What is/how to perform decarboxylation & isomerization?

[dope_roor]

I'm trying to figure out exactly how decarboxylation and isomerization of THC occurs and what methods can be employed to do so.

I have some some background organic chemistry knowledge and understand that decarboxylation of marijuana is the conversion of THCA into THC, THCA being psychoinactive whereas THC is. On a molecular level, it's the removal of a COOH group from the THC molecule, which can be done under conditions of high heat or presence of a strong base.

I've read that perhaps the process of curing buds is actually a slow decarboxylation process and thus the increasing of potency we generally observe.

Based on this, it's reasonable to assume that applying heat increases the potency of marijuana. And there's evidence of this in making cannabutter from schwag or whipping up BHO over heat or the heat pressing of kief into hash. some sort of increase in potency from the original product.

Is it not then also plausible that washing or soaking the bud in an alkaline (basic pH >7) should also cause decarboxylation? Perhaps a more thorough decarboxylation than whipping over heat? And, as long as the solution is polar, the THC should not be affected?

The implications of this are perhaps washing our buds in an alkaline solution before performing our preferred method of extraction could increase the end potency of the extract?


Onto isomerization, I understand that it is the rearrangement of the molecule structure. What causes THC to isomerize? I believe the cannabis alchemy articles and other info from the 70's use a strong acid to cause the isomerization. First of, is there any truth in this?Can other methods cause such isomerization?


Just trying to clear things up, it seems that some people confuse the two, and I'm thinking that these are two distinct processes that can occur/be performed to increase potency

 

[hades]

I can answer the decarboxylation question. I just recently got through reading a patent for extracting cannabinoids from cannabis using CO2 extraction, and the first step after drying, before they do anything else, is a decarboxylation step. They performed experiments to find the most efficient temp/time and found:

Therefore laboratory studies demonstrate the optimum conditions for the decarboxylation of: Chemovar producing primarily THC to minimise CBN formation, is 1 to 2 hours at 105° C. or 1 hour at 120° C.

This took into account that the heat used to convert the THCA to THC will also cause the THC already present in the sample to degrade into CBN, and they found the best temp/time under both considerations. They also say that as the size of the batch increases, the temp/time would also need to be increased, due to uneven heating of the material in the oven.

Now, it is true that over time THCA will convert to THC naturally. The curing process will actually increase potency, but it's real advantage comes from allowing the other plant products to break down like chlorophyll, etc..., that give the smoke a harsh taste. This is because most people decarboxylate the THCA when they smoke or cook it, with the heat from the fire/flame to light/cook it. This is not as efficient as cooking it in an oven at a known temperature for a known time for maximum conversion, but it does the job well enough that most people would never know the difference.

 

[reckon]

the way I understand it is:

1) DECARBOXYLATION: removing carbon dioxide from THC-A to convert it to (biologically active) THC,...this is done with heat, either buy burning, like in a pipe, joint, bong etc,..., or by heating in an oven, or in a lipid such as butter or oil (I hear coconut oil rocks), with the oven/butter methods intended for ingestion.

2) ISOMERIZATION: in the plant CBN degrades into THC-A, which dries, and loses carbon dioxide, then becomes THC (as above) and then further degrades into CBD (if I got it backwards someone will correct me, I'm rather medicated) if your plant has a LOT of CBN, you can "FAKE" the degradation by adding a strong acid (I used hydrochloric when I did it) in a reflux setup with a solvent, this adds a double bond on the benzene ring or something like that, and makes a molecule that is an isomer of THC (great explanation, huh?), so you end up with almost no CBN, because it's now converted into THC-isomer, which WILL get you baked, because your body cant tell the difference between it and THC,.........the trouble with this is most weed in the last 30 years has very little CBN even when picked early, so isomerization will work AWESOME if you have a field of kentucky ditch weed (wild hemp, considered a nuisance, grows all over the state), but not so great on your "crap I got mites, I have to harvest 25 days early" northern lights super dank,.......but it will increase the potency of the extracted oil, by the factor of how much CBN was available when you did the reflux/isomerization.

for the record, I never put the extracted "honey oil" back on the buds, I just mixed it with some dry sift to make what we called "putty", but is now referred to as jelly hash.

I hope that answered your question,.......you can read "marijuana chemistry" by michael starks, he has a whole section on isomerization, pretty well written, and is where I learned about the process WAY back in the late seventies

 

[Gray Wolf]

I'm trying to figure out exactly how decarboxylation and isomerization of THC occurs and what methods can be employed to do so.

