At very high pressures, methane becomes a supercritical fluid at the slightly more reasonable temp of -80C. That could yield some interesting results when run in a CO2 like manner.
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I wonder if Mercaptan would stay with the extract? Unless you could access pure methane without that added…
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I was gonna go with purified methane off the start, and maybe play with purifying it myself off of my LNG line down the road
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What equipment would you run this on?
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Not sure tbh.
Probably start with a chill and soak to check initial returns. Then either soxhlet or tube style pending on what works well?
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Mercaptans can be removed from a liquid or gas stream with either 13x zeolite or just copper scrubby pads.
turbeville2006.pdf (654.4 KB)
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I read @Photon_noir vanderwal forces post and still wasn’t really clear on how methane would preform in relation to the other alkanes. I’m leaning towards a lower solvency on cannabinoids than the rest of the alkanes? Seem like heptane is best and they kind of lower in solvent power the simpler the molecules become?
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IIRC the longer the chain on the hydrocarbon the more solvation power. So yes the simpler molecules will have less power of solvation.
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Ah, so I’m going the absolute worst route… nice… lol
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lol i mean…
Methane sitting at -86c will rest somewhere around what, 880 psi? i cant even imagine what room temp would push.
Im very interested in ethane however, its critical point is very similar to that of co2, so could be operated in a co2 unit if the seals and gaskets were appropriate. id be terrified of a blowout tho, The worst parts of co2 and hydrocarbon combined, at 5000psi would methane self ignite if it blew a gasket just on friction? @drjackhughes @MagisterChemist @Photon_noir
As you go down the lines of alkane liquids solubility definitely decreases, but who knows as far as in its critical state. all bets are off.
I do think with any of these liquid solvents, anything colder than -80 really doesnt make sense to me, excluding critical conditions. Being so cold is just gonna freeze terps and not extract them.
Would love to see it either way,
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The critical point for methane is 673 psi and -82.6 C. It’s actually lower pressure than needed for co2. You ought to be same to use it in a co2 machine.
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The only thing better than super high pressure, is highly flammable under super high pressure 
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Yeah I saw that, thats wild, Throw a Huber 815 or 915 on a co2 machine and ensure all exposed gaskets are viton and youd be in business as long as your pumps are suitable
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@Roguelab are you any closer to getting the revco online so you can test extraction with ethane?
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Viton isn’t approved for uses below -60C. Usually I don’t have issues pushing those boundaries but on something like this i’d rather be sure!
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So the ethyl or methyl groups don’t affect cannabanoid affinity? Obviously there’s no inherent comparison base here. But methanol and ethanol have higher cannabanoid affinity compared to other alcohols don’t they?
Or are alcohols entirely different in solvent properties?
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The alcohols do have entirely different properties. The hydroxyl group dominates their intermolecular interactions. I’m not even sure it’s true that ethanol and methanol are far above other alcohols. Isopropyl alcohol is also a very active solvent for cannabinoids. I haven’t heard of anyone using a butyl alcohol, but I suspect it would work good too.
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Nice, figured that was right, hoping it wasn’t. Lol.
This is an interesting concept, but I am not sure how it would play out. Methane and ethane are about as non-polar as CO2, and they are similarly small inflexible molecules. Running liquid methane or ethane would be similar to running liquid CO2… they would extract terpenes and, vicariously, cannabinoid acids dissolved in those terpenes, and they would also strip out vegetable oils and epicuticular wax to some degree, just like CO2 and other alkanes.
One would simply need more molecules of solvent to extract the same amount of oleoresin as the longer alkanes, and with their low boiling points, more terpenes would be left behind in the oleoresin product. At those temperatures, THCa would very likely quickly precipitate out of the solution, so these could be used to make the ultimate live resin… probably with higher yields than butane or propane, as long as enough solvent was used, due to their lower surface tension and therefore high permeability into the small spaces around the frozen plant matter.
I would not recommend using these small alkanes in supercritical phase, for the same reasons supercritical CO2 is ill advised… the solvent does not need to penetrate through any cell walls to extract cannabinoids. Supercritical phase matter is used to penetrate every part of the biomass in order to reach hard-to-get molecules inside cells and tough cellulosic and lignacious materials, which is entirely unnecessary to get through the thin membranes of glandular trichomes.
Finally, there are the inherent safety problems of working with methane and ethane. They are extremely inflammable, and require high pressures and low temperatures to compress them and keep them in liquid state. Their NFPA hazard class is probably at least one step higher than the LP gases like propane and butane.
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The potential for there to be so little residual solvent because of the super low boiling point gets me pretty stoked though. None of that 3 days in the oven I’d assume.
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