August 25, 2019, 04:19:25 PM
Forum Rules: Read This Before Posting


Topic: Struggling with a question about acid-base washes to separate starting material  (Read 1200 times)

0 Members and 1 Guest are viewing this topic.

Offline suckingalemon

  • Very New Member
  • *
  • Posts: 1
  • Mole Snacks: +0/-0
Quote
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

  • Full Member
  • ****
  • Posts: 196
  • Mole Snacks: +17/-1
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

  • Chemist
  • Sr. Member
  • *
  • Posts: 3779
  • Mole Snacks: +242/-16
When writing out acid-base chemistry, I find it helpful to draw out the lone pairs, especially on nitrogen.

Sponsored Links