The chemistry of opium extraction

[Solipsis]

Hopefully this is considered okay - as, might I add, many other types of extractions if you look at PD centralized threads - it is not synthesis.

I am planning extraction of opium, not broad spectrum with say an alcohol, but rather the morphine-codeine selective calcium salt mediated extraction. However I am having trouble understanding the mechanisms behind the commonly used techniques. Apparently after opium is dissolved (hot water I guess) and heating it up to simmering but boiling temps, calcium hydroxide is added. This forms calcium morphenate which is more soluble in water even at higher pH (weird, aren't soluble salts present as separate ions? I never get that type of association.), the other alkaloids, with exception to codeine, do not form such salts and upon the rise of pH from calcium hydroxide they precipitate as freebase. After separation, morphine is crashed out by adding ammonium chloride. I guess this cancels the previously formed association? Is the formation of NH3 the reason?

If I would use calcium chloride to form the calcium morphenate, and would use NaOH to raise the pH to get rid of other substances... would it work? Or does this not provide the same kind of supportive conditions for the alkaline soluble morphine salt?

I also found this information:

The alkaloids in papaver somniferum are present in the plant their pure form, and are combined with so called vegetable acids. Combined with acids, alkaloids tend to be more soluble than the free bases. An early method for the extraction of morphine involved addition of calcium chloride to the filtrate of opium 'soup'. The calcium would precipitate the calcium salt of these vegetable acids as a sort of soap scum leaving a crude morphine hydrochloride.

https://www.erowid.org/chemicals/opiates/opiates_faq.shtml

This both contradict https://erowid.org/archive/rhodium/chemistry/morphextr.html as well as suggest that me adding CaCl2 will result in precipitation...

If need be I could combine NaOH with CaCl2 in a limited volume of water and the limited solubility of Ca(OH)2 should precipitate the latter unless I am mistaken...

I guess it is not the pKa of morphine that is important per se, but the pH should be raised significantly enough to deionize all the secondary alkaloids, correct? I guess pH 10-11 is okay - do I really need extremely accurate pH measurement or is indicator paper okay?

Say this is figured out and I get more info, or I make the calcium hydroxide and follow directions, I may filter/decant from the initial insolubles, and I guess acid/base extraction with cyclohexane is right to do afterwards, and/or using active carbon before reX in ethanol?

(edit: oh I see that at the bottom of that Erowid page there is a pretty comprehensive procedure detailed.. I don't think calcium hydroxide is used, is that why the exact pH measurements are done to single out morphine? In other words can the calcium strategy be used to do this with the work-up of the erowid procedure?)

 

[tryp2fun]

Hopefully this is considered okay - as, might I add, many other types of extractions if you look at PD centralized threads - it is not synthesis.

I am planning extraction of opium, not broad spectrum with say an alcohol, but rather the morphine-codeine selective calcium salt mediated extraction. However I am having trouble understanding the mechanisms behind the commonly used techniques. Apparently after opium is dissolved (hot water I guess) and heating it up to simmering but boiling temps, calcium hydroxide is added. This forms calcium morphenate which is more soluble in water even at higher pH (weird, aren't soluble salts present as separate ions? I never get that type of association.), the other alkaloids, with exception to codeine, do not form such salts and upon the rise of pH from calcium hydroxide they precipitate as freebase. After separation, morphine is crashed out by adding ammonium chloride. I guess this cancels the previously formed association? Is the formation of NH3 the reason?

If I would use calcium chloride to form the calcium morphenate, and would use NaOH to raise the pH to get rid of other substances... would it work? Or does this not provide the same kind of supportive conditions for the alkaline soluble morphine salt?

I also found this information:


https://www.erowid.org/chemicals/opiates/opiates_faq.shtml

This both contradict https://erowid.org/archive/rhodium/chemistry/morphextr.html as well as suggest that me adding CaCl2 will result in precipitation...

If need be I could combine NaOH with CaCl2 in a limited volume of water and the limited solubility of Ca(OH)2 should precipitate the latter unless I am mistaken...

I guess it is not the pKa of morphine that is important per se, but the pH should be raised significantly enough to deionize all the secondary alkaloids, correct? I guess pH 10-11 is okay - do I really need extremely accurate pH measurement or is indicator paper okay?

Say this is figured out and I get more info, or I make the calcium hydroxide and follow directions, I may filter/decant from the initial insolubles, and I guess acid/base extraction with cyclohexane is right to do afterwards, and/or using active carbon before reX in ethanol?

(edit: oh I see that at the bottom of that Erowid page there is a pretty comprehensive procedure detailed.. I don't think calcium hydroxide is used, is that why the exact pH measurements are done to single out morphine? In other words can the calcium strategy be used to do this with the work-up of the erowid procedure?)

I don't see that the calcium does anything besides being a cation. Any hydroxide should work. Morphine is a phenol, so at pH above 10 it forms a soluble morphenate, whereas the other alkaloids remain insoluble and can be separated. The NH4Cl acts as a weak acid and buffer to drop the pH back to ~9, which is the pH where morphine is least soluble and precipitates.

 

[Solipsis]

I don't see that the calcium does anything besides being a cation. Any hydroxide should work. Morphine is a phenol, so at pH above 10 it forms a soluble morphenate, whereas the other alkaloids remain insoluble and can be separated. The NH4Cl acts as a weak acid and buffer to drop the pH back to ~9, which is the pH where morphine is least soluble and precipitates.

Ah! Thanks for pointing out the phenolic nature...
http://pubs.acs.org/doi/abs/10.1021/ef00010a028?journalCode=enfuem

Turns out phenols can form hydroxy calcium phenoxides, so at the very least one would need a divalent hydroxide salt - more likely one of a divalent alkaline earth metal, and not even sure strontium would work. Anyway great, now that I know that calcium hydroxide must be used, not calcium chloride... and it explains why calcium chloride can result in precipitation instead.

Furthermore, in this recent thread there was similar discussion, about the solubility of morphine not seeming simply linear but having a minimum in this case.
http://www.bluelight.org/vb/threads/406576-Very-unexpected-results-from-morphine-a-b-extraction

It probably has nothing to do with dissociation by an acid, but with the morphenate salt just being more soluble at higher pH where the calcium morphenate is hydroxylated which I suppose is important for solubility - in any case in that form it is more soluble, while at lower pH it's just protonated morphine which is not charged and thus less soluble in the polar protic solvent that is water.

NH4Cl is easily made so I won't be looking for another alkaline buffer.

 

[neurotic]

i can't answer your question but i just felt the need to say (what you might already know yourself, and might not be important for you for whatever reasons) that, in my experience, the opium high is infinitely better than morphine (or codeine) alone, no matter the dose or ROA, even though i can't make (much) sense of it pharmacologically.