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Lab 4 The synthesis of acetaminophen
- Course
- CHM 2123 (CHM2123)
- Institution
- University Of Ottawa (U Of O )
A copy of answers and feedback for the laboratory of organic chemistry course.
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CHM 2123 — Laboratory ReportFall 2022
The synthesis of acetaminophen
Student(s) Name(s) Asha Doughty
and Number(s) : 300226452
This report is: Individual
Date: October 27, 2022
Teaching Assistant: Samuel Delisle
Weekly Lab Period Thursday
COMMENTS
• Your report is submitted electronically via Brightspace into the dedicated folder.
• This report can be completed individually or in pairs, with your assigned lab partner, to each student’s
preference. If done in pairs, each student must submit an identical copy of the pre-lab. Make sure to include
both your names and student numbers above. Both students will receive the same marks and comments.
• This lab report is due on the week of October 24th, by the beginning of your respective lab section. Do
not trust Brightspace’s due date: since every students share the same Brightspace page, the due date found
online is for the last section of the week.
• Type all the answers using Arial font, size 12 pt, directly in the cells provided. The cells are representative of
the length of the expected answer, and their sizes have been locked to discourage superfluously long
answers. Anything exceeding this expected length may be ignored by the TA.
• Molecular figures must be drawn using ChemDraw.
• Late penalty is 20%/day, starting the moment the report is due and going up every 24h.
Point distribution
Introduction and Experimental Section /7
Results and Observations /12
Discussion /27
Post-Lab Question /21
Conclusion /5
Appendix /2
TOTAL /74
, Introduction and Experimental Section
Explain briefly (3–5 sentences), and in your words, the objective(s) of this experiment and a short
description of the reaction involved. (3 pts)
In this experiment, the goal was to synthesize and isolate a solid product of acetaminophen.
This was done by reacting two chemicals, para-aminophenol, and acetic anhydride. The
nucleophilic nitrogen from the amine will attack the electrophilic carbon from the carbonyl. In
return, an intermediate zwitterionic molecule will form. Next, intramolecular proton transfer will
create a neutral alcohol. Finally, the amine turns into an amide functional group, thus creating
the target molecule, acetaminophen. As well, a by-product of acetic acid is formed.
Provide a short summary of all of the steps taken throughout this experiment (including synthesis,
purification and analysis). Your explanation must include a brief description of what each step
entails and its role/importance (i.e. why are you doing each step). (4 pts)
The first step was refluxing a reaction. This was done by heating the reaction mixture in a
round bottom flask with a heating mantle. To prevent evaporation of the solvent, a water
condenser was added on top of the flask. The reflux set up was necessary to speed up the
rate of the reaction. Afterwards, once the mixture had boiled, it was put in an ice bath to
precipitate out the product. Before the precipitate occurred, a sample of the mixture was
spotted on a TLC plate along with a reference sample of para-aminophenol. The results of the
TLC indicated if the reaction had gone to completion. The solid precipitate was filtered from
the reaction mixture by using a vacuum filtration set up. The solid remained in the Buchner
funnel, while a hand pump filtered the liquid into a flask. Recrystallization was an optional step
to further purify the solid. The crude solid was boiled in an Erlenmeyer flask with water. Once
the solid was dissolved, it was set to cool at room temperature and in an ice bath which
precipitated a recrystallized solid. The solid was then dried using a water aspirator. The solid
sat on top of one flask which was connected to a second flask. The second flask was hooked
to a water tap. The stream of water created an air vacuum, thus drying the solid. Once the
solid (recrystallized or crude) was dry, it was weighed. Finally, TLC and melting point analysis
were performed. Some of the solid (recrystallized or crude) was dissolved and spotted on a
TLC plate, along with the para-aminophenol sample. Another portion of the solid was stuffed
in a melting point capillary and analyzed by slowly melting the sample in a melting point
apparatus. The melting point of the solid was a range starting from the temperature at which
the first drop of liquid appeared to the temperature at which all the solid dissolved. This melting
point range was compared to the known value for acetaminophen to identify the product.
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