February 3, 2013
Organic Chemistry Lab 226
1. % Recovery= grams recovered compoundgrams crude compound X 100 % Recovery= 0.040 grams0.256 grams X 100
% Recovery= 0.16 x 100=16%
There are many reasons why the percent recovery is much less than 100%. For example, one source of error may have been that the separatory funnel containing the acidified phenylalanine and ethyl acetate may not have separated well enough after being shaken together in the funnel. Not allowing an adequate amount of time for the aqueous and organic layers to separate will cause portions of the layers to be contaminated. This would affect the experimental results because when the aqueous layer was drained into a separate beaker, some of the phenylalanine would also drain out too. This would result in a loss of recovered compound. One way that this was limited was by repeating the mixing and draining process two more times; however, one cannot entirely ensure that all of the compound has been removed.
A second source of error may have occurred during the vacuum filtration step. After the flask containing the organic solution and drying reagent was poured into the Hirsch funnel, the “mother liquor” was collected in the flask below. This liquid contained the phenylalanine compound that would later be recovered. After this step, ethyl acetate was used to rinse out the original flask containing the solution to ensure that all of the phenylalanine has been retrieved along with the drying reagent. One error may have been that the original flask may not have been rinsed well enough and some of the phenylalanine remained in the original flask. This would affect the end results by lowering the percent recovery due to the left behind phenylalanine in the original flask.
2. Infrared Spectrum
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