SWilkin676
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Temperature of Decomposition for Phytochemicals
Does anyone know of a good reference for temperature of decomposition of phytochemicals?
Standard fare such as our Merck and even extensive internet searches are failing to find some of the ones I'm interested in.
Patent databases seem to be the best source I've found for determining how much heat I should use when doing herbal extractions.
Suzee
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JohnWW
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It would depend on the chemistry of exactly which natural products you are trying to extract from plant matter, presumably for use as herbal remedies.
Steam distillation often employs a still in the form of an autoclave, with the plant material immersed in water, with some degrees of superheating
above the normal boiling-point of water, with the temperature able to be inferred from the pressure using a steam table. The mixed vapors, of steam
and volatile organic compounds e.g. terpenoids, are passed through a pressure-relief valve and then through a condenser, being generally collected in
a separating funnel on condensation.
However, if even normal boiling-point of 100ºC is too high not to result in decomposition of a desired volatile compound, you would, instead, have
to look at solvent-extraction (with something like diethyl ether, isopropanol, acetone, petroleum-ether, kerosene, benzene, toluene, depending on the
chemical nature of the desired compounds, although this entails a distinct fire hazard), or (usually for vegetable lipid oils) cold-pressing using a
powerful mechanical press.
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Barium
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Steam distillation can of course be done at lower pressures than atmospheric and, hence, at lower temperatures.
For example, water boils at 40 deg C at 70 mbar. That's pretty gentle if you ask me.
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Panache
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Quote: Originally posted by Barium  | Steam distillation can of course be done at lower pressures than atmospheric and, hence, at lower temperatures.
For example, water boils at 40 deg C at 70 mbar. That's pretty gentle if you ask me. |
you tend to get poor extractions at lower temperatures, something that has always bewildered me, it would seem to intuit that as the solubility (in
water) and vapour pressure of the organic dropped it should steam distill more effectively. i fall asleep every time i try to read about it in Aitken.
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SWilkin676
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Right, I know a few different ways to extract things and am learning more every day. But what I'm trying to find is exactly what the temperature of
decomposition is before I decide on an extraction method, that way I don't go to a lot of trouble trying to keep things low temp when I don't need to.
I'm not much of a chemist, but I'm usually pretty good with research (I'm computers by trade). We've got TWO Mercks in the house but they both seem a
little weak on phytochemicals (probably cause they weren't as "hot" as they are now).
For example, what is the temperature of decomposition of kavalactones? One Kava grower said it went bad at 140 F but none of the chemical data showed
a temperature that low, so we couldn't figure out what "active ingredient" he was referring to.
I've seen several databases of chemicals but they don't seem to have it for the chemicals I'm working with either - at least so far.
Simple works sometimes like just googling it. Just thought someone might now a giant chemical book in the sky...
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