[nicolodn]

Why does aniline and N-phenylacetamide both contain nitrogen but only aniline is soluble in a solution of aqueous HCl.
---I get that NH2 the amine if added to HCl makes it charged , but it doesn't affect the amide.
But, the question is worth 4 marks, and I don't know what else to add.

Chemist converts benzoic acid to methyl benzoate. Analysis of the crude product shows that there is 10% of starting benzoic aced present. Outline an ether extraction procedure that the chemist could carry out to remove benzoic acid and isolate methyl benzoate. No need to isolate benzoic aced. Use eqns.
-----I know to add organic solvent ie diethyl ether and place solution in separating funnel the add base and shake. Benzoic acid then converted to watersoluble sodium salt. Then aq and organic layers separate ,, drain lower layer, evaporate organic layer.
Also, I actually don't get what adding the diethyl ether actually does.What's its role? (Just to dissolve both?)
And what would I do if it said isolate the acid?

Thank you

[AC Prabakar]

Why does aniline and N-phenylacetamide both contain nitrogen but only aniline is soluble in a solution of aqueous HCl.
---I get that NH2 the amine if added to HCl makes it charged , but it doesn't affect the amide.
But, the question is worth 4 marks, and I don't know what else to add.

Yes of course!!

Although it seems to be simple this above example will explain the basicity of "N" present in amine and amide.
The ability to share/donate its("N") electron with other moities can be explained to add more value to your answer.
i.e.the imine form of amide which will not allow "N" to share its lone pair can be compare with amine.
Other than that it is good.

Chemist converts benzoic acid to methyl benzoate. Analysis of the crude product shows that there is 10% of starting benzoic aced present. Outline an ether extraction procedure that the chemist could carry out to remove benzoic acid and isolate methyl benzoate. No need to isolate benzoic aced. Use eqns.
-----I know to add organic solvent ie diethyl ether and place solution in separating funnel the add base and shake. Benzoic acid then converted to watersoluble sodium salt. Then aq and organic layers separate ,, drain lower layer, evaporate organic layer.

This part is fine.

Also, I actually don't get what adding the diethyl ether actually does.What's its role? (Just to dissolve both?)

Diethyl ether is acting as a solvent to separate the product by facilitating the layer separation from water.
Diethyl ether is water immiscible solvent, hence if water is added to that it will results in two layers i.e. water layer(aqueous phase) and ether layer(organic layer). As we know when acid(in this case benzoic acid)  is basified with base it will form salt and will dissolve in water(other words dissolved in basic water).
The left over benzoate(in this case) which is water insoluble and soluble in organic solvent(here ether) will be extracted along with ether.

This is a commonly employed method of work up in which we can separate acid or base form neutral moieties or form its counter part.

And what would I do if it said isolate the acid?

So simple! Just take the above aqueous layer(after separation of ether layer) and adjust the pH to acidic(preferably near to the pKa of the particular acid-here benzoic acid).You will be ending in the acid.