The Purification of Poisoned Excedrin
Introduction
As a budding organic chemist you are faced with a very common problem: a drug
you need has been poisoned with an unwanted organic compound. The drug you
need is Excedrin (a mixture of caffeine, acetaminophen, and aspirin), and it
has been poisoned with 1,4-dimethoxybenzene. You will work in a team of two
or three students. Your team's task is separate the four compounds from each
other and then characterize them to find out how successful your separation was.
Theory
Read the brief section on "Chromatography: Purifying Organic Compounds"
in your McMurry text on pp 431-432. View the chromatography
animation
on the College of Wooster chemistry website.
Pre-Lab
Your team must come up with a written strategy (showing all of the
structures of the molecules) which outlines how you will be separating the
mixture, characterizing the separated compounds, and determining how well
your separation worked. Construct a flow chart similar to the one from the
Acid-Base Extraction experiment. You only need to turn in one strategy and
flow chart per team. In order to assist you, the following chemicals will be
available in the lab:
pure caffeine, acetaminophen, aspirin, and 1,4-dimethoxybenzene
hexane, ether, dichloromethane, acetone, methanol, water, 3M NaOH, 3M HCl
You should probably discuss your strategy with your instructor before coming to lab. You will turn in your strategy and flow chart before lab begins (make two copies so that you have one to look at in lab).
Experimental Procedure
You will get a vial that contains 1 gram each of all four compounds.
The separation procedures for each team will probably be different. Your team
must be flexible: don't stick to a plan if it looks like things are not working.
You will have two weeks to complete this experiment.
Results and Discussion