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Isolation of THCA

HG23

HG23

Member
I have been giving this some thought lately.

From what I have read and seen on IG, the CBD (not CBDa) molecule will crystallize quite easily (lattice energy?) if it's concentrated enough. It seems like people are extracting and distilling CBD cultivars to obtain a saturated solution and then placing it under different conditions to come up with the different crystal formations. You can find several time lapse videos of this happening. People have also started to show blocks of large quartz-looking crystalline CBD.

I think the lattice energy, or some other property of the THC (not THCa) molecule must be such that it doesn't want to crystallize in the same way, but THCa seems to.

It seems the issue is easily coming up with a super saturated solution of THCa. The heat required for distillation causes decarb. Using Pangea's slow evap method seems to work pretty good but you still have all of the "contaminates" that are in the extract diluting the solution. With the volume Guild seems to be pumping out, I'm thinking they've got something else going on.

The separation method that pops out to my head is column chromatography, I know it has been mentioned here a few times before. Is anyone on the board who isn't too cool to talk about it using this technique to separate extracts? I've thought about trying to setup a vacuum assisted chromatography column to separate the raw extract and come up with high purity THCa fractions to use for crystallization. When you look at some of Guild's photos you can find some that look like powder, some that look like small stand alone crystals and some that even look like they're chunks broken off of something larger.

But I'm also pursuing a distillation apparatus.

Crystalline products are cute, and some people may need the THCa for medical reasons. But if you are just going to be dabbing for pleasure or medical reasons what is the real difference between starting with THCa or THC distillate? It sure would be cool to make crystalline THCa, but as distillates continue to hit the market and the price goes down I think demand for the more expensive crystalline will drop. What do you think?
 
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weedaholic721

Member
Chromatography is definatly the way to go to purify extracts at a large scale, IMO. There are automated systems with prefilled columns that could do the job while you sit back and watch.

Multiple companies have brought THCA to the market and most seem to using the slow evaporative crystallization that Pangea posted using various solvents. I do not think anyone is using A/B extraction commercially.

Horatio uses a column to purify his THCA, he doesn't appear to grow large crystals but makes a fine powder. This is probably useful to avoid inclusions in crystals that could trap solvent.

THCA has also been isolated in fractions produced during CO2 extraction, but that always seems low yielding and a bit extreme to be economically viable.

The price companies like guild are charging I think are just due to not many companies making it. If it is ever mass produced, Im sure the price would drop substantially. Most high quality BHO is mostly THCa , so I can nott see it costing significantly more.
 
O

Old Gold

Active member
I find it extremely strange that nobody would be utilizing acid-base extraction for larger scale productions of THCa. As HG23 mentioned, the issue is sometimes efficiently attaining a super-saturated solution to form crystal structures from. Acid-base extraction seems like the best way (besides running a chromatography column) to achieve specifically that. THCa-salt is pretty well-soluble in water, and it shouldn't be too difficult to pinpoint a minimal amount of alkaline water to precipitate it from.
And starting with something fully dewaxed already, I see lots of easy efficiency with it. I've had to put the project away for some time, sadly.

As far as the CBD crystal formations, I think some of the prettiest crystals come from methods like Pangea suggested for "washing" his THCa seeds. Starting with super-saturated distillate and using minimal amounts of solvent to wash off the impurities. However, as weedaholic721 notes, powder is probably most void of solvent and other impurities, and nice, slow recrystallization should still yield big ole xtals.

Has anyone tried crystallizing ∆9-THC in very cold conditions? Again, in a super-saturated (or less-than saturated?) solution, and perhaps cooled to the point of stability (without freezing the solvent used)
Surely it won't stay in form at room temperature, but I wonder if it is possible to form any crystal lattice from it. And what temperature that storage may need to be to keep it's form..
 
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thegreenman91

Member
Old Gold said:
I find it extremely strange that nobody would be utilizing acid-base extraction for larger scale productions of THCa. As HG23 mentioned, the issue is sometimes efficiently attaining a super-saturated solution to form crystal structures from. Acid-base extraction seems like the best way (besides running a chromatography column) to achieve specifically that. THCa-salt is pretty well-soluble in water, and it shouldn't be too difficult to pinpoint a minimal amount of alkaline water to precipitate it from.
And starting with something fully dewaxed already, I see lots of easy efficiency with it. I've had to put the project away for some time, sadly.

