Day Four: Characterization

Today's primary objective was characterization of our cyclohexanone samples.  We began with IR scans, since we are more familiar with the technique.  The scan showed a clear carbonyl peak near 1700 cm-1, which confirmed the formation of a C=O functional group; however, a prominent OH peak was present at 3500 cm-1.  Initially, we assumed that the product had not finished drying and added extra drying agent to our samples for about half an hour.

To determine whether the peak was due to excess water or unreacted cyclohexanol, we prepared samples to test by gas chromatography in the following steps:

1. Insert a glass pipet into the liquid product to extract a small amount (just a tip-full)
2. Fill a plastic pipet with ether solvent
3. Push the ether through the glass pipet so that a mixture of product and ether collects in a sample vial

The gas chromatogram displayed an ether peak between 1.28 and 1.36 minutes, which accounted for nearly 100% of the peaks registered.  A cyclohexanol peak appeared between 2.65 and 2.76 minutes, while a cyclohexanone peak appeared between 2.76 and 2.84 minutes.  The cyclohexanone peak was only five times greater than the cyclohexanol.

Based on these results, we decided to perform the oxidation reaction again tomorrow.  We plan to use fresher bleach reagent and attempt to better stay within the desired temperature range of 40-45 degrees Celsius.  Because my temperature dropped below 40 degrees for longer than ten minutes, I believe that my reaction rate slowed over the 30-minute reaction period such that the reaction did not proceed to completion - hence the need for sodium bisulfite to neutralize the unreacted bleach.

Additionally, we plan to begin a Baeyer-Villiger oxidation reaction of standard cyclohexanone tomorrow.  From the procedure given by Dong Tian, et. al. (see below), the cyclohexanone, m-CPBA, and dichloromethane reagents will be in reflux for 15 hours, so we will start the process early in the morning and spend the rest of the day with the regular oxidation reaction.

Here's to another day of research, hopefully with fewer set-backs!



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References:
Tian, Dong, Philippe Dubois, Christian Grandfils, and Robert Jerome.  "Ring-Opening Polymerization of 1,4,8-Trioxaspiro[4.6]-9-undecanone: A New Route to Aliphatic Polyesters Bearing Functional Pendent Groups."  Macromolecules 30 (1997): 406-409.  Print.