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Functional Groups
Alcohols
CHEMISTRY 11
MS. MCGRATH
Alcohols
• An alcohol is an organic compound that contains the –OH, or hydroxyl,
functional group
• Depending on the position of the hydroxyl group, an alcohol can be
primary, secondary or tertiary (see page 386)
• Primary – the hydroxyl group is bonded to a carbon that is bonded to
only one other carbon
• Secondary – the hydroxyl group is bonded to a carbon that is bonded to
two other carbons
• Tertiary – the hydroxyl group is bonded to a carbon that is bonded to
three other carbons
Alcohols
General Formula: R-OH
Alcohols - Nomenclature
1) Locate the longest chain that contains an -OH group attached to one of the
carbon atoms. Name the parent alkane by dropping the “e” of the alkane and
adding “ol”
2) Number the main chain of the hydrocarbon so that the hydroxyl group has
the lowest position number. The position of the hydroxyl group -OH is indicated
by the number on the carbon where it is attached. If there is more than one OH group, leave the –e in the name of the parent alkane, and put the
appropriate prefix (di, tri, or tetra) before the suffix ol
3) The hydroxyl group -OH is always located on the carbon with the lowest
possible number. It has priority over the double bond, or triple bond, or any
other substituent
Alcohols – Physical Properties
• the –OH bond is very polar
• as the number of carbons increase, the alkyl’s group’s non-polar nature
becomes more important than the polar –OH bonds. Therefore small
alcohols are more polar than alcohols with large hydrocarbon portions
• the capacity for alcohols for hydrogen bonding makes them extremely
soluble in water. The solubility of an alcohol decreases as the number of
carbon atoms increases
• because of hydrogen bonding, most alcohols have higher melting and
boiling points than alkanes with the same number of carbon atoms
Alcohols – Reactions
Alcohols can undergo:
1) Combustion reactions
2) Substitution reactions
Alcohols - Practice
Complete #8 – 10 page 388