[Jfalken]

So I was evaporating ethanol which takes forever.
There was some left in the rotovap flask when I decided to stop it and proceed with the purification.
I had water soluble reagents in excess, and an organic product, so I added toluene and water in excess.
Now, where does the ethanol go?
As it is miscible with water but can also mix in Toluene.
The product can dissolve in ethanol, slightly in toluene but now in water.

Now at the sep. funnel stage and I would really like to get rid of the water and ethanol but keep the toluene (given that the product is still there).
Any ideas?

[Borek]

where does the ethanol go?

Basically you are asking what is the partition coefficient, don't you?

[Jfalken]

where does the ethanol go?

Basically you are asking what is the partition coefficient, don't you?

Ethanol and water are miscible at all concentrations.
Ethanol and Toluene on the other hand?

Ethanol + Water forms 1 phase.
Toluene + Water forms 2 phases.

Ethanol + Toluene forms how many phases?
Ethanol + Water + Toluene forms how many phases?
If two phases, will the ethanol be in the water phase or organic phase?

Will it even matter if the product is non-soluble in water?
Would it not then rather go to the organic phase, even though there is an EtOH/H2O solution present in the sep funnel?
 

[Borek]

You are missing the point and - sorry to say that - it looks like you don't understand the physics/chemistry behind. Ethanol will be in both phases, real question is: what is the ratio of concentrations (partition coefficient) of ethanol in both phases. And chances (not too large though) are that someone measured the partition coefficient for this system and it was published.

[Babcock_Hall]

This may be off topic.  However as a practical matter I have sometimes used toluene to strip off other compounds during rotary evaporation, including methanol (but not ethanol).  If your product is in the toluene phase, why not just proceed onto rotary evaporation?

[Jfalken]

You are missing the point and - sorry to say that - it looks like you don't understand the physics/chemistry behind. Ethanol will be in both phases, real question is: what is the ratio of concentrations (partition coefficient) of ethanol in both phases. And chances (not too large though) are that someone measured the partition coefficient for this system and it was published.

I think we are talking about the same thing.
The ethanol will be in both phases, but will it rather be in the water or in the toluene?

Where can I find a table presenting the values?
I would rather have it in the water phase so the water phase will only be slightly ethanolic (low concentration) and thus, the product should "prefer" the organic phase.

This may be off topic.  However as a practical matter I have sometimes used toluene to strip off other compounds during rotary evaporation, including methanol (but not ethanol).  If your product is in the toluene phase, why not just proceed onto rotary evaporation?

So the product is insoluble in water, and only slight soluble in toluene (the impurities however are soluble in toluene). Just want to decant the toluene basically and dry the product under vacuum.

[rolnor]

It is easy to check both water-phase and toluene-phase with TLC.