Sciencemadness Discussion Board

Salting out

morsagh - 26-11-2015 at 10:58

If i have a solution of benzyl alcohole in water (very low concentration) can i use salt to separate benzyl alcohole (just to identify that bezyl alcohole really is in solution? Can be used NaOH?

byko3y - 26-11-2015 at 18:58

Use another lipophilic solvent - it's hard to impossible to extract benzyl alcohol from water solution with a bare salt.

Amos - 26-11-2015 at 19:16

Quote: Originally posted by byko3y  
Use another lipophilic solvent - it's hard to impossible to extract benzyl alcohol from water solution with a bare salt.


This is based on what?

byko3y - 26-11-2015 at 19:23

This is based on practical observations.

Amos - 26-11-2015 at 21:05

Quote: Originally posted by byko3y  
This is based on practical observations.


Well, "a salt" refers to a few hundred readily accessible compounds that could potentially be used to separate the benzyl alcohol and water. I've had great success using anhydrous sodium acetate and chromium(III) sulfate as salting-out agents before, and they work on things that normally would be impossible with sodium chloride or potassium carbonate. So I wouldn't act as though all attempts at salting out would be fruitless.

deltaH - 27-11-2015 at 01:52

You might try anhydrous K3PO4, it's a pretty powerful salting out reagent. We've shown on another SM thread that it can salt out ethanol from liquor forming a near 100% alcohol second layer.

The problem with salting out dilute solutions is the volume of the second solution is too small. A workaround may be to add alcohol to the water, say enough to obtain a 30% solution (ethanol, isopropyl alcohol or even 'rubbing alcohol'), then salt out the alcohol AND benzyl alcohol together using anhydrous K3PO4, then simply evaporate or distill the alcohol to recover the crude product. This then becomes a combined salting-out and extraction step and so should be more powerful at recovering dilute product.

[Edited on 27-11-2015 by deltaH]