[coolkul]

I have to write a procedure for a lab in which I will be given an unknown mixture containing an organic acid and neutral impurity. I will first have to extract the organic acid from the impurity by adding a chemical that will give me two separate layers (aqueous and organic). My assumption is that this chemical is NaOH, but I'm not sure about this. After separating the mixture into two layers, I have to isolate the acidic compound from the mixture. I'm guessing I will have to take the aqueous layer and add HCl, which will form a solid precipitate which will be the acidic compound. I will then have to isolate the solid from the remaining liquid. How would I achieve this? Could someone help me out with these procedures?

*bolded items are the main things I have to achieve in this lab

The following are the chemicals we will be allowed to use
3.0 M NaOH
6.0 M HCl
diethyl ether
DI water
dichloromethane
3.0 M H2SO4
Na2SO4
0.1 M acetic acid
0.1 M NaOH

[discodermolide]

Well as you don't have filter paper available, how else could you obtain the acid from the aqueous phase?

[coolkul]

We would probably have filter paper available to us. Could someone make sure if adding NaOH would create the aqueous and organic layer? Should I be using the 3.0 M NaOH or 0.1 M NaOH? Am I correct in saying that the aqueous layer, rather than the organic layer, should have 6.0 M HCl added to it and an acid precipitate would form?

The main purpose of this lab is to essentially take that solid precipitate and find it's identity using melting point. We are given a generic/vague set of procedures and we are expected to know the correct chemicals to use in each step and how to set up things.

[AlphaScent]

Think about solubilites of the compounds (functionality) in each solution. 

Hint: what happens to a carboxylic acid if it is treated with base?

[discodermolide]

We would probably have filter paper available to us. Could someone make sure if adding NaOH would create the aqueous and organic layer? Should I be using the 3.0 M NaOH or 0.1 M NaOH? Am I correct in saying that the aqueous layer, rather than the organic layer, should have 6.0 M HCl added to it and an acid precipitate would form?

The main purpose of this lab is to essentially take that solid precipitate and find it's identity using melting point. We are given a generic/vague set of procedures and we are expected to know the correct chemicals to use in each step and how to set up things.

You will only get 2 layers if you have a solvent present that is insoluble in water.
You have done this already.
You have re-generated the acid by adding HCl.
Now you got a solid which you have to isolate. How will you attempt this? This is where you are now.

[coolkul]

In order to isolate the solid from the liquid, I could filter it by vacuum filtration using a Hirsch funnel. This should leave behind the dry solid acid precipitate. Am I correct?

[discodermolide]

Yes that's one way, you could always re-extract it back into a fresh organic layer and evaporate the solvent.

[avatarmocha]

Yes that's one way, you could always re-extract it back into a fresh organic layer and evaporate the solvent.

How exactly would you do that?

[discodermolide]

Well take the suspension you have and add dichloromethane and shake it up. The solid acid may well dissolve. If it does separate the layers. Take the dichloromethane layer and evaporate the solvent, the solid will be left.
If it does not dissolve then you will have to filter it.

[avatarmocha]

thank you!!