I wanted to make some more THH and needed a new load of Harmalas. I was using different sources on about at which pH I need to stop freebasing ... my old protocol (retrieved from somewhere here) told to stop at pH 7. That is just neutral and therefore I was wondering if indeed you can already freebase a huge load even in the acidic range (pH 6,5 -> 7). Then the VDI Protocol was not somewhat clear, but those complicated diagrams seemed to show that you should slowly freebase until 7,6 to get mostly pure Harmalin.
I used a pH electrode and calibrated with 3 points before doing the separation, but man ... even at pH 7,6 there was no precipitation.
So I went rather freestyle and just throw inside a huge load of NH3 in increments. After every load I I exchanged the pot and collected that fraction. I got 4 in total, but because I did not even dare measuring same amounts of NH3, the total amount of every fraction was completely random. To then have a chance to know which one I might use for THH conversion, 1H-NMR spectroscopy was conducted. That post here now is rather just informative as I have that data anyways.
Still it shows that at least i nmy case even at the beginning the Harmine precipitating is not completely pure. But I have to add, that this might also come because of just dropping a huge bomb of NH3 inside: In the respective volume element the amount of Harmaline might drop so fast that then freebasing of Harmaline (which only should appear later) will also occur, as there is no other Alkaloid to be freebased instead. The perfect way would have rather included stirring the solution at the absolute maximum, while only dropping NH3 inside at the absolut minimum.
So while it might be possible to precipitate the Harmine more carefully, it could still be used as a reference for kitchen chemistry, as people might also more do the ghetto method like I did, rather than titrating their Harmine with 1 ml NH3 / minute.
There are 3 ways to identify the different Harmalas and calculate the ratio from that:
I. ratio of the indolic NH-signals #1
= bad as these protons are loosely bound and their integral not to be trusted too well
II. occurence of additional 2x sp2 R-CH=R units from Harmine (position #6 + #7) at 7,80 ppm and 8,15 ppm
= better than I. in terms of reliability, but it can be even better
III. ratio of R-CH3 peak of Methyl #4 at 2,26 ppm (Harmalin) and 2,73 ppm (Harmin)
= good, but might be hidden with trance impurities
IV. ratio of MeO-R peak #14 at 3,80 ppm (Harmalin) and 3,89 ppm (Harmin)
= Signals are partially mixed, so not perfectly accurate, but well enough to give a +- 5 % ratio I just assume.
Actually I. and IV. are so remote from the actual structure unit that is changed between both, that it should have no influence on the signal anymore ... but seems like it still can have indeed, good for us.
Now all the NMRs are not posted here. I only took the time to align the signals to the structure to the first one. But just refer to this one to identify the rest. To see spectrum, just click on the name.
Fraction I= 31 % of total precipitated Alkaloid content
= 89 % Harmin
Fraction II= 31+16 = 47 % of total precipitated Alkaloid content
= 77 % Harmin
Fraction III= 47+13 = 60 % of total precipitated Alkaloid content
= 25 % Harmin
Fraction IV= 60+40 = 100 % of total precipitated Alkaloid content
= 16 % Harmin
Sidenote here:Again no Vasicin can be seen. We would easily identify it at ~ 4,50 ppm with a Singulett, Integral = 2 which is derived from the middle ring R-CH2-N Unit. It's not here so I conclude no Vasicin present. And that is important because I did not do any Manske and just went with
1. Cook at pH 3
2. Basify to pH 11
3. Wash until neutral
That is a much faster way than doing the re-precipitations for multiple cycles and as I would say based on that spectrum are not having any benefit, when excessive washing also leads to no Vasicin present (if it was present at all ...).
Now here is just a small graph showing everything:
So what I can say is that at least in my case the separation seems not to happen in such perfect windows, but it's probably ok as a good starting material for THH conversion. Also at first these points may seem a little random, therefore I also added a sigmoidal curve fitting to illustrate what is actually happening. Now you can clearly see how the content of Harmin is high at the beginning and then quickly drops at around 54 % in favor of Harmalin. But to really identify the ratio between both the NMR of the combined extracts must be measured like here, which shows roughly a 1:1 or at maximum 1,05:1 of Harmin:Harmalin.
Now a small funny anecdote last:
I just took a look at those NMR samples again after a few days. And I saw something weird. To me Harmalas have always been a little boring in a chemical sense, bad solubility, low reactivity (Once by accident I roasted Harmalas for 10 h at 160 °C and nothing happened). It took even quite a while to dissolve 10 mg Harmalas in 400 µl DMSO at 70 °C, but now after those days I saw some precipitate again. Well not too crazy, but it was WHITE:
So I did not remove DMSO so far and maybe coloration will change a little. But I was thinking Harmalas are always tan? And that NMR does not show any major impurities, so it must be the Harmalas itself?
Would be funny if that tan colour is just some remainder from the seed extraction. Will now just throw like 100 mg Harmalas in boiling DMSO and see how it looks after several days ...
PS: THH purification is further down.