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You are separating anthracene from benzoic acid via an extraction between ethyl acetate and a basic aqueous solution in a separatory funnel. How would you recover the anthracene?

 

A.

Collect the bottom layer, dry with Na2SO4, and evaporate the solvent.
 

B.

Collect the top layer, dry with Na2SO4, and evaporate the solvent.
 

C.

Collect the bottom layer and add HCl to precipitate the compound.
 

D.

Collect the top layer and add HCl to precitipate the compound.
 

E.

Collect the bottom layer and add NaOH to precipitate the compound.
 

F.

Collect the top layer and add NaOH to precipitate the compound.

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Related questions

Experiment: Extraction to seperate benzoic acid and naphthalene.

Procedure-

Place 2 g of a 1:1 (by weight) mixture of benzoic acid and naphthalene in a small beaker; record the exact mass of the mixture in your notebook. Add 35 mL of dichloromethane to the beaker and stir until the solid mixture has completely dissolved. Carefully pour the solution into a separatory funnel.

Add 20 mL of 3.0 M NaOH to the separatory funnel, stopper it, and shake the mixture with frequent venting. When the layers have separated, drain the bottom portion into a clean flask. Pour the aqueous layer into another clean flask labeled “aqueous layer.” Pour the organic layer back into the separatory funnel and extract with a second portion of 3.0 M NaOH. Drain the bottom layer into a clean flask labeled “organic layer” and pour the aqueous layer into the “aqueous layer” flask.

Put the organic layer back into the separatory funnel and shake with 20 mL of saturated NaCl solution. Drain the organic layer into a clean, dry flask and add a small amount of anhydrous calcium chloride to dry the solution. Allow this solution to stand for at least ten minutes, with occasional swirling, then remove the drying agent by gravity filtration; place the filtrate in a round-bottom flask and remove the solvent by simple distillation or by using the rotovap. Once the dichloromethane has been removed, scrape the crystals out of the round-bottom flask into a clean, labeled, tared vial, and determine the weight and melting point of the naphthalene crystals.

Acidify the combined aqueous layers with 6.0 M HCl until the solution tests acidic to litmus paper. A white precipitate of benzoic acid should develop as the solution is neutralized. Chill the solution in an ice bath for at least ten minutes to finish precipitating the solids, then collect the benzoic acid by vacuum filtration. Wash the crystals with a small amount of cold water; then scrape the crystals into a clean, labeled, tared vial and allow to dry. Once the crystals are dry, determine their weight and melting point.

Post-Lab Question:

Write a balanced equation (using structures) for the reaction that takes place when the aqueous layer is acidified with HCl. Why does the precipitate form when the solution is neutralized? (HINT: benzoic acid (slightly soluble in water) and sodium benzoate (soluble in water)

Organic chemistry question about extraction lab...?
Procedure:
Place 2.0 g of the mixture of sucrose, acetylsalicylic acid and acetanilide into a 125 mL Erlenmeyer flask.
Add 50 mL of methylene chloride (dichloromethane) and dissolve as much of the solid as possible.
Remove the insoluble sucrose via gravity filtration using fluted filter paper. Allow to dry until the next lab period.
Add the methylene chloride solution to the separatory funnel and extract it with two 25 mL portions of 5 % sodium bicarbonate (aqueous).
Place the combined aqueous layers into a 400 mL beaker and add enough concentrated hydrochloric acid to make it very acidic (less than pH of 2) – approximately 10 mL
Allow the solid to crystallize from the aqueous layer. Chilling in an ice bath may be required.
When lots of solid has been formed, collect the solid by vacuum filtration. Wash the solid with approximately 5 mL of cold water
Allow the solid to dry open until the next lab period.
Dry the organic layer (methylene chloride) over anhydrous sodium sulfate.
Decant the solvent from the drying agent (or gravity filter through fluted filter paper) into a clean, dry a pre-weighed 100 mL round-bottom flask.
Evaporate the solvent using rotary evaporation and allow the residue to dry open over the week.
The following lab period, weigh all 3 solids, take the melting points of all 3 solids and calculate the percent composition of the original solid.

Drying agents:
Equations for drying agents:
MgSO4 (s) + 7 H2O(l) ïƒ MgSO4.7H2O(s)
CaSO4(s) + 2 H2O(l) ïƒ CaSO4.2H2O(s)
CaCl2(s) + 6 H2O(l) ïƒ CaCl2.6H2O(s)
Na2SO4(s) + 7 H2O(l) ïƒ Na2SO4.7H2O(s)

1. The original organic solution was extracted two times with aqueous sodium bicarbonate. After the extraction, what compound(s) were in the organic layer? What compound(s) were in the aqueous layer?

________________________________________________________________________________________________________________________________________________________________________________________________________________________

2. Assume that both acetylsalicylic acid and acetanilide are soluble in diethyl ether, and that diethyl ether was used in place of the methylene chloride. Would the ether layer be the bottom layer in the separatory funnel or the top layer? Explain your answer.

________________________________________________________________________________________________________________________________________________________________________________________________________________________

3. Assume that both acetylsalicylic acid and acetanilide are soluble in methanol, and that methanol was used in place of the methylene chloride. What problem(s) might occur during the extractions? (Careful, this is a trick question.)

________________________________________________________________________________________________________________________________________________________________________________________________________________________

4. Historically, the solid residue that is left after the methylene chloride solution is evaporated has a lower melting point that its literature value, due to impurities. Explain what impurities are present and why.

________________________________________________________________________________________________________________________________________________________________________________________________________________________


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