I followed instructions in "The DMT Handbook" (with 201208 in the title, so presumably the 2012/08 edition) to convert DMT freebase to DMT fumarate. (This was probably a poor choice, as I have been told here that some of the information found in the booklet is misinformation.) Specifically: 500mg previously-recrystalized, off-white freebase powder dissolved into 10ml acetone and 200mg fumaric acid dissolved into 50ml acetone. Solutions mixed and let to stand, covered.

A couple of unexpected things...

Between hours 12 and 24, no visible change occurred in the crystals that had formed; however, almost as soon as the acetone was decanted into a second container, crystals began forming there, too. After 24 hours, the second container had approx 1/3 as much salt as the first. (Have not weighed yet, still drying.) My understanding was that since the DMT fumarate is not soluble in acetone, the amount that had precipitated out would not be an impediment to further precipitation. What might have been going on here?

The first batch was washed and drying begun. There is a thin film of goo on the glass drying surface. I've read that many DMT salts are goo but fumarate is not—and, indeed, before washing I detected no gooeyness and after washing there is plenty of powder. Is this unreacted freebase or what?

I just read the technique of adding excess fumaric acid to acetone and decanting it once saturated. This seems like a better method than weighing out the fumaric acid. Whoops.

The goo dried hard and scrapes up to look like the rest of the salt, so I'm hoping that it is like the rest of the salt. I still feel like I'm lacking a significant piece of information though: If the DMT fumarate is not soluble in acetone, how was this sticky film formed?

When the original acetone mixture was moved to a third container, it continued to precipitate a small quantity of salt. My assumption is that I simply deceived myself about the crystals having stopped growing the first time and that formation and precipitation of all the fumarate can take 48+ hours.

If, just to be sure that my work product is reasonably pure, I wanted to test the powder for the presence of unreacted freebase, would the right thing to do be to ensure that it is well powdered, place it into a small quantity of acetone, stir thoroughly, and test the pH?

If the acetone has absorbed moisture from a humid atmosphere, more DMT fumarate may dissolve in it.

To test the pH of your acetone, you'd need to put a drop of it onto a pre-moistened piece of indicator paper.

I found working with FASA and DMT freebase to be a bit fiddly at times too. Some of this might be down to polymerisation of the DMT and various facets of the ensuing non-linear behavior.

Humidity hovers around 50% here lately but I do not have a good means to seal the acetone-containing beakers. I've used foil and a rubber band.

I'm not sure what to take from this comment, though. It makes sense that any water in the acetone could hold DMT fumarate but my feeble brain is having a hard time fitting this into what's happening with my process. Are you offering the presence of water as an explanation for how I could end up with the gooey stuff that dried hard? Makes sense but I'm not certain that is what you meant.


Good tip. Thank you. Does pH test paper always require an aqueous solution? Does that come down to practical knowledge or is there a principle by which I could have derived that information?


Ah, yes. Of course. ;-) (Way over my head.)

pH paper is indeed designed for use with aqueous solutions. It may be the case that dry pH paper would still show a useful colour change with FASA, but as a rule a drop of water can only help when looking for a rough indication of acidity in a non-aqueous solution. It's simply easier than trying to determine the presence of unreacted fumaric acid using any other method.

[I'm not sure how I learnt this - some of it from classes, some of it from practical labwork, some of it from tips from other chemists along the way including over a decade of interactions here at the Nexus.]

That's about right. Some small proportion of the DMT fumarate gets held in solution by dissolved water, at least possibly.

Moisture in the acetone might also promote polymerisation of the DMT freebase, or we might be seeing an excess of fumaric acid. The fact that it's a goo suggests it could even be a mixture of these things.

Another possibility is that it's a small amount of NMT (showing up as the fumarate), which is known to occur at a trace level in MHRB. Without a proper chemical analysis of the goo this is all just informed speculation.