As far as the CBD crystal formations, I think some of the prettiest crystals come from methods like Pangea suggested for "washing" his THCa seeds. Starting with super-saturated distillate and using minimal amounts of solvent to wash off the impurities. However, as weedaholic721 notes, powder is probably most void of solvent and other impurities, and nice, slow recrystallization should still yield big ole xtals.

Has anyone tried crystallizing ∆9-THC in very cold conditions? Again, in a super-saturated solution, and perhaps cooled to the point of more than stability (without freezing the solvent used)
Surely it won't stay in form at room temperature, but I wonder if it is possible to form any crystal lattice from it. And what temperature that storage may need to be to keep it's form..
Click to expand...

AND also.... Shouldnt 99.997% THC-A (guildextracts) decarboxilate at room temperature?
 
O

Old Gold

Active member
Good point. It should, but at what rate exactly?
The few recorded graphs I've seen regarding this show that at low temperatures, decarboxylation does peak to a pretty decent extent, and I have not seen temperatures as low as even 50-60°C recorded.
 
D

DrNibs

New member
weedaholic721 said:
Chromatography is definatly the way to go to purify extracts at a large scale, IMO. There are automated systems with prefilled columns that could do the job while you sit back and watch.

Multiple companies have brought THCA to the market and most seem to using the slow evaporative crystallization that Pangea posted using various solvents. I do not think anyone is using A/B extraction commercially.

Horatio uses a column to purify his THCA, he doesn't appear to grow large crystals but makes a fine powder. This is probably useful to avoid inclusions in crystals that could trap solvent.

THCA has also been isolated in fractions produced during CO2 extraction, but that always seems low yielding and a bit extreme to be economically viable.

The price companies like guild are charging I think are just due to not many companies making it. If it is ever mass produced, Im sure the price would drop substantially. Most high quality BHO is mostly THCa , so I can nott see it costing significantly more.
Click to expand...

couple people I know have switched from the traditional SPD to a motified Pope Unit WFE Wiped Film Evaporation or distillation, doesn't use any solvent just that coloum that has blades inside it and it only uses heat and preasure to make its fractions, herd there doubling there production and with better results, however expect to spend a pretty penny $$:moon:
 
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weedaholic721

Member
@Dr. Nibs, This thread is referring to THCA, which decarbs with heat, so distillation is out.

I think your referenceing delta9THC , which yes wiped film evaporators are the direction large producers are going. These extracts rarely top 95%,however. To get to higher purities, chromatography would still be a very viable route, again referencing d9THC here.

For THCA, what you quoted above is correct. Check out more in this thread, and the thread Preparation of THCA
 
G.O. Joe

G.O. Joe

Well-known member
Veteran
Pangea said:
I was able to ramp it up and get a melt point, only took some pics at the 115c mark to show they were still stable and solid.

They melted at 135c, almost double the cited 70c, wtf.

Slow bubbling started at 140c, it solidified quickly when cooled, and seems to powder the same as pre melt.
Click to expand...

G.O. Joe said:
THCA will not melt that high. It could be one a lot of odd things - anything but THCA.
Click to expand...

Hi Pangea and everyone, that was bullshit - sorry, sorry, sorry.

Has anyone analyzed anyone's big pure THCA crystals to determine whether they are the A or in fact the B acid or a mixture? On TLC...acid B is considerably more polar - see next.

THCA-B has been presented as a minor component present in some strains and absent in others but you know what? Always read up on the first time something was isolated or synthesized in pure form. CBGA, THCA-B, and CBDA are separated by column chromatography:
http://dx.doi.org/10.1016/S0040-4039(01)88158-2

The acid B (III) was found in hashish soles which contain very little or none of the acid I. It is conceivable that the differences in THC acid content may be due to biochemical variation and may have chemotaxonomic importance.

Maybe that was because the THCA-A had already decarboxylated? Or do certain strains make only or mostly THCA-B? If it's a rare quality it could be valuable? Do the different acids have different receptor binding or other interesting properties? How about the melting point?

