Functional Groups
Common Organic Chemicals
Methanol
†CH3OH
Wood alcohol.
Indirectly poisonous;
ingestion of 50 ml
usually fatal
Ethanol
†
C2H5OH
Alcohol, the socially
acceptable intoxicating
beverage. Acts as a
depressant through
interaction with
chemicals in the brain
responsible for
transmission of
information
Formaldehyde
†
CH2O
Contains C=O group.
The simplest aldehyde.
Pungent colorless gas,
used in solution as a
preservative, formalin
Acetaldehyde
†
C2H4O
Pungent liquid, which
is the primary
metabolic product of
alcohol during the
process of becoming
acetic acid; responsible
for hangovers
Formic Acid
†
CH2O2
The simplest
carboxylic acid.
Prime constituent of
the venom produced
by ants
Acetic acid
†
C2H4O2
Colorless liquid
with sharp odor; is
the acid component
of vinegar.
Produced by
oxidation of ethanol
Lactic Acid
†
C3H6O3
Contains both –OH and
-CO2H groups.
Widespread in nature,
produced by anaerobic
fermentation of sugars,
and the action of
enzymes on glucose.
Build-up in muscles
during intense physical
activity.
Glycerol
†
C3H8O3
Propane with three –
OH groups. Masses of
H-bonds makes for a
very viscous liquid.
Several applications in
cosmetics and foods.
Foundation for a group
of molecules called
triglycerides.
Stearic Acid
†
C18H36O2
A typical fatty acid:
long hydrocarbon
portion with a
carboxylic acid
group. Long chain
allows for variety of
secondary structure
Tristearin
†
C57H110O6
A triglyceride – three fatty
acid molecules condensed
with one glycerol molecule.
There are no H atoms
attached to O atoms and
hence no H-bonds. Hence
fats do not dissolve in
water. Important because
they will not be washed out
of the body.
Butanoic Acid
†
C4H8O2
Fats and oils in cow’s
milk have triglycerides
made from short-chain
acids like butanoic
acid. This makes butter
soft rather than waxy.
Butanedione
†
C4H6O2
A double ketone
(contains two C=O
groups). Ketones are
responsible for many
flavours and smells.
This one is cheese-like.
Also contributes to the
smell of perspiration.
Oxalic Acid
†
C2H2O4
Oxalic acid occurs
in many leafy green
plants
Citric Acid
†
C6H8O7
Common
component in citrus
fruits. Contains
three carboxylic
acid groups.
Benzaldehyde
†
C7H6O
Colorless liquid that
smells of bitter
almonds. Benzene
ring replaces the H
atom in
formaldehyde.
2-Heptanone
†
C7H14O
Liquid with a clovelike odor.
Responsible for the
odor of many fruits
and dairy products,
e.g. blue cheese.
3-Methylbutane-1-thiol
†
C5H12S
Like an alcohol, except
the O is replaced by S
(same group). Known
collectively as thiols.
Typically very pungent
aromas. This molecule
is squirted out in
abundance by skunks.
Putrescine
†
C4H12N2
Amines (contain NH2
groups) commonly have
vile smells and this one is
no exception. Cadaverine
is another closely related
molecule with morbid
associations. Interestingly,
one of the constituents of
nylon (hexamethylene
diamine) is related to
putrescine by the addition
of two –CH2- groups.
Trimethylamine
†
C3H9N
Derived from
ammonia by the
replacement of each
H by –CH3 A gas
(boiling point 2°C),
with the odor of
rotten fish.