I have some some background organic chemistry knowledge and understand that decarboxylation of marijuana is the conversion of THCA into THC, THCA being psychoinactive whereas THC is. On a molecular level, it's the removal of a COOH group from the THC molecule, which can be done under conditions of high heat or presence of a strong base.

I've read that perhaps the process of curing buds is actually a slow decarboxylation process and thus the increasing of potency we generally observe.

Based on this, it's reasonable to assume that applying heat increases the potency of marijuana. And there's evidence of this in making cannabutter from schwag or whipping up BHO over heat or the heat pressing of kief into hash. some sort of increase in potency from the original product.

Is it not then also plausible that washing or soaking the bud in an alkaline (basic pH >7) should also cause decarboxylation? Perhaps a more thorough decarboxylation than whipping over heat? And, as long as the solution is non polar, the THC should not be affected?

The implications of this are perhaps washing our buds in an alkaline solution before performing our preferred method of extraction could increase the end potency of the extract?


Onto isomerization, I understand that it is the rearrangement of the molecule structure. What causes THC to isomerize? I believe the cannabis alchemy articles and other info from the 70's use a strong acid to cause the isomerization. First of, is there any truth in this?Can other methods cause such isomerization?


Just trying to clear things up, it seems that some people confuse the two, and I'm thinking that these are two distinct processes that can occur/be performed to increase potency

I typically decarboxylate the extractions for oral application in a hot oil bath at 250F for ~30 minutes.

We ran an isomerization experiment using sulfuric acid to isomerize the BHO in an ethanol suspension and ammonia to neutralize it.

We then added hexane to steal away the cannabinoids from the alcohol, separated them using a separatory funnel, flashed off the hexane, and voile!

Sadly our ability to make stuff has progressed faster than our fractional separation and measuring project, so we don't know what we did, other than four of us lab rats did an unofficial test by vaporizing some and smearing a couple of raw papers, which I rolled some Blueberry in.

Even sadder, all four of us testing are high tolerance patients who no longer experience euphoric highs and though all of us noticed it over our background medication, and three out of four of us experienced it as headier than the base Shiskaberry/Blackberry oil before isomerizing it, none of us were blown away.

The 6'7" 250# ostensibly lowest tolerance member of the group was the dissenter, and said that it seemed about the same but gave him a mild headache.

I did note that while I noted the enhanced head effect, typical of elevated THC, I didn't experience any speedy or bruxing effect, which usually accompany high THC for me.

Due to the absence of some of the high THC symptoms that I usually experience, I also wonder if the isomerization process itself didn't finish the evolutionary cycle of cannabinoids not only from CBD to THC, but also from THC to CBN in some cases.

Higher CBN to accompany the higher THC would explain the absence of speed and bruxing due to its sedative effect.

More info on the subject after we get volunteer test panel results back, which include a range of medical conditions and tolerances.

My impression so far is that it works just like the books say, but Shiskaberry and Blackberry are not high CBD strains, so the effect was not earth shaking.

We have acquired a high CBD medicinal strain that we will re-run the experiment on when we harvest her babies.

We are also continuing to plod along with our actual empirical measuring experiments so we have more than just subjective and anecdotal test data. More then, when I actually know what I am talking about.

GW

 

[G.O. Joe]

I have already posted the best available decarboxylation articles; time now for the isomerization articles.

Obtaining Δ9 THC by isomerization looks to be out of reach for most.

The procedure using sulfuric or tosic acid was shown to convert CBD (or Δ9 THC) to only the less active Δ8 THC. Using HCl instead gives a mixture and a very low yield of Δ9 THC.

CBD and BF3.Et2O, or hydrochlorination of Δ8 THC with Lucas-type reagent/dehydrochlorination with NaH, gives a THC mixture greater in Δ9 THC. Using potassium t-pentoxide for dehydrochlorination gives better yields of Δ9 THC.

http://ifile.it/nar2wzm

Δ8 THC is reported to be a more effective anti-emetic.

 

[Haps]

The straight skinny is, forget isomerization, big work, minimal if any resulting improvement, I did a mess of it decades ago. And converting with a liquid is messy, with potential residue implications, and not needed, heating it works the trick easily, with little mess or cost.

There are many paths, not all lead to doors worth opening.
H

 

[reckon]

The straight skinny is, forget isomerization, big work, minimal if any resulting improvement, I did a mess of it decades ago. And converting with a liquid is messy, with potential residue implications, and not needed, heating it works the trick easily, with little mess or cost.

