CHM 238 Arizona State University Grignard Reagent Lab Report

General Format for Written Lab ReportsThe ability to write technical information in a way that is clear to others is an important skill for
any scientist. Like any other skill, you can only acquire this by practice.
Submission Requirements:
 The full report (with all figures and structures) must always be turned in electronically on
Canvas. The assignments will be checked using antiplagiarism software.
 All students must submit their own report, there are NO group reports.
 The file name should contain the experiment and your name. However, the file name should
not be too long.
Academic Integrity:
 Academic Integrity is expected of all students: https://provost.asu.edu/academic-integrity
 Academic dishonesty will result in punishments varying from failing the assignment along
with a deduction of 50-100 points from your overall class score, failing the class, failing the
class with the grade of “XE” (failure due to academic dishonesty), or even expulsion from the
university: https://provost.asu.edu/academic-integrity/policy
 Make sure to cite all references (internet, lab manual, journal articles, books, etc.). Include
both in-text citations and list of references.
 References can be in one of several styles but you must be consistent. The most common are
American Chemical Society: (http://chemistry.library.wisc.edu/writing/acs-styleguidelines.html#printeditions),
and APA Style: (https://owl.english.purdue.edu/owl/section/2/10/).
 Only credible sources should be used for the report such as books, journals or your own lab
packet. Wikipedia, About.com, ehow.com, buzzle.com etc. are not considered acceptable
reference sources.
 It is allowed to directly quote a small portion of a reference, as long as you correctly use
quotations marks. However, large quoted sections will not be accepted and will result in a
loss of points.
 If you obtained permission to use someone else’s data (e.g., because you were sick or the
experiment failed), then clearly indicate the source in your report.
 Your submission will be checked using “TurnItIn” for plagiarism, where you copied from
other sources and did not cite them, and also for SELF PLAGIARISM, where you copy and
paste something that you wrote previously, for example, from a previous lab report. You are
advised that you need to rewrite, revise and re-word content from your previous lab reports.
General Formatting:
 Your report must be typed and double spaced.
 Each page must contain a page number, with an exception of the first page.
 Organic structures, equations and mechanisms must be created by you. They can be drawn
using computer software, or, you can draw them by hand then photograph and paste them
into your report. In either case your images must be very clear, very neat, legible, be straight,
and should not have excessive white space around them. ONLY high quality images will
receive full credit. If you are unsure if your image is high quality, speak to the Lab
Coordinator before you turn it in.
 To paste an image into Microsoft Word use the “Insert Image” function that usually
generates a smaller file size compared to pasting from a graphics program in order to reduce
problems when it comes time to upload your report to Canvas.
 The file you will upload must be in pdf format. You are responsible for making sure that
your final file size is less than 10 MB or you will not able to upload it onto Canvas.
 Figures of non-chemical structures (i.e. apparatus diagrams) may be taken from outside
sources as long as the source is clearly cited.
 All figures and structures must be properly labeled and described directly under the figure.
For example, Figure 1: Reflux apparatus
Scheme 1: Synthesis of 4-methylcyclohexene from 4-methylcyclohexanol.
 Do not use “I” or “we” or any other types of pronouns.
 Verb Tenses –
o When the experiment is already finished (Abstract, Experimental, Results, and
Discussion), use the past passive voice:
 The objective of the experiment was…
 The apparatus was placed…
o Since the report, theory and permanent equipment still exist (Introduction) you should
use the present or future tense:
 Distillation theory states…
Refer to the specific lab report template for what to include in each report.
Synthesis of [Name of the Product]
via [Name of the Reaction] Reaction
Your Full Name
TA: Your Lab TA’s full name
Lab Day and Time
Abstract
Writing Guidelines:
•
The abstract should be written in full sentences in past passive voice.
•
The abstract should be concise but comprehensive⎯a paragraph long (about 5-7
sentences). It should including the following:
o The purpose of the lab
o Describe the product i.e. liquid or solid, color, etc.
o Indicate the isolation and purification techniques. Only state the names of the
techniques. Do not include experimental details.
o Indicate the methods that were used to characterize the product
o Indicate the name of the final product
o Indicate percent yield
Introduction
Writing Guidelines:
•
The introduction should be written in full sentences using present or future tense.
•
An introduction should be roughly ONE to TWO pages long (two pages max), doublespaced.
•
The Introduction should include the following:
o The purpose of the lab and a very brief introduction to the synthesis
o Describe all related reactions.
o Draw all chemical reactions or overall reaction scheme i.e. the reactions to form the
Grignard reagent, the adduct, and the final product.
o All chemical pictures/images must be generated by YOU. Any chemical images copy
and paste from the lab packet or other sources will earn a 0 point even with citations.
o Mention all the techniques used in this lab. Do not include the experimental details.
