Naming Ethers

Definition of Ethers

• Ether Structure: Typically written as R-O-R', where:
  • R and R' are carbon chains or different groups.
  • Example: Two methyl groups connected to oxygen, or a methyl and an ethyl group connected to oxygen.

IUPAC Naming Rules for Ethers

1. Identify Longest Carbon Chain
   • This becomes the parent chain.
2. Naming Steps
   • Determine the prefix from the longest chain (e.g., "meth" for one carbon, "eth" for two carbons).
   • Use "ane" as the suffix for single bonds.
   • The shorter chain attached to oxygen becomes an "alkoxy" substituent:
     • Take the prefix for the carbon number and add "oxy" (e.g., "methoxy").
   • Final name example:
     • Methoxymethane for two methoxy groups.
     • Methoxyethane for a methoxy and ethyl group.

Common Naming for Ethers

• Name the two substituents followed by "ether".
• If substituents differ, arrange alphabetically.
  • Example:
    • "Dimethyl ether" for two identical methyl groups.
    • "Ethyl methyl ether" if groups differ.

Ethers in Larger Molecules

1. Identify Parent Chain
   • Number from side giving ether the lowest number.
   • Example: 2-ethoxybutane for a two-carbon ether substituent on butane.
2. Cyclic Substituents
   • Identify the ring size and structure.
   • Example: Cyclopentoxycyclohexane for a five-carbon oxy substituent on a six-carbon ring.

Multiple Ethers in a Molecule

• Number the carbon holding each ether.
• Use "di" for two ethers.
  • Example: 1, 5-diethoxypentane for ethers on carbons 1 and 5.

Ethers with Alcohols

• OH group takes priority.
  • Number molecule for lowest OH positioning.
  • Example: 3-methoxy-2-butanol considering OH takes precedence over OCH3.

Special Case: Epoxides

• Two carbons and an oxygen in a ring is called an epoxide or oxirane.
• Relevant in organic chemistry reactions, to be detailed in future lectures.