Experiment 3B Fractional Semi-microscale Distillation Separation of Hexane and Toluene
Chem 2203 Sec 026
27/September/2013
Experiment 3B: Fractional Semi-microscale Distillation Separation of Hexane and Toluene.
Objective: The main goal of this lab is to learn how separation of binary liquid mixtures is performed. Especially when the two liquids have boiling points varying by about 30° C. Hexane can be separated from toluene in this experiment because of the difference in their boiling points. Since toluene has a higher boiling point, it will left at the bottom while the hexane starts to boil out and collect in the Hickman still. GC measurements help us in determining how accurate our data is by making a graph of the amount of hexane and toluene in each fraction. Also this lab gives experience with semi-micro distillation in order for experiments in the future that might need this purification setup.
Experimental Procedure: This lab follows the experimental procedure of the book as outline in the Mayo book on pages 133 and 134. However; the following modification were made to the procedure:
Use gas chromatography instead of refractive index
Collect GC for only fraction 1 and fraction 3 because of time constraints.
Reaction Scheme:
Data and Results:
Compound
Amount (mL)
Boiling point (°C)
Hexanes
1.5
62-69
Toulene
1.5
110-111
Distillation
GC
Fraction Collected
Temp. Range (°C)
Peak
Retention Time (min)
Peak Area (mm2)
Identity of Peak
1
35-42
1
1.2
200
Hexanes
2
4
27.5
Toulene
3
50-63
1
1.3
5.25
Hexanes
2
4
231
Toulene
Observations:
Mixed exact quantities in 5mL conical vial
Temperature moved really slowly but kept boiling throughout.
Collected Fraction 1 at 35°C
Temperature dropped after a short while from 55°C to about 45°C.
Larger amounts of vapor/liquid during Fraction 2 collected.
Started collecting fraction 3 at 0°C.
Calculations:
Retention Time:
Fraction 1:
Peak 1: distance from starting point = 1.2cm, therefore time = 1.2 minute.
Peak
27/September/2013
Experiment 3B: Fractional Semi-microscale Distillation Separation of Hexane and Toluene.
Objective: The main goal of this lab is to learn how separation of binary liquid mixtures is performed. Especially when the two liquids have boiling points varying by about 30° C. Hexane can be separated from toluene in this experiment because of the difference in their boiling points. Since toluene has a higher boiling point, it will left at the bottom while the hexane starts to boil out and collect in the Hickman still. GC measurements help us in determining how accurate our data is by making a graph of the amount of hexane and toluene in each fraction. Also this lab gives experience with semi-micro distillation in order for experiments in the future that might need this purification setup.
Experimental Procedure: This lab follows the experimental procedure of the book as outline in the Mayo book on pages 133 and 134. However; the following modification were made to the procedure:
Use gas chromatography instead of refractive index
Collect GC for only fraction 1 and fraction 3 because of time constraints.
Reaction Scheme:
Data and Results:
Compound
Amount (mL)
Boiling point (°C)
Hexanes
1.5
62-69
Toulene
1.5
110-111
Distillation
GC
Fraction Collected
Temp. Range (°C)
Peak
Retention Time (min)
Peak Area (mm2)
Identity of Peak
1
35-42
1
1.2
200
Hexanes
2
4
27.5
Toulene
3
50-63
1
1.3
5.25
Hexanes
2
4
231
Toulene
Observations:
Mixed exact quantities in 5mL conical vial
Temperature moved really slowly but kept boiling throughout.
Collected Fraction 1 at 35°C
Temperature dropped after a short while from 55°C to about 45°C.
Larger amounts of vapor/liquid during Fraction 2 collected.
Started collecting fraction 3 at 0°C.
Calculations:
Retention Time:
Fraction 1:
Peak 1: distance from starting point = 1.2cm, therefore time = 1.2 minute.
Peak
Cited: Mayo, D. W.; Pike, R. M.; Forbes, D. C. Microscale Organic Laboratory with Multistep and Multiscale Syntheses, 5th ed.; John Wiley & Sons, Inc., 2011; pp 132-135. Additional Instructions for Expt 3B: Fractional Distillation, Blackboard document