Fischer Esterification Discussion PDF

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The TA's name was Chathuri Kombala. ...

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Dana Woods Chathuri Kombala Chem 243A 19 October 2015 Fischer Esterification Discussion The overall goal of this experiment was to synthesize an acetate ester from an acid and an alcohol using the process of esterification. After the products were formed, distillation was done to purify ester. Finally, we had to determine if the obtained product was our desired product, so some identification procedures were performed.

1-pentanol was the alcohol we were assigned, which yielded pentyl acetate as our ester product. In order to obtain our product, an esterification procedure was done. Acetic acid was the acid we reacted with 1-pentanol, and it was added in excess. This was because of the Le Chatelier’s principle, which states that “a system at equilibrium adjusts so as to minimize any stress applied to it.” By adding acetic acid in excess, it makes 1pentanol the limiting reactant. If the procedure is done correctly, it will allow us to yield the maximum amount of pentyl acetate. Sulfuric acid was used as a catalyst, and once all of the starting materials were added together, the esterification process was able to start. Once the reaction completed, the organic layer (with our desired product) had to be removed from the aqueous layer. Aqueous sodium bicarbonate was added, which

allowed the aqueous substances to coagulate with the sodium bicarbonate while the organic substances separated out. Next, the water that was formed along with the pentyl acetate needs to be removed. Anhydrous sodium sulfate was added to accomplish this. A distillation procedure was then done to not only purify the product, but to also determine the boiling point of the pentyl acetate. The boiling point calculated was 58.5°C. Since the actual boiling point is 149°C, there are some impurities in the product. This could be due to additional acetic acid and/or water that was not removed. The final steps were calculating percent yield and running an IR spectra and NMR spectra for identification. The percent yield 37.21%. This could be due to factors out of my control, such as some of the product reforming the reactants (to stay in equilibrium) or a side reaction that produced undesired products. Human error could also contribute, since all of the final product may not have been collected because I did not wait long enough during the distillation process. Even though the experiment did not yield the full amount of product, we know we at least got the desired product by looking at an IR spectra and NMR spectra. According to the structure above, the functional groups present are an sp3 CH group, a C=O group, and a C−O group. These peaks can be seen on the IR spectra at ~3030, 1700-1800, and 1050-1275, respectively. The NMR spectra allowed us to look at the bonding patterns of the protons present in the product. Pentyl acetate has five groups of different “types” of protons. By observing my NMR, there are five major peaks, each corresponding to a group. I was able to assign the groups based on the number of neighboring protons as well as where they should be along the axis. Overall, even though I did not obtain a lot of my product, the product was still obtained and it was pure according to the tests performed.

University of Arizona

Fischer Esterification

Dana Woods Organic Chemistry Chathuri Kombala 19 October 2015...