For example, mention only ether extraction or aqueous extraction (do not include the
details of the extraction such as the mixture will be extracted with 3 mL ether, etc.).
o Mention the methods for characterization.
o All Organic structures and equations in the lab report must be created by you, and
must be in high quality (See General Format for Written Lab Reports for details).
page number
Experimental
Writing Guidelines:
•
The Experimental section must be written in full sentences using past passive voice.
•
The experimental section for this lab should be about ONE page and must not exceed
1.25 page long.
•
Start this section with “According to the procedure described in the Grignard lab packet
(Arizona State University, Year),…”
•
This section should be detailed enough so that anyone could repeat the experiment, but it
should NOT be just a repeat the detailed procedure given in the lab package.
•
The idea of an experimental section is that it is supposed to be “expert to expert”, which
means that you don’t have to say things like, “the experiment used roughly 150 mg of X
and the exact weight measured was 145 mg”, instead you say “145 mg of X was added
to….”.
page number
Results
Writing Guidelines:
•
Tabulate ALL of your lab data
•
Show the following calculations:
o moles of all reactants
o indication of the limiting reactant
o theoretical yield
o moles of the crude product
o percent yield of the crude product
o moles of the pure product
o percent yield of the pure product
o percent recovery from recrystallization
•
Give a brief explanation for each step of your calculation.
•
Include the melting point range data of the product.
•
Include IR spectrum of the product in this section.
o On the IR spectrum, draw the structure of the final product.
o Label of the major IR peaks above 1500 cm-1.
•
Include the Table of Frequencies and Assignments for peaks of the IR spectrum as shown
in the table template below.
Frequency (cm-1)
Specific Bond Vibration
Functional Group
•
Be sure to include captions for each Table, Figure, and Equation
•
The figures, diagram, and spectra should be clear, neat, legible, straight, no excessive
white space or shadows or nonrelated items present.
•
All calculation equations in the lab report must be created by you, and must be in high
quality (See General Format for Written Lab Reports for details).
page number
Discussion
Writing Guidelines:
•
The Discussion section must be written in full sentences using past passive voice.
•
This section should be no more than TWO pages double-spaced.
•
Discuss the reaction and mention percent yield (about 1 paragraph).
•
Draw the mechanisms of the related reactions.
•
Discuss each and every step of the related reactions.
•
Discuss in detail about the techniques used for isolation and purification.
•
Discuss in detail about the techniques used for characterization i.e. melting point and IR
•
Discuss your IR results in detail.
•
Discuss the melting point and IR data of your final product in detail as related to the
purity of your product.
•
Discuss of what was learnt or observed and possible reasons for experimental errors,
formation of side products (be specific), etc. Note that mentioning “human errors” is not
sufficient.
•
All Organic structures and equations in the lab report must be created by you, and must
be in high quality (See General Format for Written Lab Reports for details).
page number
Conclusion
Writing Guidelines:
•
The Conclusion section must be written in full sentences using past passive voice.
•
A conclusion is about a paragraph long (5-7 sentences).
•
Write a concise summary of the experiment. Briefly mention the experimental techniques
used. Indicate whether your synthesis was successful. Mention the name of the final
product and percent yield.
Work Cited
Writing Guidelines:
•
Include ALL the references used. Each lab packet can be cited in the following format:
Arizona State University (Year, Month and Day of retrieval). Name of the Lab Packet.
Retrieved from https://canvas.asu.edu/courses/75289
•
For other references, follow the APA or ACS format.
page number
Copyright, Arizona State University
Arizona State University: CHM 238 : Organic Chemistry Lab II
Grignard Lab Package
Synthesis of Triphenylmethanol
Grignard Reactions
successfully
performed HERE
Tempe (AZ)
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Grignard reactions need to be kept dry, but they can be performed in wet places – from experience!
This is a “virtual” lab where you will watch the instructors perform the experiment for you. After watching the
Recitation video, you must watch additional videos of the actual experiment being performed in order for you to
gather data for your lab report and related assignments for this lab.
Grignard Recitation Video: Posted on Canvas
Performing Experiment Video Part 1: https://asuonline.wistia.com/medias/xtqx6a8zhz
Performing Experiment Video Part 2: https://asuonline.wistia.com/medias/7qmpi347ct
Performing Experiment Video Part 3: https://asuonline.wistia.com/medias/anl97ivqp5
1. Background
• In this lab, you will perform an important carbon-carbon bond forming reaction – the Grignard reaction (after
Victor Grignard, French chemist, 1871 – 1935).
• This lab teaches you new techniques, and the importance of having good technique!
