[emphen]

When doing liquid-liquid extraction, can one of the solvent be a miscible mixture of two solvents?
For example,
Just like we extract some compounds from aqueous into organic medium, Is it possible to use  50 % aqueous acetone extract in place of aqueous extract. i.e. 50 % acetone will be one solvent and we extract compounds into another solvent that will be miscible with acetone, but immiscible with water.
Can it work?

Thanks.

[lavoisier]

When doing liquid-liquid extraction, can one of the solvent be a miscible mixture of two solvents?

Yes. EtOAc+iPrOH, DCM+iPrOH, 2-butanone+H2O are some examples.

For example,
Just like we extract some compounds from aqueous into organic medium, Is it possible to use  50 % aqueous acetone extract in place of aqueous extract. i.e. 50 % acetone will be one solvent and we extract compounds into another solvent that will be miscible with acetone, but immiscible with water.

I don't get what you mean.

[emphen]

I really apologize that i could not explain properly.

Suppose we extract some organic compounds from plant aqueous extract  in organic solvent e.g. from aqueous extract (Solvent A) to ethyl acetate (Solvent B).

My question is if we use a plant extract which is in 50 % water:acetone (v/v) in place of simple water extract, and want to  extract desired compound from this 50 % acetone extract (Solvent A) in ethyl acetate (Solvent B), will it work??

Is it clear now?

[Jd1828]

Yes this will work but you have to play with the ratios of the solvents a lot.  You are pretty much describing the idea behind counter current chromatography.

[lavoisier]

I really apologize that i could not explain properly.

Suppose we extract some organic compounds from plant aqueous extract  in organic solvent e.g. from aqueous extract (Solvent A) to ethyl acetate (Solvent B).

My question is if we use a plant extract which is in 50 % water:acetone (v/v) in place of simple water extract, and want to  extract desired compound from this 50 % acetone extract (Solvent A) in ethyl acetate (Solvent B), will it work??

Is it clear now?

Maybe. The way I understand it is:
1. You treated some plant with acetone and water. This extracted a compound you're interested in, plus other stuff.
2. Now you want to extract one specific compound from this aqueous-organic mixture using ethyl acetate, and you're worried that acetone might interfere, being miscible in both water and ethyl acetate.

If this is what you're saying, there are two cases:
A. if you're sure the compound you want to extract is soluble in EtOAc, then it's easy to eliminate the potential interference of acetone: just evaporate the acetone/H2O extract in vacuo until only the aqueous residue remains, then carry on with your extraction with EtOAc. It's common practice to do so.
B. if you're not sure, try extracting the mixture with EtOAc directly and see what happens. Chemistry is still an experimental science as far as I know. And actually, you can often extract acetonitrile/H2O or THF/H2O mixtures directly with EtOAc. Only occasionally this makes your product stay in water.

[emphen]

Maybe. The way I understand it is:
1. You treated some plant with acetone and water. This extracted a compound you're interested in, plus other stuff.
2. Now you want to extract one specific compound from this aqueous-organic mixture using ethyl acetate, and you're worried that acetone might interfere, being miscible in both water and ethyl acetate.

Right, i wanted to say the same.

A. if you're sure the compound you want to extract is soluble in EtOAc, then it's easy to eliminate the potential interference of acetone: just evaporate the acetone/H2O extract in vacuo until only the aqueous residue remains, then carry on with your extraction with EtOAc. It's common practice to do so.

This is what i have tried but it caused problems. Evaporation of acetone caused the precipitation of those compounds that were extracted from plant leaves due to acetone (means they were soluble in acetone).
When i extracted from this aqueous extract with ethyl acetate, that insoluble particles collected at the entire interface of two liquids. I was confused that it might affect the extraction of desired compounds.
That's why i thought to use the aqueous acetone extract directly.

B. if you're not sure, try extracting the mixture with EtOAc directly and see what happens. Chemistry is still an experimental science as far as I know. And actually, you can often extract acetonitrile/H2O or THF/H2O mixtures directly with EtOAc. Only occasionally this makes your product stay in water.

Yes this will work but you have to play with the ratios of the solvents a lot.  You are pretty much describing the idea behind counter current chromatography.

OK. It means that I can try it. But it will also extract those constituents in ethyl acetate that were soluble in acetone part of extract (that precipitated if acetone was evaporated). Because acetone will also dissolve in ethyl acetate. Am I right in this point???



A lot of thanks for help.

[skbuncks]

I would expect the acetone to partition between the aqueous and organic layers. This may or may not lead to separation issues. You will certainly have to perform a couple of EtOAc extractions to extract all of the desired material. If you find that the layers are slow to separate or that you get a large cloudy interface then I would suggest throwing in some brine to aid the separation.
As someone else said, chemistry is an experimental science so just get stuck in and do it

skb

[lavoisier]

This is what i have tried but it caused problems. Evaporation of acetone caused the precipitation of those compounds that were extracted from plant leaves due to acetone (means they were soluble in acetone).
When i extracted from this aqueous extract with ethyl acetate, that insoluble particles collected at the entire interface of two liquids. I was confused that it might affect the extraction of desired compounds.
That's why i thought to use the aqueous acetone extract directly.

If your compound really is soluble in EtOAc, no 'insoluble particle' will stop it from being extracted. Unless your product has more affinity for these particles than for EtOAc! But how likely is that?
You can always add EtOAc before evaporating the acetone. The difference in boiling point is large enough. Or you can filter the biphasic suspension after adding EtOAc. These are all very common practices in the lab.
But I still get the impression that we're worrying too much in advance; the best way forward is indeed trying it out.

[emphen]

Or you can filter the biphasic suspension after adding EtOAc. These are all very common practices in the lab.

OK. I think filtration of suspension is also one of the best solution.

All the suggestions i got here, really helped me a lot.
I am really highly grateful to all of you.

Again thanks a lot.