How to separate hydrophilic / lipophilic substances out of an alcoholic mixture?

Question

The problem with your answers is that both water and acetone will dissolve into the alcoholic solution, so you end up with one layer anyway =(

Lane - Great suggestions. Just one remark: chloroform is denser than water, so I guess it will constitute the bottom layer.

How about adding some NaCl to displace the less hydrophilic solutes?

Answer 1

There are several answers to your problem. But here are some old tricks.

First, evaporate enough alcohol so that the solution is very concentrated. Then, layer on a top phase of hexane, as was suggested below, or, even better, some petroleum ether, also known as ligroin. Shake it up in a separation funnel. Some alcohol will partition into the pet ether phase, but so will the hydrophobic substances. The hydrophilic materials will remain in the alcohol that does not dissolve in the pet ether, they will most likely precipitate.

Now, to clinch the separation, add a bottom phase of water or acetonitrile. This will solubilize the hydrophilic substances. The alcohol will partition between the two phases, but since it is no longer the dominating solvent here, in terms of polarity, the hydrophilic substance will be extracted to the water phase. Pet ether/acetonitrile separations are an old way of separating fats from other substances.

A second way is to dilute your concentrated alcohol solution with water. Now the hydrophobic substances will start to precipitate. You could simply filter them out. Or, you could layer on a top phase of 2:1 chloroform:isoamyl alcohol, shake it up, and have the hydrophobics partition to the top (chloroform) phase. This is an old way of obtaining the membrane constituents, phospholipids, glycolipids (they partition to the water/chloroform interface), sterols, from other cellular components.

Answer 2

Lipophillic is easy. Add some organic solvent (acetone should work), shake up the mixture and use a pipette (or turkey baster) to suck out the organic solution. This is called extraction if my memory serves me.

Hydrophillic is a little harder. Depending on the boiling point of the hydrophillic substance, you may be able to use distillation. If the b.p. is more than 20 degrees (C) from the solvent, you can use simple distillation. If it's closer than 20 degrees, you can use fractional distillation. So go buy yourself a still if this isn't being done in a chem lab.

Edit: hmm good point about acetone & water solubility. You could use a host of other organic solvents though, like dichloromethane.

Answer 3

I'd suggest adding organic solvent like hexane and shaking vigorously. The lipophilic substance will enter the hexane phase. Separate by decanting or better if you have a separating funnel. The hydrophilic material may be harder to isolate. It may help if we know what the alcohol phase is and what the unknown material is.

Answer 4

Hydrophilic = "water-loving"
Lipophilic = "oil-loving"

Simply pour some water into a beaker, then pour your mixture on top of the water, then pour oil on top of the mixture.

The mixture will be simultaneously absorbed from both sides by the water and oil, until there's none left. After that, you must filter the materials in question out of the water and oil, which may be easy or difficult, depending on what the materials are. Distillation may be required.

Answer 5

Kadel, the pre-disposition to substance abuse is a genetic make up, not a learned trait. Much as depressive parents and schizophrenia runs in family genes. Alcoholism does not work like abuse, which is a learned trait. Obama has a good chance of becoming one but will he? We will have to wait and see.