There are many paths, not all lead to doors worth opening.
H

 

[Sam_Skunkman]

the way I understand it is:


2) ISOMERIZATION: in the plant CBN degrades into THC-A, which dries, and loses carbon dioxide, then becomes THC (as above) and then further degrades into CBD (if I got it backwards someone will correct me, I'm rather medicated)

Wrong, it is conversion of CBD to THC.
Which in general is a complete waste of time as western drug types have almost zero CBD to start with.
As for decarboxylation you do not need to do it unless you plan to eat the Cannabis. Smoking, even vaporization converts almost all the THCA to THC.
-SamS

 

[Honkytonk]

Michael Starks: Marijuana Chemistry: Genetics, Processing, Potency

 

[Sam_Skunkman]

This is old info that has been proven to be wrong. THC comes from CBG not CBD, CBD also come from CBG, each different Cannabinoid has its own synthase that converts CBG to the end Cannabinoids.
-SamS

 

[jump117]

It relates to both topics

I had a couple of ambers like twins. I put one of them in flat-bottomed conical lab glass and placed in the oven for 20 minutes at 122C.
First amber melted into a puddle, five minutes later the whole puddle was covered with tiny bubbles, which in ten minutes gone.
I think that is carbon dioxide released during decarboxylation. I didn't pictured this now but before in "home-made charas".
Within the next 10 minutes to appear only rare microscopic bubbles.
I think extra time after bubbles gone was useless and harmful.
No bubbles, no decarboxylation, only oxydation.
Ex-twins to compare. The colour turns darker. Consistensy changed from brittle amber for a thick sticky resin.

................. ..............
Absolute Decarboxylated is absolutely odorless.

 

[Gray Wolf]

Decarboxylated and isomerized samples. Isomerized beaker on left and decarboxylated beaker on right.

The pick marks in the beaker are where samples were taken.

The specks on the walls of the right beaker are gnats, which love the stuff.

GW

 

[spurr]

I can answer the decarboxylation question. I just recently got through reading a patent for extracting cannabinoids from cannabis using CO2 extraction, and the first step after drying, before they do anything else, is a decarboxylation step. They performed experiments to find the most efficient temp/time and found:

This took into account that the heat used to convert the THCA to THC will also cause the THC already present in the sample to degrade into CBN, and they found the best temp/time under both considerations. They also say that as the size of the batch increases, the temp/time would also need to be increased, due to uneven heating of the material in the oven.

Now, it is true that over time THCA will convert to THC naturally. The curing process will actually increase potency, but it's real advantage comes from allowing the other plant products to break down like chlorophyll, etc..., that give the smoke a harsh taste. This is because most people decarboxylate the THCA when they smoke or cook it, with the heat from the fire/flame to light/cook it. This is not as efficient as cooking it in an oven at a known temperature for a known time for maximum conversion, but it does the job well enough that most people would never know the difference.

Hades,

Please correct me if I am wrong, but that patent looked at raw plant matter (like buds), no? Also, could you post the link to that patent? TIA.

If a person wants to decarboxylate THCA-A in an extract (ex., BHO/BHC, etc.), one may want to consider the following info (ex., via hot oil bath if extract is liquid or oven if extract is solid):

Ideal temp/time for greatest decarboxylation of THCA-A (from an extract like BHO/BHC) into THC (i.e., 70%), without oxidation of THC into CBN is 150'C (302'F) for 15 min; if I read the study correctly.

The following study is about decarboxylation of THCA-A before using HPLC to get the same (or very similar) quantitative results of Δ9-THC as from GC assay (which decarbs the THCA-A from the heat used during GC assay). The authors also describe why HPLC and GC results are often different even if using the same standard, re "total thc" (THCA-A + Δ9-THC) vs Δ9-THC.

When reporting THC content the lab analysis should report by total THC, especially if they used HPLC. Most preferably the assay report with list THCA-A and Δ9-THC, as well as total THC.

