Question

From You have a mixture of benzoic acid, hexamethylenediamine, and 1-octanol dissolved in diethyl ether. You wish (for some reason) to separate these compounds and have pure samples of each. Devise a liquid-liquid extraction protocol that would allow you to do this. (up to 20 points) Your answer should be clear and concise. Ambiguous answers or those that are difficult to read will NOT receive points. Search entries or author Unread Subscribe Reply

Answer 1

1. Extraction with a basic aqueous solution to extract the benzoic acid in its deprotonated form, which will be soluble in water. This aqueous phase can then be neutralized to obtain the protonated benzoic acid, which can be back-extracted in diethyl ether and the evaporated to obtain the pure compound.
2. Extraction of the remaining organic phase (which has the amine and 1-octanol by now) with an acidified water portion. In this way, the protonated amine will be extracted into the water, which can be then neutralized to recover the amine. This can be then back-extracted to diethyl ether, which can then be evaporated to obtain the pure amine.
3. Finally, the only compound in the original organic phase is 1-octanol, which is scarcely soluble in water and can be directly obtained by evaporating the diethyl ether.