Gas Chromatography Lab

Objective:
The purpose of this experiment is to learn how to use fractional distillation to separate a mix of isopropyl acetate and toluene, redistill them, and use gas chromatography to examine the separation.
Techniques:
Chemical Name Molecular Weight Appearance Density Amount Boiling Point
Isopropyl Acetate 102.1 g/mol Colorless liquid .88 g/mL 1.5 mL 89°C
Toluene 92.15 g/mol Colorless liquid .87 g/mL 1.5mL 111°C
• Distillation
• Gas Chromatography
Physical Data Table:

Procedures: The following procedures were performed using pages 27-29 in Dr. Morvant and Dr. Halterman’s Organic Chemistry Laboratory Manual. 1.5mL of Isopropyl acetate and 1.5mL of Toluene were added to a 5mL conical vial by a calibrated Pasteur pipette, and then the spin

Aluminum foil was not used during the experiment to wrap around the Hickman still. The temperature of the hot plate continuously increased because the thermometer temperature increased very slowly. The stillhead started to collect condensate around 50°C which is much lower than the 80-90°C that the thermometer was supposed to read. A bent pipette was used to collect around 1.5mL of distillate that was put into a .5-dram vial. This vial was named “Fraction 1.” The hot plate temperature was increased a little more to increase the thermometer temperature in the Hickman still. .6mL of distillate was collected, using the same bent pipette, and put into another .5-dram vial named “Fraction 2.” The hot plate was turned off, and everything was left to cool for a little bit. After it cooled, around 1.2 mL of clear liquid was left in the original vial and transferred to another vial named “Fraction 3.” The syringe for gas chromatography was flushed with acetone and then with Fraction 1 before any reading was done. Because the syringe only collects .2µL of Fraction 1, the liquid wasn’t visible to the naked eye. The needle had to be twisted and rotated gently to insert into the injection port. When the LabQuest collected to data, there was one tall peak and a few little ones. The Percent Area for peak 1 was -197.78 and peak 2 was 297.78, and the Retention time for peak 1 was .700

Distillation is used to separate liquids with different boiling points. Because toluene and isopropyl acetate have different vapor and composition phases, fractional distillation was used. Isopropyl acetate’s boiling point is lower than toluene’s boiling point (89°C and 111°C), meaning that Fraction 1 was isopropyl acetate while Fraction 2 was a mixture of the two, and 3 was pure toluene. Gas chromatography was only performed on Fraction 1 and 3, and a packed column was used. Isopropyl acetate and toluene’s polarity were important because the more polar the molecule, the longer it takes to come off of the column in the GC. The number of peaks showing on the gas chromatography analysis shows how many compounds are in the sample. For example Fraction 1 had two peaks, meaning there were two compounds in the sample, while Fraction 3 only had one peak. The longer the retention time, the more polar the compound was. Fraction 3 had the longest retention time, meaning it was more polar than Fraction 1. Fraction 3 was toluene, which is a more polar compound than isopropyl acetate in Fraction 1. Gas chromatography also identifies the concentration of the compound or the size of the peaks. A tall and wide peak means that there was a lot of a compound passing over the detector in the gas