Isolation of D9-THCA-A from hemp and analytical aspects concerning the determination of D9-THC in cannabis products
Franz E. Dussy, Cornelia Hamberg, Marco Luginbuhl,Thomas Schwerzmann and Thomas A. Briellmann
Forensic Science International, Vol. 149 (2005) pp. 3–10
(I uploaded the full text to this post)

​

2.6. Decarboxylation of D9-THCA-A

A solution containing 500 mg D9-THCA-A was put into a gas tight vial. The solvent was evaporated under a gentle stream of nitrogen and the vial was closed. The prepared vial was then put in a GC oven-heated to the desired temperature for 15 min. The reaction product was taken up in 500 mL methanol. 1 mL was analysed by HPLC. Fig. 3 shows stacked HPLC chromatograms of the reaction mixtures from the decarboxylation at different temperatures.

Fig 3.

Fig. 7 and 8

 

[spurr]

RE: Decraboxylation of THCA-A into Δ9-THC by alkaline solution:


(@ Gray Wolf; I would love your input on this topic)


I have been thinking about ways to carry out decarboxylation of THCA-A (and other cannabinoid 2-COOH acids) during the concrete washing stage with EtOH. I would rather not heat the EtOH wash or the absolute at 150°C for 15 minutes, ex., with hot oil bath or oven, respectively. Even though that method should provide peak decarboxylation (i.e., ~70% conversion) of THCA-A into Δ9-THC (Dussy, et al., 2005), because that may also boil off some terpenes, flavonoid aglycones and sterols. For example, the boiling point of the terpene β-caryophyllene is 119°C and the boiling point of the aglycone sterol β-sitostero is 134°C (McPartland and Russo, 2001). Also, if the temperature is not tightly controlled to stay at or below 150°C, if heating for 15 minutes (or greater), Δ9-THC will begin to oxidize into CBN (Dussy, et al., 2005).

What I am thinking about is instead of using heat to decarboxylate THCA-A into THC, I may try using a basic ethanol wash of the n-butane concrete. Ex., 0.1 mol/L ethanolic potassium hydroxide or ethanolic sodium hydroxide; however, the latter is much more reactive and 'dangerous' if not made and used/handled properly.

We all know alkaline conditions can decarboxylate THCA-A (and other cannabinoid acids), but I wonder at what pH is decarboxylation most effective. It seems that pH 13 has been found to work well according to a few patents, however, such a strongly basic pH can make THCA-A from a salt (US 2009/0253783). I would prefer to use a less strong basic ethanolic KOH (ex., < 12) verses strongly basic to prevent THCA-A from forming salt. THCA-A can form a salt at pH 12-14; greatest at pH 12.5-13.5 (US 2009/0253783).

According to Bridges and Williams (1967), ethanolic KOH (aka "c(KOH)") has a pH of 13. Granted, pH is generally only for solutions with water so I assume the ethanol was not anhydrous or the authors converted pKa to pH. The other issue with the claim of pH 13 for c(KOH) is the mol/L concentration of KOH was not listed.

What I am unsure about is whether using a strongly basic ethanolic KOH wash of n-butane concrete will only decarboxylate THCA-A, and/or from THCA-A salts. I am also unsure about the impact of adding KOH in terms of the final absolute, e.g., will the KOH affect the absolute in some way? E.g., when I evaporate the c(KOH) will any KOH be left behind? And should I consider neutralizing the basitity before evaporating the EtOH? If I should neutralize the EtOH solution should I make it acidic? I ask becuase an acidic concentrate is supposed to slow/reduce degradation of Δ9-THC into CBN.

I am thinking about making 0.1 mol/L c(KOH), aka 0.1 N c(KOH), following these directions (link) and using c(KOH) in place of EtOH to re-dissolve the concrete. If I do make c(KOH) I assume I should use EtOH azeotrope, yes?

I lack sufficient organic chemistry know-how to do anything but fumble along, so I hope Gray Wolf, or anyone else might be able to offer insight. Making 0.1 mol/L c(KOH) or 0.5 mol/L c(KOH) is easy enough, but I am not sure if it will do what I want. I am a bit concerned adding KOH may screw up the extract...


