Solvent Extraction Lab Report PDF

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Solvent Extraction Ryan Huckaby CHEM 2123-540 2-27-2020

Ryan Huckaby Dr. Srinivasan 2123-540 2-27-2020 Solvent Extraction ABSTRACT Solvent extraction is a method used to separate and purify compounds. In the case of the this experiment the compound that will be extracted is dibenzyl acetone. The extraction technique heavily depends on a compounds solubility to separate the organic phase from the aqueous phase of a mixture. Organic compounds are less dense than water and will always be displayed on top of the aqueous solution. About 43% of the dibenzyl acetate was recovered in this experiment.

INTRODUCTION An extraction is a technique used for the separation and purification of organic compounds. In the extraction process water insoluble organic compounds can be extracted from an aqueous solution into an organic solvent. Extraction solutions are mixed thoroughly with an immiscible solvent. Once mixed it is transferred into the solvent that is similar solubility allowing the organic solvent to separate and purify. Once the solvents are separated, they are extracted in separate beakers as they have been purified into an aqueous and organic phase. The denser layer is always on the bottom of the separatory funnel. Organic solvents are less dense than water and aqueous solutions, so it will always be displayed as the top layer.

MATERIALS & METHODS 

Separatory funnel



Beakers

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Ring stand



Hotplate

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Graduated cylinder

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Funnel

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Buchner funnel

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Vacuum filtration apparatus

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Grease

Ryan Huckaby Dr. Srinivasan 2123-540 2-27-2020  Litmus Paper 

Stopcock

NaCl MW: 57.96 g/mol Density: 2.165 g/cm3 Dibenzyl Acetone MW: 58.04 g/mol Density: 0.79 g/cm3 Na2SO4 MW:142.04 g/mol Density: 2.68 g/cm3

Benzoic Acid MW: 122.12 g/mol Density: 1.26 g/

cm 3

NaOH MW:39.99 g/mol Density: 2.13g/

cm

3

HCl MW: 36.46g/mol Density: 1.19g/

cm 3

PROCEDURE 1. 0.36 g of mixture was weighed out, crushed finely, transfer to a test tube, then 10 mL of dichloromethane was added, and dissolved by stirring with microspatula until homogeneous. 2. The mixture was then transferred to a separatory funnel. 3. The organic solution was then extracted two times with 5 mL of 1.0 M NaOH aqueous. solution. 4. Combined aqueous extracts in a beaker were acidified by addition of 6 M HCl aqueous solution. Then the solution was tested with litmus paper. 5. The organic layer was dried by addition of 5 mL of saturated aqueous NaCl solution followed by gentle shaking. Phases were allowed to separate. 6. After separating and draining the organic phase, it was dried by portion addition of Na2SO4 anhydrous until salt was “free flowing” and no “clumping” was observed. 7. The organic phase was then decanted and poured into a pre-weighed beaker. 8. The organic phase was then gently heated to evaporate dichloromethane out of the dibenzyl acetone.

Ryan Huckaby Dr. Srinivasan 2123-540 2-27-2020 9. After the dibenzyl acetone fell to room temperature it was then weighed to observe how much had been recovered from the mixture. 10. Percent recovery of the dibenzyl acetone was then calculated.

DIAGRAMS

RESULTS & DISCUSSION Following the experiment, it was determined that approximately 42.7% of dibenzyl acetone was extracted from the organic solvent. The amount of recovery of the dibenzyl acetone may be smaller than expected due to addition of an excessive amount of hydrochloric acid. The amount recovered also may be slightly off, the beaker was not weighed before use, and a different beaker was weighed in it’s place.

Ryan Huckaby Dr. Srinivasan 2123-540 2-27-2020 CALCULATIONS 15.377 g – funnel and dibenzyl acetone 15.334 g – funnel 30.822 g – Beaker including dibenzyl acetone 30.665 g – Beaker 15.377 g−15.334 g=.043 g Dibenzyl acetone 30.822 g−30.665 g=.157 g Dibenzyl Acetone

.043 g+ .157 g=.200 g of dibenzylacetone recovered 0.200 ×100=42.7 % of dibenzylacetone recovered .367 SAFETY AND DISPOSAL According to the lab instructor chemicals used were to be disposed in the designated glassware at the front of the laboratory. Glassware was rinsed and dried after use and placed back into equipment drawers. The hotplate was cooled before placing back in its designated drawer.

CONCLUSION After the extraction process from mixture, to organic phase, to dibenzyl acetone, 42.7% was recovered. Due to lab error about 43% of the dibenzyl acetone was recovered from the solvent extraction. During the acidifying process some of the dibenzyl acetone may have been loss with an excessive amount of HCl. Some of the dibenzyl acetone may have been loss during the drying process as well.

REFERENCE Mohrig, J.R., Albert, D.G., Hofmeister, G.E., et al; Laboratory Techniques in Organic Chemistry, 4th ed., W.H. Freeman and Company, New York: 2014. Pp 142-155, 161-163, Extraction

Ryan Huckaby Dr. Srinivasan 2123-540 2-27-2020 POST-LAB QUESTIONS

1. An extraction procedure specifies that an aqueous solution containing dissolved organic material be extracted twice with 10 mL portions of diethyl ether. A student removes the lower layer after the first extraction and adds the second 10 mL portion of ether to the upper layer remaining in the separatory funnel. After shaking the funnel, the student observes only one liquid phase with not interface. Explain. Diethyl ether has a lower density than water meaning it was the liquid on top. After the water was drawn out, all that was left was the diethyl ether. After shaking there is only one layer because the only solvent present is the ether. 2. A crude nonacidic product mixture dissolved in diethyl ether contains acetic acid. Describe an extraction procedure the could be used to remove acetic acid from the ether. A salt will be created from NaCl and Acetic Acid. Then that solution is to be acidified. Then distilled at a moderate temperature. 3. What precautions should be observed when a aqueous sodium carbonate solution is used to extract an organic solution containing traces of acid? The extraction should be done under cold conditions, and shaken very well during extraction process. 4. When 2 layers form during a petroleum ether / water extraction, what would be an easy, convenient way to tell which layer is which if the densities were not available? Most organic compounds are soluble in ether. Therefore one can observe which solvent is on top due to the fact that organic solvents are less dense than water. Water also does not have a smell as an organic solvent will because it is volatile. 5. You have 100 mL of a solution of benzoic acid in water: the amount of benzoic acid is estimated to be 0.30 g. The distribution coefficient of benzoic acid in diethyl ether and water is approximately 10. Calculate the amount of benzoic acid that would be left in the water solution after four 20 mL extractions with ether. Do the same calculation using one 80 mL extraction with ether to determine which method is more efficient. 0.033 grams left

Ryan Huckaby Dr. Srinivasan 2123-540 2-27-2020...