3,Purification of Liquids by Distillation
3.1,Competent Chemist Rating:,How Did the Peach Get in the Banana?”
Techniques Checklist,
Setting up distillation glassware correctly?
Performing atmospheric pressure distillations?
Using Gas Chromatography (GC) to analyze samples?
Pre-lab Discussion and Required Reading,
Theory of distillation,Zubrick Ch,36,LLP Ch,11.3
Distillation glassware and how to set it up,Zubrick Ch,20
Use of the GC,Zubrick Ch,32
Equipment,
Round-bottomed flasks (1x25-mL,1x50-mL)
Magnetic stir bar
Distillation kit (distillation head)
Ground glass thermometer
Keck clips
Glass wool and aluminum foil (optional)
Heating mantle (w/ sand) and variac
Goal,
To purify a mixture of two liquids using distillation.
Experiment Outline,
You will receive a vial containing 11.20 g of a mixture of 2 compounds whose
boiling points differ by about 40 °C (See possible compounds below.),
Analyze the mixture using the GC - see GC Sample Preparation and GC
Operation Guides,
Perform atmospheric pressure distillation - see Distillation Guide,
Prepare a GC sample of your purified low-boiling product.
Obtain a mass and a gas chromatogram of your purified low-boiling compound.
24
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
CH
3
O CH
3
O CH
3
H
3
C
H
3
C O CH
3
O
Ethyl Isobutyrate (Peach) Isoamyl Acetate (Banana)
(BP 112–113 °C) (BP 142–143 °C)
N CH
3
O
CH
3
N CH
3
H
3
C O
2,3-Dimethylpyrazine Ethyl Heptanoate
(BP 156 °C) (BP 188–189 °C)
Helpful Hints,
Make sure all of your joints are lightly greased and sealed well,Otherwise,you
will lose your product into the atmosphere,
Insulate your distillation head with cotton and foil to speed things up.
Do not heat your mixture too fast,or your entire sample will end up in your
collection flask,
Be aware that the temperature reading on the thermometer may not correlate
accurately with the boiling point of the distilling liquid,
Results,
To obtain your "CC Rating" in Purification of Liquids by Distillation,you must
obtain at least 7.00 g of the low-boiling material that is 92% pure or better as determined
using GC analysis,You must also correctly identify the two components of your mixture,
Think boiling points and smell!
25
3.1,Competent Chemist Rating:,How Did the Peach Get in the Banana?”
Techniques Checklist,
Setting up distillation glassware correctly?
Performing atmospheric pressure distillations?
Using Gas Chromatography (GC) to analyze samples?
Pre-lab Discussion and Required Reading,
Theory of distillation,Zubrick Ch,36,LLP Ch,11.3
Distillation glassware and how to set it up,Zubrick Ch,20
Use of the GC,Zubrick Ch,32
Equipment,
Round-bottomed flasks (1x25-mL,1x50-mL)
Magnetic stir bar
Distillation kit (distillation head)
Ground glass thermometer
Keck clips
Glass wool and aluminum foil (optional)
Heating mantle (w/ sand) and variac
Goal,
To purify a mixture of two liquids using distillation.
Experiment Outline,
You will receive a vial containing 11.20 g of a mixture of 2 compounds whose
boiling points differ by about 40 °C (See possible compounds below.),
Analyze the mixture using the GC - see GC Sample Preparation and GC
Operation Guides,
Perform atmospheric pressure distillation - see Distillation Guide,
Prepare a GC sample of your purified low-boiling product.
Obtain a mass and a gas chromatogram of your purified low-boiling compound.
24
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
CH
3
O CH
3
O CH
3
H
3
C
H
3
C O CH
3
O
Ethyl Isobutyrate (Peach) Isoamyl Acetate (Banana)
(BP 112–113 °C) (BP 142–143 °C)
N CH
3
O
CH
3
N CH
3
H
3
C O
2,3-Dimethylpyrazine Ethyl Heptanoate
(BP 156 °C) (BP 188–189 °C)
Helpful Hints,
Make sure all of your joints are lightly greased and sealed well,Otherwise,you
will lose your product into the atmosphere,
Insulate your distillation head with cotton and foil to speed things up.
Do not heat your mixture too fast,or your entire sample will end up in your
collection flask,
Be aware that the temperature reading on the thermometer may not correlate
accurately with the boiling point of the distilling liquid,
Results,
To obtain your "CC Rating" in Purification of Liquids by Distillation,you must
obtain at least 7.00 g of the low-boiling material that is 92% pure or better as determined
using GC analysis,You must also correctly identify the two components of your mixture,
Think boiling points and smell!
25
