Experiment: Aldol Condensation
Week 7

Have you learned your NMR, yet? How about the theory and analysis of DEPT spectra?

Make sure you use a spin vane in this week's reaction. Boiling stones (the alternative to spin vanes) look too similar to the aldol product (tetraphenylcyclopentadienone). Separating your product from the spin vane will be much easier than from a boiling stone. Of course, the weight of a boiling stone is significant and, if left in with your product, will result in a percent yield over 100.

I would strongly advise the use of a Hirsch funnel as the text suggests. A Buchner funnel (which would probably work -- and I know some of you prefer it because it is easier to handle) requires a bigger filter paper. It might have not been evident in past labs with your light-colored product crystals, but you will invariably lose some product to the filter paper. You should be able to observe this phenomenon in this week's lab. The larger filter paper means a larger surface area in which your product may be trapped. Ultimately, your overall percent yield will be compromised.

Take extra caution when washing your glassware after this week's reaction. Tetraphenylcyclopentadienone, with its large extinction coefficient, can linger in the crevices of your glassware -- the result will be a purple reaction mixture (contaminated) in next week's lab.

Use caution when handling the TLC (Thin Layer Chromatography) plates. Refer to pgs 754-769 in your text to learn about the theory of Thin Layer Chromatography. The plates are coated with silica gel. Ideally the silica gel should be securely adhered to the plastic backing (there are also glass-backed TLC plates), but occasionally some of the silica gel breaks free in the form of a fine powder. This powder is of a size much smaller than the dust particles in the air. Therefore, the your nose's defense systems cannot stop the entry of these silica gel particles into your lungs. This phenomenon, somewhat similar to the miners who inhaled asbestos during their work, can lead to respiratory complications and even worse. If you work carefully with the TLC plates, there should be no problem.