Notes

[1] Use a dry container of appropriate size. Remember, if the container is too small, some of the reaction mixture might splash or foam over the top (rule-of-thumb: never fill a container more than halfway). If the container is too large, stirring will spray the mixture over the container's surface and make it hard to recover your product. BACK TO PROCEDURE

[2] Since AlCl₃ is a highly reactive reagent, it is common practice to cool the mixture in an ice bath to compensate for any exotherms and to prevent a runaway reaction or fire (pre-cooling is standard procedure whenever highly reactive materials are mixed). Since we are running this reaction on small scale and our solvent is nonflammable, exotherms are unlikely in this experiment. But do add only a small amount of AlCl₃. The reaction mixture should have a slight peachy color after the addition. BACK TO PROCEDURE

[3] The reactants and product do not absorb the radiation produced by our UV lamps. Therefore, you will need to use the same chemical "dip" reagent used in Experiment 6 to detect these compounds. BACK TO PROCEDURE

[4] The heat gun gets extremely hot. Always hold it by its handle (never grab the nozzle). Remove all solvents and flammable reagents from the hood before using the gun (your apparatus should not contain any compounds at this point). BACK TO PROCEDURE

[5] A pre-weighed sample of "instant ylide" will be provided to you. BACK TO PROCEDURE

[6] Adding THF to the phosphonium salt and base allows them to mix and react with each other. The result is a yellow ylide-containing solution and NaBr. BACK TO PROCEDURE

[7] A microcolumn is constructed from a disposable pipet, glass wool, sand, and a powdered stationary phase, usually alumina or silica gel.

Place a small amount of clean glass wool in a clean, empty pipet and poke it down to the narrow end. Next, add a small amount of sand on top of the wool, followed by the stationary phase (powder) on top of the sand (wool and sand are needed to keep the powder from falling out of the pipet). It is necessary to use pressure to force a liquid through the microcolumn. Attach a rubber pipet bulb to the column, squeeze the bulb to force the liquid into the column, remove the bulb from the column while still squeezing it, then release the bulb. Repeat the attach-squeeze-remove-release sequence as needed.

BACK TO PROCEDURE

[8] The GC-MS instrument is located in the sub-basement (first floor). Instructions for using the instrument will be provided in the instrument lab. BACK TO PROCEDURE

[9] Select Groups: Alkenyl to build the diene. Then select sp³ C to add the methyl group. BACK TO PROCEDURE

[10] You can adjust a molecule's conformation at any point by performing an internal rotation around a single bond. To do this, click on the Add Fragment button (or select Add Fragment from the Build menu). Activate the bond that you want to rotate by clicking on it (a red arrow encircles the activated bond). Finally, rotate the bond by simultaneously pressing the ALT key and LEFT mouse button while moving the mouse. BACK TO PROCEDURE

[11] The picture in the lab manual shows isoprene with a planar pi system. Your model may not be planar, but small deviations from planarity do not affect MO energies much. BACK TO PROCEDURE

[12] Select Groups: Alkenyl to build ethylene. Select Groups: Carbonyl to add the carbonyl group. Finally, select sp³ C to add the methyl group. BACK TO PROCEDURE

[13] There are many ways to build the MVK-AlCl₃ adduct, but they are all rather circuitous. Here is a method that is guaranteed to work:

Build MVK. Select double-bond N in the Organic builder and double-click on the oxygen atom. This should replace O with NH.

Click on the Inorganic builder tab.

The Inorganic builder requires you to select an element and a geometry for each atom that you want to add to a model. To select aluminum, click the button underneath the large box that shows the current atom, and select Al from the pop-up periodic table. There are eight geometry buttons listed underneath the current element button. To select tetrahedral geometry, click the XTetrahedral geometry button (bottom row, left). You should now see tetrahedral Al in the main box. Add tetrahedral Al to N.

Next, assemble terminal (or monovalent) Cl. Clcik the button under the main box, and select Cl from the periodic table. Click the XSingle geometry button (top row, left). Add three terminal Cl atoms to Al.

Finally, click the element button under the main box, and select O from the periodic table. Double-click on N; this should replace N with O. Once you have the all of the desired atoms in place, use internal rotation to correct the molecule's conformation. BACK TO PROCEDURE

[14] E.F. Lutz and G.M. Bailey, "Regulation of Structural Isomerism in Simple Diels-Alder Adducts", Journal of the American Chemical Society, 1964, 86, 3899.

To access this article electronically, go to the Reed College Library home page from an on-campus computer. Select Print & E-Journals from the Resources menu. Then perform a Title search for Journal of the American Chemical Society and click on the American Chemical Society Legacy Archives link.

Once the journal's web page has opened completely, click on back issues. Select the appropriate decade, volume, and issue (base the latter on the article's page number) and click on Go. Locate the article in the journal's table of contents and save (and/or print) the PDF file. BACK TO REPORT