‐
49
‐
Experiment
Isolation
of
Clove
Oil
by
Steam
Distillation
7
Objectives
1)
To
isolate
clove
oil
from
cloves
by
steam
distillation
and
extraction.
2)
To
characterize
the
product
using
simple
chemical
reactions.
Introduction
Simple
and
fractional
distillations
are
carried
out
on
miscible
mixtures.
Ideal
mixtures
follow
Raoult’s
law
:
the
total
vapor
pressure
of
the
system
is
determined
by
adding
together
the
products
of
the
vapor
pressure
and
the
respective
mole
fraction
of
each
compound
.
For
a
two
‐
compound
system,
this
relationship
is
shown
in
Equation
1,
where
P
T
is
the
total
vapor
pressure,
P
1
0
and
P
2
0
are
the
vapor
pressures
of
pure
compounds
1
and
2,
and
X
1
and
X
2
are
their
respective
mole
fractions.
P
T
=
P
1
0
X
1
+
P
2
0
X
2
(Eq.
1)
Distillation
can
also
be
performed
on
mixtures
in
which
the
two
compounds
are
not
miscible
.
This
process
is
called
co
‐
distillation
.
When
one
of
the
compounds
is
water,
the
process
is
called
steam
distillation
.
When
two
immiscible
liquids
are
distilled,
the
total
vapor
pressure
P
T
above
the
liquid
is
equal
to
the
sum
of
the
vapor
pressure
of
each
compound.
This
relationship,
known
as
Dalton’s
law
,
is
shown
in
Equation
2.
The
respective
mole
fractions
are
not
included
in
this
equation
because,
in
an
ideal
situation,
each
liquid
vaporizes
independently
of
the
other.
When
P
T
is
equal
to
atmospheric
pressure
of
760
torr,
compounds
1
and
2
begin
to
co
‐
distill,
with
each
compound
contributing
to
P
T
.
P
T
=
P
1
0
+
P
2
0
(Eq.
2)
‐
50
‐
Consider
water
as
compound
1.
The
vapor
pressure
of
pure
water
at
its
boiling
point
of
100
°C
is
760
torr.
Because
compound
2
also
contributes
to
P
T
,
the
mixture
will
distill
at
a
temperature
less
than
100
°C.
The
actual
distillation
temperature
will
depend
on
the
vapor
pressure
of
compound
2.
Steam
distillation
offers
an
advantage
in
that
volatile
compounds
that
are
unstable
or
have
high
boiling
points
can
co
‐
distill
with
water
at
relatively
low
temperatures.
This
process
avoids
decomposition
that
might
occur
at
the
normal
boiling
point
of
the
compound
of
interest.
For
example,
eugenol
,
the
major
compound
of
clove
oil,
boils
at
a
relatively
high
temperature
of
254
°C.
Steam
distillation
avoids
this
high
temperature
and
results
in
the
distillation
of
eugenol
at
a
temperature
slightly
less
than
100
°C.
In
practice,
steam
distillation
is
usually
carried
out
by
one
of
two
methods.
In
the
first
method,
an
excess
amount
of
water
is
added
to
the
compound
of
interest
in
a
distilling
flask.
The
mixture
is
then
heated
to
the
boiling
point.
The
resulting
vapor
is
condensed
and
collected
in
a
receiving
flask.
The
compound
of
interest
is
then
separated
from
water,
often
by
extraction.
In
the
second
method,
steam
is
bubbled
into
the
compound
of
interest
to
effect
the
distillation.
In
this
experiment,
the
first
method
will
be
used
because
it
is
easier
to
set
up.
Clove
oil
belongs
to
a
large
class
of
natural
products
called
the
essential
oils
.
Many
of
these
compounds
are
used
as
flavorings
and
perfumes
and,
in
the
past,
were
considered
to
be
the
“essence”
of
the
plant
from
which
they
were
derived.
Cloves
(
กานพล
in
Thai
)
are
the
dried
flower
buds
of
the
clove
tree,
Eugenia
caryophyllata
,
found
in
India
and
other
locations
in
the
Far
East.
Steam
distillation
of
freshly
ground
cloves
results
in
clove
oil,
which
consists
of
several
compounds.
Eugenol
is
the
major
compound,
comprising
85
‐
90
%.
Eugenol
acetate
comprises
9
‐
10
%.
These
structures
are
shown
in
Figure
1.
