Question

Hello. I have these questions regarding a lab on the extraction of a 3-component mixture. The three compounds are listed under the first question. I need help with 3, 4, and 6.

Answer 1

Answer 3.

To separate the mixture in to its components, pKa has an important role. If one component is acidic (lower pKa), we need to add basic solution (e.g. NaOH) to make it soluble by increasing its polarity while other components remain insoluble. We can separate this acidic component by separating funnel using ether as a solvent in which insoluble component will go in Etheral layer and acidic component will go in basic aqueous layer. The water layer further can be neutralize futher by acid to make acidic component insoluble in aqueous solution and can be easily separated out. Similarly, basic component can be seperated out by using acid solution.

Answer 4.

Change in pH values will cause ethyl 4-amino-benzoate to be polar or non-polar due to protonation or deprotonation of -NH₂ group. When we add a strong acid like HCl (lower the pH), we protonate amine group of ethyl 4-amino-benzoate and it become polar as it has positive charge on nitrogen. By adding strong base like NaOH, we deprotonate amine group that make it non-polar.