FluoroPunch
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Steam distillation followed by liquid-liquid extraction?
I tried looking around to find out why sometimes we do liquid-liquid extraction following a steam distillation to no avail.
In an undergrad lab we did the steam distillation of cloves to get the oil followed by extraction with ether. My question is, why didn't we just wait
for the layers to separate? The oil is essentially (pun fully intended) immiscible with water so why wouldn't that work? Also from what I've seen for
orange oil this is not entirely necessary? Are there some cases where it would be appropriate but others where it's not?
Could someone please explain? It might just be because it forms an emulsion (which I doubt given the densities) but perhaps since the volume
difference is so high? I don't know. (Probably makes sense though considering the water after my orange oil extraction smelled strongly of oranges.)
Thanks.
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kulep
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when you steam distill you are not getting a pure substance, there can be many that act as emulsifiers. Also the volume difference as you said
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unionised
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If you can open this
https://pubs.acs.org/doi/abs/10.1021/je990278a?journalCode=j...
you can find out how soluble eugenol- which is the major part of clove oil is.
But even without access to the paper you can tell that the stuff must be at least slightly soluble, or they wouldn't have studied it.
So the claim "The oil is essentially (pun fully intended) immiscible with water " isn't quite true.
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Metacelsus
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Yes, the solvent extraction helps remove all of the desired compound from the aqueous phase.
Interesting fact: "rose water" is the aqueous phase from steam distillation on rose petals (the rose oil is also used in perfume).
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FluoroPunch
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Thanks guys, I think that makes sense then.
So would it be appropriate to do an extraction every time after a steam distillation?
| Quote: | | Interesting fact: "rose water" is the aqueous phase from steam distillation on rose petals (the rose oil is also used in perfume).
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That's pretty neat, I didn't think about that but it makes sense. Friggin guys trying to squeeze every buck out of that steam distillation  Now in think I could do a rose petal distillation if I find enough petals...
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