Figure
1
Structures
for
(a)
eugenol
and
(b)
eugenol
acetate
Eugenol
contains
a
carbon
‐
carbon
double
bond
and
an
aromatic
hydroxyl
group
called
a
phenol.
These
functional
groups
provide
the
basis
for
simple
chemical
tests
used
to
characterize
the
clove
oil.
A
solution
of
bromine
(Br
2
)
in
chloroform
decolorizes
as
Br
2
reacts
with
the
double
‐
51
‐
bond
to
form
a
colorless
compound,
as
shown
in
Equation
3.
A
positive
test
is
the
disappearance
of
the
Br
2
color.
A
potassium
permanganate
(KMnO
4
)
solution
can
oxidize
a
double
bond
at
room
temperature
to
form
a
1,2
‐
diol
with
the
simultaneous
reduction
of
Mn
7+
in
manganese
oxide
(MnO
2
),
as
shown
in
Equation
4.
A
positive
test
is
the
disappearance
of
the
purple
KMnO
4
and
the
appearance
of
MnO
2
as
a
brown
precipitate.
Phenols
(ArOH)
react
with
the
Fe
3+
ion
in
iron(III)
chloride
(FeCl
3
)
to
give
complexes
that
are
blue,
green,
red,
or
purple,
as
shown
in
Equation
5.
The
color
may
last
for
only
a
few
seconds
or
for
many
hours,
depending
on
the
stability
of
the
complex.
In
this
experiment,
you
will
steam
distill
clove
oil
from
freshly
ground
cloves.
Following
the
distillation,
clove
oil
and
water
will
be
present
in
the
receiving
flask.
Because
clove
oil
will
be
a
minor
fraction
of
the
distillate,
the
clove
oil
must
be
extracted
from
the
water
into
an
organic
solvent
such
as
dichloromethane.
Removing
dichloromethane
leaves
clove
oil
as
the
product.
‐
52
‐
Experimental
Procedure
Part
A:
Isolation
of
Clove
Oil
1)
Weigh
5
g
of
dry
cloves.
Grind
them
to
a
coarse
powder
using
a
mortar
and
pestle.
Reweigh
the
powder
and
record
the
weight.
2)
Transfer
the
ground
cloves
to
a
100
mL
round
‐
bottom
flask.
Add
50
mL
of
distilled
water
and
a
few
boiling
chips.
3)
Assemble
the
distillation
apparatus
(Figure
2).
Use
the
100
mL
round
‐
bottom
flask
as
the
pot
and
50
mL
graduated
cylinder
or
Erlenmeyer
flask
as
the
receiver.
Start
the
flow
of
water
through
the
condenser.
Figure
2
Distillation
set
up
4)
Ask
your
instructor
to
inspect
your
equipment
set
up.
Turn
on
the
heating
mantle.
When
the
mixture
boils,
adjust
the
heat
to
maintain
a
distillation
rate
of
approximately
1
drop
per
second
.
5)
Stop
the
distillation
when
approximately
30
‐
40
mL
of
distillate
has
been
collected.
6)
Allow
the
distillate
to
cool
to
room
temperature.
Carefully
pour
the
distillate
into
a
separatory
funnel.
Add
10
mL
of
saturated
NaCl
solution.
‐
53
‐
7)
Rinse
the
inside
of
the
condenser
and
the
receiver
with
5
‐
10
mL
of
CH
2
Cl
2
into
the
separatory
funnel.
8)
Cap
the
separatory
funnel
and
gently
swirl
the
contents
for
several
seconds.
Vent
the
separatory
funnel
frequently.
After
the
pressure
has
been
vented,
shake
the
contents
vigorously
to
thoroughly
mix
the
two
layers.
9)
Allow
the
layers
to
separate.
Drain
the
CH
2
Cl
2
layer
into
an
Erlenmeyer
flask.
10)
Repeat
the
extraction
of
the
aqueous
layer
twice
,
each
time
with
5
mL
portion
of
CH
2
Cl
2
.
Combine
organic
layer
in
the
same
Erlenmeyer
flask.
11)
Dry
the
combined
CH
2
Cl
2
solution
with
anhydrous
Na
2
SO
4
.
12)
Decant
the
CH
2
Cl
2
solution
into
a
pre
‐
weighed
ceramic
evaporating
dish,
making
certain
that
no
Na
2
SO
4
is
transferred
with
the
solution.
