Lab+Report+Enzymatic+Reduction+of+a+Ketone+to+a+Chiral+Alcohol

This lab uses yeast cells to reduce a ketone to a chiral alcohol. Other methods of reducing ethly acetoacetate do not produce a chiral product as the reagents attack from both sides, leaving a reacemic product. This lab is considered green because it uses a biological organism to accomplish the reduction instead of using sodium borohydride or lithium aluminum hydride. This lab doesnt require anything other than food for the yeast and the reactant. The reaction doesn't, though the workup does. The reaction is suspected to be facilatated by an enzyme in the yeast because of the enantiometeric excess of S(+)-Ethyl 3-hydroxybutanoate. The enantiometeric excess for this lab is expected to be between 70% and 97%. While the use of enzymes is green and can be very helpful, it is also quite unpredictable when dealing with new applications. This is because it is nearly impossible to predict which sterioisomer will be favoured.
 * Introduction:**

please show me the reaction! I need you to tell me specifically which ketone you are reducing.

Procedure adopted from Williamson, K.L. (2003). //Macroscale and microscale organic experiments//. Boston: Houghton Mifflin Company. Enzymatic Reaction: A Chiral Alcohol from a Ketone and Enzymatic Resolution of DL-Alanine
 * Procedure:**

Dissolve 2.3g of sucrose and 15mg of disodium hydrogen phosphate in 8.5 mL of 35 degree tap water. Place 0.5g of dry yeast into the tap water and sucrose. Swirl the mixture. After 15 minutes while fermentation is taking place add 150mg of ethyl acetoacetate. Store the flask in a warm place for 7 days. Once complete add 0.5g Celite and remove the yeast cells by Hirsch funnel filtration. Rinse cells with 1.5 mL of distilled water; then saturate the filtrate with 5g of sodium chloride to decrease the solubility of the product. Please see solubility calculation below. Next 1.5 mL portions of ether is (are) added to the solution 5 times and mixed gently. After each additional portion of ether an extraction of the top layer is completed. Calcium chloride pellets are added to the ether layer until they rolled freely on top of the clumpy portion of the drying agent. Allow this mixture to sit for 15 minutes the ether solution is then transfered into a test tube and heated in a 65 C warm water bath. During this process the ether gas can be captured by setting by a distillation system and catch vessel placed in an ice bath. I'd rephrase this, to say that the ether can be removed and recaptured by setting up a low-temperature distillation. After the evaporation has taken place weight the remaining residue, test the residue with iron III chloride, and conduct an IR spectroscopy.

This section changes tense a number of times, which makes for difficult reading. Watch your writing mechanics when you write your reports.

How many sig figs should you have in your answer? Not 3!
 * The number of grams of NaCl to use was determined by first finding the solubility of NaCl on Wikipedia: 360g NaCl for every 1 kg of solution/solvent.**
 * Filtrate = 14g**
 * 14 x 1kg/1000g x 360g/1kg = 5.04g**




 * Results:**
 * __Hailey's Data:__**
 * Weight of test tube= 15.65g** Sig figs error in measurement here, and in Sol's data as well.
 * Weight of test tube + final product / residue = 15.87g**
 * Weight of residue=.22g**




 * __Solyana's Data:__**
 * A)Weight of test tube= 18.54g**
 * B)Weight of test tube + final product= 18.86g**
 * Weight of final product= B-A = 0.32g**


 * Philips Data;**
 * Weight of test tube: 19.305g**
 * Weight of test tube and less than half of the product: 19.382g**
 * Weight of remaining products: 0.077g**



Some sources of error in this lab were. There was significant error in the amount of product from Philip. This was due to not weighing the product before using 4 drops in the various tests. Another source of error was the extraction, the extraction of the product using ether could not have been complete, Although it appears that the extractions were quite successful due to the high yield. There is always loss of product through transferring from beaker to beaker, however due to only 2 transfers the loss of product can be considered insignificant. One of the samples had to be discarded as during the vacuum filtration the pressure built up and water backlogged. It is also important to note that Hailey's IR spectra has a larger alcohol peak this is most likely due the contamination of water.
 * Error**

This lab is fairly conclusive based on the fact that the experiment was completed 3 times. When the experimental infrared spectrums are compared to the IR spectrum of ethyl 3-hydroxybutanoate certain known absorption bands can be identified. The experimental IR spectrums has the first significant peak between 3390-3361cm this represents the presences of the bond between hydrogen and oxygen. The next set on peaks located between 2977-2869cm show alkane bonding. The last and final peak shows the presence of a carboxyl group between 1736-1717cm. These peaks match the known absorption frequencies for types of bonds that identify ethyl 3-hydroxybutanoate. The known IR spectrum lists 3450cm for the alcohol, 3000-2800cm for the alkanes, and 1740cm for the ketone. Further confirmation of the product can be determined based on negative iron (III) chloride test for all 3 samples of residue.
 * Discussion/Conclusion**

There is an interesting difference between Sol's IR and the other two. Hers has a fairly prominent peak at 1736. Did you look into that at all?

I would like to hear a bit more about the problems you encountered with the filtration. There are some good lessons to be learned in that experience.

Avoid judgments: while we all love to have an experiment come out with a high yield of pure product, doing the synthesis is not like hitting the bullseye on a target. Tell me about all the richness of your experience, with flaws described as thoroughly as data that meets your expectations, and avoid telling me you were "successful" or that the reaction was "conclusive." After all, we don't know that our reaction really favored one enantiomer....and we don't know that yields like you saw could be considered "good."