Crash Course Organic Chemistry: Lecture Summary

Introduction to Organic Chemistry and Language

• Organic chemistry communication is complex, similar to language differences.
• Common names for chemicals can vary and be confusing.
• The International Union of Pure and Applied Chemistry (IUPAC) standardizes chemical nomenclature.

IUPAC Naming System

Historical Context

• Organic chemistry existed over 100 years before IUPAC.
• Common names were often based on origin, smell, or color.
• IUPAC created systematic naming for global consistency.

Basic Steps in IUPAC Naming

1. Find the Longest Carbon Chain
   • Assign a root name based on the number of carbon atoms.
   • Carbon chains’ root names:
     • 1: meth-, 2: eth-, 3: prop-, 4: but-
     • Mnemonic: Monkeys Eat Purple Bananas
     • 5 to 12 carbon chains use geometric shape names (e.g., pent-, hex-).
2. Identify the Highest Priority Functional Group
   • Add a suffix to the root name.
   • Types of hydrocarbons:
     • Alkanes (single bonds): suffix -ane
     • Alkenes (double bonds): suffix -ene
     • Alkynes (triple bonds): suffix -yne
3. Identify Substituents and Positions
   • Add numbered prefix to root name for substituents.
   • Numbering the chain from the end closes to substituents or functional groups.

Hydrocarbons and Functional Groups

Alkanes

• Only single bonds, less reactive.
• Naming: add suffix -ane to root name.

Alkenes and Alkynes

• Functional groups involve double or triple bonds.
• Naming requires identifying position of bonds:
  • Alkenes: add suffix -ene, e.g. pent-1-ene
  • Alkynes: add suffix -yne, e.g. oct-4-yne

Substituents in Naming

• Substituents can replace hydrogen atoms with other atoms/groups.
• Examples of substituents: -CH3, halogens (chloro-, bromo-, iodo-).
• Prefixes added alphabetically; use di-, tri-, tetra- for multiples.
• Example with multiple substituents: 3-chloro-2,4-dimethylhexane.

Systematic Naming of Complex Molecules

• Combine root name, suffix, and substituent prefixes.
• Example: 4-bromo-3-methylhept-1-ene-6-yne.

Common Names vs. Systematic Names

• Common names (e.g., methylene chloride) vs. systematic names (e.g., dichloromethane).
• Common names can be less precise; systematic names provide structure clarity.

Conclusion

• The systematic approach allows chemists to effectively communicate complex structures.
• Next steps: naming molecules with functional groups containing heteroatoms.