13)
Place
the
evaporating
dish
on
a
hot
water
bath
to
remove
CH
2
Cl
2
.
14)
When
all
of
the
CH
2
Cl
2
has
been
evaporated,
allow
the
evaporating
dish
to
cool
to
room
temperature.
Weigh
it
to
the
nearest
0.001
g
and
record
the
weight.
Subtract
the
mass
of
the
empty
dish
to
obtain
the
mass
of
the
clove
oil.
15)
Report
the
weight
and
percent
yield
of
clove
oil
to
your
instructor.
Part
B:
Characterization
of
the
Isolated
Clove
Oil
1)
Dissolve
the
clove
oil
in
2
‐
3
mL
of
methanol.
2)
Obtain
six
test
tubes
and
label
them
1
‐
6.
Label
tubes
2,
4,
and
6
as
“blank”.
Add
1
mL
of
methanol
to
all
6
test
tubes.
3)
Add
5
drops
of
clove
‐
oil
solution
to
tubes
1,
3,
and
5.
Gently
swirl
each
tube.
4)
Add
5
drops
of
bromine
in
chloroform
to
tubes
1
and
2.
Gently
swirl
and
record
your
observation.
5)
Add
5
drops
of
KMnO
4
solution
to
test
tubes
3
and
4.
Gently
swirl
and
record
your
observation.
6)
Add
a
few
drops
of
FeCl
3
solution
to
test
tubes
5
and
6.
Gently
swirl
and
record
your
observation.
Laboratory
Safety
Precaution
1)
Wear
safety
goggles
and
lab
coat
at
all
times
while
working
in
the
laboratory.
2)
Dichloromethane
is
irritating
and
toxic.
Prevent
eye,
skin,
and
clothing
contact.
3)
Anhydrous
sodium
sulfate
is
irritating
and
hygroscopic.
‐
54
‐
4)
Methanol
is
flammable
and
toxic.
Keep
away
from
flames
or
heat
sources.
5)
Bromine
and
potassium
permanganate
are
toxic
and
irritating.
Prevent
eye,
skin,
and
clothing
contact.
6)
Wash
your
hands
thoroughly
with
soap
or
detergent
before
leaving
the
laboratory
‐
49
‐
Experiment
Isolation
of
Clove
Oil
by
Steam
Distillation
7
Objectives
1)
To
isolate
clove
oil
from
cloves
by
steam
distillation
and
extraction.
2)
To
characterize
the
product
using
simple
chemical
reactions.
Introduction
Simple
and
fractional
distillations
are
carried
out
on
miscible
mixtures.
Ideal
mixtures
follow
Raoult’s
law
:
the
total
vapor
pressure
of
the
system
is
determined
by
adding
together
the
products
of
the
vapor
pressure
and
the
respective
mole
fraction
of
each
compound
.
For
a
two
‐
compound
system,
this
relationship
is
shown
in
Equation
1,
where
P
T
is
the
total
vapor
pressure,
P
1
0
and
P
2
0
are
the
vapor
pressures
of
pure
compounds
1
and
2,
and
X
1
and
X
2
are
their
respective
mole
fractions.
P
T
=
P
1
0
X
1
+
P
2
0
X
2
(Eq.
1)
Distillation
can
also
be
performed
on
mixtures
in
which
the
two
compounds
are
not
miscible
.
This
process
is
called
co
‐
distillation
.
When
one
of
the
compounds
is
water,
the
process
is
called
steam
distillation
.
When
two
immiscible
liquids
are
distilled,
the
total
vapor
pressure
P
T
above
the
liquid
is
equal
to
the
sum
of
the
vapor
pressure
of
each
compound.
This
relationship,
known
as
Dalton’s
law
,
is
shown
in
Equation
2.
The
respective
mole
fractions
are
not
included
in
this
equation
because,
in
an
ideal
situation,
each
liquid
vaporizes
independently
of
the
other.
When
P
T
is
equal
to
atmospheric
pressure
of
760
torr,
compounds
1
and
2
begin
to
co
‐
distill,
with
each
compound
contributing
to
P
T
.
P
T
=
P
1
0
+
P
2
0
(Eq.
2)
‐
50
‐
Consider
water
as
compound
1.
The
vapor
pressure
of
pure
water
at
its
boiling
point
of
100
°C
is
760
torr.
Because
compound
2
also
contributes
to
P
T
,
the
mixture
will
distill
at
a
temperature
less
than
100
°C.
