IMPORTANT NOTES Experiment 6: Reducing Benzil Using Sodium Borohydride -- CER REAC 715 Experiment 6 will be carried out in pairs. But each student provides separate prelab, recordings and post-lab. Only the execution of the labs is done in pairs. 1. Work in pairs on this experiment. 2. Perform the semi-microscale procedure (begins bottom of p. 7). 3. Nuclear Magnetic Resonance (NMR) analysis will be introduced. Review the appropriate chapter in the textbook. You also might use some of the learning resources and tutorials on NMR which are provided in the "Web Destinations" of the course web site. We particularly recommend: Dr. Rzepa's NMR Spectroscopy 4. The TLC standards for meso-hydrobenzoin and (±)-benzoin will be provided. 5. The IR analysis will be performed in the following way: Dissolve the product in methylene chloride and drop a small amount of the solution on a salt plate (NaCl or KBr pellets). Your TA will demonstrate how toprepare the sample. Please be extremely careful with the salt plates used for IR analysis. Hold them by touching the edges only and never put water on them. The IR spectra of all three possible products are provided "In the Laboratory". Compare these spectra with your spectrum, mark diagnostic peaks in your spectrum, and explain how your IR spectrum supports your findings. Include the following Table in your lab book. This is the "table" referred to in the file "grading scheme".
Reducing Benzil with Sodium Borohydride gram mol percent Amount of benzil used ________ _______ Amount of sodium borohydride used ________ _______ Product theoretical yield *________ *_______ Product obtained ________ *_______ *______ (*) provide info after product identification!
Analytical Data Melting Point (oC) Product ____________ Melting Point with (±)-Benzoin, (oC) ____________ Melting Point with meso-Hydrobenzoin, (oC) ____________ IR Analysis, include spectrum. TLC analysis with standards. Draw picture of TLC plate with spots identified Product identification ______________________________