Separation of Organic Liquids Report

Topics: Distillation, Chromatography, Gas chromatography Pages: 6 (1196 words) Published: June 7, 2014

ORGANIC CHEMISTRY LAB 2: Separation of Organic Liquid Mixtures

Introduction: In this experiment, a mixture of two compounds, cyclohexane and toluene, was separated into fractions by the techniques of simple and fractional distillation. The individual fractions that were gathered from the distillation were analyzed using gas chromatography (GC) and used to compare the efficiencies of the two different distillation techniques. The ultimate goal of this experiment was to determine whether simple or fractional distillation was the more efficient means of separating volatile compounds.

Key Experimental Details, Observations, and Results:
Key Experimental Details and Observations:
Simple and Fractional Distillation set up:
To set up distillation apparatus:
1.For simple distillation: Connect a distilling flask to the bottom of the side-arm joint. For fractional distillation: Connect a distilling flask to the bottom of the fractionating column, wrapped in aluminum foil. Connect the top of the fractionating column to the bottom of the side-arm flask. 2.Insert the thermometer into the top of the side-arm joint through the rubber stopper. The bottom tip of the thermometer should rest within the side-arm joint in a position slightly lower than the bottom of the condenser. 3.Attach the side of side-arm joint to the end of the condenser. 4.Attach the remaining end of the condenser to the vacuum adaptor. 5.Connect the receiving flask to the bottom of the vacuum adaptor. 6.Connect water hose from sink faucet to condenser water intake nozzle. Connect a second water hose from condenser exhaust nozzle to sink for drainage. 7.Stabilize the entire apparatus with clamps.

To prepare gas chromatography injections:
1.Dilute fractions by combining 10µL of fraction sample with 990µL of dichloromethane (DCM). 2.Prepare syringe by filling syringe entirely with DCM and discharging it into waste container. Do this ten times. Afterwards fill the syringe with the diluted fraction sample and discharge into waste container five times. 3.Draw 1µL of air into syringe, followed by 1µL of the fraction sample, then followed by 1-2 µL more of air. The 1µL of sample should be suspended between the air pockets. 4.Insert syringe into injection port and discharge quickly and smoothly. Remove syringe promptly. 5.Repeat for remaining fractions once gas chromatography for previous sample has completed. GC Instrument Number:

Simple distillation fractions for this lab were analyzed using gas chromatography machine #2. Fractional distillation fractions for this lab were analyzed using gas chromatography machine #2.

Results:
Literature boiling point and temperature recordings:
Cyclohexane (C6H12) boiling point: 80.7°CToluene (C7H8) boiling point: 111.0°C Table of Volumes:
Fraction 1
5.3 mL
Fraction 2
8.2 mL
Fraction 3
2.6 mL

Fractional Distillation
Simple Distillation
Time (Minutes)
Temperature (°Celsius)
Time (Minutes)
Temperature (°Celsius)
0.0
82.0°C
0.0
88.0°C
1.0
86.0°C
1.0
91.0°C
2.0
89.0°C
2.0
92.0°C
3.0
92.0°C
3.0
93.0°C
4.0
95.5°C
4.0
94.0°C
5.0
101.0°C
5.0
95.0°C
6.0
106.0°C
6.0
96.5°C
7.0
108.5°C
7.0
99.0°C
8.0
108.5°C
8.0
101.5°C
9.0
108.5°C
9.0
104.5°C
10.0
108.5°C
10.0
107.0°C

11.0
109.5°C

12.0
110.5°C

13.0
111.0°C

GC Results:

Rt peak 1
Rt peak 2
% area peak 1
% area peak 2
Fraction 1 – Simple
0.382 min
1.061 min
64.5%
35.5%
Fraction 2 – Simple
0.377 min
1.054 min
49.4%
50.6%
Fraction 3 – Simple
0.377. min
1.054 min
17.0%
83.0%
Fraction 1 – Fractional
0.375 min
1.053 min
74.4%
25.6%
Fraction 2 – Fractional
0.379 min
1.057 min
49.3%
50.7%
Fraction 3 – Fractional
0.372 min
1.049 min
1.4%
98.6%
Cyclohexane Standard GC #1
0.289 min

Toluene Standard GC #1
0.81 min

Cyclohexane Standard GC #2
0.377 min
Toluene Standard GC #2
1.06 min

Discussion and Conclusion:
The compounds used in...
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