• One purpose of this lab is to introduce you to a realistic organic synthesis, which are usually significantly longer
than conventional organic labs you performed in this class. Therefore, there is a lot going on in this lab, and the
lab is quite long. You will need to come to lab prepared, and you will need to work efficiently!
1.1 The Various Steps for this Synthesis are a Little Different from Previous Syntheses
The overall reaction scheme:
• We can break the procedure down into the following stages:
prepare to do
the Grignard reaction
prepare the
Grignard
do the Grignard
reaction
DRY GLASSWARE
reaction
NEXT reaction
acid workup
purification / characterization
• The preparation to get ready to do the Grignard reaction requires more attention than usual!
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1.2 Preparation
• Grignard reactions must be performed in the absence of any water.
• Grignards are strong Bronsted bases and will react with any water that sticks to the glassware or even water in the
atmosphere.
• All glassware must be dry, and the reaction needs to be protected from the atmosphere in the lab (Grignard
reactions can go very wrong in a humid climate, but they can be performed successfully in one of the wettest cities, in
one of the wettest countries in Europe, so you should be able to do one in Arizona!).
• Grignard reactions must be kept dry because Grignard reagents are very strong Lewis and Bronsted bases, and they
will remove a proton from any water molecule that they encounter.
• You will thoroughly dry all of the glassware in the oven for a full 30 minutes to remove as much water as
possible.
1.3 Reaction to Form the Grignard Reagent
• The reaction container needs to be sealed against the atmosphere.
• The procedure and a photograph of the apparatus is shown below:
• A rubber septum is used to keep atmospheric oxygen and moisture out of the reaction mixture.
• Reagents are introduced through the septum using a syringe needle.
• When the syringe is not in use, leave the syringe needle in the septum in order to keep the needle dry between
uses.
• The Grignard reaction usually has to be started by warming (touch the flask to the block), but do not overheat or
else you will lose your volatile ether solvent.
• You may have to scratch/crush the magnesium metal turnings and/or add a small crystal of iodine to make the
reaction start.
• Consult your TA if you do not observe the reaction start.
• You will know that the reaction is going because bubbles will form, and the metal will slowly appear to dissolve into
the organic solvent. When the metal disappears into the organics, you will be amazed!
• Once the reaction gets going, you can then add the remaining bromobenzene/ether mixture slowly over 15 minutes
in small increments! Do not add too quickly, or you will not make the Grignard reagent properly!
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1.4 Formation of the Grignard Adduct to Benzophenone
• Grignards are very reactive. Their reactions do not need heat to increase the collision energy!
• Add the benzophenone solution in ether slowly over 5 minutes in increments while stirring vigorously!
• At the end of the reaction, pour the contents into the 50 mL beaker, and wash out the round bottom flask with water
to make sure everything goes into the beaker.
1.5 Aqueous Acid Workup Step
• The isolation of the alcohol product from the Grignard reaction is an example of an acid workup step.
• The aqueous acid hydrolyzes the O-Mg bond to make the alcohol, which sets up for the subsequent extraction into
an ether solvent.
• Aqueous workup steps are common in organic reactions and are used to:
1.6 Extraction Using a Separatory Funnel
• The organic reaction product is isolated using extraction.
• You will learn a new extraction technique because the scale of this reaction is larger
than you have done in the past. You will use a separatory funnel in this lab.
• One of the aqueous extractions will use brine instead of plain water.
• Brine is a saturated solution of sodium chloride in water.
• It is useful in extractions since it effectively increases the polarity of the water, which helps
to separate the aqueous and organic layers. It also prevents the formation of an emulsion,
where tiny droplets of organic materials and water mix and do not separate well.
• Brine also helps to extract water from the organic layer due to the strong ion-dipole
intermolecular forces between the ions and water.
• There is a particular technique that you should do when using a separatory funnel.
You should watch the video clip below:
YOUTUBE: Using a Separatory Funnel: https://youtu.be/NuMl6ndwvfk
1.7 Crystallization
• The crystallization solvent is petroleum ether, which has an unfortunate historical name, since it is not actually
an ether!
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• Petroleum ether is a mixture of hydrocarbons that do not contain ether functional groups, see above.
• Petroleum ether is a very non-polar solvent and is, in effect, very different from the diethyl ether that was used
throughout this experiment.
1.8 Formation of Side-Products
• Grignard reagents are very reactive, and they can form side-products.
• Specifically, phenylmagnesium bromide can react with water to form benzene as a side-product.
• Phenylmagnesium bromide can also react with bromobenzene to give biphenyl as a side-product (although the
mechanism of this reaction is not clear).
• Side-products reduce the overall yields of chemical reactions.
