Carboxylation - Adding the "a" back to THC

I assume that’s a typo, and you’re not trying to suggest making THC-acetate in order to crystallize out of say water as an isolation method :wink:

my reading has not yielded a method for crystallizing THC. I have to admit I haven’t explicitly gone looking for it.


Thc distillate is an isolated cannabinoid. Most thc isolate you see is in fact thca cryatals. I don’t see where you’d add the carboxylic group to? Or the need to add it?
The purpose of adding the group to a distillate product is to grow bulk lots of more desirable crystals . These have a much higher market value than the distillate, adding the carboxylic group also increases the weight of the product. One gram of distillate will produce more than one gram of thca isolate.


That part

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right…diamonds are precious. even sans sauce.

although making diamonds and decarbing seems like less work than distillation at some level. remind me again why we’re here?

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Thc distillate is somewhat pure but i have never seen “thc distillate” as a 99+ thc mix usually there are several other compounds in the mix as well as 80% thc.

You have the propensity to carboxylate several other compounds and cannabinoids in the distillate mix.

The overall purpose of this process is to increase the amount of crystals able to be grown from decarbed thc distillate correct?

Can you be more specific on your last statement on yields?

In my experience after the carboxyl group leaves thc has no method of attaching itself to one another. So adding the group is the only way you could actually achieve crystalline growth.
Your yield question: the carboxyl group has mass, adding it back would increase the mass of each molecule. Try this as an experement, take some thca isolate record the weight, decarbed it and record the weight. Note the difference.


Yes of course when decarboxylating the CO2 will not attach to other molecules most likely, however when adding CO2 back onto a mix of molecules contained in thc distillate you run a risk of carboxylating other molecules in that mix.

Right right this would add an additional 44 g/mol onto the thc molecule.

Have people been able to crystallize thc when it is decarboxylated or is that the problem we are trying to solve? Because if we can isolate thc in its decarboxylated form we should do that then REcarboxylate to avoid the risk of side products/reactions.

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I beleive @Soxhlet meant that once decarbed, THC looses it’s attraction to other THC molecules. aka “it won’t crsytallize”.

yeah, I think so. I have not explicitly scoured the interwebs, but I have not stumbled across it, and that does seem to be the consensus of the opinions I’ve read.

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I see! That would make more sense.

If we cannot crystallize thc in its decarboxylated form I would suggest trying to attach a sugar onto the free alcohol with a 1:1 molar ratio of sugar to thc. Purify this reaction. Crystallize. Remove the sugar then REcarboxylate if necessary!

Or instead of sugars, could use a sulfate/phosphate group, may be even easier to attach and remove!


What sugar structure would you suggest? I have a variety of cyclodextrins, dextrose, sucrose, fructose.

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I would start with Dextrose, mannose. Simple 6 member ring sugars. I may have to look into some carbohydrate literature if you are really serious about trying this im super down. I would steer you away from fructose because it is a non-reducing sugar.

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these guys are using biology rather than chemistry, but the end point is presumably similar…

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This topic is all over the place. You’re all correct, except for the errant typo here or there. The steric hindrance of the original position of the carboxylic acid nowithstanding, there isn’t much we can do to make a carboxylic moiety just stick to a phenolic ring wherever we want it to.


We are not trying to attach and phenols or aromatics to the carboxylic acid…

I think you may have digested our plans differently than what we intended to do.

I guess that we are just looking at it from different angles. A phenol (benzene ring with an OH group on it) is precisely what the middle of the THC molecule is, which is where people want to “reattach” the carboxylic acid for some unknown reason. Does that make sense?


Just a quick summary…

THCa can be crystallized, THC without the acid (carboxyl) group can not be AFAWK

The acid group adds mass, making it favorable economically. Also, if we were able to crystallize distilled THC we could possibly achieve greater purity than if we had only distilled. (I can see this being beneficial for already decarbed material)

The goal is then to reintroduce the carboxyl group, for which the following suggestions have been made:

-“Attach a sugar onto the free alcohol”

I have gone down long and deep wormholes on this topic, to little avail… But perhaps this will be a more helpful lead for someone other than I

Kolbe-Schmitt Reaction

Ive been informed this specific method will not work, but there is some promising literature down this line of thinking.

A side note, @DrJosh this is the second time I’ve seen you jump into a conversation to claim “I can do it, no problem” and then proceed to offer zero proof to back up your claim. This is far from helpful and slightly annoying. Pictures or it didn’t happen.


@Future. Thanks for the summary.

the sugar attached to the free alcohol was not a suggestion for attaching the carboxyl group. it was the reason @Photon_noir was chastising us for wandering.

It was suggested as a way of attracting cannabinoids (now cannabosides) to each other for the purpose of purification via crystallization. with THC-gluc crystallized (and thus isolated). one could perform the required REcarb step(s) on 99+% purity and be less likely to make junk.

the paper I linked uses enzymes to add the sugar(s). with the goal of increasing water solubility & thus bioavailability. my chemistry was a loooong time ago.

Edit: mind you, after being chastised for wandering, I went back and read the thread a 1/2 dozen times. It hangs together. just. With THC-acetate thrown in there as a red herring for 10100 to get a hold of.


What if one was to use a (de)carboxylase enzyme? @Shadownaught


As suggested in this paper?


one could certainly be evolved for the task in short order. the enzyme they used looks like it’s target is close enough structurally to use as a starting point.

you amplify the gene (PCR) under low fidelity conditions, and look for clones that decarb our favorite cannabinoids.

I’d wager an enzyme would be the most regio-specifc way to put the carboxyl back too. the best candidate from above might be a good starting point, under different reaction conditions, but screening through the first pool as well makes good sense.

If I could see a good way to make decarbing/REcarbing THC a life saving (and thus selectable) trait, it would be faster.

Edit: …and now we’re officially off topic. thread title is “Chemistry”!!


@cyclopath actually OP asked about carboxylation, so I edited the title to match and hopefully draw in more conversation