Well, I proceeded with other extraction, but this time I did
HCl salting/titration from the (few times reused)toluene. It estimated 2,7% contents of the alkaloids. I have pulled(after basification by NaOH) it few times with hot(60C) heptane and recrystallized in a freezer. This yielded 1,33% of white crystals and 1,56% of yellow fraction, which after drying crystallized to hard yellow crystalline powder. The yellow fraction was not recrystallized for better purity, because the fuller spectrum might be preferred by some.
Both fractions were FASA'd to get dmt fumarate in next step.
This approach seems to be better than direct FASW salting where some problems were detected before. The result (2,89%) is in line with the estimated 2,7%, which is much better than when fumaric acid was used for salting/titration. Re-x with heptane is far easier than re-x of fumarate with IPA, which hardly worked for me.
For the white fraction - even last traces of yellow were removed when doing FASA. I used hot acetone for FASA, put it there within a minute (not slow addition), stirred it and let it sit for about 20 minutes to hour. Then I poured off the tone and pure white fumarate was acquired. If I let the tone with the fumarate for a day, the traces of yellow covered the top of the white fumarate. I suspect it stays dissolved in the tone when hot and precipitates when getting to room temperature.
For the yellow fraction - yellow fumarate is the final result. Which was expected and appreciated
Anyway, the results are :
1. Toluene seems to be good for initial extraction. It gets everything out of the basic MHRB solution.
2. HCl salting/titration is good for getting goods out of the toluene. The toluene can be immediatelly used for next pull and we know whether next pull is necessary. And there is no need to reduce the np for freeze-precip, we can reuse it all
3. Hot heptane pulls leave behind a lot of impurities in the water(mostly the red color, hot heptane is yellow) and they serve as a re-x at the same time, which separates the yellow
4. Classic FASA for fb=>fumarate conversion is much better than salting/titration by FASW. It generates better crystalls than water crystallization. Much easier to work with