Strange Color Change when using Acetone

Hi guys, so a couple weeks ago, I noticed something strange happen, after having dissolved some extracts in acetone, and evaporating it in natural atmosphere, as opposed to under vacuum. I saw the same thing happen with two completely different sources of material (Indoor nugs AND outdoor trim), and two different sources of butane were used (one sourced from cans, the other tank claimed 99.5% but was never distilled).

After almost all of the acetone had evaporated - to where the extract doesn't flow across the dish when tilted, but still low enough in viscosity to scrape with ease - I scraped the extract onto PTFE paper in a thin slab to be vacuum purged. Still everything was normal, until about 12 hours later. I noticed what could be a color change, or it could be simply compounds dropping out of the saturated solution. The bit of residue left on the blade after drying separated into two distinct colors. Heavy maroon, and bright piss yellow. I thought it was oxidation/sunlight causing color change, but I did the same thing in complete darkness, and about 12 hours later, the maroon emerged again!!

The blade led me to believe it was spots of oxidation/degradation of some sort, but the pyrex dish still had lots of THC residue around the edges. And really looked to me like two layers had separated out, as I could very visibly see maroon "downhill" from the golden THC (which has now been smoked - very smooth with no strange residues).

My thoughts were originally to look at the solvent used, but considering acetone is aprotic, it wouldn't really affect the pH of any compounds would it? Ethanol might have more of an affinity for doing so, as it does have an acidic hydrogen available for donation. In acetone, the oxygen and it's free electrons seem like a great place for hydrogen bonding to occur (probably hydrogens from THC), so I can see that the acetone would want to stay with the THC.

Looking back on my THCa experiments, what I previously thought to be anthocyanins (and it still could be) could be whatever I have in front of me here. Basically something turned exactly this color of maroon, and it formed a separable emulsion between the alkaline aqueous solution and the nonpolar solvent (picture & link just below). What confused me at that time was why the color stopped at maroon-purple which would indicate a pH of ~6-7 from anthocyanin response, when I surely brought the aqueous phase up to 12-13.

https://www.icmag.com/ic/showpost.php?p=7717690&postcount=156

I am thinking that the maroon may be some sort of carotene. Having such a long hydrocarbon chain and it's heavier molecular weight would give it reason to perhaps crash out of a supersaturated solution.

Any further opinions? Thanks for any insights!
I think I've seen this happen before, and chalked it up to using standard mason jar lids, as the acetone vapors alone are enough to eat the red rubber seal. No jar lids here...

It wouldn't be a surprise if the purple was oxidized cannabinoid. Perhaps air alone is incapable of this under those conditions, but air plus some terpenes or some other easily oxidized catalyst will be more capable and attractive as a possibility. It would be interesting to know if this happens or not with vacuum or another solvent with a similar evaporation rate.

Solutions of cannabinoids should never be exposed to oxygen, and if they are to be kept liquid it would be wise to sparge with something and bottle with no or inert headspace. Especially if there are terpenes.

You may have found CBD or CBG with a Beam test earlier. The color would go away with acidification.

I'll note that the amount of maroon (most of it is pictured) was next-to-nothing in comparison to the weight of the oils (about an 30g total).

You bring up very interesting points though, and I haven't forgotten that you mentioned this before. I should have played with the pH a bit this time. It was extremely unexpected, and I didn't have the tools/time to play with it much.

Old Gold said:

I'll note that the amount of maroon (most of it is pictured) was next-to-nothing in comparison to the weight of the oils (about an 30g total).

You bring up very interesting points though, and I haven't forgotten that you mentioned this before. I should have played with the pH a bit this time. It was extremely unexpected, and I didn't have the tools/time to play with it much.

Click to expand...

I note that anthro cyanins change from red to blue with ph changes.

Gray Wolf said:

I note that anthro cyanins change from red to blue with ph changes.

Click to expand...

...which is exactly why I'm not convinced we have anthocyanins in my THCa experiment (along with it's lack of water solubility in aqueous NaOH). Unless someone can convince me that they stopped reacting and crashed out of solution for some reason, but I don't see anything logical in that, especially considering the number/location of hydroxyl groups in anthocyanins.
I think G.O. Joe was onto something with the beam test. It could be where much (or all) of my yield went...

In this current post however, you could definitely be correct, Gray Wolf. The pH of the cannibanoids should have been slightly acidic, nearly neutral. So if the solution stayed entirely in that realm, the color would make sense for anthocyanins. But anthocyanins aren't necessarily lipid-soluble. Carotenes are though. I'm still leaning a bit in that direction (technically carotenoids I assume).

I once saw maroon globs separate out in the evaporation dish.

It was the ethanol soak extraction I did on some ground flower after a normal butane extraction. I made a joke post about it, the product turned out nasty looking!!

Stuff in the little round jar, you can see it's not actually black, but appears red if you can get enough light through it.

https://www.icmag.com/ic/showpost.php?p=7691915&postcount=226

More evidence of such...

You wouldn't even know it's there. I left a gram or two of residue on the dish, and it was golden/clear. As soon as I forcefully scraped it really thin, this emerged again.

Same strain/source as one of the previous times I saw this...

I remember reading that back in the early days of oil extraction (when it was gaining popularity in the 90's I believe) in Canada, red oil was made two ways, with ether (Neville nearly blew himself up using it if I remember right) and with filtering it through activated charcoal. Is this the first time you used acetone or done so many times and this is the first result? Same strains as before or different and was the ripeness the same, atmosphere the same etc? I am just curious about environmental conditions if they have an effect.

Limeygreen said:

I remember reading that back in the early days of oil extraction (when it was gaining popularity in the 90's I believe) in Canada, red oil was made two ways, with ether (Neville nearly blew himself up using it if I remember right) and with filtering it through activated charcoal. Is this the first time you used acetone or done so many times and this is the first result? Same strains as before or different and was the ripeness the same, atmosphere the same etc? I am just curious about environmental conditions if they have an effect.

Click to expand...

These posts were the first time I saw it consistently, and as noted early on, from two very different sources of material. One of which was outdoor trimmings that I really don't know as much about as I would like; and the other was indoor, soil-grown OG nugs from a close family friend.

I use acetone all the time, because it's easier to remove than ethanol and I am able to bring it below the sensory threshold while sometimes still retaining a hint of flavor.
I noticed the oxidation first after leaving a dish out and unused for a week or so. The most recent photo was within 12 hours of evaporating acetone to nearly stabilize the resin

I've made some very vibrant and bright maroon shatter a few times, using 2-3 year old nugs or adding lots of kief (fresh or old) to a run. I'll dig for a photo, but doubt I have one. Very similar to the red seen here, but what I ran recently was not old.

ive seen something like this from qwiso , but not quite as high contrast.

What is your source of acetone

happens in salvia divinorum crystal extraction, the red glow, chlorophyll reactions

I'll second that it's probably anthocayanins. They come through in Polar extractions much easier but the worst I've seen it is from the first separator in a waters machine. It can be removed with a carbon scrub, or separated by distillation with some tricks, like a full-laminar path and the condenser at 155C.

HashoftheTitans said:

I'll second that it's probably anthocayanins. They come through in Polar extractions much easier but the worst I've seen it is from the first separator in a waters machine. It can be removed with a carbon scrub, or separated by distillation with some tricks, like a full-laminar path and the condenser at 155C.

Click to expand...

looks like everybody's learnin' all the sudden
A little enthalpy goes a long way

was that maroon color stuff, good ?
smokeable ...?


axle robot