July 10, 2020, 03:47:42 PM
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Topic: Struggling with a question about acid-base washes to separate starting material  (Read 1569 times)

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Offline suckingalemon

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Impure paracetamol produce via synthesis from 4-aminophenol might contain the following impurities (structures in image):

It is possible to isolate paracetamol from left over starting material and by-products by protonating or deprotonating certain groups which then make them soluble or non-soluble in water.
By constructing a flowchart, describe a series of acid-base washes isolates paracetamol 2 from unreacted starting material 1, O-acylated by-product 3 and acetic acid 4, with the structural changes (protonations/deprotonations) that occur. TIP: Use HCl as your acid, and NaOH as your base.

I'm guessing that 4 (acetic acid) will react with the base (NaOH) in some way.

I'm not sure how this will effect it's solubility though. I think it will go to a salt which is ionic so will dissolve in water but not an organic solvent? I'm not quite sure what the salt will look like either.

For the others, I need a bit more of a pointer, I think.

Can anyone give me some suggestions how I might start on this problem? I'm not really sure how to approach it.

Thank you.

Offline OrganicDan96

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for acetic acid, what do you think the product you get when you react an acid and a base? how do you think you could separate a water soluble salt from other organic material?

what functional groups are present and what happens to them in acid or base?

Offline Babcock_Hall

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When writing out acid-base chemistry, I find it helpful to draw out the lone pairs, especially on nitrogen.

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