• Using the non-polar petroleum ether as a crystallization solvent helps to remove the non-polar benzene and
biphenyl side-products because they dissolve well in the non-polar petroleum ether solvent. The side-products will
remain in the solvent, and the more polar alcohol product will crystallize out of solution.
• This method helps the product to be at least partially separated from the unwanted organic side-products.
2. What You Will Do
1. Pre-Lab: You must watch the online recitation for the Grignard Lab (Canvas), complete the gapped notes
(Section 1 of the packet), complete the Pre-Lab notes in the notebook (see Section 3), and complete the Pre-Lab
activity worksheet (see Section 4). Each student must complete all of these and submit the work on Canvas upload
link.
2. In Lab, you will be watching the instructors perform the experiment for you. You must watch the three videos
or else you cannot collect the necessary results that you will need for your lab report OR the assignments
related to this lab. You will not have to wear PPE for this lab.
3. Post-Lab: Complete the Post-Lab assignment. Each student must turn their own completed copy on Canvas.
4. LAB REPORT: Complete the lab report for this experiment. Each student must turn their own completed copy on
Canvas. See the course syllabus for due date.
2.1 Synthesis of the Grignard Phenylmagnesium Bromide Adduct to Benzophenone
2.1.1 Getting Ready to do the Reaction
You will need to watch THREE videos of the instructors performing this lab:
Video 1: https://asuonline.wistia.com/medias/xtqx6a8zhz
Video 2: https://asuonline.wistia.com/medias/7qmpi347ct
Video 3: https://asuonline.wistia.com/medias/anl97ivqp5
• All glassware must be scrupulously dried before use in this reaction. Place the following in the laboratory oven for
at least 30 minutes prior to beginning the experiment:
• 1 x 25 mL round bottom flask
• 1 x magnetic stir bar
• 1 x 3 mL conical vial
• 1 x 5 mL conical vial
• 1 x 50 mL Erlenmeyer flask
• 1 x Claisen adapter
• 1 x drying tube
• 5 x glass Pasteur pipets
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• Obtain plastic syringes and needle from your TA. Check with your TA for the procedure to dispose of the
syringes.
• Once dry, remove the glassware from the oven, and use septa and black screw caps to seal the glassware as they
cool down. Prepare the drying tube with anhydrous calcium chloride as it is cooling.
2.1.2 Preparation of Phenylmagnesium Bromide Grignard Reagent
• Add 0.150 g of shiny magnesium turnings and a magnetic stir bar to the 25 mL round bottom flask, and quickly
assemble the apparatus as shown. Be sure to leave your syringe with the needle inserted through the rubber
septum in order to keep it dry between uses.
• Pour roughly 20 mL of anhydrous diethyl ether into a 50 mL Erlenmeyer flask using its graduated markings. Use a
rubber septum to keep the flask sealed.
• Set the hotplate to its lowest setting, and begin heating a square aluminum block.
• Using the syringe, add 0.7 mL of bromobenzene to a preweighed 5 mL conical vial, and record the exact mass that
you start with. Transfer 4 mL of anhydrous diethyl ether to the vial using a glass Pasteur pipet, reseal the vial, and
then mix gently to fully dissolve the bromobenzene.
• Use the syringe to transfer 0.8 mL of this solution to the reaction vessel through the rubber septum. Leave the
syringe inserted through the septum following this and every addition.
• Bubbles will evolve from the magnesium turnings when the reaction begins. You will likely need to initiate the reaction
using one or more of the following methods:
1) Apply gentle heat to the round bottom flask by resting it on the aluminum block. These flasks cannot be
inserted into the block, however simply touching the block at a low heat setting will suffice. Be careful not to
overheat since this will lead to complete evaporation of the ether solvent.
2) If heating does not initiate the reaction, detach the Claisen adapter, and crush the magnesium turnings against
the walls of the flask using a glass rod with a twisting motion. Be careful not to crack the flask by applying too
much pressure. Re-attach the Claisen adapter as soon as you see the bubbles on the surface of the
magnesium turnings to prevent moisture from entering the reaction vessel.
3) If the reaction still has not begun, add an iodine crystal to the reaction mixture and then apply gentle heat to
the flask.
• As the reaction proceeds, it will turn yellow/brown and cloudy.
• Begin slowly adding the remaining bromobenzene solution in increments to the reaction mixture over a period of
about 15 minutes. Stir gently to avoid throwing the turnings onto the sides of the flask. The reaction will need to be
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heated periodically to maintain a steady rate of reaction as the Grignard reagent forms. Make sure that you replace
the anhydrous diethyl ether that is lost by evaporation (add more) as necessary.
• Once the entire solution has been added, use 2 mL of fresh anhydrous diethyl ether to rinse the conical vial and then
transfer the wash to the reaction vessel.