References:

Isolation of D9-THCA-A from hemp and analyticalaspects concerning the determination of D9-THC in cannabis products
Franz E. Dussy, Cornelia Hamberg, Marco Luginbuhl,Thomas Schwerzmann and Thomas A. Briellmann
Forensic Science International, Vol. 149 (2005) pp. 3–10
(full text study uploaded to my previous post)​

Cannabis and Cannabis Extracts: Greater Than the Sum of Their Parts?
John M. McPartland and Ethan B. Russo
The Haworth Integrative Healing Press (2001)
(full text PDF) http://www.omma1998.org/McPartland-Russo-JCANT%201(3-4)-2001.pdf​

Production of Delta 9 Tetrahydrocannabinol
US 2009/0253783
(full text patent) http://www.freepatentsonline.com/y2009/0253783.html​

The fluorescence of indoles and aniline derivatives
J.W. Bridges and R.T. Williams
(full text study) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1198649/pdf/biochemj00730-0098.pdf​

 

[spurr]

Re: Isomerization of CBD into Δ9-THC


I for one know very little about this process but I do have a decent collection of study references and a patent as well as the patent application. The following isomerization processes are described:

• CBD (cannabidiol) to Δ8-THC and Δ9-THC
• CBN (cannabinol) to Δ9-THC
• CBD to CBN.

Considering most drug biotype (i.e., chemotype I) Cannabis cultivars and strains we grow have very low CBD I think isomerization might not be worth the effort.

However, because growing fiber biotype (i.e,. chemotype III) Cannabis cultivars and strains is not illegal in many countries, it could be worthwhile to look into isomerization of CBD to Δ9-THC. That is, one could grow a large crop of hemp outdoor, legally in many places, and then simply extract and convert the CBD (and CBD-A) into Δ9-THC. That is something I have long thought about doing...

Anyway, here are the studies and patent on the process. If one is trying to learn and is not a chemist by training or a self-taught chemist, reading and trying to following the patent might be the best bet.

(I could probably upload those papers sometime next week, I will see if I can get them for free from my Uni.)

Conversion of CBD to Δ8-THC and Δ9-THC
United States Patent 7399872 (2008)
http://www.freepatentsonline.com/7399872.html


Conversion of CBD to Delta8-THC and Delta9-THC
United States Patent Application 0221339 (2008)
http://www.freepatentsonline.com/y2008/0221339.html

• That patent application is the application for the patent "Conversion of CBD to Δ8-THC and Δ9-THC"; often times the patent application can be more helpful than the actual patent

Structure of cannabidiol. VI. Isomerization of cannabidiol to Tetrahydrocannabinol, a physiologically active product. Conversion of cannabidiol to cannabinol
Adams, R., Pease, D.C., Cain, C.K., and Clark, J.H.
J. Am. Chem. Soc., 1940, 62 (9), pp 2402–2405
DOI: 10.1021/ja01866a040


Structure of cannabidiol. XII. Isomerization to Tetrahydrocannabinols
Adams, R., Cain, C.K., McPhee, W.D., and Wearn, R.B
J. Am. Chem. Soc., vol. 63, 1941, pp. 2209-2213
(full text study) http://www.scribd.com/doc/27849551/Isomerizationcannabidiol-Tetrahydrocannabinols-2200-of-To


Hashish-VII: The isomerization of cannabinol to Tetrahydrocannabinols
Gaoni, Y., and Mechoulam, R.
Tetrahedron, vol. 22, 1966, pp. 1481-1488
DOI: 10.1016/S0040-4020(01)99446-3
​

The following study looks interesting and seems relevant for those that ingest extracts that contain CBD. Gastric juice is located in the GI tract and IIRC the pH range for most humans (non-obese) is 1-2. The pH of gastric juice is so low thanks to hydrochloric aid (HCL); which G.O. Joe pointed out will convert CBD to Δ9-THC. I however wonder about CBD-A, whether the same isomerization to Δ9-THC would take place. So, it seems humans should be able to 'self-isomerize' CBD into Δ9-THC considering mice are model organisms for humans :

(I want to point out I do not agree with testing on animals...)

Conversion of cannabidiol to Δ9-tetrahydrocannabinol and related cannabinoids in artificial gastric juice, and their pharmacological effects in mice
Watanabe, K., Itokawa, Y., Yamaori, S., Funahashi, T., Kimura, T., Kaji, T., Usami, N., and Yamamoto, I.
Forensic Toxicology
Volume 25, Number 1, pp. 16-21
DOI: 10.1007/s11419-007-0021-y

