Overview
This lecture introduces the IUPAC system for naming organic compounds, focusing on breaking down compound names into prefix, root, and suffix, and demonstrating the process with detailed examples.
IUPAC Naming System Overview
- Organic compounds have millions of varieties, making a systematic naming method necessary.
- IUPAC names consist of three parts: prefix, root, and suffix.
- The goal is to build a solid foundation for naming organic molecules before addressing specific functional groups.
The Root: Longest Carbon Chain
- The root identifies the longest continuous chain/branch/ring of carbon atoms in the molecule.
- Count the carbons to determine the root: e.g., seven carbons = "hept".
- Common roots: 1=meth, 2=eth, 3=prop, 4=but, 5=pent, 6=hex, 7=hept, etc.
- Always identify the longest possible chain for the root.
The Suffix: Type of Compound/Functional Group
- The suffix indicates the family/type of compound or key functional group.
- For all single bonds, use "-ane" (alkane); double bonds use "-ene".
- Example: a seven-carbon chain with only single bonds is "heptane".
The Prefix: Substituents and Location
- Prefixes identify groups (substituents) attached to the parent chain, not part of it.
- Substituents such as CH₃ (methyl) are named with location numbers on the chain (e.g., 4-methyl).
- For multiple identical substituents, use prefixes (di-, tri-, tetra-) and list all locations (e.g., 2,3-dimethyl).
- Place a dash between numbers and letters, and a comma between multiple numbers.
Naming Example Breakdown
- Find the longest carbon chain (e.g., heptane for seven carbons).
- Identify and number substituent location(s) (e.g., methyl on carbon 4).
- Combine for the full name: 4-methylheptane.
Key Terms & Definitions
- IUPAC — International Union of Pure and Applied Chemistry, sets naming rules.
- Root — base name from the longest carbon chain.
- Suffix — ending indicating molecule type or functional group (e.g., -ane, -ene).
- Prefix — indicates attached groups/substituents outside the main chain.
- Substituent — group replacing hydrogen on the parent chain.
- Alkyl group — hydrocarbon substituent (e.g., methyl, ethyl).
Action Items / Next Steps
- Create flashcards for common roots, suffixes, and alkyl group names.
- Practice naming organic compounds using prefix-root-suffix format.
- Read textbook section on functional groups for more suffix practice.