0.2 Grignard reaction  (Page 5/5)

 Page 5 / 5

Caution

The addition of water causes the evolution of heat. An ice bath should be handy to cool the solution if it begins to reflux rapidly.

2. Now add 4-5 drops of 3 M HCl. Remove the vial, cap it, and stir it at room temperature for 5 min. Remove the vial from the stir plate and test the aqueous layer with litmus paper. The solution should be slightly acidic. Too much or too little aqueous HCl will cause problems in the subsequent workup procedure. Be careful in this step. NOTE: The water layer is the bottom layer. You will need to withdraw a few drops of the aqueous layer with a Pasteur pipette and drip it onto the litmus paper.

3. Remove the magnetic spin vane with forceps and set it aside to be rinsed with an ether wash. Cap the vial tightly, shake it, vent carefully, and allow the layers to separate.

4. Using a Pasteur pipette, transfer the aqueous (lower) layer to a clean 5.0 mL vial (see picture below). Save the ether layer since it contains the crude reaction product.

5. Now wash the aqueous layer that you have previously transferred to a 5.0-mL vial, with three 1.0-mL portions of diethyl ether:

6. Hold the magnetic spin vane with clean forceps and rinse it with the first portion of ether as it is added to the vial. Upon addition of each portion of ether (using a calibrated Pasteur pipette, see picture below), cap the vial, shake it (or use a Vortex mixer), vent carefully, and allow the layers to separate. With the aid of a Pasteur pipette, remove each subsequent ether (i.e. top) layer and combine it with the ether solution retained above. After the final extraction, do not forget to save the aqueous (lower) layer until you have isolated and characterized the final product.

NOTE: Pipette calibration: 1.0ml (diagram shows a previous version where we only used 0.5 mL. NOW we use 1.0 mL.) of ether which will give approximately 1.0 in height of solvent in the pipette above its "shoulder"

7. Extract the combined ether fractions with 2.0-mL of cold water to remove any acidic material.

8. Dry the ether solution by transferring it, using a Pasteur pipet, to a Pasteur filter pipet filled with 0.5g of anhydrous sodium sulfate. The elute is collected in a test tube. In the hood, remove the ether solvent from the elute by simply, putting the solution on an evaporation dish and allow the ether to evaporate.

Alternate Method of Removing Solvent: 1. Attach a Pasteur pipette to an air-line, turn the air on (gently) and place pipette in test tube to evaporate the ether (Ask TA for demonstration). 2. Gently warming the elute in a hot water bath to concentrate the solution to a weight less than 90 mg.

1. the product, 4-methyl-3-heptanol, will be used as is with no further purification. once all the solvent is gone, mass the product and the test tube (the mass of which has already been recorded). assuming no impurities, calculate the yield (remember, one of the reagents was taken in excess though).

2. Take this sample and dissolve in it in a small amount of methylene chloride (add 2 mL first then add 1 mL each time if you really need it). Prepare two TLC plates. On each plate spot both of the starting materials as well as the product mixture and standard provided by TA (i.e. four spots on each plate). Run one TLC plate in 100% Methylene Chloride, the other in 1:9 ethyl acetate: hexane. Record both plates under UV light and with the p-Anisaldehyde stain.

3. Calculate the ${R}_{f}$ of all of the compounds for both plates. Draw TLC plates in the notebook.

4. One sample will be taken for NMR and GC-MS studies.

Waste disposal

Syringes and needles are to be disposed separately. Needles will go into the Sharps waste basket and syringes in the waste basket. Pipettes should not go into the Sharps waste basket. Organic and inorganic waste should be disposed in their proper containers.Approximate Lab time: 2-2.30 hours

Report Questions (Total 30 points)

Note: In preparing this report you are free to use references and consult with others. However, you may not copy from other students’ work or misrepresent your own data (see honor code).

Name(Print then sign): ___________________________________________________

Lab Day: ___________________Section: ________TA__________________________

1. Explain why Grignard reagents cannot be prepared from an organic halide that also contains a hydroxyl (-OH), a carboxyl ( $-{\text{CO}}_{2}H$ ), a thiol (-SH), or an amino ( $-{\text{NH}}_{2}$ ) group. (2 points)

2. Why does the 2-bromopentane not appear under UV light for TLC? (2 points)

3. Draw and show your ${R}_{f}$ calculations for each TLC run. Which solvent was better? (3 points)

4. Show your theoretical and percent yield calculations. (4 points)

5. Draw the structure of your product and assign a proton to each peak in your NMR spectrum. Try and determine, if any, the impurities are in the sample. (4 points)

6. An NMR and GC-MS of the product are provided. What information can you obtain from the GC-MS? (5 points)

7. Write the major product of the following reactions: (10 points)

8. Identify the compounds (A-F). (Extra credit 6 points)

Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
how did you get the value of 2000N.What calculations are needed to arrive at it
Privacy Information Security Software Version 1.1a
Good
Berger describes sociologists as concerned with
Got questions? Join the online conversation and get instant answers!