I have started working on how to make the CBD isolation and purification process more efficient. My plan to do this is by optimizing the solvent
system employed for the crystallization, and winterization steps. I have spent time looking online but I have been unable to find very many references
for exact solubilities of CBD in different solvents, and almost nothing on the solubility in solvents with respect to temperature. The most common
solvents for recrystallization are Pentane and Heptane, while for Winterization Methanol and Ethanol are commonly used.
Does anyone have any data on this that they would be willing to contribute, or at least point me in the right direction?
If I am unable to find reliable values, I will likely carry out the solubility studies on my own, and hope to report the results here.XeonTheMGPony - 29-9-2021 at 17:02
I been looking into bulk extraction via chloroform, then a dewaxing step that's about where I stopped investing time.violet sin - 29-9-2021 at 21:41
CBD is a naturally occurring cannabinoid and, as such expected to show different stability rates in both natural and synthetic mediums. External
factors like light and temperature are also expected to affect the rate of stability of CBD on prolonged storage. Currently, only a few research
information is available on the stability of CBD as a result of its strict use regulations. One of the most prominent papers examining the stability
of CBD and its preparations on storage was published by the Journal of Pharmacy of Pharmacology.
As reported, cannabinoids respond significantly to light sources and common industrial solvents. CBD is significantly less stable in Chloroform, even
in the dark. Using chloroform of a spectrograde quality, the investigators reported rapid decomposition of CBD in both artificial and natural light.
Ethanolic extract of this compound was found to be relatively stable in the dark with a fair rate of decomposition in the light. Temperature studies
also revealed that at a temperature below 20˚, decomposition was not marked in CBD samples; however, at 37 and 50˚, significant loss of compound was
recorded. Result documentation also suggested that the rate of decomposition on exposure to oxygen is minimal and can also depend on the purity of the
compound
...
CBD samples are mostly delivered as a solution in methanol. For specific use in other solvents, the methanol can be evaporated under a gentle stream
of nitrogen. Different research inquiries have examined the solubility of CBD in ethanol, methanol, DMSO, and dimethylformamide. The solubility of CBD
in these solvents was suggested to be approximately 35, 30, 60, and 50mg/ml, respectively. ... XeonTheMGPony - 9-10-2021 at 07:15
I been looking into bulk extraction via chloroform, then a dewaxing step that's about where I stopped investing time.
Recent research has added Heptane / Pentane as excellent candidates for the first stage extraction, Chloroform is right there with them still as well
So purifying Heptane atm.
Final stage still seems absolute ethanol is holding its current place.
My selection criteria is a medium range bp, as vacuum is easy to reduce it, as I want it to be easy to handle, be readily recoverable, why I did not
opt for Hexane or Butane.
[Edited on 9-10-2021 by XeonTheMGPony]violet sin - 9-10-2021 at 11:35
Note the light fastness of CBD in chloroform and ethanol, included in my quote above, from the source linked above. That part was intentionally
included after your statement about previous use of chloroform for the extractions. Prob better all around to make it snappy, cool and sin luce, when
using that extraction method.
My selection criteria is a medium range bp, as vacuum is easy to reduce it, as I want it to be easy to handle, be readily recoverable, why I did not
opt for Hexane or Butane.
[Edited on 9-10-2021 by XeonTheMGPony]
Just curious, why is Hexane out, but Pentane is OK? S.C. Wack - 9-10-2021 at 14:42
You realize of course that the plant does not make neutral cannabinoids...they have to be decarboxylated if you want to talk about CBD...chloroform is
widely used in the analytical chemistry of cannabinoids, and extraction when it was a more common solvent...it's unlikely to present any more of a
problem than anything else, if washed free of acidic cpds...the high volatility means it would spend less time in the light (in glassware) while being
evaporated and at a lower temperature...
I believe the most relevant solubility data would be "miscible". CBD(A) is readily crystallized from something, and this data has been hidden for the
past 120 years, but someone here knows? And that's why CBD for sale is universally called "CBD oil"? (Yes I'm aware it can be crystallized...would
people even buy it in crystalline form, now?)
[Edited on 9-10-2021 by S.C. Wack]walruslover69 - 11-10-2021 at 11:34
I have come across most of these sources regarding the solubility. I think I will end up conducting my own experiments. I hope to have a graph of
solubility of CBD in pentane, hexane, heptane, ethanol and methanol with respect to temperature ranging from -10C to their boiling points. I am
familiar with the processes of recrystallization and winterization. My goal is to find a optimized procedure. Hopefully I will be able to post the
results here within the next month.
There is so much junk science surrounding cannabinoids, for example just common things like boiling points can be hard to track down. Just from a
google search there are a lot of non literature sources citing boiling points for THC as 155C, 157C, 184C. These values are clearly boiling points
under some vacuum as the true literature value is 425C, but none of them cite the pressure along with the boiling points. It's very frustrating and
makes me question the data from many of these websites.
I'm not aware of CBD being prescribed as a chemo agent, however CBD and THC are commonly used along side chemo drugs to reduce nausea. I'm sure in
very high doses it has the opposite effect.
