1,Transfer and Extraction Techniques
1.2,Expert Experimentalist Rating:,Into Thin Air”
Techniques Checklist,
Cannula transfer?
Vacuum manifold use?
Manipulations under an inert atmosphere?
Solvent de-gassing?
Pre-Lab Discussion and Required Reading,
Air sensitive techniques,LLP Ch,9
Equipment,
Vacuum manifold
Solvent trap
Magnetic stir plate
Cannula needle
25-mL Schlenk flask
Schlenk frit
100-mL Round-bottomed flask - 14/20
Small round-bottomed flask - 14/20
Disposable purge needles
UV-Vis cuvettes - quartz
14/20 rubber septa
Smaller,tan septa (to fit cuvettes)
Keck clips (14/20)
Fresh bottle of tetrahydrofuran (THF) (you will only need 50 mL)
Activated 4? molecular sieves
17
WARNING NOTICE,The experiments described in these materials are potentially hazardous and require a high level
ofsafety training,special facilities and equipment,and supervision by appropriate individuals,You bear the sole
responsibility,liability,and risk for the implementation of such safety procedures and measures,MIT shall have no
responsibility,liability,or risk for the content or implementation of any of the material presented,Legal Notices
Goal,
You will be given a small sample of cobaltocene
(dicyclopentadienylcobalt) in a nitrogen-filled Schlenk flask,Your task
Co
is to carry this material through an "obstacle course" of manipulations
without allowing your sample to decompose - as determined by UV-Vis
spectroscopy,Beware,This sensitive compound will quickly
Cobaltocene
decompose upon exposure to air!
Experiment Outline,
All of your glassware should be CLEAN and oven-dried (put the glassware in the
oven the day before you perform the experiment),
De-gas about 50 mL of THF in a 100-mL round bottom flask - see No-Air
Techniques Guide,
While your solvent is de-gassing,evacuate your filtration apparatus - see No-Air
Techniques Guide,
Attach the Schlenk flask containing your sample to a hose on the manifold (secure
with copper wire),and carry out several vac-fill cycles to clear all of the air from the
length of the tubing,
At some point,you will need to purge the cuvettes,fill with degassed THF (you
can use a cannula or syringe) and blank the spectrophotometer - see UV-Vis
Operation Guide,If the spectrophotometer is not busy,you can do this while your
various components are de-aerating,
Carefully cannulate THF into the sample flask,You will need a dilute solution for
the UV-Vis experiment,so add solvent until you get a pale solution – about 10 mL,
Carefully filter the solution into the receiving Schlenk flask - see No-Air
Techniques Guide,Filtering,
Using a cannula,transfer the solution to a N
2
-purged,septum-capped cuvette,
(Put a little grease over the puncture wounds on the septa to maintain their
integrity.)
Blank the UV-Vis spectrophotometer with THF,then obtain your spectrum,
Results,
To obtain your "EE Rating" in Transfer and Extraction Techniques,your UV-Vis
spectrum must contain a single peak at 347 nm,If λ
max
is below 347 nm and if a shoulder
appears around 392 nm,your sample has decomposed,Go back to the start and try again!
18
1.2,Expert Experimentalist Rating:,Into Thin Air”
Techniques Checklist,
Cannula transfer?
Vacuum manifold use?
Manipulations under an inert atmosphere?
Solvent de-gassing?
Pre-Lab Discussion and Required Reading,
Air sensitive techniques,LLP Ch,9
Equipment,
Vacuum manifold
Solvent trap
Magnetic stir plate
Cannula needle
25-mL Schlenk flask
Schlenk frit
100-mL Round-bottomed flask - 14/20
Small round-bottomed flask - 14/20
Disposable purge needles
UV-Vis cuvettes - quartz
14/20 rubber septa
Smaller,tan septa (to fit cuvettes)
Keck clips (14/20)
Fresh bottle of tetrahydrofuran (THF) (you will only need 50 mL)
Activated 4? molecular sieves
17
WARNING NOTICE,The experiments described in these materials are potentially hazardous and require a high level
ofsafety training,special facilities and equipment,and supervision by appropriate individuals,You bear the sole
responsibility,liability,and risk for the implementation of such safety procedures and measures,MIT shall have no
responsibility,liability,or risk for the content or implementation of any of the material presented,Legal Notices
Goal,
You will be given a small sample of cobaltocene
(dicyclopentadienylcobalt) in a nitrogen-filled Schlenk flask,Your task
Co
is to carry this material through an "obstacle course" of manipulations
without allowing your sample to decompose - as determined by UV-Vis
spectroscopy,Beware,This sensitive compound will quickly
Cobaltocene
decompose upon exposure to air!
Experiment Outline,
All of your glassware should be CLEAN and oven-dried (put the glassware in the
oven the day before you perform the experiment),
De-gas about 50 mL of THF in a 100-mL round bottom flask - see No-Air
Techniques Guide,
While your solvent is de-gassing,evacuate your filtration apparatus - see No-Air
Techniques Guide,
Attach the Schlenk flask containing your sample to a hose on the manifold (secure
with copper wire),and carry out several vac-fill cycles to clear all of the air from the
length of the tubing,
At some point,you will need to purge the cuvettes,fill with degassed THF (you
can use a cannula or syringe) and blank the spectrophotometer - see UV-Vis
Operation Guide,If the spectrophotometer is not busy,you can do this while your
various components are de-aerating,
Carefully cannulate THF into the sample flask,You will need a dilute solution for
the UV-Vis experiment,so add solvent until you get a pale solution – about 10 mL,
Carefully filter the solution into the receiving Schlenk flask - see No-Air
Techniques Guide,Filtering,
Using a cannula,transfer the solution to a N
2
-purged,septum-capped cuvette,
(Put a little grease over the puncture wounds on the septa to maintain their
integrity.)
Blank the UV-Vis spectrophotometer with THF,then obtain your spectrum,
Results,
To obtain your "EE Rating" in Transfer and Extraction Techniques,your UV-Vis
spectrum must contain a single peak at 347 nm,If λ
max
is below 347 nm and if a shoulder
appears around 392 nm,your sample has decomposed,Go back to the start and try again!
18
