Day Five: Multi-tasking

It was one of those days that I arrived at 8 a.m. and monitored as many as four processes at once.  That isn't to say that I didn't enjoy the work; I love being in the lab and performing reactions that I understand on a basic level.  I am, however, quite tired and hopeful that today's experiments will yield good results tomorrow.

I began my day setting up a simple reflux apparatus for the addition of m-CPBA to cyclohexanone in dichloromethane:

Originally, Dr. Bass and I added heat to the reaction flask and deposited the m-CPBA solid through the West condenser.  On review of the procedure, however, we realized that the m-CPBA was to be added prior to setting the heat.  We also found that the solid tended to clump inside the condenser, though we were able to force the solid through by adding more dichloromethane.  The next time we run this reaction, we will add the solid straight to the reaction flask rather than through the narrow tube.  This mixture was left to reflux until about 5:00 this afternoon.

My second reaction was the re-run of the oxidation of cyclohexanol.  Following my notes from the previous day made adjusting the reaction conditions much easier, so that the solution stayed within the proper temperature range the entire time that bleach was being added dropwise.  Actually, the bleach was sufficient to maintain the heat without a mantle, and I removed the outside heat source once the mixture reached 40 degrees, even though that slowed the overall process.  I also used two 80-mL portions of bleach instead of 72-mL.

In the case that bleach was in excess, I prepared 100 mL of saturated sodium bisulfite solution, just as I did the other day.  This reaction was performed during the 20-minute stirring period after the addition of bleach was complete.

Halfway through the experiments, after the 20 minutes, I prepared a GC sample to test for unreacted cyclohexanol.  I extracted a 2-mL sample from the reaction flask into a small Erlenmeyer flask.  A potassium iodide starch paper test revealed that the sample contained excess bleach, so I added a few drops of the prepared sodium bisulfite to neutralize it.  Afterwards, I transferred the sample to a vial and added 2 mL of ether, capping the bottle and shaking until two separable layers formed.  The top (ether) layer was extracted into another vial, and ether was added by the same procedure as yesterday.

The GC scan confirmed formation of cyclohexanone and absence of cyclohexanol, signifying a complete reaction.  (YAY.)

The rest of the experiment proceeded as modified after the first run, except for one key point.  After the addition of solid sodium chloride on Monday, some of the salt crystals transferred into the separatory funnel and clogged the stop-cock area.  To avoid this, I performed a vacuum distillation of the salted solution to extract the hydrated crystals and be left with two clean layers.  Extracting the organic layer was much simpler, and it is being left to dry with solid magnesium sulfate.

Tomorrow's focus will be characterization of the product and a closer look at the Baeyer-Villiger oxidation!

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Now, for your viewing pleasure: what chemists do before, during, and after reactions...multiple times...sometimes more often than actually running experiments.

In case anyone wondered, we wash glassware.  A lot.  My roommates wonder why I put off washing dishes after a meal.  It's just a reality of the industrial and researching world that I will enjoy for quite awhile.