Hello all, obligatory "im not sure if this is the correct place to post this". I've been here reading for a few months now and have almost finished my first extraction on ACRB (defatted before FB) but I only ran into issues after the fumarate conversion using FASA (not FASW). I wanted to remove excess FA and read that you can remove excess FA via a water wash (dmt-f is soluble while FA isnt), however after washing and evaporating my previously stable crystals were converted into a goo that absolutely will not become powder and is VERY hygroscopic (i already removed fats before initial FASA), its been pain in the butt trying to convert it back this past 8 days.

I've read of a few others who have run into the same issue after a FASW or a water wash of fumarate and many solutions to this issue, ive tried almost all of them except converting it back to FB (via sod. carb solution instead of paste) and doing a FASA again, i had high hopes for the boiling IPA re-x however it wouldn't crash out of the (highly reduced and sub-zero temp) IPA. Currently the conversion tek is going as described (clouding, fb floating to top, etc.) and carbonate mix is in the cooler on day 2. [Edit: i should add, i do have some unwashed crystals from the same batch but no washed in acetone, they are as expected dry and highly active.

My questions are:

1. Is this a common occurrence (ive read people doing a water wash with 0 issue).

2. Is it normal for the FB to linger at the top when doing a sod. carb. conversion? It have a large amount of brown liquid FB just sitting on the top layer and if i followed the tek right it should convert to crystals right?

3. I just want to thank the whole community for providing a knowledge base, especially Endlessness. Their numerous posts in the FAQ section always helped direct me to a solution. So if you're reading this, Thanks for taking time to help educate. Same goes to the other knowledgeable chemists whom contribute to this site.

I don't really have an answer for how common it is, or what the super hygroscopic bit is.

I used to do FASW until i learned about FASA. When i do FASA, i never wash the fumarate crystals with water. There shouldn't really be fumaric acid contam, because its concentration drops due to reacting with the freebase to form the salt, and all of the fumaric acid was in solution even before that drop occurred. So the only way i see for fumaric contam to happen, is due to evaporation of residual FASA if not washing the precipitated fumarate with dry cold clean acetone enough.

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I have done water/sodcarb conversions several times, and yes it is pretty normal for the freebase to form an oily layer on top. It may or may not harden on its own, what i used to do was place it in the freezer and take it out when the freebase was hard but the water wasn't frozen yet.

There is (at least) one way to get crystals in the bottom in a water/sodcarb conversion, you probably read that. I've made it work once, and tried two more times but ended up with the layer on top. I'm not sure which are the crucial points that made it work that one time.

In my attempts, once the freebase did form a layer on top, it would not sink and produce crystals anymore. You could re-x in heptane for large beautiful crystals

Thanks for the input HT, at least i know its somewhat normal. The salt contam occured because i added too much FA but now in hindsight it wasnt necessary to wash, FA is safe orally i just had to adjust my calculations.

As far as ive seen you're correct, the oil doesnt seem to be dropping but very few light brown crystals have started to gather at the bottom. I would pull and re-x but im all out of NPS until next week. At this point my next steps look like; decant/filter the goopy fb, then dissolve in hot acetone and perform A FASA again. Hopefully that'll take me back to stable crystals. Otherwise im going just have basify and pull with hexane.

Thanks again for sharing your experience with the sod.carb. conversion.

Edit 48 hours later: So the sodcarb conversion didnt work for me, although the ph was correct and I did get fb goo, it didn't crystallize. I've filtered the solution and am drying the FB, next step add acetone and do a FASA. Wish me luck.

Update: After drying the FB and dissolving in acetone, i did added FASA and the expected crystalline formations are building. So it turned out a success although in positive i have some decent yield loss from so many experiements. Next time i know, if you got goo and want fb crystals, re-x in light NPS. If you have goo and want fumarate crydtals do a FASA.

Various things have been learned but mainly NEVER EVER wash the fumarate in water just wash in cool acetone, if converting from fumarate do the paste>pull->freeze precip. method or just do a STB-pull. IPA re-x of fumarate is mostly theory from what ive gathered by endless and the others. I'll be around leaving notes on things i think may help future explorers.