The
actual
distillation
temperature
will
depend
on
the
vapor
pressure
of
compound
2.
Steam
distillation
offers
an
advantage
in
that
volatile
compounds
that
are
unstable
or
have
high
boiling
points
can
co
‐
distill
with
water
at
relatively
low
temperatures.
This
process
avoids
decomposition
that
might
occur
at
the
normal
boiling
point
of
the
compound
of
interest.
For
example,
eugenol
,
the
major
compound
of
clove
oil,
boils
at
a
relatively
high
temperature
of
254
°C.
Steam
distillation
avoids
this
high
temperature
and
results
in
the
distillation
of
eugenol
at
a
temperature
slightly
less
than
100
°C.
In
practice,
steam
distillation
is
usually
carried
out
by
one
of
two
methods.
In
the
first
method,
an
excess
amount
of
water
is
added
to
the
compound
of
interest
in
a
distilling
flask.
The
mixture
is
then
heated
to
the
boiling
point.
The
resulting
vapor
is
condensed
and
collected
in
a
receiving
flask.
The
compound
of
interest
is
then
separated
from
water,
often
by
extraction.
In
the
second
method,
steam
is
bubbled
into
the
compound
of
interest
to
effect
the
distillation.
In
this
experiment,
the
first
method
will
be
used
because
it
is
easier
to
set
up.
Clove
oil
belongs
to
a
large
class
of
natural
products
called
the
essential
oils
.
Many
of
these
compounds
are
used
as
flavorings
and
perfumes
and,
in
the
past,
were
considered
to
be
the
“essence”
of
the
plant
from
which
they
were
derived.
Cloves
(
กานพล
in
Thai
)
are
the
dried
flower
buds
of
the
clove
tree,
Eugenia
caryophyllata
,
found
in
India
and
other
locations
in
the
Far
East.
Steam
distillation
of
freshly
ground
cloves
results
in
clove
oil,
which
consists
of
several
compounds.
Eugenol
is
the
major
compound,
comprising
85
‐
90
%.
Eugenol
acetate
comprises
9
‐
10
%.
These
structures
are
shown
in
Figure
1.
Figure
1
Structures
for
(a)
eugenol
and
(b)
eugenol
acetate
Eugenol
contains
a
carbon
‐
carbon
double
bond
and
an
aromatic
hydroxyl
group
called
a
phenol.
These
functional
groups
provide
the
basis
for
simple
chemical
tests
used
to
characterize
the
clove
oil.
A
solution
of
bromine
(Br
2
)
in
chloroform
decolorizes
as
Br
2
reacts
with
the
double
‐
51
‐
bond
to
form
a
colorless
compound,
as
shown
in
Equation
3.
A
positive
test
is
the
disappearance
of
the
Br
2
color.
A
potassium
permanganate
(KMnO
4
)
solution
can
oxidize
a
double
bond
at
room
temperature
to
form
a
1,2
‐
diol
with
the
simultaneous
reduction
of
Mn
7+
in
manganese
oxide
(MnO
2
),
as
shown
in
Equation
4.
A
positive
test
is
the
disappearance
of
the
purple
KMnO
4
and
the
appearance
of
MnO
2
as
a
brown
precipitate.
Phenols
(ArOH)
react
with
the
Fe
3+
ion
in
iron(III)
chloride
(FeCl
3
)
to
give
complexes
that
are
blue,
green,
red,
or
purple,
as
shown
in
Equation
5.
The
color
may
last
for
only
a
few
seconds
or
for
many
hours,
depending
on
the
stability
of
the
complex.
In
this
experiment,
you
will
steam
distill
clove
oil
from
freshly
ground
cloves.
Following
the
distillation,
clove
oil
and
water
will
be
present
in
the
receiving
flask.
Because
clove
oil
will
be
a
minor
fraction
of
the
distillate,
the
clove
oil
must
be
extracted
from
the
water
into
an
organic
solvent
such
as
dichloromethane.
Removing
dichloromethane
leaves
clove
oil
as
the
product.
‐
52
‐
Experimental
Procedure
Part
A:
Isolation
of
Clove
Oil
1)
Weigh
5
g
of
dry
cloves.
Grind
them
to
a
coarse
powder
using
a
mortar
and
pestle.
Reweigh
the
powder
and
record
the
weight.
