Chemistry 350 - Principles of Organic Chemistry I
Fall Semester 2015, Winona State University

Experiment #1 - Preparation of 4-Acetylbiphenyl 

References:

Smith, Chapter 14 (C-13 NMR), Mohrig, Techniques 11 and 12 and 14. Chapter 21.1-21.3, 22.1-22.3

Additional Pre-Lab Assignment:

Install the JEOL Delta software on your laptop according to the following directions.

For PCs running Windows 8:

  1. Use copy and paste to enter \\appsrv1\apps\Installs\pc\Chemistry in a Windows Explorer address bar.
  2. Double click the Install_Delta_5.0.2_PC file.
  3. Once installed you will need to unlock the program by entering the license key, which is available at the course D2L site and also in the "Install_Delta_PC_or_Mac" file present in the installation folder. Start the Delta program then select "Installation" under the file menu and enter the license key there.

For Macs:

  1. You must be on campus connected via your wired network connection. Make sure wireless is turned off during the install.
  2. Click Go -> Connect to Server
  3. Type: smb://appsrv1/apps/Installs/mac/Chemistry/Delta and click Connect
  4. Drag the DeltaInstaller file to your desktop
  5. Double click on the DeltaInstaller file on your desktop
  6. The installer will launch and warn that, "You need an Administrator password to install the software" -Click on the lock icon and enter your password (same as your email password) Click OK
  7. Click Next
  8. Click "I accept the terms of the License Agreement"
  9. Click Next
  10. Click Next
  11. Click Install. Click Cancel when it asks to Update Spectrometer
  12. Click Done. Delta will be installed to your Applications folder.
  13. Once installed you will need to unlock the program by entering the license key, which is available at the course D2L site and also in the "Install_Delta_PC_or_Mac" file present in the installation folder. Start the Delta program then select "Installation" under the file menu and enter the license key there.

Overview. You will use a microwave-assisted Suzuki reaction to prepare 4-acetylbiphenyl from 4-bromoacetophenone and phenylboronic acid (eq 1). A balanced version of the equation is also shown (eq 2). The lab will also serve as an introduction to two standard techniques used in the organic chemistry lab, extraction and NMR. You will use extraction to purify the product mixture so as to obtain a relatively pure product (a process generally referred to as a "work up"). Then you will use mp determination and C-13 NMR to verify the structure of and "characterize" the product.



Running the Reaction. Place 1.0 mmol each of phenylboronic acid, 4-bromoacetophenone, and tetrabuylammonium bromide (TBAB) in a glass microwave reaction vessel. Add 3.0 mmol of Na2CO3, 0.004 mmol of palladium acetate, and 2.0 mL of distilled water. Add a small teflon-coated magnetic stir bar and then seal the vessel using the provided screwcap to the proper torque using the provided torque tool. Label the vessel with a Sharpie and then place it in the microwave carousel noting its position. Once all student teams have completed this step, the instructor will demonstrate the operation of the microwave reactor and set it up to heat the reaction mixtures to an internal temperature of 150° C and hold it there for 5 min. Once the reaction mixture has cooled to near 50° C then it can be opened and the work up commenced.

Work Up Procedures. Transfer the reaction mixture into a separatory funnel, washing the vessel with 30 mL ethyl acetate and using a spatula to scrape out any remaining solid from the vessel into the sep funnel. Add 30 mL water and then stopper the sep funnel and shake the contents with frequent venting. (The instructor will demonstrate but also see Mohrig Technique 11). Separate and identify the layers (one is organic, the other aqueous). The organic layer should then be washed in the sep funnel with 30 mL of NaCl(sat). After final separation of the layers, the organic layer is drained into a dry Erlenmeyer flask and dried over sodium sulfate (Mohrig Technique 12). Decant the dried liquid into a pre-weighed round bottom flask. We will then use a rotary evaporator (Mohrig p 140) to evaporate off the ethyl acetate solvent leaving the product. Weigh the flask and determine your yield and percent yield and make sure to record both in your notebook.

Characterization of the Product. The product is to be characterized through measurement of the melting point (mp) range and obtaining its C-13 NMR spectrum.

Melting Point Procedures - A Mel-Temp apparatus (Mohrig, Fig 14.2, p 177) is to be used for all mp determinations in this course. See chapter 14.3 in Mohrig for details of how to properly obtain the melting point. 

NMR Procedures- Please note that you will be expected to obtain NMR spectra many times in this course and eventually be able to obtain them unassisted. Therefore, you should take note of the procedures you use in this lab.
Preparing the NMR Tube.
  • NMR tubes and solvents are very costly so please be very careful with the tubes and do not waste the solvent. Also, be very careful when capping and uncapping your NMR tube. The tubes are fragile and the caps are tight so it is easy to break a tube in the process of capping or uncapping it.
  • Use a small spatula to place a small amount of your product in an NMR tube. For C-13 NMR a good amount of compound is needed so make sure the height of the solid in the tube is at least 3 mm (and no more than 5-6 mm).
  • Add the NMR solvent, CDCl3,  to a height  of approx  5 cm in the tube. Invert and/or agitate the tube in order to dissolve the solid in the solvent (warning - the caps can leak). Label your tube by writing on the side of the cap with a permanent felt tip marker. 
Obtaining the C-13 NMR Spectrum. The instructor will assist you in obtaining the NMR. The basic steps that need to be carried out are;
  • Place tube in spinner and adjust height.
  • Place tube with spinner at top of magnet.
Then use the Delta software to...
  • Lower the tube and spinner into the magnet.
  • Check that tube is spinning and the correct solvent is selected.
  • Lock and shim the sample.
  • Set up the desired experiment (in this case C-13) with a file name of your choosing.
  • Submit the experiment.
  • Eject the tube from the magnet.

Disposal and Clean Up. NMR sample solutions should be drained into the waste solvent container when finished. Be very careful when removing the plastic cap as it is easy to break the top of the tube when doing so. Rinse the tube several times with acetone into the waste solvent container. Store the tube uncapped so the acetone will fully evaporate by the time of its next use.

Product Submission - Submit your product in a fully labeled 2"x2" ziploc bag. (See the lab report guidelines.)

NMR Processing. General Instructions for Using Delta

  • Copy the file to your desktop (or other preferred folder on your computer). Then double click on it to open it in Delta.
  • To annotate the spectrum with peak chemical shifts use the "Auto Peak Pick" icon,
  • Use the zoom tool (looks like a magnifying glass) to zoom in as necessary by simply clicking and dragging on the spectrum. Clicking and dragging in the gray area below the x-axis just zooms in along the x-axis with the y-axis remaining at full scale. Use the keyboard key "hyphen" to revert to the previous (unzoomed) view.
  • Print the spectrum by simply clicking on the icon that looks like a printer and selecting the desired printer from the scroll list.