Synthesis of tert-BuCl
CHEM 315
Week of November 8th, 2010
Alexis Patanarut
Due dates
Today
• GC of Distillate lab report - at the beginning of class
• Carbon copies from your lab notebook - at the end of
class
Two weeks (after Thanksgiving break)
• Synthesis of t-BuCl lab report
– Includes synthesis scheme of t-BuCl
– See http://classweb.gmu.edu/chemlab/sws/flow2.gif for
example)
Purpose
• To synthesize t-BuCl and learn how to do
liquid-liquid extraction using a separatory
funnel
Procedure – initial reaction
•
Obtain t-Butyl alcohol (11 mL) from instructor. Weigh
vial and its contents, then pour the alcohol into a 125
mL separatory funnel. Weigh the empty vial and take
the difference to find the weight of the alcohol
–
–
•
Make sure the stopcock is closed before pouring anything
in!
If the alcohol has solidified, you can liquify it again by
warming it between your hands
Add 25 mL concentrated HCl to the alcohol on the
separatory funnel and gently swirl the mixture for ~1
minute, unstoppered
Procedure – initial reaction
• Put the stopper on the funnel and press down
firmly, then gently invert funnel without shaking
and carefully open the stopcock to vent
• Close the stopcock again and shake the funnel
several times, then release pressure through the
stopcock
– Repeat this shake/vent step for 2 - 3 minutes, then
allow the mixture to separate into two layers.
• Separate the two layers.
– Which layer is on top based on density?
Extraction procedure
• Must be done quickly, since t-BuCl is unstable in water
and sodium carbonate
– Use 10 mL portions of extraction solvents
– Organic layer will be extracted (swirl and shake) once with
water, two (2) times with sodium carbonate and once
again with water
• Swirl the contents gently in unstoppered funnel. Then
put on stopper and carefully invert it, opening to
stopcock to vent
• Gently shake the funnel with frequent venting for ~1
minute, then allow layers to separate
• Drain the lower aqueous/bicarbonate layer into waste
beaker and keep top organic layer in funnel
Drying procedure
• Drain organic layer into a small (50 mL) clean, dry beaker
and add anhydrous sodium sulfate to the crude product,
swirling until clear
– Add drying agent using tip-fulls of large microspatula (0.5 g to
1.0 g), one portion at a time
• Swirl the mixture during drying period
– Watch for clumping of drying agent; if drying agent clumps, add
a bit more
– You want to add drying agent until you see some of it not
clumping, at which you stop adding the drying agent; avoid
adding too much drying agent, as that could reduce product
recovery
• When the solution is clear (dry), carefully decant the
produce into a distilling flask using a funnel to prevent
contamination of the flask neck
Distillation procedure
• Add 1-3 boiling chips into distilling flask and
distill crude product using simple distillation
set-up
• Collect distilled product into receiving vessel
over ice
– Might want to preweigh receiving vessel for later
mass calculation purposes
– Product will distill 3-4 deg C before and after
literature b.p. of t-BuCl
For next lab period
1. Weigh the product and determine product
(%) yield
2. Find refractive index
3. Get IR spectrum
Final notes
•
•
•
•
Store your t-BuCl in a tightly capped vial since it
can evaporate very easily
Dispose aqueous solutions in the sink with
plenty of water
Pour distillation waste into waste jar in the hood
Take good notes in your lab notebook!
– Last two labs are more or less cumulative in the
techniques you’ve learned this semester, so be sure
to take good and thorough notes in your notebook
– I will be checking your carbon copies for this!