2)
Transfer
the
ground
cloves
to
a
100
mL
round
‐
bottom
flask.
Add
50
mL
of
distilled
water
and
a
few
boiling
chips.
3)
Assemble
the
distillation
apparatus
(Figure
2).
Use
the
100
mL
round
‐
bottom
flask
as
the
pot
and
50
mL
graduated
cylinder
or
Erlenmeyer
flask
as
the
receiver.
Start
the
flow
of
water
through
the
condenser.
Figure
2
Distillation
set
up
4)
Ask
your
instructor
to
inspect
your
equipment
set
up.
Turn
on
the
heating
mantle.
When
the
mixture
boils,
adjust
the
heat
to
maintain
a
distillation
rate
of
approximately
1
drop
per
second
.
5)
Stop
the
distillation
when
approximately
30
‐
40
mL
of
distillate
has
been
collected.
6)
Allow
the
distillate
to
cool
to
room
temperature.
Carefully
pour
the
distillate
into
a
separatory
funnel.
Add
10
mL
of
saturated
NaCl
solution.
‐
53
‐
7)
Rinse
the
inside
of
the
condenser
and
the
receiver
with
5
‐
10
mL
of
CH
2
Cl
2
into
the
separatory
funnel.
8)
Cap
the
separatory
funnel
and
gently
swirl
the
contents
for
several
seconds.
Vent
the
separatory
funnel
frequently.
After
the
pressure
has
been
vented,
shake
the
contents
vigorously
to
thoroughly
mix
the
two
layers.
9)
Allow
the
layers
to
separate.
Drain
the
CH
2
Cl
2
layer
into
an
Erlenmeyer
flask.
10)
Repeat
the
extraction
of
the
aqueous
layer
twice
,
each
time
with
5
mL
portion
of
CH
2
Cl
2
.
Combine
organic
layer
in
the
same
Erlenmeyer
flask.
11)
Dry
the
combined
CH
2
Cl
2
solution
with
anhydrous
Na
2
SO
4
.
12)
Decant
the
CH
2
Cl
2
solution
into
a
pre
‐
weighed
ceramic
evaporating
dish,
making
certain
that
no
Na
2
SO
4
is
transferred
with
the
solution.
13)
Place
the
evaporating
dish
on
a
hot
water
bath
to
remove
CH
2
Cl
2
.
14)
When
all
of
the
CH
2
Cl
2
has
been
evaporated,
allow
the
evaporating
dish
to
cool
to
room
temperature.
Weigh
it
to
the
nearest
0.001
g
and
record
the
weight.
Subtract
the
mass
of
the
empty
dish
to
obtain
the
mass
of
the
clove
oil.
15)
Report
the
weight
and
percent
yield
of
clove
oil
to
your
instructor.
Part
B:
Characterization
of
the
Isolated
Clove
Oil
1)
Dissolve
the
clove
oil
in
2
‐
3
mL
of
methanol.
2)
Obtain
six
test
tubes
and
label
them
1
‐
6.
Label
tubes
2,
4,
and
6
as
“blank”.
Add
1
mL
of
methanol
to
all
6
test
tubes.
3)
Add
5
drops
of
clove
‐
oil
solution
to
tubes
1,
3,
and
5.
Gently
swirl
each
tube.
4)
Add
5
drops
of
bromine
in
chloroform
to
tubes
1
and
2.
Gently
swirl
and
record
your
observation.
5)
Add
5
drops
of
KMnO
4
solution
to
test
tubes
3
and
4.
Gently
swirl
and
record
your
observation.
6)
Add
a
few
drops
of
FeCl
3
solution
to
test
tubes
5
and
6.
Gently
swirl
and
record
your
observation.
Laboratory
Safety
Precaution
1)
Wear
safety
goggles
and
lab
coat
at
all
times
while
working
in
the
laboratory.
2)
Dichloromethane
is
irritating
and
toxic.
Prevent
eye,
skin,
and
clothing
contact.
3)
Anhydrous
sodium
sulfate
is
irritating
and
hygroscopic.
‐
54
‐
4)
Methanol
is
flammable
and
toxic.
Keep
away
from
flames
or
heat
sources.
5)
Bromine
and
potassium
permanganate
are
toxic
and
irritating.
Prevent
eye,
skin,
and
clothing
contact.
6)
Wash
your
hands
thoroughly
with
soap
or
detergent
before
leaving
the
laboratory
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