UCO Chemistry Synthesis of Benzyl Methyl Ether Paper

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Williamson Ether Synthesis – 1
For this assignment, the target compound that you should synthesize is benzyl methyl ether. This is a substitution reaction. Examine the product and
determine which bonds may be formed. Keep in mind the substitution pattern of the product and the nature of the mechanism accommodated by this
arrangement.
Synthesis Procedures
1. To start this activity, click this link for Williamson Ether Synthesis –1 . The lab will load in a new tab. Click back to this tab to read further
instructions and complete the questions below. Use the available reagents in the Alkyl Halide Solvolysis section in the Stockroom tab 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 contents of the flask are visible in Live Data. 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.
3. Start the reaction by clicking on the dials 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 (if you have not previously completed the activity Using Thin Layer Chromatography, please see the note at the bottom of that
assignment regarding TLC in Beyond Labz). You can advance the laboratory time using the clock on the wall. 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 doing a separatory funnel extraction. Drag and drop the separatory funnel on the flask
and then add the appropriate solvent to the funnel. Remember that the addition of any aqueous solvent also adds diethyl ether, although this is not
shown (see note at the bottom of the activity Performing a Separatory Funnel Extraction). Either the organic or the aqueous layer can be removed
by clicking and dragging it to the bench. Your target compound should be in one of these layers. The other layer can be discarded into the red bin.
Rot
&
Remember that subscripts (A ) and superscripts (A ) can be included as needed using the _ and ^ characters respectively. Reagent
a
List the starting materials, solvent, reagent, and products formed: starting period
B
B
Event
NaOme
+
D
—
How long did it take to finish the reaction?
ins
minutes
What is the TLC value (Rf) for the Starting Materials?
0.0
If none are present enter “0”
What is the TLC value (Rf) for the Products?
8,0
If none are present enter “0”
Draw a mechanism for this reaction.
Please attach a file containing your drawn reaction diagram.
Choose File
no file selected
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
13
C 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 below. The FTIR spectrum can also be saved to the lab book for later
analysis.
When entering values for the FTIR please enter them in order from left to right on the spectrum to ensure they match the grading rubric.
Position (1)
cm-1
Functional Group 1
Position 2
cm-1
Functional Group 2
6. To collect a 1H NMR spectrum of your product, click on the NMR magnet 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 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.
When entering values for the NMR please enter them in order from left to right on the spectrum to ensure they match the grading rubric.
Peak (1) Chemical Shift
Specify the multiplicity as a singlet (s), doublet (d), triplet (t), quartet (q), or multiplet (m).
Peak (1)
s
t
m
q
d
Specify the number of hydrogens associated with this peak.
Peak (1)
Peak (2) Chemical Shift
Specify the multiplicity as a singlet (s), doublet (d), triplet (t), quartet (q), or multiplet (m).
Peak (2)
m
s
q
t
d
Specify the number of hydrogens associated with this peak.
Peak (2)
Peak (3) Chemical Shift
Specify the multiplicity as a singlet (s), doublet (d), triplet (t), quartet (q), or multiplet (m).
Peak (3)
t
d
m
q
s
Specify the number of hydrogens associated with this peak.
Peak (3)
Peak (4) Chemical Shift
Specify the multiplicity as a singlet (s), doublet (d), triplet (t), quartet (q), or multiplet (m).
Peak (4)
m
q
t
s
d
Specify the number of hydrogens associated with this peak.
Peak (4)
7.
Do the FTIR and NMR spectra you measured and recorded above confirm that you synthesized the assigned target compound? Explain.
Williamson
synthesis.
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Dhwani. Desai
Dr. Pogban Toure
Chemistry 212
March 3, 2023
Alcohol Dehydration 5-4: Synthesis of cyclohexene
I) Purpose of experiment:
The purpose of this activity is to learn thin layer chromatography which is a powerful and
widely used analytical technique. The chemistry behind the synthesis of cyclohexene from
hexanol and the interpretation of FT-IR and NMR spectra is also the purpose of this activity.
II) References:
•
Prabhu, Azhagapillai, et al. “Prominent catalytic activity of mesoporous molecular
sieves in the vapor phase dehydration of cyclohexanol to cyclohexene.” Journal of Rare
Earths 31.5 (2013): 477-484.
•
Costa, M. Conceiçao Cruz, et al. “The mechanism of gas-phase dehydration of
cyclohexanol and the methylcyclohexanols catalysed by zirconium phosphate and
zirconium phosphite.” Journal of Molecular Catalysis A: Chemical 142.3 (1999): 349360.
•
Akiya, Naoko, and Phillip E. Savage. “Kinetics and mechanism of cyclohexanol
dehydration in high-temperature water.” Industrial & engineering chemistry
research 40.8 (2001): 1822-1831.
•
Bele,
Archana
A.,
and
Anubha
Khale.
“An
overview
on
thin
layer
chromatography.” International Journal of Pharmaceutical Sciences and Research 2.2
(2011): 256.
