ALKENES AND ALKYNES
The MCAT does not explicitly test reactions of alkenes or alkynes, but you may still see the suffixes
- ene and –yne, which signify double and triple bonds, respectively. Keep in mind that many of these
compounds will also have common names, and it is vital to know these common names as well. On
Test Day, you are most likely to encounter double bonds in the context of unsaturated fatty acids or
other biochemical compounds. The double or triple bond is named like a substituent and is
indicated by the lower-numbered carbon involved in the bond. The number may precede the
molecule name, as in 2-butene, or it may be placed near the suffix, as in but-2-ene; both are correct.
If there are multiple multiple bonds, the numbering is generally separated from the suffix, as in 1,3-
butadiene.
ALCOHOLS
Alcohols are named by replacing –e in the name of the corresponding alkane with –ol. The chain is
numbered so that the carbon attached to the hydroxyl group (–OH) gets the lowest possible number
—even when there is a multiple bond present. The hydroxyl group takes precedence over multiple
bonds because of the higher oxidation state of the carbon. If the alcohol is not the highest-priority
functional group, then it is named as a hydroxyl substituent (hydroxy–). Figure 1.6 demonstrates a
few alcohols and their IUPAC names.
Figure 1.6. Naming Alcohols
Alcohols are more oxidized than multiple bonds, so they take priority in nomenclature and are
indicated with the suffix –ol.