• The reaction will take roughly 30 minutes from its initiation to reach completion.
2.1.3 Reaction of the Grignard Reagent with Benzophenone
• While preparing the Grignard reagent, add 1.09 g of benzophenone to a 3 mL conical vial. Then add roughly 2 mL of
anhydrous diethyl ether, seal it, and shake gently until the benzophenone completely dissolves.
• Once bubbles cease to evolve from the magnesium turnings in the round-bottom flask when removed from the
heating block, allow the reaction mixture to cool to room temperature.
• While vigorously stirring, use the syringe to add the benzophenone solution to the reaction mixture in increments over
a time period of roughly 5 minutes. Add the solution as quickly as possible, but not too quickly. If you add too quickly,
the solution will boil, and your goal is to avoid boiling. The solution should turn pink/red and white solids will form as
the reaction proceeds.
• Once the benzophenone solution has been added, use 1 mL of fresh anhydrous diethyl ether to rinse the conical vial
and then transfer this wash to the reaction vessel.
• After 15 minutes, transfer the entire reaction mixture to a 50 mL beaker. Be sure to scrape as much of the solids as
possible into the beaker. Use 10 – 20 mL of distilled water to help dissolve and/or rinse the remaining solids into the
beaker if necessary.
2.1.4 Hydrolysis of the Grignard Adduct to Form Triphenylmethanol
• Add 6 mL of 6M HCl to the beaker containing your crude product from the previous section. Use a glass stirring rod to
break up the solids that has formed.
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• Add 10 mL of diethyl ether to the beaker.
Do not confuse the diethyl ether solvent you need for this part of the synthesis with the petroleum ether
you will use later. The diethyl ether will be in a bottle that is labeled as “Diethyl Ether”, or “Anhydrous
Ether”, do not use the bottle that is labelled “Petroleum Ether”
• Stir vigorously until two clear layers form, this may take a few minutes. Add additional diethyl ether in 1 mL portions to
dissolve any remaining solids.
2.1.5 Extraction and Separation of the Triphenylmethanol
• Obtain a 60 mL separatory funnel, and secure it to the manifold with a clamp. Add roughly 1 mL of DI water to the
funnel to make sure that the stopcock is properly sealed. Tighten the nut if necessary. It is important that your funnel
does not leak at the stopcock! You do not want your hard work draining out of your funnel! Consult your TA if the
funnel continues to leak. Pour the water out before proceeding.
• Once all of the solids in the beaker have dissolved, transfer all of the liquid (both layers) to the separatory funnel. Be
sure the stopcock is closed and that the stir bar is not transferred also to the funnel.
• Put the stopper on the funnel, invert it, and hold it as shown in the images below. Grip and rest the stopper in
the palm of one hand (so that it doesn’t fall out!). Hold the stopcock in the other hand (so that it doesn’t fall
out!). You will also open the stopcock with that hand.
• Shake the funnel gently while holding the stopper. The stopcock end should be pointing slightly up and away
from everybody!
• Open the stopcock to release
the pressure formed by
evaporation of the volatile ether
solvent.
• Gently shake again, and again
release the pressure via the
stopcock.
• Return the funnel securely to the
manifold, and wait for the layers
to separate.
• Remove the stopper and then
slowly drain the lower aqueous
layer into a large beaker. This
beaker will be used to collect all
aqueous (waste) layers
throughout this procedure.
Collect the remaining organic
layer that is left in the funnel in a
25 mL Erlenmeyer flask.
• You have now performed one
extraction from the aqueous
layer (extracted the organic
product into the ether solvent).
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• Return the aqueous layer (lower layer in the beaker) to the separatory funnel, and add 5 mL of fresh diethyl ether.
• Repeat the procedure from above. Place the stopper on the funnel, invert it while making sure the stopper is
securely in place, and shake gently several times. Periodically open the stopcock to release the pressure.
Secure the separatory funnel with a clamp and allow the layers to separate. Remove the stopper, and drain the
lower aqueous layer into the waste beaker. You have now performed a second extraction from the aqueous
layer (further extracted the organic product into the ether solvent).
• Leave the organic layer in the separatory funnel for the next step.
• Combine the two ether layers together by adding the first ether extract solution in the Erlenmeyer flask back into
the separatory funnel. Add 10 mL of saturated sodium chloride to the combined ether layers. Place the stopper to
the funnel, invert it while making sure the stopper is securely in place, and shake gently several times. Periodically
open the stopcock to vent the pressure that builds in the vessel. Secure the separatory funnel with a clamp
and allow the layers to separate. Remove the stopper and then drain the lower aqueous layer into the waste
beaker. The concentrated aqueous sodium chloride (brine) solution will help to extract any water from the
ether layer.
