Discuss how bromobutane was made (the mechanism) and then how it was purified. Discuss success of the reaction in terms of yield and purity. Based on the mechanism, do you expect this to be a high yielding reaction? Why/why not? What could be changed (if anything) about the way the reaction was performed to increase the yield? Was the product isolated pure (discuss the IR)? Why was the product isolated the way that it was (what was the point of the different wash steps) and could it have been purified another way? Did the purification method cause significant loss of product (impacting the yield)? and if so, what could be done to prevent that in the future?

Chemistry by OpenStax (2015-05-04)
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ISBN:9781938168390
Author:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark Blaser
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Chapter15: Equilibria Of Other Reaction Classes
Section: Chapter Questions
Problem 11E: The Handbook of Chemistry and Physics (http://openstaxcollege.org/l/16Handbook) gives solubilities...
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Discuss how bromobutane was made (the mechanism) and then how it was purified. Discuss success of the reaction in terms of yield and purity. Based on the mechanism, do you expect this to be a high yielding reaction? Why/why not? What could be changed (if anything) about the way the reaction was performed to increase the yield? Was the product isolated pure (discuss the IR)? Why was the product isolated the way that it was (what was the point of the different wash steps) and could it have been purified another way? Did the purification method cause significant loss of product (impacting the yield)? and if so, what could be done to prevent that in the future?

EXPT. 8A 1-bromobutane from 1-butanol
Reaction:
H+
H,C
HO.
HBr
+
H,0
Br
Procedure:
Place 6.2 mL of 1-butanol into a 100 mL round bottom flask. Add 10 mL of 48% hydrobromic
acid (HBr) to the flask with swirling. Slowly, cautiously, and with swirling, add 4 mL of
concentrated sulfuric acid (H2SO4) to the flask. If the flask gets extremely hot, cool it in an ice
bath. Add 1-2 boiling chips to the flask and connect a reflux condenser to the top of the round
bottom flask. Connect the water hoses to the condenser (water goes in the bottom nozzle, out the
top nozzle). Since some noxious fumes may be generated during the heating period, connect a
vacuum connecting tube to the top of the condenser. Leave the ground glass joint open,
connect a vacuum hose to the gas outlet of the connecting tube. Be sure that the other end of the
vacuum hose is connected to the SINK aspirator (via the trap) and turn the aspirator water on full
blast. Feel for a slight suction when you place one of your fingers over the open joint of the
vacuum connecting tube. Once the apparatus is connected and the sink aspirator is working
correctly, heat the reaction mixture at reflux for 45 minutes. During the reflux period, perform
EXPT. 8B, SN1 reaction rate studies. Allow the flask and its contents to cool to almost room
temperature (cooling in an ice bath is acceptable). Slowly, carefully and with swirling, add 10
mL of de-ionized water to the mixture by pouring it through the condenser. Add a new boiling
chip (or two) and convert the apparatus to a simple distillation apparatus (disconnect the
vacuum). Distill the contents of the flask into a 25 mL round bottom flask which has been
immersed in an ice bath. Stop distilling when the temperature of the distillate reaches 100°C.
Remove the aqueous layer from the distillate using a transfer pipet. DO NOT THROW
ANYTHING AWAY UNTIL YOU GET VERIFICATION OF PRODUCT BY IR
SPECTROSCOPY!!! Add 5 mL of de-ionized water to the organic layer of the distillate,
mixing well with the transfer pipet. Separate the aqueous layer from the organic layer. Combine
the aqueous layer with the original aqueous layer. Wash the organic layer with 5 mL of 5 %
sodium bicarbonate solution, again separating the layers and combining the aqueous layers in a
"waste flask". Wash the organic layer once more with 5 mL of de-ionized water, separating the
layers and combining the aqueous layer with the other aqueous washes. Dry the organic layer
over anhydrous sodium sulfate. Decant or pipet the dry organic layer into a clean, dry, pre-
weighed sample bottle (with a cap). Weigh the product and run an IR spectrum on the product.
Calculate the % yield of the reaction.
and
Transcribed Image Text:EXPT. 8A 1-bromobutane from 1-butanol Reaction: H+ H,C HO. HBr + H,0 Br Procedure: Place 6.2 mL of 1-butanol into a 100 mL round bottom flask. Add 10 mL of 48% hydrobromic acid (HBr) to the flask with swirling. Slowly, cautiously, and with swirling, add 4 mL of concentrated sulfuric acid (H2SO4) to the flask. If the flask gets extremely hot, cool it in an ice bath. Add 1-2 boiling chips to the flask and connect a reflux condenser to the top of the round bottom flask. Connect the water hoses to the condenser (water goes in the bottom nozzle, out the top nozzle). Since some noxious fumes may be generated during the heating period, connect a vacuum connecting tube to the top of the condenser. Leave the ground glass joint open, connect a vacuum hose to the gas outlet of the connecting tube. Be sure that the other end of the vacuum hose is connected to the SINK aspirator (via the trap) and turn the aspirator water on full blast. Feel for a slight suction when you place one of your fingers over the open joint of the vacuum connecting tube. Once the apparatus is connected and the sink aspirator is working correctly, heat the reaction mixture at reflux for 45 minutes. During the reflux period, perform EXPT. 8B, SN1 reaction rate studies. Allow the flask and its contents to cool to almost room temperature (cooling in an ice bath is acceptable). Slowly, carefully and with swirling, add 10 mL of de-ionized water to the mixture by pouring it through the condenser. Add a new boiling chip (or two) and convert the apparatus to a simple distillation apparatus (disconnect the vacuum). Distill the contents of the flask into a 25 mL round bottom flask which has been immersed in an ice bath. Stop distilling when the temperature of the distillate reaches 100°C. Remove the aqueous layer from the distillate using a transfer pipet. DO NOT THROW ANYTHING AWAY UNTIL YOU GET VERIFICATION OF PRODUCT BY IR SPECTROSCOPY!!! Add 5 mL of de-ionized water to the organic layer of the distillate, mixing well with the transfer pipet. Separate the aqueous layer from the organic layer. Combine the aqueous layer with the original aqueous layer. Wash the organic layer with 5 mL of 5 % sodium bicarbonate solution, again separating the layers and combining the aqueous layers in a "waste flask". Wash the organic layer once more with 5 mL of de-ionized water, separating the layers and combining the aqueous layer with the other aqueous washes. Dry the organic layer over anhydrous sodium sulfate. Decant or pipet the dry organic layer into a clean, dry, pre- weighed sample bottle (with a cap). Weigh the product and run an IR spectrum on the product. Calculate the % yield of the reaction. and
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