Abstract

Cannabidiol (CBD), a nonpsychoactive cannabinoid, was found to be converted to 9α-hydroxyhexahydrocannabinol (9α-OH-HHC) and 8-hydroxy-iso-hexahydrocannabinol (8-OH-iso-HHC) together with Δ9-tetrahydrocannabinol (Δ9-THC), a psychoactive cannabinoid, and cannabinol in artificial gastric juice. These cannabinoids were identified by gas chromatography-mass spectrometry (GC-MS) by comparison with the spectral data of the authentic compounds. Pharmacological effects of 9α-OH-HHC and 8-OH-iso-HHC in mice were examined using catalepsy, hypothermia, pentobarbital-induced sleep prolongation, and antinociception against acetic acid-induced writhing as indices. The ED50values (effective dose producing a 50% reduction of control; mg/kg, i.v.) of 9α-OH-HHC and 8-OH-iso-HHC for the cataleptogenic effect were 8.0 and 30.4, respectively. 8-OH-iso-HHC (10 mg/kg, i.v.) produced a significant hypothermia from 15 to 90 min after administration, although 9α-OH-HHC failed to induce such an effect at the same dose. However, both HHCs (10 mg/kg, i.v.) significantly prolonged pentobarbital-induced sleeping time by 1.8 to 8.0 times as compared with the control solution with 1% Tween 80-saline. The ED50values (mg/kg, i.v.) of 9α-OH-HHC and 8-OH-iso-HHC for the antinociceptive effect were 14.1 and 39.4, respectively. The present study demonstrated that CBD can be converted to Δ9-THC and its related cannabinoids, 9α-OH-HHC and 8-OH-iso-HHC, in artificial gastric juice, and that these HHCs show Δ9-THC-like effects in mice, although their pharmacological effects were less potent than those of Δ9-THC.

 

[spurr]

Is it not then also plausible that washing or soaking the bud in an alkaline (basic pH >7) should also cause decarboxylation? Perhaps a more thorough decarboxylation than whipping over heat? And, as long as the solution is non polar, the THC should not be affected?

The implications of this are perhaps washing our buds in an alkaline solution before performing our preferred method of extraction could increase the end potency of the extract?

I thought about that a few years ago, but I do not think it would be effective because of nature of trichomes: they repel water. I could be wrong, but it seems to me using basic aqueous solution as wash for buds will not decarboxylate THCA-A into Δ9-THC. Sadly, there is very little real 'how to' information in terms of using alkaline solution to decarboyxlate THCA-A, either from academia or elsewhere. I have been unable to find more than a snippet of info about what pH will decarboxylate THCA-A; let alone what pH is ideal.

 

[spurr]

I have already posted the best available decarboxylation articles; time now for the isomerization articles.

Where did you post the articles? I have not seen your posts and you have me intrigued...

 

[spurr]

Hey Sam,

As for decarboxylation you do not need to do it unless you plan to eat the Cannabis. Smoking, even vaporization converts almost all the THCA to THC.
-SamS

I am not sure that is the whole story. In a few studies I have read the decarboxylation of THCA-A into Δ9-THC via smoking (ex., with a joint, vaporizer and THCA-A laced tobacco cigarette) was rather inefficient. Thus the quantity of Δ9-THC that would have been inhaled was also reduced due to rather inefficient decarboxylation of THCA-A.

A decent amount of THCA-A is not decarboxylated into Δ9-THC when smoking (Dussy, et al., 2005). Possibly due to destruction of THCA-A from the very high temps of a flame and more so the hot amber, which can reach up to and greater than 600°C; as well as the rather short time frame for decarboxylation to occur, of only a few seconds (Grotenhermen and Russo, 2002).

According to Dussy, et al. (2005), "Maximal conversion [i.e., decarboxylation of THCA-A] in an optimised analytical equipment [i.e., 150°C at 15 minutes for THCA-A extract] yields about 70% D9-THC. In the simulation of the smoking process [tobacco cigarette laced with 5 mg THCA-A], only about 30% of the spiked substance [THCA-A] could be recovered [from decarboxylation] as D9-THC."

Also according to Dussy, et al. (2005), "Only about 30% D9-THC of the spiked cannabinoid [THCA-A] could be recovered in the first bottle and about 8% in the cigarette end, the vast majority being destroyed in the gloom (Table 2). As the cigarette was sucked by a gentle stream of air generated by a vacuum pump, only negligible amounts of D9-THC are expected to be lost in the side smoke. In the literature, it is described that about 50% D9-THC is available [due to decarboxylation] in the smoke [7]."

​

Optimal decarboxylation of THCA-A means THCA-A is converted into Δ9-THC (~70%); 100% of the THCA-A is not decarboxylaed to my knowledge. Thus it seems evidenced a person would get more Δ9-THC smoking bud or extracts that were optimally pre-decarboxylated verses smoking smoking bud or extracts that were not pre-decarboxylated.