• Collect the organic layer remaining in the separatory funnel into a clean, dry 25 mL Erlenmeyer flask.
• Add enough sodium sulfate to the Erlenmeyer flask to dry the solution, and let it stand, covered, for several
minutes. Free flowing particles (not “clumped”) of sodium sulfate will be observed when enough has been added.
Do not add too much!
• Decant the dried solution into a 30 mL beaker. Rinse the sodium sulfate left in the Erlenmeyer flask with 2 x 2 mL
diethyl ether and decant the rinse into the same beaker.
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2.1.6 Purification and Characterization of the Triphenylmethanol
• Add 7 mL petroleum ether to the beaker containing the dried organic extracts.
• Set the hotplate to a low setting, between 30-100°C for those with a temperature dial, or to number 2 for
those with a number dial. Do not set the temperature higher than this!
• Reduce the solution volume via slow evaporation until solids are observed in the solution that do not
redissolve. Immediately remove the beaker from the hotplate when the solids start to from, and allow it to cool
to room temperature for slow formation of crystals.
• After a few minutes at room temperature, move the beaker to an ice bath and allow further crystallization.
• Filter the crystals via vacuum filtration using a Hirsch funnel. Rinse with 2 x 2 mL portions of petroleum
ether. Dry the crystals by drawing air through them for several minutes.
• If necessary, transfer the crystals to a drying block to remove any residual solvent.
• Weigh the dry crystals and calculate a % yield of the crude product based on the limiting reagent
from your experiment.
• Recrystallize the crude product in a small beaker from a minimum volume of boiling isopropyl alcohol to
obtain a purer product. Using vacuum filtration with a Hirsch funnel, isolate the pure product, and dry it by
drawing air through the filer paper. If drawing air is not sufficient to dry the product, use a drying stone.
Weigh the pure, dried product.
• Measure the melting point and collect a solid reflectance IR spectrum of the dried product.
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2.2 Safety
Although we will constantly remind you of the proper use of PPE and lab safety procedures, if and
accident/injury/incident happens and you feel any irritation on your skin due to contact with the chemicals used in
this lab, you need to bring this to the attention of your TA immediately.
In this lab you may use a small quantity of iodine. If you have an iodine allergy, bring this to the attention
of the TA before you start the lab!
This lab uses bromobenzene and diethyl ether. Bromobenzene is a skin irritant. If your skin comes into contact with
bromobenzene, rinse the skin with soap and a lot of water/shower. Do not touch your skin with any glove you have
used to handle bromobenzene. Diethyl ether is very flammable, so be sure to keep it away from any potential
sources of ignition. Diethyl ether is also volatile, and is therefore a potential inhalation hazard. However, with the
quantities you are using, this risk will be small.
Other Chemicals: The other chemical you will use are not specifically dangerous in the quantities you will be
using them, nevertheless, you should take just as much care to avoid skin contact. Do not touch your skin with
gloves that have been handling any chemical.
Eye contact: Rinse eyes for 15 min in the eyewash while keeping your eyes open. This can be very uncomfortable
so ask for assistance to keep your eyes open and count the time. Seek immediate medical attention.
Accidental Inhalation: If you accidentally inhale diethyl ether, quickly move to a place where you have fresh air,
rest in a comfortable position for breathing, inform your TA, and seek medical attention.
It is very important to try to remain calm if an accident or injury happens and immediately inform the TA to receive
the appropriate care as needed.
2.3 Waste Disposal
• Dispose of unused organic chemicals in the organic waste container in the back hood
• Check with your TA for disposal of other materials
3. Pre-Lab and In-Lab Notebook (10 pts)
3.1 General Lab Notebook Guidelines
A lab notebook is the standard way to organize, collect, and maintain data generated in lab. A well-kept lab notebook
should contain all of the information necessary for a third party to reproduce the experiment and corresponding data.
The lab notebook should be bound (a composition notebook works best) without perforated pages. A “spiral” lab
notebook is not acceptable, as the pages can be torn out easily.
The general guidelines for setting up your lab notebook are as follows:
• Page 1: Name; Course & Semester; Contact information (email)
• Page 2-3: Table of Contents
• Page 4 to the end: See the lab packet for each experiment for the details of what to include in the PRE-LAB
and IN LAB each week
Occasionally you will make a mistake while writing in a lab notebook. This is completely acceptable, science is messy
and you are learning. If you make a mistake, simply cross the mistake out with a single line (regardless of the size of
the error), initial the line, and date it. This lets everyone who reads the notebook know that you made a mistake and
that the piece of information is invalid. It is also important to use only a single line so that the original information can
still be read. Other things NOT to do in a lab notebook include:
• Adding or editing information after the lab period has ended.
