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Ethers

Ethers

Ethers are compounds that contain the functional group –O–. Ethers do not have a designated suffix like the other types of molecules we have named so far. In the IUPAC system, the oxygen atom and the smaller carbon branch are named as an alkoxy substituent and the remainder of the molecule as the base chain, as in alkanes.

As shown in the following compound, the red symbols represent the smaller alkyl group and the oxygen atom, which would be named “methoxy.” The larger carbon branch would be ethane, making the molecule methoxyethane. Many ethers are referred to with common names instead of the IUPAC system names. For common names, the two branches connected to the oxygen atom are named separately and followed by “ether.” The common name for the compound shown in the example below is ethylmethyl ether:

A molecular structure is shown with a red C H subscript 3 group bonded up and to the right to a red O atom. The O atom is bonded down and to the right to a C H subscript 2 group. The C H subscript 2 group is bonded up and to the right to a C H subscript 3 group.

Example

Naming Ethers

Provide the IUPAC and common name for the ether shown here:

A molecular structure shows a C H subscript 3 group bonded down and to the right to a C H subscript 2 group. The C H subscript 2 group is bonded up and to the right to an O atom. The O atom is bonded down and to the right to a C H subscript 2 group. The C H subscript 2 group is bonded up and to the right to a C H subscript 3 group.

Solution

IUPAC: The molecule is made up of an ethoxy group attached to an ethane chain, so the IUPAC name would be ethoxyethane.

Common: The groups attached to the oxygen atom are both ethyl groups, so the common name would be diethyl ether.

Ethers can be obtained from alcohols by the elimination of a molecule of water from two molecules of the alcohol. For example, when ethanol is treated with a limited amount of sulfuric acid and heated to 140 °C, diethyl ether and water are formed:

This figure shows a reaction. The first molecule, which is labeled, “ethanol,” is a two C atom chain. The first C atom is bonded to three H atoms and a second C atom. The second C atom is bonded to a red O atom with two sets of electron dots. The O atom has a red bond to a red H atom. There is a plus sign. The next molecule, which is labeled, “ethanol,” is a red H atom with a red bond to a red O atom with two pairs of electron dots. The O atom is bonded to a C atom which is bonded to two H atoms and a second C atom. The second C atom is bonded to three H atoms. There is a green dotted box around the red H atom in the first molecule, the plus sign, and the red H and O atoms in the second molecule. To the right o the second molecule there is an arrow labeled H subscript 2 S O subscript 4 above and Greek capital delta below. The arrow is labeled, “sulfuric acid.” The resulting molecules are a C atom bonded with three H atoms and a second C atom. The second C atom is bonded to two H atoms and a red O atom. The red O atom has two sets of electron dots. The O atom is bonded to a third C atom which is bonded to two H atoms and a fourth C atom. The fourth C atom is bonded to three H atoms. This molecule is labeled, “diethyl ether.” There is a plus sign and a red H O H.

In the general formula for ethers, R—O—R, the hydrocarbon groups (R) may be the same or different. Diethyl ether, the most widely used compound of this class, is a colorless, volatile liquid that is highly flammable. It was first used in 1846 as an anesthetic, but better anesthetics have now largely taken its place.

Diethyl ether and other ethers are presently used primarily as solvents for gums, fats, waxes, and resins. Tertiary-butyl methyl ether, C4H9OCH3 (abbreviated MTBE—italicized portions of names are not counted when ranking the groups alphabetically—so butyl comes before methyl in the common name), is used as an additive for gasoline. MTBE belongs to a group of chemicals known as oxygenates due to their capacity to increase the oxygen content of gasoline.

Resource:

Want more practice naming ethers? This brief video review summarizes the nomenclature for ethers.

This lesson is part of:

Organic Chemistry

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