Diels Alder Lab Report same as before. Do not use outside resources………………………………….. CHEM 3112 Beyond Labz Experiment 8: Diels-Alde | Course Hero

Diels Alder Lab Report same as before. Do not use outside resources………………………………….. CHEM 3112
Beyond Labz Experiment 8: Diels-Alder
The Diels-Alder cyclization process was first described by German chemists Otto Diels and Kurt
Alder in 1928. They were awarded the Nobel Prize in Chemistry for their work in 1950. What
they observed was a cyclization of a conjugated diene and a dienophile (a substituted alkene or
alkyne) to form substituted cyclohexene derivatives. The Diels-Alder reaction is a useful tool to
prepare both simple and complex ring structures with predictable stereo- and region-chemical
outcomes.
The Diels-Alder reaction is a thermal process, so the methods used in the lab to perform the
reaction can vary. Some processes require extremely high temperatures (>300 °C), and thus must
be performed in special equipment. If the temperature requirement is lower, solvents such as
mineral oil, silicon oil, or polyethylene glycol can be employed. It is also common to perform
Diels-Alder reactions neat (solvent-free).
In this experiment, you will be synthesizing bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylic
acid dimethyl ester via a Diels-Alder cyclization. Choose the appropriate diene and dienophile.
Directions:
1.
2.
3.
4.
5.
Open Beyond Labz Client.
Choose the “Worksheets” tab.
Choose “Organic Chemistry”.
Choose “Diene Reactions”.
Choose “Diels Alder – 4”; this should bring up a PDF file with the experimental
procedure.
6. Back in the Beyond Labz Client, choose the “Labs” tab, and open “Organic Chemistry”
7. Under “Organic Worksheets” choose “Diene Reactions” then “VCL 3-7: Diels Alder 4”. This should bring you to the lab bench.
8. You are now ready to attempt the experiment.
Lab Report Questions:
1. List the starting materials, solvent, reagent, temperature range (low, room temp, or high)
and products formed:
2. How long did it take to finish the reaction?
3. List any important IR peaks (If no noteworthy peaks, answer “none”).
4. List any IR peaks NOT PRESENT that indicate the product was formed? (Hint: think
about the functional groups of the starting material and the product) (If not, answer
“none”)
5. List the 1H NMR peaks. List the peak number, chemical shift, multiplicity (splitting
pattern), and the integration.
6. List the 13C NMR peaks. List the peak number and the chemical shift.
3-7: Diels Alder – 4
For this assignment, the target compound that you should synthesize is bicyclo[2.2.1]hepta-2,5-diene2,3-dicarboxylic acid dimethyl ester. This is a cycloaddition reaction. Examine the product to
determine the reactive partners. Keep in mind the position of the alkenes in the product. Try pushing the
electrons backwards to reveal the needed substrates.
Synthesis Procedures
1. Start Virtual ChemLab and select Diels Alder – 4 from the list of assignments on the whiteboard.
After entering the synthesis laboratory, use the available reagents on the stockroom shelf and identify
the appropriate starting materials required to synthesize the target compound and add them to the
round bottom flask. Now add ether (Et2O) as a solvent and drag the flask to the Stir Plate on the lab
bench.
2. The round bottom flask containing the starting materials should now be on the stir plate, and the
contents of the flask should be visible on the chalkboard. From the group of reagents found on the lab
bench, select the correct reagent to synthesize the target compound and add it to the flask on the stir
plate. Now attach the heater, condenser, and N2 gas to the round bottom flask so the reaction mixture
can be heated.
3. Start the reaction by clicking on the Stir button on the front of the stir plate. You should be able to
observe the reaction mixture stirring in the flask. Monitor the progress of the reaction using TLC
measurements as necessary until the product has formed and the starting materials have been
consumed. You can advance the laboratory time using the clock on the wall. With the electronic lab
book open (click on the lab book on the stockroom counter), you can also save your TLC plates by
clicking Save on the TLC window.
4. When the reaction is complete, “work up” your reaction by first dragging and dropping the separatory
funnel on the flask and then adding H2O to the funnel. Extract the organic layer in the funnel by
clicking on the top layer and dragging it to the cork ring on the lab bench. Your target compound
should now be in this flask.
List the starting materials, solvent, reagent, and products formed:
How long did it take to finish the reaction?
What are the TLC values (Rf) for (a) Starting Materials:
(b) Products:
Write a mechanism for this reaction:
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FTIR and NMR Spectra
After completing a reaction and working up the products, it is still necessary to confirm that the correct
product was formed. The most common tools used for this analysis are Fourier Transform Infrared (FTIR)
and Nuclear Magnetic Resonance (NMR) spectroscopy. In the virtual laboratory, 1H and 13C NMR
spectra are available. Details on interpreting FTIR and NMR spectra are found in your textbook. Your
instructor may or may not ask you to perform this section depending on how your class is structured.
5. To collect an FTIR spectrum of your product, click on the FTIR spectrometer located to the right of
the lab bench and drag the salt plate icon to the flask on the lab bench. A window containing the FTIR
spectrum for your product should now open. Identify the relevant peaks in the FTIR spectrum and
record the position and associated functional group for each in the FTIR table below. The FTIR
spectrum can also be saved to the lab book for later analysis.
FTIR
List position (cm-1) & functional group
4.
1.
5.
2.
6.
3.
7.
6. To collect a 1H NMR spectrum of your product, click on the NMR magnet located to the right of the
chalkboard and drag the NMR sample tube to the flask on the lab bench. A window containing the
NMR spectrum for your product should now open. You can zoom into various portions of the NMR
spectrum by clicking and dragging over the desired area. The Zoom Out button is used to zoom back
out to view the full spectrum. Identify all of the peaks in the NMR spectrum and record the chemical
shift, the splitting, and the number of hydrogens for each peak in the NMR table below. The NMR
spectrum can also be saved to the lab book for later analysis. If necessary to confirm the structure of
your product, you can measure the 13C NMR for the product and record the chemical shifts for the
peaks. Mass spectrometry is also available if needed.
1
H NMR
Structure:
O
OMe
OMe
O
Peak
Chemical
Shift (?)
Multiplicity†
H‡
Peak
1
7
2
8
3
9
4
10
Chemical
Shift (?)
Multiplicity†
H‡
Bicyclo[2.2.1]hept
5
11
a-2,5-diene-2,3dicarboxylic acid
6
12
dimethyl ester
†
Specify the multiplicity as a singlet (s), doublet (d), triplet (t), quartet (q), or multiplet (m).
‡
Specify the number of hydrogens associated with each peak.
7. Do the FTIR and NMR spectra you measured and recorded in the tables above confirm that you
synthesized the assigned target compound? Explain.
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