EXP281

=Researcher= Matthew McBride =Objective= To synthesize trans-dibenzalacetone from acetone and benzaldehyde in an ethanol solvent and using piperidine as the catalytic base =Procedure= Add piperidine to ethanol. Then in a separate flask mix benzaldehyde and acetone together in a 2:1 molar ratio. Add the benzaldehyde and acetone mixture to the ethanol solution in a drop-wise manner. Allow the solution to reflux until crystals form. The following [|Reaction Preparation Sheet] was used to plan this synthesis. =Results= The [|NMR Spectrums] demonstrate the content of the reaction mixture at T=0, 1, 18 and 24 hours. The spectrum of the piperidine used for this reaction is also included. =Discussion= No crystals were formed from this reaction. The presence of the piperidine was not visible in the HNMR spectrums until after an additional 2 mL were added at T=18 hours. This low concentration of piperidine could be the reason that no product formed.

At T=0, the benzaldehyde peak is visible at 10.4 ppm. And acetone peak appears to be at 2.54 ppm. Based on observing these peaks, there does not seem to be a 2:1 ratio of benzaldehyde to acetone, but closer to a 1.25:1 ratio. In the future, the exact amount of each reactant will be weighed out and recorded.

At T=24, the benzaldehyde peak had disappeared, but it was difficult to see whether any product had formed. If there was product present, it was very little. =Conclusion= This reaction was not successful in producing trans-dibenzalacetone. =Log=

2012-07-12
15:49 Added 20 mL of ethanol to a 125 mL Erlenmeyer flask. 15:53 Added 1 mL of piperidine to the flask. 16:00 Added 1.5 mL of acetone and 4.0 mL of benzaldehyde to the flask and allowed the solution to stir on the stir plate. 16:05 The solution was clear with no crystals visible. A few drops of the solution was removed and added to the inner coaxial NMR Tube 1. A loose fitting cap was placed on the flask and the heat was turned on to reflux the reaction mixture. 16:16 The solution was still clear (no crystals), but had obtained a slight yellow color. 16:45 NMR Tube 1 was placed into a thin-walled NMR tube containing CDCl3. Then the sample in NMR Tube 1 was analyzed by 500MHz HNMR and the file of the spectrum was saved as UCEXP281_t0 (reaction mixture when all of the reactants were first added together). 16:54 The solution was still clear and without crystals, but the yellow coloring of the solution was a bit stronger. A few drops of the solution was removed and added to the inner coaxial NMR Tube 2. 17:05 NMR Tube 2 was placed into a thin-walled NMR tube containing CDCl3. Then the sample in NMR Tube 2 was analyzed by 500MHz HNMR and the file of the spectrum was saved as UCEXP281_t1 (reaction mixture after 1 hour).

2012-07-13
10:23 The refluxing reaction mixture was clear with no crystals visible, but had obtained a darker yellow color. 10:33 A few drops of the reaction mixture was removed and added to the inner coaxial NMR Tube 3. 10:38 A few drops of the piperidine used for this experiment was added to the inner coaxial NMR Tube 4. 11:04 The samples in NMR Tube 3 and NMR Tube 4 were placed in a thin-walled NMR tube containing CDCl3. Then the samples were analyzed by 500MHz HNMR and the files of the spectrums were saved as UCEXP281_t18 (reaction mixture after 18 hours) and UCEXP281_piperidine. 11:08 Added 2 mL of piperidine to the reaction mixture and kept it on the hot plate to stir and reflux. 16:19 No crystals visible in the reaction mixture. A few drops of the reaction mixture removed and placed in the inner coaxial NMR Tube 5. This Tube 5 was placed in a thin-walled NMR tube containing CDCl3 and analyzed by 500MHz HNMR. The file of the spectrum was saved as UCEXP281_t24 (reaction mixture after 24 hours).