Does anyone have a reference they can cite for the conversion rate from CBGa to CBG. I have heard that it is much lower than the .877 factor used for THCa to THC. Does anyone here have personal experience ?
TIA- Mike
316.485/360.5*100=87.8%
Mol weight cbg/mol weight cbga * 100% =
I don’t see why it’d be any different.
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That was my thinking but I wanted to make sure that I wasn’t missing something.
A carboxyl group is a carboxyl group!
This paper: Decarboxylation Study of Acidic Cannabinoids: A Novel Approach Using Ultra-High-Performance Supercritical Fluid Chromatography/Photodiode Array-Mass Spectrometry - PMC. Says the CBGA converted much slower than THC/CBD and the seemed to degrade as the sum of CBGA+CBG dropped unlike THC/CBD. Good paper for general decarb knowledge!
Conversion rate of CBGA at 110C:
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I think they got some catalyst in their extracts and have isomerized both cbd and cbg. You normally dont observe any loss when peoceeding on a “clean” extract.
I was a bit surprised to see a net loss with both CBD and CBG, but none with THC, especially considering they are using a vac oven devoid of oxygen. But I can believe it I guess since they are somewhat different from THC structurally. Have you experienced differently when decarbing CBG?
Dont exactly see how a catalyst would get in their extract during decarb though seeing as they did not use a catalyst anywhere else in their methods.
Oxygen is not necessary for such reactions.
These are accelerated by heat, in particular if catalyst are present (acids, activated carbon, clays…).
I don’t think they that they were aware of the global composition of their extracts.
I believe that the catalyst was already there. The THC extract was somehow cleaner.
Those decarb results are all from the same extract. As in the THC, CBD, and CBG decarb results are all quantified from the exact same reaction. So there is no way a catalyst was in a separate CBG or CBD reaction. They also verified the net loss of CBD happens outside of matrix by converting a pure CBDA standard, there was slightly less loss in the pure standard.
Now it may be possible they were evaporating some CBD or CBG (or intermediate) while under vacuum, that was not evaping with THC. They really should have done it in an evacuated N2 or argon environment.
But my personal hypothesis is that CBD and CBG results may have been somehow effected by their concentrations being vastly lower than THC in the extract, as this was a marijuana extract. Maybe the reaction equilibrium was effected by their low levels, maybe the authors quantitation method was effected leading to a perceived loss when none actually happened, donno. The paper is free and its a decent read, id skip the “kinetic analysis” portion of the discussion though… its some armchair chemist’s pet chapter.
And oxygen may not be necessary for decarboxylation, but it is useful for oxidation and other reactions that would generate products other than the neutral forms right? And they are only measuring the acid and neutral forms, so such biproducts would result in a net loss. But those conditions (oxygen) were not there, and evidently any catalyst present would have also effected THC since it was all in the same extract.
What have you experienced when decarbing CBGA? I am genuinely curious because I will be decarbing a batch of CBG material soon. Do you notice it needs a higher temperature and longer time?
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My bad. At first glimpse, I did not look the paper into details…
I just read “eytractS” and though they had different range of THC, CBG, and CBD dominant extracts… in facts it looks like they used a series of extracts from the same flowers with a ratio THC:CBD of 1:1, with low CBG.
At some point they write: “It might also be an indication of com-pound evaporation under vacuum condition or uniden-tified products produced at the higher temperature.”
The former seems highly unlikely… but the later. 
They dont provide much details, but they also look at delta 8 THC and other cannabinoids. If isomerization would happen, they should see something regarding delta 8 and unknown intermediates or by-products.
Indeed, they checked with pure CBDA, but that is their own standard as well. Could be contaminated (eg with AC, the same way)… One must emphasize that they are looking at very tiny amoubts of samples. Without such details, one can still only speculate…
The most likely explanation is that their calibration for CBGA, and CBDA in house standards is wrong (should have been crossed check with a GC).
Otherwise yes, oxygen is necessary for oxidation. But isomerization reaction do not necessary imply oxidation. CBD to THC can be achieved in inert atmopshere for instance.
And yes, THC should also be affected in the same pot. They only not a slight decrease. But since it is an intermediate product of CBD degradation as well, one could imagine that they were in the perfect condition to keep it at constant level… but it is even more speculative then. As said above, I’d rather think there calibration for acids may not be right.
Regarding your CBG question. I did not look that into much details so far, but you can use the same conditions as you use for CBD.
Decarboxylation Study of Acidic Cannabinoids:
A Novel Approach Using Ultra-High-Performance
Supercritical Fluid Chromatography/Photodiode
Array-Mass Spectrometry
56% of yield not for stoichiometry but for side reactions. Maybe it’s better to decarb on the flower. I’m going to do some testing and come back to you
Regards,