Question for my lab pratctical tomorrow. I just need some help please please ple

Question

Question for my lab pratctical tomorrow. I just need some help please please please

so we are going to be given an unknown solid or liquid mixture and be told to puify it through extraction or recrystallization.

I need help clarifying some things with the extraction part.

it is going to be a a neutral compound and we will be informed what organic solvent it is dissolved in. We will be told what the nature of the impurity is (acid or base), and HOW MUCH HCL or NaOH for the extraction step. We don't have to isolate the acid or base impurity. We need to figure out whether or not to use hcl or NaOH for the extraction step.

My question is... i know that if we have an acid impurity, we have to extract with NaOH to remove a proton from the acid in order to have it ioninze in the aqueous layer, and then we add HCl to the extracted layer t add proton back to the conjugate and have the acid precipitate out.

Do i wash with brine still? and the desired layer will be the bottom layer in the funnel when I initially extract?

I dont know what else to do after i extract with the proper solvent. Do i wash with brine, and then anhydride?

Explanation / Answer

Do i wash with brine still?

Yes, brine is used to increase yields, the brine increase ions in solution, therefore the ionic strenght increases, forming our product

And the desired layer will be the bottom layer in the funnel when I initially extract?

the desired layer is the one with our extract,...

we are interested in our organic acid so:

initially --> it was in aqueous/organic layer, after deprotonation, it went to aqueous layer ( since it is ionic)

then, we add H+ (Acid) in excess to favour the ionic acid to become molecular

this will be in our aqueous layer, which typically is the bottom layer ( since water is denser than pretty much all common organic solvents)

Do i wash with brine, and then anhydride?

Correct, addition of any anhydride will aid in dissicant process. Therefore, our final product will have no humidity.

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