•
Iborra, J. Osé Luis, et al. “TLC preparative purification of picrocrocin, HTCC and
crocin from saffron.” Journal of Food Science 57.3 (1992): 714-716.
III) Reaction and reaction mechanism:
IV) Procedure
The activity was started by clicking on Alcohol Dehydration and a new tab was opened. All
the instructions were read carefully and from the reagent section Alcohol Halogenation, the
appropriate chemicals were selected. Then a three-necked round bottom flask was selected and
water as solvent was added to it. This assembly was set on a stir plate which was dragged on
the lab bench. From the reagent on the lab bench, cyclohexanol and H2SO4/H3PO4 were
selected and added o the reaction assembly. Then by clicking the start button of the stir dial
reaction was started and the progress of the reaction was monitored with the help of TLC. The
reaction proceeded till all the reactants were consumed and the product was formed. When the
reaction was completed, the workup of the reaction was done on separatory funnel extraction.
The separatory funnel was dragged and dropped on the flask and water and diethyl ether were
added. The organic layer was separated out and further distillation was performed on a stir plate
under an N2 supply at an elevated temperature to remove all kinds of by-products. The
observations were noted and calculations were performed.
V) Results, observations, and calculations
i) A screenshot of the experiment right after the reaction was started.
ii) A screenshot of the experiment after the reaction was completed.
Based on the results achieved, the time to finish this reaction was about forty-five minutes.
The following formula is used to calculate the Rf values of the starting materials and the
product: Rf = (distance traveled by solute) / (distance traveled by solvent).
The Rf value for the starting materials is: Rf = 5.1/7 = 0.73 cm.
The Rf value for the products is: Rf = 3.4/7 = 0.49 cm.
Since the Rf value for the product is smaller, it shows that it is more polar, and it travels
slower. The Rf value for the starting materials is larger, and less polar, which means it travels
faster. After completing this reaction and working up the product, FTIR is used to confirm
that the target product was formed.
FTIR:
FTIR Reading:
Position
Functional Group
Absorption (cm -1)
(1)
= C-H stretch (sp2)
~3022
(2)
C-H stretch (sp3)
~2925
(3)
C=C stretch
~1665
The FTIR spectrum showed three relevant peaks at around ~3022 cm-1, ~2925 cm-1, and
~1665 cm-1.
Next, an NMR spectrum is performed to confirm that the target compound was formed. The
spectrum for the NMR showed three peaks.
H1 NMR
1
H NMR Reading:
Peak
Chemical Shift
Multiplicity
# of Hydrogens
associated
(ppm)
1
5.66
Triplet
3
2
1.99
Quartet
4
3
1.65
Triplet
3
VI) Discussion
Thin layer chromatography is based on the attraction between the analyte and the TLC plate
which is made up of silica. Almost all the reactants show different bonding strengths with silica.
Hence the reactant with a strong bond with the plate will stay on the plate while others will
move on. The time of illusion of reactants is different from each other.
Hence, every reactant has a different value of retention factor i.e Rf. It is defined as the ratio
of distance traveled by reactant molecules from baseline to the distance traveled by solvent
molecules. It can be calculated by using following formula,
𝑅! =
𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑐𝑜𝑣𝑒𝑟𝑒𝑑 𝑏𝑦 𝑐𝑜𝑚𝑝𝑜𝑛𝑒𝑛𝑡
𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑐𝑜𝑣𝑒𝑟𝑒𝑑 𝑏𝑦 𝑠𝑜𝑙𝑣𝑒𝑛𝑡
The FT-IR and H1 NMR spectra helped us to confirm the formation of the product.
VII) Conclusion
In conclusion, I will say that this activity helped us a lot in learning the chemistry behind the
synthesis of cyclohexene. Cyclohexene is prepared by the acid-catalyzed dehydration of
secondary alcohol, particularly hexanol. The use of thin layer chromatography was learned
which helped to monitor the progress of a reaction. The calculation for predicting Rf values
were performed and FT-IR and H1 NMR spectra were interpreted.
VIII) Questions:
1.) List the starting materials, solvent, reagent, and product formed.
Starting material: Cyclohexanol
Solvent: not required
Reagent: Sulfuric Acid
Products formed: Cyclohexene, (Byproduct: 1,1-Oxybis-cyclohexane)
2.) How long did it take to finish the reaction?
The reaction took about forty-five minutes to complete.
3.) What is the TLC value (Rf) for the starting material?
The TLC value (Rf) for the starting material is: 5.1/7 = 0.73 cm.
4.) What is the TLC value (Rf) for the products?
The TLC value (Rf) for the products is: 3.4/7 = 0.49 cm.
5.) Do the FTIR and NMR spectra you measured and recorded above confirm that you
synthesized the assigned target compound? Explain
Yes, the FTIR and NMR spectra we measured and recorded above confirmed the synthesis of
the assigned compound. The FT-IR spectra provide the functional group analysis, with
characteristic peaks for double bond and CH stretching as well as bending vibrations at reported
positions. Moreover, H1 NMR spectra provide the structural information for the synthesis of
cyclohexene.