Author Topic: Essential oils, extracting from plants...solvent choices questions etc.  (Read 117 times)

Tsathoggua

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Essential oils, extracting from plants...solvent choices questions etc.
« on: June 20, 2011, 06:34:37 PM »
This might not be as exciting as say, extracting a few liters of safrole from rootbark etc, but I'm about to go and harvest a large quantity of lemon balm (Melissa officianalis), I fancy some balm tea right now after all the work today, sweating and roasting in a small shed, on a searing hot day, with a welding torch and hotplate constantly turned up to the max.

A member of the mint family, spreads like wildfire once it gets established. I have a small plant in my garden now, split off from a larger plant and given as a gift by a neighbour a couple of houses down. Going to water it with a dilute solution of aspirin/a salicylate salt after base saponification of the acetyl group to encourage even faster growth. It was a tiny scrap a month and a bit ago, that had been picked and left to wilt for most of a day in the hot sun. Now its a healthy, moderate sized plant. With very low dose auxin activity, and addition of fertilizer, it should grow faster than the bubonic plague in a medieval city. The tea has both memory/cognitive enhancing properties, containing substances that modulate nicotinic and muscarinic acetylcholine receptor activity, and contains a potent GABA-transaminase inhibitor, makes for a nice soothing anxiolytic/gently sedating drink that tastes great...like citrus without the acid, very lemony but with a taste all of its own.

I figure I'll collect enough to make some oil from it too, reflux in water with condenser attatched to flask should allow the oil to separate, and be distilled off, no?

Other option is a solvent extraction. A simple reflux in MeOH and distilling off the methanol is attractive, but for the toxicity of MeOH, residual methanol in the oil would be damn dangerous to the user.

So...what do you guys suggest? on hand are methanol (and lots of it, 15-20 liters or so), ethyl acetate, acetone, THF, dichlor, and toluene.  Chloroform could also be made via the haloform rxn, although I don't have very much acetone on hand at the moment, I'm running low. Or distillation a better idea? the intent is to pull the essential oil out of the plant material, and also, extract the things that aren't typically (to my best knowledge) in the essential oil, such as the GABA-transaminase inhibitor rosmarinic acid, and the other strongly active compounds in there.

Think I will do the same with some catnip, just for fun and practise. Essential oil of catnip sounds really nice, never, ever, ever seen it sold anywhere, but there is no reason whatsoever not to do it, or that it couldn't be done in the exact same manner as say, lavender oil is prepared, or rose otto.

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salat

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Re: Essential oils, extracting from plants...solvent choices questions etc.
« Reply #1 on: June 20, 2011, 11:24:55 PM »
This is right up my alley.  I don't have a specific answer right now, because I haven't worked with that plant before.  What I do have is some time tested methods for coming up with extraction methods.

First go to Dr. Duke's Phytochemical Database and get a list of what's in the plant and in what parts of the plant.  This one doesn't have as much specificity as I like - he doesn't always say how much of something is in the plant.  This one does seem to have a lot of catechins and right off hand I recall those can be heat sensitive critters.  In fact green tea is best made without excessive heat.  That is usually the first thing I like to know  -how heat sensitive are the components and which components are most active.

I usually browse the journals for the plant - even if I can't get the whole article, I look at the abstract which will usually say something like "ethanolic extract" does x,y, and z effects.  Also look at patents, if they seem to be doing lots of things like CO2 extractions that might tell you that important parts are heat sensitive.  

You don't see essential oil of those things because it takes tons of them to produce a decent quantity.

You may be better off drying the plant and making tea from it, or freezing it.  I do methanolic extracts of stuff all the time and I think someone on here actually told me all I needed to do was heat it well above 68 till all the Alcohol evaporated off.  Doesn't always work though.  Haven't been able to separate brahmi from alcohol.  Sometimes I add glycerin before evaporating off the solvent so the chemicals have something to dissolve in.  Sometimes I use vacuum to keep from excessively heating stuff.

Salat
« Last Edit: June 20, 2011, 11:27:00 PM by salat »
Salat

heisenberg

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Re: Essential oils, extracting from plants...solvent choices questions etc.
« Reply #2 on: June 20, 2011, 11:41:47 PM »
Have you considered steam distillation? You could make a still in a steel trash can, and the condenser from pvc pipe and copper refrigeration tubing. The plant material would hang in a perforated metal bucket inside the trash can. You could either heat it with a propane burner, or perhaps a wood fire.
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Tsathoggua

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Re: Essential oils, extracting from plants...solvent choices questions etc.
« Reply #3 on: June 20, 2011, 11:50:53 PM »
Yes, I am well aware that it may take a lot of plant material to produce a decent quantity of an essential oil. But damned if I'm not going to try. I went and picked a decent load of lemon balm earlier actually.

Going to try distilling it from water or perhaps MeOH., no harm in experimenting, I can always get more.

As for brahmi...watch it there salat, I seem to recall reading that that plant bioconcentrates lead to quite a substantial degree. I.e absorbs lead from the environment in which it grows and stores it, just as does Amanita muscaria with vanadium (although I have no idea if its done like fly agaric does it, by creating a really funky chelating complex that acts as a selective ligand for binding vanadium.)

Catnip essential oil appeals to me for some reason, no idea why, but it just does.

Green tea,...not a huge fan, I will drink it, but its not my favourite. I like white tea personally, or failing that, really strong, dark black tea.
Nomen mihi Legio est, quia multi sumus

I'm hyperbolic, hypergolic, viral, chiral. So motherfucking twisted my laevo is on the right side.

salat

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Re: Essential oils, extracting from plants...solvent choices questions etc.
« Reply #4 on: June 20, 2011, 11:51:43 PM »
Did a bit of digging.  This one you may want to save for it's flavor but here are some papers.
Salat
Salat

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Re: Essential oils, extracting from plants...solvent choices questions etc.
« Reply #5 on: June 21, 2011, 12:32:07 AM »
done my share of steam distillations..
when a hydrosol forms, put it in a sep funnel, and add dcm.
separate the dcm layer, evap, and you'll have the essential oil. 
"Experiments are the only means of knowledge at our disposal. The rest is poetry, imagination." - Max Planck

Sedit

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Re: Essential oils, extracting from plants...solvent choices questions etc.
« Reply #6 on: June 22, 2011, 10:57:43 PM »
Ani is right on the money, Steam distill the oils and extract with DCM. Distill or evaporate this slowly over a warm water bath to recover your oils.
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