The info I presented from the study and book, among a few other studies, are why I think I am going to decarboxylate all my concentrates I intend to smoke or vaporize. I also have data about decarboxylation of THCA-A with a Volcano vaporizer; ex., at 200'C and 230'C, more THCA-A is decarboxylated than from a cigarette. However, in both cases (vaporizer and smoking) the amount of THCA-A decarboxylated was considerably less than the amount of THCA-A decarboxylated via optimum methods before vaporizing/smoking. I will try decarboxylating dry sift kif and water hash, too.

If you see flaws in my interpretation of the data please let me know


References:

Isolation of D9-THCA-A from hemp and analyticalaspects concerning the determination of D9-THC in cannabis products
Franz E. Dussy, Cornelia Hamberg, Marco Luginbuhl,Thomas Schwerzmann and Thomas A. Briellmann
Forensic Science International, Vol. 149 (2005) pp. 3–10


Cannabis and cannabinoids: pharmacology, toxicology, and therapeutic potential
Franjo Grotenhermen, Ethan Russo
Routledge; 1 edition (April 15, 2002)
ISBN-13: 978-0789015082
​

 

[G.O. Joe]

Where did you post the articles? I have not seen your posts and you have me intrigued...

Well I don't have a lot of posts, an advanced search of my posts in this resin forum might not be a complete waste of time; I don't know, it's hard to be objective.
https://www.icmag.com/ic/showpost.php?p=2436055
https://www.icmag.com/ic/showpost.php?p=3327725
+
choosy posters choose gif.
https://www.icmag.com/ic/showpost.php?p=4236263

We all know alkaline conditions can decarboxylate THCA-A

Not all of us. I don't remember hearing of it. In fact that 2005 article uses 2% NaOH for extraction of THCA. There is a patent that uses concentrated alkali for the same thing. But I don't really get what you're proposing with the ethanolic KOH.

The part about HCl and CBD, from the attached Mechoulam article that was mentioned, which was in the now dead ifile link I posted along with the patent: "Boiling cannabidiol (Ia) with dilute hydrochloric acid in ethanol for 18 hr, as described by Adams gave a complicated mixture of compounds which was only partially separated on chromatography." I will pass on smoking that.

Also included is the article where Adams did this, and also used sulfuric and tosic acids to obtain mostly delta8-THC.

 

[spurr]

Well I don't have a lot of posts, an advanced search of my posts in this resin forum might not be a complete waste of time; I don't know, it's hard to be objective.
https://www.icmag.com/ic/showpost.php?p=2436055
https://www.icmag.com/ic/showpost.php?p=3327725
+
choosy posters choose gif.
https://www.icmag.com/ic/showpost.php?p=4236263

Thanks, I'll check those out

We all know alkaline conditions can decarboxylate THCA-A

Not all of us. I don't remember hearing of it.

My bad, I thought the claim about alkaline conditions decarboxylating THCA-A was common knowledge. There are quite a few occasions of that claim in various (respected) books and in academia too. However, in all but one instance the claim is simply something like 'alkaline conditions decarboxylate THCA' or 'basic conditions decarboxylate THCA'. I have only found one instance where a pH was listed.

Here are some references with some quotes:

Development and application of a LC-MS/MS method for the analysis of plasma bioavailabilities of different cannabinoids after the administration of Cannabis sativa L. extracts and Marinol
Sandra Béatrice Grauwiler
Thesis paper (2008)
(full text) http://edoc.unibas.ch/784/1/DissB_8333.pdf​

Alkaline decarboxylation of THCA-A, see page 22:

The decarboxylation of THC acids to the corresponding phenols (Figure 3) occurs readily over time, upon heating, or under alkaline conditions.

Alkaline decarboxylation of CBD-A, see page 23:

Decarboxylation of CBD acid to the corresponding phenol occurs readily over time, under heating or alkaline conditions [31].

Pharmacokinetics and pharmacodynamics of cannabinoids
Grotenhermen, F.
Clinical Pharmacokinetics, Volume 42, Number 4, 2003 , pp. 327-360(34)​

Taken from the International Association for Cannabinoid Medicines webiste (link):

In the plant the cannabinoids exist mainly in their carboxylic forms as cannabinoid acids. However, the phenolic form of THC is responsible for the psychotropic and the most medicinal effects. Decarboxylation (separation of CO2) to the phenolic form occurs readily over time, upon heating or under alkaline conditions.

