WARNING NOTICE: The experiments described in these materials ar ally hazardous and require a high level fsafety training, special facilities and equipment, and IsIon individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures a and measures. mit shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. Legal Notices 1. Transfer and Extraction Techniques 1. 2. Expert Experimentalist Rating:"Into Thin Air Techniques Checklist m manifold use Manipulations under an inert atmosphere Solvent de-gassing Pre-Lab Discussion and required reading: Air sensitive techniques: LLP Ch 9 quipment Vacuum manifold Solvent trap Magnetic stir plate ·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 Smaller, tan septa( to fit cuvettes) Keck clips(14/20) Fresh bottle of tetrahydrofuran (tHf)(you will only need 50 mL) Activated 4 A molecular sieves
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 Å 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
roa You will be given a small sample of cobaltocene (dicyclopentadienylcobalt) in a nitrogen-filled Schlenk flask. Your task is to carry this material through an " obstacle course"of manipulations without allowing your sample to decompose -as determined by UV-Vi 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 N2-purged, septum-capped cuvette (Put a little grease over the puncture wounds on the septa to maintain their ntegrity) 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 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!
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 N2-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 λmax 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