• Writing in pencil.
• Scratching out information so it is no longer legible.
• Adding or removing pages.
• Using white out.
• Falsifying data.
Learning to organize and maintain a useful lab notebook is a skill that you will use in many scientific careers
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3.2 Pre-Lab (5 pts)
You must have the following Pre-lab completed in your notebook. All parts of the Pre-lab must be handwritten in
ink. You will submit a photo of your notebook with the other documents on Canvas. Include all of the following as part
of your pre-lab assignment:
1. Title and date of the experiment.
2. Purpose of the experiment.
3. Reaction (IF applicable).
4. A completed version of the Table below. Look up the molecular structure, molecular weight, melting point and MSDS
information (you may already have this information from a previous experiment, check your notebook!)
Name
Molecular
Structure
Molecular
Weight (g/mol)
bromobenzene
Boiling Point
(◦C)
N/A
benzophenone
MSDS (Hazards
Identification)
N/A
diethyl ether
magnesium
N/A
N/A
iodine (some people
have an iodine allergy!)
N/A
N/A
The information you will need to complete this table is available from several websites, a good one is the Sigma
Aldrich website (www.sigmaaldrich.com). On the Sigma Aldrich site:
– Search for the compound
– The search will generate a list of different forms of the compound that the Sigma Aldrich sells.
– Choose the link for a pure form of the compound (not a solution, for example), and you should be able to find
the compound’s molecular structure, molecular weight, and melting point.
– Below the compound’s name, there should be a button “MSDS”. Click the button to get a pdf file of the
Materials Safety Data Sheet. Scroll to Section 2.2 of the document (“Hazards Identification”) and write down the
relevant information under “Hazard Statement(s)”.
1. Write in your notebook a response to the following SAFETY Questions
• What should you do if your skin gets in contact with bromobenzene?
• What should you do if you accidentally inhale some diethyl ether?
2. Complete the Table below using information in Section 2 of this packet
Waste
Where to Discard
Aqueous Solutions
Organic Chemicals
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3.2 In-Lab (5 pts)
You will need to watch THREE videos of the instructors performing this lab in order to collect the necessary
in-lab data for this lab.
Video 1: https://asuonline.wistia.com/medias/xtqx6a8zhz
Video 2: https://asuonline.wistia.com/medias/7qmpi347ct
Video 3: https://asuonline.wistia.com/medias/anl97ivqp5
Your in-lab notes should adhere to the guidelines given on the previous page, i.e. it should include, as appropriate:
Quantities (all weights, volumes etc. recorded)
Observations (colors, solids, precipitates etc.)
Resulting Data (e.g. melting point ranges, Rf values, IR spectral data)
Calculations (yields, recoveries etc.) Must show work and include all the units
Conclusions (Did the experiment work? Based on melting point, % recovery, yield, IR data, etc.)
Everything written in your lab notebook must be legible and handwritten in ink, not pencil. The book should be
clean (no chemical spills etc.), should use correct notebook style with mistakes crossed out with a line
Your notebook will be graded based on the completeness AND correctness of each component in your
Pre-Lab and In-Lab.
Have your notebook checked by your TA before you leave the lab!
The IR spectrum for the product that you will need to interpret and include in your lab report and to answer
postlab questions is attached at the END OF THIS LAB PACKET. You must neatly organize the relevant bond
vibrations for the product in your lab report and interpret the spectrum to receive full credit.
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4. Turn-in Pre-Lab Assignment – Experiment and Objectives (10 pts)
You MUST turn this assignment on Canvas at the start of the LAB SESSION!
YOUR Name: _
_
Give brief, 1 sentence (max) responses to the following questions.
1. (1 pt.) What is the purpose of placing the glassware in an oven for this experiment?
2. (1 pt.) Which of the following will a Grignard reagent react with in the air: oxygen, water, hydrogen, or nitrogen?
3. (1 pt.) What is the purpose of the rubber septum that is used in the apparatus?
4. (1 pt.) Why might you add a small crystal of iodide in this experiment?
5. (1 pt.) How long will it take to make the Grignard reagent once the reaction is initiated?
6. (1 pts) Which solvent will you use to run the Grignard reaction, diethyl ether or petroleum ether?
7. (1 pt.) Which solvent will you use to recrystallize the product, diethyl ether or petroleum ether?
8. (1 pt.) Does petroleum ether contain any ether functional groups?
9. (1 pt.) What will happen if you add the benzophenone to the Grignard reagent too quickly?
10. (1 pt.) Which two methods will you use to characterize your reaction product?
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5 Post-Lab Assignment (20 pts.)
