Question

 

1. The three compounds below were dissolved in a solution of dichloromethane and then extracted two times with 3M sodium hydroxide. 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 butanol, and that butanol was used in place of the methylene chloride. What problem(s) might occur during the extractions? (Careful, this is a trick question.)

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

4. When a separatory funnel is shaken too vigorously, an emulsion may form. What would be the best way to quickly (!) break the emulsion?

Answer 1

Three compounds I assumed are acetylsalicylic acid (acidic), acetanilide (basic), and a neutral compound.

1. The three compounds below were dissolved in a solution of dichloromethane and then extracted two times with 3M sodium hydroxide. After the extraction, acetanilide (basic) and neutral compounds will be in the organic layer and aectylsalicylic acid is in the aqueous layer in the form of a sodium salt of acetylsalicylic acid .

2. If acetylsalicylic acid and acetanilide are soluble in butanol, and that butanol was used in place of the methylene chloride.

2. If one uses butanol in place of methylene chloride as a solvent since butanol is soluble in water during extractions, the butanol having acetylsalicylic acid and acetanilide will be miscible with water layer and some the compounds may lose in water layer due to the use of butanol as a solvent.

3. If acetonitrile was used in place of the methylene chloride for extractions, acetonitrile layer will be at the top layer in the separatory funnel as its density (0.786g/mL) is lesser than water (1g/mL) , methylene chloride density 1.33g/mL) s more than water and hence it will be in the bottom layer during the aqueous extractions.

4. The best way to quickly break the emulsion is by adding brine solution (saturated aqueous NaCl solution) into the separatory funnel, which clears the emulsion.