Bart was a truly superb organic laboratory student. Unfortunately, his partner H

Question

Bart was a truly superb organic laboratory student. Unfortunately, his partner Homer was a bit careless. Bart was carefully saving solid samples of benzoic acid and ethyl-4-aminobenzoate in his lab locker; he needed to run melting point determinations on these samples after they had dried for a week. Before he got a chance, Homer picked up both samples, dumped them together in a beaker, and was about to carry them to a waste jar. Bart recovered the beaker, and decided he could easily separate the two components. How would Bart best recover the ethyl-4-aminobenzoate from the solid mixture ?

A) Dissolve the solid mixture in ether, extract the ether solution with 10% aqueous sodium hydroxide, collect the aqueous layer and add an acid.

B) Dissolve the solid mixture in ether, extract the ether solution with 10% aqueous hydrochloric acid, collect the aqueous layer and add a base.

C) Dissolve the solid mixture in ether, extract the ether solution with 10% aqueous sodium hydroxide, collect the ether layer and let the ether evaporate.

D) Dissolve the solid mixture in ether, add about the same volume of water, shake, separate and discard the aqueous layer, let the ether layer evaporate and collect the product.

Explanation / Answer

Benzoic acid is soluble in ether.

Ethyl 4-aminobenzoate has an amino group and an ester group. Due to the presence of the amino group the compound is very soluble in acid, because amines are basic. The compound won't be soluble in NaOH solution, because it has no acidic functional groups.

So the answer is B

[B) Dissolve the solid mixture in ether, extract the ether solution with 10% aqueous hydrochloric acid, collect the aqueous layer and add a base].

Here the benzoic acid will go to ether solution

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