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Functional groups you should know
These are important in both artificial polymers and in biochemistry, not to mention organic chemistry in
general.
Alcohol: An oxygen atom singly-bound to one
hydrogen atom and one carbon atom.
R
Aldehyde: A carbonyl group that is singly-bound to one
hydrogen atom and one carbon atom. Notice that if,
instead of the carbon atom, you have oxygen or
nitrogen, you do not have an aldehyde but rather an
acid/ester or an amide, respectively.
Alkene: A carbon-carbon double bond. Sometimes
called a “vinyl group”, though technically the term only
refers to the specific group -CH=CH2.
OH
O
C
R
H
R
H
R
C
C
C
R
R
R
alkene
H3C
Alkyne: A carbon-carbon triple bond.
C
H
C
H
vinyl group
C
CH3
O
Amide: A carbonyl group that is singly-bound to a
nitrogen atom. In biochemistry, the group is called a
peptide and the carbon-nitrogen linkage is called a
peptide bond.
C
R
R
N
H
Amine: A nitrogen atom bound to at least one carbon
atom is an amine, unless it is bound to a carbonyl group,
when it is part of an amide.
H
R
N
H
R
Arene or “benzene ring”: A six-membered ring with
three double bonds (six “extra” electrons).
Carbonyl: A carbon-oxygen double bond. The carbon
atom has two bonds left over that can be attached to
other atoms.
1
R
sometimes
represented as
O
C
Carboxylic acid: A carbonyl group singly-bound to an
oxygen which is in turn singly-bound to a hydrogen
atom.
O
C
R
H
O
O
Ester: A carbonyl group singly-bound to an oxygen
which is in turn singly-bound to a carbon atom.
C
R
R
Ether: An oxygen atom singly-bound to two carbon
atoms.
R
O
O
R
O
Ketone: A carbonyl group that is bound to two carbon
atoms.
C
R
R
Peptide: What biochemists call an amide. Normally
used to refer to proteins.
Other functional groups
These groups are found in important artificial polymers: polycarbonate (Lexan) and various
polyurethanes.
Carbonate: A carbonyl group that is singly-bound to two oxygen atoms, that are in
turn singly-bound to carbon atoms.
O
R
C
O
Isocyanate: A carbonyl group that is doubly-bound to a nitrogen atom, that is in
turn singly-bound to a carbon atom. Isocyanates are combined with alcohols to
make urethanes.
Urethane: A carbonyl group that is singly-bound to one oxygen atom and one
nitrogen atom, each of which is in turn singly-bound to a carbon atom. Urethanes
are made by reacting isocyanates with alcohols. This is also known as a carbamate.
N
R
C
O
O
C
R
N
H
2
R
O
R
O