I'm a bit confused. The wiki ( https://wiki.dmt-nexus.me/The_FASA_Method ) says:


Does this literally mean DMT saturated acetone, or just acetone that contains any concentration of DMT (not necessarily at the saturation point)?
The common interpretation would be the former, but then it says:


Nothing in this paragraph implies that it relies on the acetone being saturated with DMT.

Neither does it imply that it relies on the FASA being saturated with fumaric acid, although I guess the requirement of saturation may be a practical way to ensure it has enough fumaric acid for volume X to convert Y amount of DMT. This quote seems to confirm that:

Acetone from which some fumaric acid has been removed by means of reacting with DMT to create DMT fumarate is no longer FASA. So acetone containing fumaric acid (but not necessarily saturated with it) can be used as if it was FASA, right?

Another argument is that if you mix:

1. DMT-containing (but not saturated) acetone
with
2. FASA

the mixture of #1 and #2 won't be FASA, as #1 - being under-saturated - has space for fumaric acid.

I think you answered your own question - yes the DMT in acetone solution is saturated for it to more easily and fully react with the fumaric acid.

I once asked similar question and someone told me that acetone can still dissolve some of the DMT fumarate (though very little of it) and hence we make saturated solution to minimize that effect.

I tried it this way and it seems to work much better to drive the precipitation reaction.

If I were to make DMT fumarate today, I would rather use a general solvent like alcohol, mix DMT and fumaric acid (maybe with 5-10% molar excess of DMT), remove solvent by evaporation and then wash the residue with a non-polar solvent. It is more work but ensures no contamination with fumaric acid.

The thing is acetone dissolves DMT VERY well... So to actually saturate acetone with it you'll need very little acetone for a bunch of DMT.

I've always done FASA without saturating the acetone with DMT, but def saturating the acetone with fumaric acid (hence it's called FASA).

When you have very little acetone where your DMT is dissolved, it will be harder to add the FASA slowly because each drop of FASA will be already a large percentage of the total liquid. I find that the best FASA results come from adding very small amounts of FASA slowly, to grow nice large crystals.

I think fumaric acid contamination is not really an issue with FASA.. You can test it yourself, add FASA to just acetone or xylene/limonene (whatever solvent your DMT will be dissolved in later) and see if there is any precipitation of pure fumaric acid, there shouldnt be any.

Cold acetone wont dissolve DMT fumarate in any significant way, but warm acetone might. Making FASA is easy enough to ensure you have enough fumaric acid for your DMT, it favors the reaction. Sure you don't have complete saturation AFTER it bonded with DMT since some fumaric acid will have crashed, but the reaction is already done, and the little bit of extra acetone won't be enough at that condition to dissolve DMT.

Why would you do a non-fumaric acid saturated acetone solution to add to your DMT solution, what advantage is that? Its just easier to add bunch to acetone, mix well, and decant away from excess which you can save for later. If you don't have FASA to start with to mix with your dmt acetone solution, then it might not be enough fumaric acid to react with your DMT (maybe some mono fumarate forms?), and the excess acetone may start influencing how much DMT fumarate stays dissolved ? Im not sure here but certainly some questions arise. You could test out side by side to see if there are differences, but if you don't want to use your time for that, then go for the tried and tested way, jagube.

Thanks guys.

@Endlessness: I wasn't suggesting there might be advantages to using FA under-saturated acetone, it was more a theoretical question. I was trying to understand the principle by which it works.

@blue.magic: In one practical use case, one I'm particularly interested in, where you pull your DMT from dry basified material (a drytek) with acetone (and not a NPS), you don't know how much DMT is in there and therefore you don't know whether your acetone is DMT-saturated or not. But as endlessness says, that shouldn't be a problem.
As as per my last argument in the OP, FA under-saturated acetone shouldn't be a problem either, as the DMT under-saturated acetone already brings a large excess of acetone into the mix and it still works.

I guess one could always precipitate in the fridge and then maybe evap a small fraction of the acetone (like 10%) to see if more fumarate crashes out.

One specific advantage of using FASA (i.e. the solution itself) is that it allows volumetric titration to a certain extent. You will know how much fumaric acid you've added if you're measuring the volume of FASA solution added.

There could be some advantage to using a non-saturated solution (although FASA solution is pretty dilute, all things considered). If one were to decide to use a non-saturated solution (NSFASiA???), it would be prudent to prepare it volumetrically from a known volume of FASA diluted to a specific volume. That way you can still determine the amount of fumaric acid added, and use of a dilute solution allows this to be measured more accurately as each drop contains less of the acid.

Back to the original question, it does not really matter if the DMT solution is saturated or not; indeed, as endlessness says, it's better if it's not saturated as this will promote formation of nicer crystals.

I suspect that the solubility of DMT in acetone is so great that it will behave as it does with ethanol, whereby adding a single drop of 90% ethanol to 400mg of DMT freebase crystals caused the entire mass to shrinking into a surprisingly small blob of viscous liquid.

It would be very simple to test this outline hypothesis experimentally.