Because selectively in this case is d8 vs d9. Isomerizarion reactions always have a level of selectively based on conditions and thermodynamics. You can’t get around that.
That is very true. Unfortunately, by not quantifying the level of unknowns that your chosen catalyst produces you are missing a big part of the picture.
As an example, almost all of the aluminum based organometallic catalysts convert CBD selectively to d9. None of these in this class produce much, if any, d8. Only one that I’ve worked with consistently produces d9 above 90% without byproduct formation. The way that you’re testing for catalyst specificity I suspect all of the organoaluminum catalysts would look equally selective in product formation.
Imo quantifying your percentage of unknowns is invaluable to the earliest stages of catalyst selection and scaling.
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Do you intend to produce d9 or d8 ?
Using acidified clay, d9 is in fact an intermediate (between CBD and d8/d10).
When you wrote “d8 d9 90 10”, we read that as 90% and 10%. But perhaps we were wrong and you were dealing with d8:d9 ratio. Because that’s the only valid information you can read from this kind of data (provided that values are proportional…). This, the absence of CBD, plus de presence of quite some CBN here.
In such reaction, CBD is consumed rapidly. The following steps are a bit slower.
It is more likely that samples was about 50-60% d8, and 5-6% d9.
If you want to get more solid info about the selectivity of your catalyst, you need at least to get the info on d10 as well (normally the other major component besides d8).
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I disagree that d10 is a major cannabinoid produced in this process. isomerization is driven by a proton transfer around the carbocation intermediate. For a d10 isomer to be produced as a major product one would have to create a more stable carbocation on a secondary carbon versus the tertiary carbon in the d89 position.
I will admit though the analytical references for the d10 isomer of THC is limited at best. I have not been able to find a reference d10 FTIR spectrum to support our spectroscopic analysis. However, on that now the FTIR trace suggests it’s predominantly d8
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Wait… maybe I’m wrong and it is not d10. In fact I did not identify it myself yet. Still waiting for a standard. But I m in deal to get the standard(s) (will ask for the two isomers).
Yes, this results in a d8 dominant product. There is normally another major one here, notably lower than d8, but still higher than d9. As d9 gets consumed, that one and d8 take over. At first, I believed it was 8-OH-iso-HHC. But reading thing here, I started to believe it is d10. And now I say it must be d10. 
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The problem I have and (maybe you as well) is I do not have access to the equipment needed for these analyses at this time. If you have access to an analytical HPLC with mass spectra for each peak in the chromatogram I would be happy to work together in this identification. That’s the frustrating part of these cannabinoid labs is they are all absolute cannabinoid measure-ers. When I ask for a chromatogram and representative mass spectra it’s like I just asked these guys which way to Narnia. They have no clue what they’re doing. “We just plug in your sample and it spits out this coo-pon” lol. To make matters worse the people doing similar conversions who are not a chemist are in all likelihood making a combination products that they cannot predict from their (low or non-existent) training and education. If you only put XYZ in, then it should not be too hard to differentiate what is coming out imo
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So far I use only GC-FID. Hence the need for CRMs.
Of course this those not preclude from identification, but with some indepth knowlwegde on sample origin, it can be cornered down easily…
A mass specs would not be of much help in this specific case I believe.
If you read the literature on this topic, with people using fancy hypenated MS-MS-MS things, they deal with something which have the same mass as d9, but for which they don have the CRM… as it is not d8, not exo, a likely candidate is d10.
@YumYam, we can run a sample through the mass spec. We haven’t seen much d10 in the d8 samples. Definitely see more exo, but still not very much. Adding more standards as we get them. Let us know if you all find any you’re interested in or might be new.
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Have you seen the chiral stationary phase paper released by waters? Seperation of THC isomers.pdf (789.8 KB)
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Yes, and we’d like to develop a chiral method sooner than later. The convergence chromatography is interesting. I know Chris at ProVerde uses that technology.
If there is demand for it I’ll get my team to start development with the chiral column next month.
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I’d send samples for chiral column analyses
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This is a great idea. I’ve done a lot if work on a Waters upc2. Happy to share maintenance and use techniques, they can be temperamental. I’m interested in seeing this develop.
Actually, I have a bunch of old chiral columns sitting around that I’ll never use. They’d be research only since they were last use for Toxicology. DM me if you’re interested, free of course.
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We’d definitely be in touch (and the team would be ecstatic) if we had a Waters UPC2 in house. Any Waters reps on here?
@YumYam I’ll get in touch when we’re ready.
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You can run the chiral on your regular HPLC too, although, I’m not sure how that would turn out
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Yes, thats the route we’d start on. DMing you.
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