Lecture Notes: Organic Nomenclature

Two Parts of Organic Nomenclature

• First Name (Prefix): Side chains attached to the main molecule.
• Last Name (Suffix): Backbone or the longest carbon chain.
  • Example: In "2-methylpentane", "pentane" is the backbone, and "methyl" is the side chain.

Suffixes (Functional Groups)

• Examples include:
  • Alkanes, Alkenes, Alkynes.
  • Amines, Alcohols.
• Structure examples:
  • 1-butene: Indicates a double bond at position 1.
  • 1-butanol: Contains an alcohol group.
  • Molecule configurations can be varied (same molecule, different drawings).

Prefixes and Common Errors

• Prefixes: Indicate quantity of groups (di, tri, tetra, etc.).
• Common errors:
  • "Di" is for two, not "bi".
  • "Tetra" is for four, not "quad".
• Example naming:
  • 2,2-dimethylbutane if two methyl groups are attached.
  • 2,2,4,4-tetramethylbutane for four methyl groups.

Writing Structure and Numbering

• Commas and Dashes:
  • Use a comma between numbers.
  • Use a dash between numbers and letters.
  • No spaces between names.
• Numbering System:
  • Aim for the smallest possible combination.
  • Start numbering to give the smallest location number for side chains.
  • Example: "2-methylpentane" (not "4-methylpentane").

Arranging Side Chains Alphabetically

• Side chains are listed alphabetically, ignoring prefixes.
  • Example: "3-ethyl-2-methylpentane"
  • Ethyl (E) comes before Methyl (M).
  • Order: Butyl (B) > Ethyl (E) > Methyl (M) > Propyl (P).

Priority Groups

• Priority Groups: Important for future classes.
  • Example: Aldehydes have priority over alkenes.
  • Priority affects numbering and placement.
• Topic is beyond current class scope; reserved for advanced organic chemistry.

These notes cover key points on nomenclature, naming structures, common errors, and numbering systems within organic chemistry.