Ethers & Epoxides

(The classes of compounds, in which two carbon atoms are connected to an oxygen atom; epoxides are the 3-membered, cyclic version. )

Basic IUPAC nomenclature-Ethers (See the home page for parent root names, prefixes & suffixes.)

1) The longest continuous carbon chain will be the parent name. 

2) Name the -OR group as a substituent.

The longest chain is the ethane; the OR group is methoxy. Thus, the name becomes Methoxy-  +  ethane = Methoxyethane.

3) If there are two alkoxy groups, they are handled in the same fashion. They would be diethers.

The longest chain is still ethane, but now, there are two alkoxy substituents, and they are both methoxy groups. Numbers are used to describe the positions of the alkoxy groups. Thus, this name becomes: 1,2-Dimethoxyethane also known by its abbreviation: DME.

Common Names

All ethers will also have a common name, which is often used interchangeably with the IUPAC name. To assemble the common name, the two groups flanking the O atom are named, alphabetized and the word "ether" is added.

Some examples:

IUPAC Ethoxyethane 1-Methoxy-1,1-dimethylethane Methoxyethane 1-Methoxybutane
Common Diethyl ether Methyl-t-Butyl ether (MTBE) Ethyl methyl ether Butyl methyl ether

Basic nomenclature-Cyclic Ethers

Cyclic ethers have IUPAC names and the prefix ox- indicates the presence of oxygen in the ring system. Suffixes indicate the number of atoms in the ring. The first few members of this series are shown below:

IUPAC Oxirane Oxetane Oxolane Oxane
Common ethylene oxide none tetrahydrofuran tetrahydropyran

Basic nomenclature-Epoxides

1) Simple epoxides are named as derivatives of oxirane.

2) Where the epoxide is part of another ring system, it is shown by the prefix epoxy-.

3) Common names are derived from the name of the alkene from which the epoxide is formally derived; name the alkene and the term oxide is added.


IUPAC Oxirane cis-2,3-Dimethyloxirane 1,2-Epoxycyclohexane
Common ethylene oxide cis-2-butene oxide cyclohexene oxide

EXERCISE: Write the IUPAC name for each of the following structures.

1 (S)-2,2,3-trimethyloxirane 6 1,2-Epoxy-1-methylcyclohexane
2 2-Ethoxypropane 7 Ethoxycyclohexane
3 2-isopropoxypropane 8 Epoxycyclopentane
4 trans-1,2-Dimethoxycyclopentane 9 Methoxybenzene (anisole)
5 Dimethoxymethane 10 1-methoxy-2-methylpropane



email questions & comments to: Dr. JA Colapret