Naming Alcohols Lecture Notes

Basic Naming of Alcohols

• CH3OH

  • Common Name: Methyl alcohol
  • IUPAC Name: Methanol

• CH3CH2OH

  • Common Name: Ethyl alcohol
  • IUPAC Name: Ethanol

• Isopropyl Alcohol

  • Structure: Has an isopropyl group attached to the OH group
  • IUPAC Name: 2-Propanol
  • Structure: Three carbon chain, OH on carbon 2

• Tert-butyl Alcohol

  • Structure: Three carbon chain with OH and a methyl group on carbon 2
  • IUPAC Name: 2-methyl-2-propanol

IUPAC Nomenclature

• 2-Propanol

  • Three carbon chain
  • OH group on carbon 2
  • Suffix "-ol" for alcohols, e.g., propanol

• 2-Methyl-2-Propanol (Tert-butyl Alcohol)

  • OH group and methyl on carbon 2

Naming Alcohols with Multiple Hydroxyl Groups

• Diols
  • Two OH groups
  • Example: 3,4-hexanediol
  • Six carbon chain, OH groups on carbons 3 and 4

Prioritizing Functional Groups

• Example: Alcohol vs. Alkyl Halide
  • Alcohols have higher priority
  • Start counting from the alcohol for naming
  • Example: 4-bromo-1-pentanol

Naming with Multiple Substituents

• Order of Substituents
  • Alphabetical order precedence (e.g., bromo before chloro)
  • Start counting to give the lowest number possible to substituents
  • Example: 2-bromo-4-chloro-3-pentanol

Condensed Structures

• Convert condensed structures to line structures to simplify naming
• Example: 4-methoxy-1-butanol

Naming Alcohols on Rings

• Basic Rules:

  • The OH group is automatically on carbon 1 when attached to a ring
  • Example for one substituent: Cyclopentanol
  • Example for two substituents: 3-ethylcyclohexanol

• Multiple Substituents on Rings

  • Number to give the lowest possible numbers
  • Example: 2-ethyl-5-methylcyclohexanol

Key Takeaways

• Alcohols are named based on the longest carbon chain with the OH group
• The OH group gets priority in numbering, and its position is indicated by a number
• Use "-ol" suffix for alcohols
• When multiple functional groups are present, prioritize based on established rules
• Substituents are listed alphabetically when naming the compound