[oc dummy]

Hi everyone,

I'm having trouble understanding why in a ether and aqeous base liq-liq extraction, we need to add the ether back into the aqeous.

So first, we mix 2 compounds and add diethyl ether, as well as HCl. Then I do extractions and get 2 products: the top part - triphenylmethanol/ether, and the bottom part -  benzocaine aqueous base. Since I've already separated my products, why do I have to go and pour the ether back with the aqueous base> Haven't I already separatef the triphenyl in the top layer and the benzo in the aqueous bottom?

Thanks in advance!!

[Borek]

If I understant you correctly, you are asking why - after separating aqueous solution and ether - you have to add another portion of the NEW ether to the aqueous solution? It is not the same as pouring already separated ether BACK into the mixture.

Trick is, separation of extracted substance is never perfect, there is some substance left in water.

[azmanam]

also, if you were to add base to your separated aqueous layer before adding ether, then there is a separate, and very good, reason for adding ether again.  If you are not supposed to add base before the step in question, then Borek is right - you never extract all the compound the first time.