CBD Isolate residual solvent quality

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Dear forum,

I am sure that some of you have encountered this before - so any feedback would be greatly appreciated. On the photo below there are 3 different kinds of isolate:
A : being the most expensive, white powder, no smell
A- : a slighly less white with a strange smell to it.
C : the cheapest CBD Isolate I can find around.

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By now I am aware that it is the residual toluene that causes the colour to get dark. And this darkness stays through isomerisation.

I tried rotevaping (steam bath under vacuum) , microwaving, AC mixing, Mag Oxide refluxing - but the colour doesn’t seem to go away. What are other suggestions? The disti I get at the end is very dark couloured in bulk. I havent tried WFE yet, but there must be an easier step of removing residual solvent/colour form the melted CBD isolate…

Is there a way to make the A- look like A without having to recrystallise/ditill? cause in bulk its very inefficient. Any other colour remediation tips I would happily accept. Thanks.

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Residual solvent wont cause color like this

It can cause oxidation which is what youre seeing but I’ve never heard of toluene speeding up oxidation just alcohols

Ever tried melting your isolate under vacuum? Youll find itll help with the color

Magsil and silica can also help with color remediation

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Yes, have melted under vacuum - in a rotevap even. Still very dark. Even by dissolving it in any solvent - it still gets dark instantly.

Magsil I am having trouble to find - but silica gel (for column cromatography) I have plenty… But I am clueless how to use it for colour remediation? Vacuum from below? Vacuum from above? Solvent (ethanol) dilution to speed up the process? Because my biggest column is 400*50, and given the viscousity of distillate (even hot) - how long will running a 1kg of isolate would take?

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If youre going to do chromatography to remediate color you’d want to do it in a hydrocarbon and id do it after the reaction

What temperature are you getting to during your reaction?

What solvent are you using?

What reagent are you using?

Are you using an inert atmosphere?

Are you sparging the solvent before use?

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I did indeed got told that the solvent they used to recrystilise was ethanol/toluene mix. So it could be the ethanol that causes this? But shows like 98.9% pure on my HPLC. Although solvents is hard to see. I also tried shortpath distilling the CBD, and what I got out was a yellow pale liquid which made quite a fireshow when set on fiire…

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I would’t post my method as it is quite frowned upon on this forum.

But I would be very grateful if you could help me to remediate just the starting material which is CBD isolate. I tried nitrogen sparging the cbd in ethanol - not much colour change I got.

The only thing is i used a bit of alcohol to help get the cbd isolate into the rotevap flask. Could that be causing colour issues? But why doesn’t it do so with the A quality one?

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7

just recrystallize it and be done with it. Don’t avoid crystallization, embrace it - it’s your friend.

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To be completely honest, I am unsure how to do it big-scale.

I can do it on a petri dish scale (but still I am afraid as I would be loosing more product in the mother liquor in the process…)

What solvent you suggest using? Ethanol/heptane? Do they have to be AR grade?

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This kind of stuff blows my mind. This guys is doing the aluminum chloride method and leaving behind catalyst as he cant even distill his oil without it going to 8. You’re over here converting oil but cant even figure out bulk crystallization to fix your precursor.
How do we as a community allow these type of things? I feel more members should be willing to tell someone what they are doing is wrong and not morally correct.

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Isn’t that what this forum is for? Asking questions, sharing experiences? I haven’t sold/shared a single gram of d9 made the AlCl3 way prior to getting a WFE (which ineed d9 doesn’t survive, so I don’t do d9… But does that mean I am not allowed to ask questions? really? Is that going to make the world much better you think?

So please tell me now, what I am doing wrong by just posting a question on the forum? Be it from a moral or any other perspective?

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Use pentane or heptane for recrystalization.
Dissolve in warm (40c) and stirred 1:1 cbd:solvent, under reflux. Solubility is only 14 wt.% at room temperature, and drops below 1% at -20c. Do it 2-3 times and observe the solvent color fading at each step.

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Thank you man, will try this and post a photo report if I get a chance to :slight_smile:

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The concern is specific to level of understanding of the processes. The upstream and downstream requirements. The science behind the chemistry.

Sure the forum is for sharing information and for asking the questions.

Not knowing how to recrystallize CBD means you don’t know the upstream steps of the process that happened to the isolate before it arrived at your facility. You know that you don’t like the color. You know that you don’t like the smell.

What @Dr_Jebril says is a solid method.

The concerns many of us share here is that if someone did not already understand the fundamentals of recrystallization, enough to be able to ask the right question. Then what the fuck else do they not know?

Are they putting themselves and others working with in danger because they don’t understand the chemistry of the upstream, downstream, and active processes?

