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Old Mar 28th 2017, 06:54 AM   #1
vicky1981
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help with separating a mixture

Hi there

Ok so I attempted to extract oil from the lavender plant using soxhlet extraction as the college are still waiting on the steam distillation kit arriving. I crushed up the plant and filled the thimble, using n-hexane as the solvent... at this point I seemed to have a little oil mixed with chlorophyll and other plant material.

I then used the rotary evaporator and was left with a horrible deep green mixture which im assuming was plant material and oil.

I attempted to distill off the chlorophyll in 95% ethanol to be left with the oil mixture and no green, that did not work.

I then placed mixture in a 250ml separatory funnel with 95 ethanol and shook, after the weekend I saw white precipitate at the bottom of the funnel but it was not fully separated. So now I am a bit stumped. I was hoping the chlorophyll would dissolve in the alcohol - the green had faded a lot though.

I then thought I could transfer into a larger 500ml funnel, top up the mixture to 200ml with more 95 ethanol and 200ml saturated saline solution as the Na+ forces the chlorophyll molecule to precipitate into micelles (which it did in the next step).

After about 10 minutes a clear separation had happened - there was a solid precipitate at the bottom (which im assuming is NaCl) and the top layer which was a mixture of ethanol/water and a little oily layer at the top which was covered in solid chlorophyll floaters. I let out the salty mixture at the bottom and filtered it off using a Buchner - it smells just like a lavender field! I then let out all the other mixture trying to leave the oily layer in the funnel. there is maybe 5ml left in funnel which is now green with the chlorophyll (not dissolved though)

Question is ....... as everything smells like lavender I am unsure as to what has went wrong here as the "oily layer" does not look oily when it is in the beaker, I know the most dense products should sit at the bottom and less at the top - the ethanol and lavender are the least dense so where is my oil, can anyone suggest anything to me?

thanks in advance
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Old Mar 30th 2017, 04:29 AM   #2
MatthijsM
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perhabs it's dissolved in the ethanol? I don't know if that is possible but you never know. Also for extracting lavender oil, I think you can search on the web a little and find alot about it.
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Old Mar 30th 2017, 04:59 AM   #3
vicky1981
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Hi there MatthijsM

I have researched the whole internet and found not that much, because it is an essential oil it doesn't go into the chemistry behind it, a lot of the clean up techniques lead me to skunk and cannabis websites...which is fine, if the techniques work. I will evaporate off alcohol and see if I am left with oil.

The steam distillation kit shouldn't leave me with any issues when it finally arrives.

thanks
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