Number chain starting from the end closer to the double/triple bond (takes priority over substituents).

4. Place locator number before the parent name (or suffix) indicating the first bond carbon (e.g., 2-pentene or 2-pentyne). Add cis- or trans- prefix if applicable

Naming Substituted Benzenes

• Parent name is benzene.

• Monosubstituted: No locator number used (e.g., ethylbenzene).

• Disubstituted: Assign numbers (1,2, 1,3, or 1,4) around the ring to get the lowest locator set; list substituents alphabetically.