25.3. Functional Groups http://www.ck12.org
- The two hydrocarbon groups are named using the rules for alkyl substituents, and these names come before
the word ether. If the two alkyl groups are the same, the prefixdi- is used. If the two alkyl groups are different,
they are listed in alphabetical order. - Spaces are left between the names of the alkyl groups (if different) and before the wordether.
Shown below are two examples of ethers with their IUPAC names.
Properties of Ethers
Ethers are somewhat soluble in water, but less so than alcohols. The lone pairs of electrons on the oxygen atom of
the ether can hydrogen bond with the hydrogen atoms of water molecules. As in the case of alcohols, the solubility
is greater for ethers that have shorter R groups. The boiling points of ethers are much lower than the boiling points of
alcohols. Ether molecules do not have hydrogen atoms that are covalently bonded to a highly electronegative atom,
and so ether molecules cannot hydrogen bond with each other. The weaker intermolecular forces acting between
ether molecules result in boiling points that are much closer to alkanes of similar molar mass than to alcohols.
The anesthetic effects of ether were first discovered in the 1840s. Diethyl ether was used as a general anesthetic for
patients undergoing surgery for many years. However, ethers are very flammable and have undesirable side effects,
such as nausea and vomiting. Safer alternatives to ether are now used in anesthesia, and the primary use of ethers
today is as a solvent for other organic compounds.
Aldehydes and Ketones
Aldehydes and ketones are two related categories of organic compounds that both contain thecarbonyl group, shown
below.
The difference between aldehydes and ketones is the placement of the carbonyl group within the molecule. An
aldehydeis an organic compound in which the carbonyl group is attached to a carbon atom at the end of a carbon
chain. Aketoneis an organic compound in which the carbonyl group is attached to a carbon atom within the carbon
chain. The general formulas for each are shown below.