Building upon the work by Samvidbuho @
https://www.dmt-nexus.me...mp;m=1026783#post1026783Settling during salting as a bottleneck:Experience shows that Salting freebase from a NP into acidified water can result in persistent suspensions of solids in the NP that take over 12hours to settle enough for the NPs clarity to be restored. These suspensions are even more resistant to settling than the more visible emulsions that originally occur, and high levels of alkaloids are trapped in the suspension cloud.
The presence of alkaloids in this semi-salted NP was verified by retrieving it and running a FASA test, that clouded on contact thus showing that not all alkaloids salt out.
Samvidbuho’s “A Comprehensive Guide to Salting” talks about this issue and presents many opportunities for optimization. His studies deal mostly with Fumaric Acid, but the principles he explains can be adapted to other acids with seemingly outstanding results.
Ethanol might be good at dissolving fumaric acid and transporting it between both polar and NP phases, but both ethanol and Fumaric acid are on the expensive side amongst common solvents and acids used for extractions. Ethanol also forms azeotropes with water and has a relatively high boiling point.
The merits of FASE in a 3-solvent system, as used by Samvidbuho, make it an ideal choice for quick transformation and storage of highly stable fumarate salts, but the cost makes it less ideal for initial salting out of xylenes that are freshly removed from a basic MHRB soup, since some basic or solid contaminants are always bound to make it through on this first pass in minute ammounts (micromycelles and errant particles not always visible to the eye), and this contamination might warrant a refinement mini-A/B through which the Fumaric component is wasted.
Let’s revisit Samvidbuho’s science:
Polar water and NonPolar solvent don’t mix well because they are not miscible, this impedes ion transfer at the boundary of every mycelle. This means that freebase tends to stay trapped in the NP while acid ions dissolved in the water remain in the water, more importantly, reacted alkaloid salts can ALSO remain suspended in the NP since they can’t be dissolved by anything in their vicinity until they agglomerate and fall to form the emulsion layer between the water and NP thanks to surface tension interactions that prevent them from fully migrating into the aqueous layer.
For optimized salting a third solvent with the following characteristics is required:
- The right solvent must be miscible in both Polar and NP phases
- The freebase must be freely soluble in it
- The acid used for salting has to be at least partially soluble in it
Let’s now talk about a 3-solvent salting system that uses citric or ascorbic acid in water, freebase in xylene, and acetone as an ion carrier that facilitates transport between the two phases.
Acetone is a good solvent because it is cheap and can be easily removed by low temperature evaporation since it doesn’t make azeotropes with water or the NPs. It is also a good solvent for citric and ascorbic acids.
I am currently experimenting with a mix of about 20g of ascorbic acid, 200ml of water and 100ml of acetone, the xylene and a magnetic stirrer. The results of letting xylene slide into the vessel are quite impressive.
-As soon as new xylene touches the water layer a milky white cloud forms and starts to spread through the rest of the xylene pool
(comparing that to the acetone free methods where the xylene just kinda sits there atop the water makes for dropped jaws)
-the next step was to set the magnetic stirrer to max for maybe 5-10 minutes, turn it off, wait for the emulsion to collapse within the next 5 minutes and leave behind a nearly cloudless xylene layer, with very little pockets of emulsions/sediments on the boundary layer. I am letting this sit for at least an hour and then I pipette an aliquot into a test tube for a quick FASA test that shows no clouding, this confirms that all alkaloids have been transformed into salts. **
(Comparing this to the acetone free method where clouds of suspensions would linger for over 12hours, after which seemingly clear xylene would sometimes still test positive for alkaloids on a quick FASA test)
**NOTE: From original FASA NPs regeneration procedures we know that acetone will selectively transfer to the aqueous acid layer, albeit a portion of it is likely to remain in the xylene, and I believe that I can feel the smell of acetone in the xylene when I remove it from the salting vessel even after several hours of standing. This leads me to believe that we must establish the solubility of the alkaloid salts in this acetone to find out if there are alkaloids inadvertently being removed with this xylene that carries acetone traces.
ToDo: Must test solubility of alkaloid citrate and ascorbate salts in:
-Pure acetone
-wet acetone
-citric acid saturated acetone, and
-ascorbic acid saturated acetone
Assuming that the alkaloid salts are insoluble in those acetone mixtures, the most recent good reason to choose acetone is because Benzyme established that acetone is not miscible in basic aqueous solutions with pH above 10, so even if you return the xylene with acetone traces to the basic MHRB soup vessel for another pull, all the acetone should try to migrate to the NPs layer with new alkaloids.
Acid solubilities in acetone:
( I don’t understand solubility in terms of mole fractions, and can’t translate the results to the layman's " g/100ml" )
Solubility of Fumaric acid in acetone:
4.98 10^3x (molar fraction) 1.29g/100ml @ 20c
Solubility of AscorbicAcid in acetone:
0.26 10^3x (molar fraction) @ 20c
Per:
Solubility of L-(+)-Ascorbic Acid in Water, Ethanol, Methanol, Propan-2-ol, Acetone, Acetonitrile, Ethyl Acetate, and Tetrahydrofuran from (293 to 323) K
https://www.academia.edu...ofuran_from_293_to_323_KSolubility of Citric Acid in acetone:
Wikipedia says it’s soluble in acetone.
The article below should say by how much. Do any pros have access?
Solubilities of 3-Carboxy-3-hydroxypentanedioic Acid in Ethanol, Butan-1-ol, Water, Acetone, and Methylbenzene By Yang and Wang
https://pubs.acs.org/doi/10.1021/je101167z