Root Cause Analysis: “Medusa Stones” and “Fast-Crash” in n-butane extraction solutions of THCa from Cannabis, as of May 3rd, 2022
MEDUSA STONES…
Unknowns In Isolate Conversions - Hash and Stuff / Pre/Post-Processing - Future4200
The forum comment above contains a nice illustration relevant to the principles of reaction between ammonia (NH3) or amines and THC-acid (THC-COOH). Although an organic carboxylic acid like THCa is a proton donor (a Brønsted–Lowry acid), it is also a Lewis acid (electron acceptor / electrophile). As you may know, THCa is a very weak B-L acid, because it does NOT donate its proton to water (aka “disassociate” or “ionize upon polar solvation”) in any significant concentration. This makes its Lewis acid character more obvious. That is to say, the ammonia, being a Lewis base, can simply attach to the THCa, forming a ‘Lewis adduct’, like so… THC-COOH4N
This new ‘quaternary ammonium’ compound could be called a ‘zwitterion’ (although this term is normally for a molecule wherein the + and – charges are separated by 1 or more atoms) or a ‘Lewis acid-base complex’ (although usually that term refers to a ‘ligand’ and a metal ion).
I have been discussing ammonia and amines as potential causes for “medusa stones” for quite a while, now, albeit not necessarily on the forum. It is my suspicion that the culprit (i.e., Medusa, the last of the Gorgons) is most likely a highly labile organic amine–probably secondary or even ternary amine–attaching to the THCa to form the “amine THC carboxylate” salt, molecules nucleating and organizing into a crystal lattice structure commensurate with that of the newly formed salt (evident by the macro-crystalline growth & shape of THCa medusa stones being so different from those of pure THCa crystals), then detaching as the energy of the crystallized molecules drops below the energy of solvation for this amine. Essentially, the amine is acting like a sort of crystallization catalyst, thereby remaining in the butane solvent throughout multiple batches of biomass being extracted. This ‘regenerating’ behavior could also explain how the concentration of the amine in the butane is apparently low enough to have escaped discovery by analysis for all this time!
FAST-CRASH…
I believe, although the fast-crash problem may sometimes co-occur with the medusa stone problem, that the two could have separate causes… or at least that these two different phenomena may vary according to the concentration of the offending impurity.
In other words, Fast-Crash could be caused by a different (more rapidly labile and/or precipitous) THCa salt-forming amine… or the fast-crash butane may simply have higher concentration of the salty amine than the medusoid butane. I also believe this problem is further exacerbated by increased concentrations of neopentane in the butane solvent.