The ratio of THC acids (THCA) to phenolic THC has been reported to range between 2:1 (Africa) and >20:1 (Switzerland) in leaves and flowers of Cannabis sativa. In plants grown in Middle Europe (United Kingdom) from Moroccan, Sri Lankan and Zambian seed stocks the THCA/THC ratio was 17:1 compared with 2:1 in the plants from the original areas (Africa, Asia). In hashish (cannabis resin) the THCA/THC ratio was reported to range between 6.1:1 and 0.5:1, the latter in hashish from India. Thus, the percentage of phenolic THC of all THC in cannabis products varied between less than 5% in cannabis leaves grown in Switzerland up to 65% in hashish from India.

Cannabis products with a high content of phenolic THC (e.g. hashish) may be very potent without heating, but usually the potency of cannabis products is considerably increased with heating (smoking, cooking).

Modified according to: Grotenhermen F. Pharmacokinetics and pharmacodynamics of cannabinoids. Clinical Pharmacokinetics 2001, in press

Production of Delta 9 Tetrahydrocannabinol
United States Patent Application 20090253783
http://www.freepatentsonline.com/y2009/0253783.html​

In the quote below the context is trying to extract THCA-A as a salt; not decarboxylate THCA-A per say. However, this is the only instance where I have seen a pH listed that will decarboxlate THCA-A. Granted, I do not want to use a pH at or above 12, preferably below 10, to prevent formation of THCA-A salt:

In contrast, known methods use very alkaline pH (typically in the pH range 13.5-13.9), resulting in formation of a 3-layer system, with the Δ9-THC acid salt “oiling out” between the organic and aqueous layers. This causes processing problems during subsequent phase separations. We have found that use of such high pH may also lead to degradation and decarboxylation of the desired THC-acid, thus reducing yield of Δ9-THC.

Here is an interesting post by someone with the pseduonym "Arsenal".
I do not know enough organic chemistry to know if the info Arsenal offers is correct. It seems sounds but I don't trust myself with organic chemistry. Maybe you, or others that seem knowledgeable of organic chemistry can verify if the following is correct?​

http://www.marijuana.com/medicinal-marijuana/9130-whats-ideal-temp-activatin-thc-2.html

I imagine "Alkaline Conditions" refers to THC being placed in a basic solution, hence the carboxyl group is removed and the acids neutralized.

Edit: Of course I know the chemistry for this! Gah, mega-brainfart. It goes something like this:

R-COOH + OH- -> R + CO2 + H2O, R being the alkyl group containing THC.

Makes perfect sense now. Not sure what bases are strong enough to do this (in respectable quantity and that are readily available).

In fact that 2005 article uses 2% NaOH for extraction of THCA. There is a patent that uses concentrated alkali for the same thing.

AFAIK the extraction of THCA-A (ex., salt formation) can be done with solvent(s) and strongly basic chemicals such as sodium sulfate, sodium hydroxide, etc.; used to make the solvent strongly basic (ex., > pH 12). I do not want to use a strongly basic solvent to re-dissolve the initial extract (ex., concrete). In fact, I don't know if I want to use a basified solvent at all. This is just an idea I am trying to air out.

But I don't really get what you're proposing with the ethanolic KOH.

I am proposing the use ethanolic KOH to re-dissolve the initial cannabis extract (ex., concrete), instead of using ethanol, as a wash. I am asking if, and proposing, use of basified ethanol, ex., 8-10 pH, might work well enough to decarboxylate THCA-A in place of using heat.

What I don't know is whether my suggestion is a non-starter; it very well may be. I do not know enough about organic chem to make an informed judgment.

I think using ethanolic KOH is better than ethanolic NaOH because KOH dissolves into ethanol more readily than NaOH to my understanding. Also, AFAIK it's easier to work with KOH than NaOH.

What I do not know is whether there are downsides to basifying ethanol for cannabis extracts, and if KOH is a good choice. I also do not know if adding KOH to ethanol will affect the outcome of the absolute (other than possibly decarboxylation of THCA-A).

The part about HCl and CBD, from the attached Mechoulam article that was mentioned, which was in the now dead ifile link I posted along with the patent: "Boiling cannabidiol (Ia) with dilute hydrochloric acid in ethanol for 18 hr, as described by Adams gave a complicated mixture of compounds which was only partially separated on chromatography." I will pass on smoking that.

Thanks for that; I agree on not smoking it. I did however find it very interesting that ingested CBD could possibly be isomerized to THC in our GI tracks.