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Author: Subject: Separating Oils from a Hydrosol
binaryclock
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[*] posted on 26-5-2013 at 06:25
Separating Oils from a Hydrosol


Yesterday I distilled a 1L flask of cedar and water mix so that steam distillation would help me remove the essential oils from cedar foliage. When distilling, I saw oily bubbles on the top of the water in the receiving flask - not much mind you, but it did form a layer on top.

When I poured the hydrosol/oil mix in to a separatory funnel, the oil seemed to mix with the hydrosol and disappear. I left the hydrosol over night in the funnel but the oil did not rise to the top again and now I fear it won't.

How could I go about extracting the cedar oils from the hydrosol? If I boiled the mixture would I be evaporating the cedar oils as well? I assume I would since distillation brought the oils over with the water in the first place :)

Thanks! My wife is waiting :/

PS - The cedar hydrosol smells amazing and the cedar smell is extremely strong. It would be nice to get the essential oils, but even the hydrosol would be great for more general usage.


[Edited on 26-5-2013 by binaryclock]




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Mailinmypocket
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[*] posted on 26-5-2013 at 06:33


Solvent extraction in the sep funnel would be the best option- I would try shaking ~25 ml portions of dichloromethane in the separatory funnel, draining off the solvent and then repeating a few times. Distill the combined solvent phases and you will be left with the oil in the pot. Boiling the mixture would carry off the oil in the steam. This may give you a better idea of solvent extraction:

http://www.sciencemadness.org/talk/viewthread.php?tid=10766
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binaryclock
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[*] posted on 26-5-2013 at 06:45


Wow that seems like fun! I'm going to try that for sure and see what I can come up with.. even though the oil yield in this hydrosol is small, it looks like some great practice and teaches some new methods I was not familiar with.

Thanks again bud!

Now to find some dichloromethane :/

I found this: http://www.jamestowndistributors.com/userportal/pdfs/MSDS/Sw...

But it seems to have methanol in it. I read in another post that methanol forms a 7.3% azeotrope with dichloromethane so when I distill it at 40c, I'll get some methyl alcohol with it.

Any ideas?



[Edited on 26-5-2013 by binaryclock]




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mayko
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[*] posted on 26-5-2013 at 07:57


I recently distilled some DCM from paint stripper containing toluene and methanol. I couldn't find any reference to a toluene/DCM azeotrope; I washed the DCM with water, then drying with anhydrous MgSO4. I haven't assayed the final product (is there a good wetlab test for MeOH?) but the procedure makes sense to me.
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[*] posted on 27-5-2013 at 05:58


for the methanol i remember something around that aluminium or was it aluminium oxide?
one of them will react with methanol to turn it into H2O and CO2


One of the drawbacks of methanol as a fuel is its corrosivity to some metals, including aluminum. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminium from corrosion:

6 CH3OH + Al2O3 → 2 Al(OCH3)3 + 3 H2O


there we go..

basically dump some aluminium foil into the mixture and it could potentially break the azeotrope for the methanol to react, dont know if any of these products would be soluble others than water (in which might be a problem?)




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
http://www.trimen.pl/witek/calculators/stezenia.html
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[*] posted on 27-5-2013 at 06:17


Quote: Originally posted by mayko  
(is there a good wetlab test for MeOH?)


Primary alcohols are oxidised (to corresponding carboxylic acids)easily by potassium dichromate or potassium permanganate. A dilute solution of the latter (deep purple) should clear up in the presence of dilute sulphuric acid, suspected methanol and gentle heating (if needed). You might even, depending on quantity, get a whiff of formic acid. Don't use HCl to acidify to avoid false positives.

The distribution coefficient for MeOH between water and DCM should be very large though: you should be able to wash out any MeOH with water, prior to drying.



[Edited on 27-5-2013 by blogfast25]




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[*] posted on 27-5-2013 at 07:26


Washing the DCM with water will remove most of the methanol
The reaction of aluminium with halogenated solvents like DCM can be violent or explosive so I wouldn't recommend it.
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