Are they putting consumers in danger because they don’t understand the impurities of their starting materials? The in-process materials? The finished products?

Is it moral of us as a group to tell you just enough so that you can continue forward - but without making sure that you know enough not to harm yourself or others?

I struggle with this all the time when I answer questions here. You are not the only one that asks questions that on the surface appears to a lack of understanding of the fundamentals of the work we are doing with our compounds. I am not the only person that answers those questions.

How to do chromatography large scale? Define “large”. Recrystallization is probably easier - on the starting material and it appears you are heading that way.

Chromatography side - as long as you have enough solvent and solvent recovery - you just push it. Having in-house analytics to know when you have “arrived” is good. Having a way to capture the fractions is good.

Would doing that - at all be efficient? I suppose it depends on your scale. But asking about different methods for handling chromatography also leads me to believe that you are not really sure on the fundamentals. And so then what - are you selecting the right media for your column? Are you selecting the right solvent? Are you dissolving in the right ratios? Are you collecting fractions separately enough to give you a solid end product?

Because I don’t know that you understand the fundamentals - I have to ask a lot of additional questions. Looks like others asked questions before me - but I don’t see you answering them. Is this because you haven’t had time or that you don’t know the answers to the questions?

So much is happening here. With a process that could genuinely cause you, others working with you, and consumers harm.

How is supporting you through this process not a moral issue? If by helping you insufficiently we end up causing harm to you, others working with you, and your consumers?

Its a question you should consider. At some point - people will be asking you these same kinds of questions. And you will be the one deciding if the moral risk is an appropriate risk to take.

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Tha is indeed the case. I mean, I have been enquiring/trying to guess the solvents the facility used to recrystilize the isolate in for quite a while now.

I wouldn’t be telling my full story here - but my first ever chemistry equipment purchased was an HPLC. So my interest in column chromatography merely arises from me being interested in the fundamental processes that happen inside my machine. And yes, I have tried

As it is an HPLC, and as there are no other chromatography machines for miles around me (GC with headspace would be nice) - I was trying for quite a while to guess the residual solvent used based on its physical properties. My HPLC was unable to give me an answer, till the very end I was thinking it was some isomer of xylene.

And I have not asked anything that google/chatGPT would be able to help me with. Neither I have asked what purification by recrystallization is. I was merely thinking that you guys have been at my stage years ago, and perhaps have a technique other than those books/google/AI can help me with. Or give me a new direction I could try.

Perhaps I would have been better asking “how to reduce loss to mother liquor during the process”, “what interesting solvent ratios I could try” or “why rotevaping at proper temperature/low enough vacuum doesn’t remove the residual toluene”.

The willingness to learn the upstream and downstream processes is exactly why I am here.

As if commercial conversion was my primary point of interest - I would just stick to what I have, without taking the extra effort to learn.

I have had yields above 90% on quite a few different reagents/solvents. But there were a dozen others which I attempted which gave me nothing but the satisfaction of trying them out, wondering why i have received different results to those published.

The toluene/ptsa at refluxing for 48hts alone I have tried at least 3 times at various conditions, and I am still wondering why the results I get are very far from those described in the papers.

But it is reading, testing, thinking, trying and testing again - this is how I learn.

I apologize to not answering @Kingofthekush420 questions. This is not because I ignored - but rather because I have bought an SOP from someone on this forum, and I am not sure how much would it be okay to disclose given how much effort he has put into the method.

  • the question I posted is about starting material and not about the reaction itself, specifically not to be having getting into the details of the method that doesn’t belong to me.

I have tried many different solvents and many different reagents (pretty much every single one described in patents and papers apart from those which I think I am not ready for yet, such as TIBAL from the original d9 or KotBu/KOtAm/Nah bases to try the d8-HCl-d9 route). Also haven’t tried any hydrogenation reactions.

So yes, “this guy” has been doing the AlCl3 reactions, as well as many-many others. Its not the result, its the process that matters to me. + I have access to analytics, so I don’t need to be poisoning/biotesting.

I test at least 4 times a run - but for some methods I tested every 10 minutes to see the dynamics of the reactions. If there were variables I found interesting (like solvent ratio/catalyst eq - I was running multiple reactions simultaneously. My max was conducting 5 reactions at once testing every 15 mins, thats 20 tests an hour :slight_smile:

But well, I must really be expressing my thoughts in the wrong place. @Dr_Jebril thank you, the colour indeed fades but still not quite to the “A” category

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@xdubr should just use heptane. If he’s new to doing chemical work just avoid pentane, too much can go wrong - not to mention, it boils at 36C so you won’t be able to achieve 40C

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That is the reason for reflux.
CBD solubility markedly increases at the boiling point.

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