YOUR Name: _
_
You will need to watch THREE videos of the instructors performing this lab in order to collect the necessary data
to answer the post-lab questions.
Video 1: https://asuonline.wistia.com/medias/xtqx6a8zhz
Video 2: https://asuonline.wistia.com/medias/7qmpi347ct
Video 3: https://asuonline.wistia.com/medias/anl97ivqp5
1. (2 pts.) Complete the table below. If you did not collect any data, use the data from another group or your TA.
Indicate the source of the data (if it is yours then enter “our data”) in the Source column. If you use other data, give a
brief explanation above.
Weight of the
starting
bromobenzene
Weight of
starting
magnesium
Weight of
starting
benzophenone
Weight
of the
CRUDE
product
Melting
point
range
of the
CRUDE
product
Weight
of the
PURE
product
Melting
point
range
of the
PURE
product
156.5-159.9oC
2. (1 pt.) Give the number of moles of the bromobenzene you used. Show the equations, and include all units
(assume that weight and mass are equivalent, and you will need to know the density of bromobenzene = 1.5 g/mL).
3. (1 pt.) Give the number of moles of the starting magnesium you used. Show the equation, and include all units (as
usual, assume that weight and mass are equivalent).
4. (1 pt.) Give the limiting reagent/reactant for the reaction to make the Grignard reagent from the reaction of
bromobenzene with magnesium.
5. (1 pts.) Give the maximum number of moles of Grignard reagent that can be made in the reaction (this is the
theoretical yield for formation of the Grignard reagent, but it is not the theoretical yield of the overall reaction; this will
be determined in question 8 below).
6. (1 pt.) Give the number of moles of the benzophenone you used. Show the equation, and include all units (assume
that weight and mass are equivalent).
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7. (1 pt.) Give the limiting reagent/reactant for reaction of the Grignard reagent with the benzophenone
8. (1 pts.) Give the maximum number of moles of triphenylmethanol that could be made in the reaction, i.e. the overall
theoretical yield for product formation.
9. (1 pt.) Give the number of moles of the crude product triphenylmethanol you obtained. Show the equation, and
include all units (assume that weight and mass are equivalent, and that all of the weight of the crude product is actually
the product even though you know that is probably not true).
10. (1 pt.) Calculate the percentage yield of the crude product. This yield calculation assumes that all of the crude
product is triphenylmethanol. Although that is almost certainly not true, you should assume that it is since this is always
the assumption when calculating yields of crude products.
11. (1 pt.) Give the number of moles of the pure product triphenylmethanol you obtained. Show the equation, and
include all units.
12. (1 pt.) Calculate the percentage yield of the pure product. As always, this yield calculation assumes that all of the
pure product is triphenylmethanol.
13. (1 pt.) What would happen if you tried to make a Grignard reagent in a protic solvent such as methanol?
14. (1 pt.) If the benzophenone you used was wet, you would not have formed the Grignard adduct, or you would have
formed much less of it. Instead, a side-product would have formed. What would have been this side-product?
15. (1 pt.) Ethers are almost always used as solvents for Grignard reactions. All of the reasons why they work so well
are not fully understood. Some help comes from characterizing the ether solvents. State whether they would normally
be characterized as polar or nonpolar, and whether they would normally be characterized as protic or aprotic.
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16. (1 pt.) At the end of the reaction, you washed the chemicals into a beaker using water. Why was it OK to wash with
water at this step if Grignard reagents are very reactive towards water?
17. (1 pt.) One problem with organic chemistry is that we tend to focus on one molecule at a time, and we forget that
there are many, many molecules undergoing the reaction. Assume you started with exactly 1 g of bromobenzene; how
many molecules of bromobenzene is this? (Avogadro’s number = 6.022 x 1023) Give the number of molecules to 3
significant figures and do not use scientific notation, i.e. include all of the zeros in your number. After the number,
write down the number of zeros you included in parentheses. For example, if your answer is 5.99 x 1021, you would
write it as follows: 5990000000000000000000 (19 zeros). Show your work, and include all units!
18. (1 pt.) This reaction forms triphenylmethanol from benzophenone. You could use infrared spectroscopy to show
that the ketone in the starting material benzophenone has reacted (been consumed), and the alcohol product
triphenylmethanol has been formed. To do this, you would look for disappearance of the strongest vibrational peak
characteristic of the ketone, and look for the appearance of the strongest vibration peak characteristic of the alcohol.
Which bond vibration of the ketone, and which bond vibration of the alcohol would you look for?
19. (1 pt.) Why do you hold the stopper, resting in the palm of one of the hands, of the separatory funnel? (This is not a
trick question; the answer is very basic and obvious.)
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