184-185. C.

This B acid was looked at with X-ray crystallography in 1975. A likely factor in the differences between the crystallization of A and B is that the A acid H-bonds with itself, between the OH and COOH that are next to each other - and in the B acid the same bond can only be with another molecule. The same author published CBD and CBN in the same journal in '77.
http://dx.doi.org/10.3891/acta.chem.scand.29b-0379

It was asked if THCA could come from THC instead of the other way around. FUCK NO!!! Until it was first published in 1969. CBDA and CBGA from CBD and CBG too. The MMC in DMF for this reaction has been both purchased and homemade.
http://dx.doi.org/10.1039/C29690000343

The yields are good for CBDA and less for CBGA. THC is mostly recovered unreacted so this is not as good for THCA. The product is supposed to be pure THCA-A if done carefully in one way and mostly B in a more wasteful way.
http://dx.doi.org/10.1016/j.forsciint.2012.07.019

CBG and CBGA are best made by growing CBG strains, but the synthesis is not hard for an organic chemist who wants to make them, and has the olivetol (which can be made from CBD).
http://dx.doi.org/10.1074/jbc.271.29.17411
 
B

Blassphemor

New member
weedaholic721 said:
Ok so I have an idea for a extraction technique that could theoretically yield fairly pure THCa and by extension delta9-THC.

The basis of this procedure relies on the fact that THCa is carboxylic acid. Carboxylic acids generally have a low pka, meaning a weak acid will remove the hydrogen for the carboxylic acid forming an ion that is water soluable. As this is the case a simple 5% Sodium bicarbonate solution should do the job. This technique is very similar to what is used in first semester Organic Chemistry. Due to the face that THCa is what is being isolated freshly cut and dried cannabis would give the highest yields.

Theoretical Procedure:

First the cannabis is extracted normally using solvent of your choice using minimal to no heat during purge to give a perfectly smokable extract. However, as we all know there are still some nonpolar impurities left. The extract is dissolved in a immiscible solvent, like hexane or methylene chloride and added to a separatory funnel. Then you added the 5% Sodium bicarbonate solution to the funnel and mix well, then allow layers to separate. The aqueous layer is separated into flask and organic layer is extracted again with Sodium bicarb solution. Aqueous extracts are combined, organic layer can be saved for followup or discarded.

The combined aqueous solution should now contain the deprotonated THCa. With the addition on an acid, in this case HCl, the THCa will be protonated and will precipitate out of the solution. Any remaining sodium bicarbonate leftover will react with hcl to give NaCl , H20, and CO2 gas. The precipitate can filtered and washed will cold h20 to remove any remain acid plus the NaCl formed.

Product should contain mostly THC acid and can be easily converted to delta9 using heat of a joint, bong or your stove.

The organic layer if saved could theoretically be fractionally distilled to isolate terpenes left over that could be added to THCa at a chosen ratio to give varying effects.

Discussion:

Ok, so it seems like it should work but I have not been able to try as it would require fresh plant material I do not have access too but should be easy to tell if it will work. A small chunk of BHO could be added to water and then add sodium bicarb, if the BHO dissolves then procedure should work.

I just do not have the experience to know if I am missing something major that would cause this procedure not to work. The amount of acid added would have to be determined stoichiometrically (or monitor progression with litmus) as THCa is apparently sensitive to stronger acids but other then that I can not determine why it couldn't be done which is where I leave it to the experts of this site lol
Click to expand...



Hey there,

While as a fellow chemist, I definitely like your simplistic approach to this isolation of the acid variant, you mentioned that low pka's mean weak acid. This is actually backwards. Not that I'm criticizing you at all. But if what you typed is what you meant, how will this affect your thinking on the matter? I'm currently trying to isolate out all acid variants, for obvious reasons mind you. (Tones of cool things can be done with the acid variants regardless of what the stoner community thinks, and if you aren't a scientist don't bother trying to argue this.) Regardless, I want to try out your method in my lab and see what comes out of it. Have you had any success with this method as of yet? Cheers!
 
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Blassphemor

New member
Wait, after re reading your post, what you wrote makes sense with the pka business. I'm definitely gonna have to try this out. I'll report back and let you know what I find!
 
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