Melanie McComb (partyupgal4ever) wrote in chem_haters,
Melanie McComb

Extraction Question

This is going to sound like a weird post but let me explain first. I'm retaking organic chemistry II because I wasn't doing very well in it and needed a break last year. I conveniently found some of my old labs that I wrote up, including the pre-lab I'm working on now. I didn't have a regular TA last year when I took it; I had a professor. His writing is atrocious and I can barely read anyting he wrote.

Here was the question: "Why must the organic and aqueous phases be mixed well when performing an extraction?"

I put down that you have to allow the organic phase to mix with the aqueous so that you could pull all of the organic compounds out of the aqueous phase. He said that was wrong and said something about you're actually trying to take out ? ingredients out of the organic layer (? distribution).

Can somebody please explain this to me and try to let me know what he probably meant where I put the question marks?

Thanks in advance!

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I'm guessing possibly removing polar ingredients out of the organic layer? I don't know about the distribution thing though. What exactly are you separating?
It's the isopentyl acetate lab.
Hmm, well, I know you are supposed to add base to deprotonate the excess acetic acid left over from the reaction. So acetic acid, protonated, remains in organic layer, but if you add base and mix, then it becomes deprotonated and the acetate anion would move out of the organic layer and into the aqueous layer so you can get rid of it and only have isopentyl acetate in your organic layer. So I guess that's what your professor meant: not pulling organic compounds from aqueous phase but rather the acetate from the organic phase.
Ah I see what you mean now. It's too bad that when I finally did the lab I had no sample left after drying it. :(
ha ha inefficiency