Sciencemadness Discussion Board

Salting out and phase seperation

walruslover69 - 3-1-2018 at 06:36

Hello, I was recently carrying out a dioxane synthesis following NurdRage's procedure. During the purification and dehydration NaOH or KOH are used to separate the water and Dioxane layers. I was curious what salts are best at salting out and separating an aquas layer from a miscible organic solvent. I imagine it can very by solvent so lets say I wanted to separate water/methanol, water/ethanol and water/dioxane mixtures. I am generally familiar on how the salting out process works but would be interested in knowing why some particular salts work better than other and any personal experiences.

Metacelsus - 3-1-2018 at 06:38

There was just an article about this over at In the Pipeline: http://blogs.sciencemag.org/pipeline/archives/2017/12/14/ext...

walruslover69 - 3-1-2018 at 10:18

Thanks, its very interesting.

FlaskBreaker - 3-1-2018 at 11:52

A saturated solution of NaCl in water is usually great at removing water from organic solvents.

walruslover69 - 3-1-2018 at 12:03

Ive heard of NaCL being used frequently. I was interested to know what salts would be the most efficient( least amount of salt having to be used) and economical. Any idea how MgSo4(epsom salt) would preform since it is so water soluble and commonly available?

weilawei - 3-1-2018 at 12:32

The linked paper tested dozens of salts--among them MgSO4. There's a big table several pages in (page 6).

[Edited on 3-1-2018 by weilawei]

walruslover69 - 3-1-2018 at 12:45

Quote: Originally posted by weilawei  
The linked paper tested dozens of salts--among them MgSO4. There's a big table several pages in (page 6).

[Edited on 3-1-2018 by weilawei]


The paper seemed to only indicate the solvent partition and equilibrium not the ability to cause a separation of solvents.