IUPAC Naming Basics

The IUPAC naming convention (International Union of Pure and Applied Chemistry) is a systematic method for naming chemical compounds to ensure consistency and clarity worldwide. Here is an overview of the rules and guidelines for naming organic compounds:

IUPAC Naming Procedure

1. Identify the Longest Carbon Chain (Parent Chain)

• Choose the longest continuous chain of carbon atoms as the parent chain.
• If multiple chains have the same length, select the chain with the greatest number of substituents attached.

2. Number the Carbon Chain

• The carbon numbered 1 will be the one closest to the highest-priority functional group
• If the functional groups have the same priority, numbering the chain should make the numbers of the substituted carbons as low as possible
• The more oxidized the carbon is, the higher its priority in the molecule
• Oxidation states increases with more bonds to heteroatoms (atoms besides carbon and hydrogen, like oxygen, nitrogen, phosphorous, or halogens) and decreases with more bonds to hydrogen
• Rings are also numbered starting at the point of greatest substitution, and continues in the direction that gives the lowest numbest to the highest-priority function groups
  • Double bond takes precedence over a triple bond if there is a tie in priority 

3. Identify and Name Substituents

• To clarify, substituents are functional groups that aren’t part of the parent chain
• Name substituents (side chains) as prefixes.
• Common substituents include:
  • Alkyl groups (e.g., methyl, ethyl, propyl).
  • Halogens (e.g., fluoro, chloro, bromo, iodo).
• For multiple identical substituents, use prefixes such as di-, tri-, tetra-.
• Carbon chain substituents are names like alkanes,with the suffix -yl replacing -ane. 
• The prefix n- indicates that  the alkane is normale (straight chain)

4. Assign Locants to Substituents

• Indicate the position of each substituent using the corresponding carbon number in the parent chain.
  • Multiple substituents of the same type will get di-, tri, and tetra- prefixes
• Separate numbers from each other with commas and separate numbers from letters with hyphens.

5. Assemble the Name

• Substituents are listed alphabetically, ignoring prefixes like di-, tri-, and tetra- (but not iso- or neo-).
• Combine the substituents, parent chain name, and functional group (if any).
• Numbers are separated with each other with commas, anf from words with hyphens
• We end the name with the backbone chain, including the suffix for the functional group of highest priority

6. Include Functional Groups

IUPAC Functional Group Priority Table

Priority | Functional Group  | Suffix                 | Prefix
1             | Carboxylic acid     | -oic acid             | Carboxy-
2            | Anhydride               | -oic anhydride | —
3            | Ester                         | -oate                  | Alkoxycarbonyl-
4            | Acid halide             | -oyl halide         | Halocarbonyl-
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