Kayla+Gogarty+Spring+2014


 * Spring 2014**

This term, I continued performing CRS experiments. Throughout the term, I examined several reactions with acetic anhydride and identified impurities in reagent bottles.

One reaction that I performed was acetic anhydride with ethanol. I took HNMR spectra of only three samples (pure acetic anhydride, pure ethanol, and one drop ethanol in excess acetic anhydride), because there was not enough of the other mixtures to get a good HNMR spectrum with the NMR insert tubes. With more time, this experiment would have been repeated with enough mixture for each sample.

While performing this experiment, I tested different ways of preparing the mixtures, which is the reason why there was not enough of some of the mixtures. I tried using different size well plates and different size vials. In order to determine the correct size for the well plates, the volume of the NMR inserts had to be determined. Based on calculations, the bottom of the NMR inserts holds approximately 120uL. Therefore, the 100uL well plates were determined not useful for our purposes. The other size well plates that we had were too big. Therefore, it was determined that we would continue mixing the mixtures in 1 dram vials.

Another reaction that I performed was acetic anhydride with methanol. HNMR spectra of five mixtures were taken. These five mixtures included pure acetic anhydride, pure methanol, half by volume mixture of the two, one drop acetic anhydride in excess methanol, and one drop of methanol in acetic anhydride. Based on the HNMR spectra, the peaks for the product are bigger after 18 and a half hours than after 2 hours. Therefore, the reaction was not complete after 2 hours and the reaction occurs slowly without a catalyst. Based on literature searches, the reaction is typically performed with an inorganic catalyst with heating. performed the reaction without a catalyst, but heating was required. Much time was devoted to analyzing the HNMR spectra of these mixtures. As shown on the experiment page, each peak was identified and labeled accordingly, in an attempt to determine the percent conversion of the reaction. Dr. Bradley and I were in the midst of determining this percent conversion.

I was also preparing to perform another experiment. This experiment (CRSEXP050) consisted of a three component system, including acetic anhydride, ethanol, and dimethylformamide (DMF). The goal of this experiment was to determine the effect DMF has on the reaction between acetic anhydride and ethanol. A system of testing all possible mixtures for a three component system was developed by Dr. Bradley and I. This system is shown in the Log on the experiment page. Also, a template sheet was created to determine the volume needed for each component in the mixture. This experiment was not completed because while testing the purity of each reagent bottle, impurities were found. To determine the impurity in the acetic anhydride bottle, several HNMR spectra were taken, including excess acetic anhydride with 1 drop of acetone (CDCl3 as reference), excess acetic anhydride with 1 drop of acetic acid (CDCl3 as reference), and acetic anhydride (excess CDCl3 with one drop of acetone as reference). Based on these three spectra, the impurity in the acetic anhydride reagent bottle is acetone. With this impurity determined, the next step was to complete this experiment and determine the effect of DMF.

With more time, the reaction between acetic anhydride and ethanol would have been repeated and the experiment with ethanol, acetic anhydride, and DMF would have been completed and analyzed.

A complete list of experiments that I have performed throughout the year can be found [|here].