vacuum filtration
1. used to rapidly remove solvent away from recrystallized product
ring stand with clamps to clamp
side arm flask & vacuum trap
Safeties when conducting a recrystallization
Buchner funnel with filter paper
of appropriate size
1.
2.
3.
4.
5.
6.
never leave a flask unattended on a hot plate
swirl boiling mixture constantly
recrystallize from a flask of appropriate size
cap/cool using a stopper of appropriate size
use an ice/water bath at your bench
parafilm all stoppered solutions stored in locker
rubber sleeve
Safeties when conducting a vacuum filtration
side arm vacuum
filtering flask
•
vacuum trap
hot gravity filtration
stemless glass funnel
fluted filter paper
hot plate
1.
2.
3.
4.
5.
6.
7.
never vacuum filter hot solutions
always use a vacuum trap
always remove the filtrate immediately
contaminate the pump oil, replace it immediately
always use a ring stand & clamps
use filter paper of appropriate size
don't forget your rubber sleeve
1. use hot gravity filtration to remove insoluble impurities when recrystallizing solute
2. use hot gravity filtration to remove insoluble activated charcoal
Safeties when conducting a hot gravity filtration
1. use a hot plate set to an appropriate setting
2. use water as a heat sink, don't place an empty beaker directly on a hot plate
3. use a stemless funnel
4. use fluted filter paper
5. evaporate down (concentrate down) with a boiling chip in a beaker
6. transfer filtrateto a flask of appropriate size to recrystallize
7. NEVER recrystallize in a beaker, recrystallize always in a capped Erlenmyer flask
Safeties when working with activated charcoal
1. don't breath in the dust
2. wipe up all spills with a wet paper towel
3. don't get it on your cloths
4. don't add activated charcoal to a hot solution
5. decolorize with about a thumb's worth of activated charcoal added to warm solutions
6. remove by hot gravity filtration insoluble activated charcoal
7. if crystals form in the filter paper, redissolve with hot solvent
8. place filtered charcoal in the trash
DrGergens© 2010
Part B
Recrystallization on Pure Acetanilide & Baseline Yield Data Measurement
two trials
weigh & recycle final crystals
Safeties when weighing compounds on the balances
review all safeties add 30mL
weigh 1.000g
H2O and
pure acetanilide
boil
boil
10 min
mark level
to achieve
supersaturation
cap &
cool
1.
2.
3.
4.
5.
6.
7.
use a powder funnel to transfer chemicals
measure chemicals directly over the powder funnel
never tap chemicals downward onto the balance
never measure chemicals outside the balance
never leave snail trails of chemicals
have your notebook in hand while weighing samples
contact your instructor if you have made a mess
dry crystals
FIRST CROP,
cool in
ice/water
bath
kick
seed
scratch
mixture
isolate crystals
by vacuum filtration
review safeties
filtrate
Safeties when conducting a recrystallization
1.
2.
3.
4.
5.
6.
never leave a flask unattended on a hot plate
swirl boiling mixture constantly
recrystallize from a flask of appropriate size
cap/cool using a stopper of appropriate size
use an ice/water bath at your bench
parafilm all stoppered solutions stored in your locker
concentrate
down in a
beaker
calculate % recovery
recycle crystals into waste jar
transfer
cap &
to flask
cool
of appropriate
size & concentrate
to supersaturation
Second Crop
dry crystals
vacuum
filter
waste
filtrate
into
aqueous
waste
container
Safeties when conducting a vacuum filtration
1.
2.
3.
4.
5.
6.
7.
never vacuum filter hot solutions
always use a vacuum trap
always remove the filtrate immediately
contaminate the pump oil, replace it immediately
always use a ring stand & clamps
use filter paper of appropriate size
don't forget your rubber sleeve
DrGergens© 2010
Part C
Recrystallization on Impure Acetanilide with Hot Gravity Filtration & Activated Charcoal
two trials
Hot gravitiy filtration to remove insoluble impurities
save final crystals
only one sample turned in
filtered charcoal
place in trash
hot gravity
review all safeties add 30mL hot gravity add activated
boil
filter away charcoal to warm 10 min filter away
weigh 1.000g
H2O and
insoluble
mixture to
insoluble
concentrate
impure acetanilide boil
transfer
cap &
impurities
decolorize;
act. charcoal down in a
to flask
cool
a thumb's worth
beaker
of appropriate
of act. charcoal
size & concentrate
review safeties
to supersaturation
dry crystals
cool in
ice/water
bath
kick
seed
scratch
mixture
isolate crystals
by vacuum filtration
review safeties
filtrate
turn in one sample in a correclty labeled vial
FIRST CROP,
calculate % recovery
Second Crop
dry crystals
concentrate
transfer
cap &
vacuum
down in a
to flask
cool
filter
waste
beaker
of appropriate
filtrate
size & concentrate
into
to supersaturation
aqueous
waste
container
Safeties when conducting a hot gravity filtration
1. use a hot plate set to an appropriate setting
2. use water as a heat sink, don't place an empty beaker directly on a hot plate
3. use a stemless funnel
4. use fluted filter paper
5. evaporate down (concentrate down) with a boiling chip in the beaker
6. transfer filtrateto a flask of appropriate size to recrystallize
7. NEVER recrystallize in a beaker, recrystallize always from a capped Erlenmyer flask
Safeties when working with activated charcoal
1. don't breath in the dust
2. wipe up all spills with a wet paper towel
3. don't get it on your cloths
4. don't add activated charcoal to a hot solution
5. add about a thumb's worth to cold or warm solutions to decolorize
6. remove by hot gravity filtration insoluble activated charcoal
7. if crystals form in the filter paper, redissolve with hot solvent
8. place filtered charcoal in the trash
DrGergens© 2010