Any strong acid will work fine, but so far by far the best results i've seen have been when using phosphoric acid. I'm not sure why exactly, but perhaps DMT phosphate is more readily soluble in water than other DMT salts, plus phosphoric acid may penetrate cell walls more effectively than other acids. Since using vinegar (acetic acid) i have seen yields consistently more than double
A pH of 4-5 is ideal. As I understand it, for 99% of the molecule to be salted, the pH needs to be lowered to greater than 2 of the pKa of the molecule. Eg, pKa of DMT is 8.86, so 6.86 should be adequate. Another two points for good measure.
Furthermore, the DMT to phosphate bond is seemingly very solid and it can withstand concentrated pH solutions. This counts in during the reduction of combined acid cooks (but is not limited to). It seems that the DMT to acetate bond is not that strong, and when the DMT acetate molecules are being bombarded by free acetate molecules wanting to form bonds, the DMT acetate breaks apart resulting in the reduced yield. Phosphoric acid and likely other strong acids (HCL, sulphuric) may not have this problem
One byproduct that i'm aware of that will be formed when basifying are salts formed by unused acid molecules. Eg, you will have a lot of DMT phosphate plus a lot of phosphoric acid molecules. When basified, DMT phosphate is formed as well as some kind of phosphate based salt (like how HCl and NaOH produce NaCl and H2O). I Guess the other product formed is water. Either way, both these products are water soluble and will stay in the aqueous and not migrate into the NP.
I haven't had any experience with Na Carb so I can't comment on how it behaves differently from NaOH
Also, if you carefully control your temperature when doing the NP pulls, you don't really need to worry about defatting. Say you reduce your acid cooks, once done, pour the reduced liquid into an extraction vessel (5L HDPE jug is the best). Pour the liquid into the vessel right after you turn off the heat, then let the liquid sit for 15-20 mins. Then add your NaOH (premix with water while you are waiting) and NP and shake and separate. This gives enough time for it to cool to a temperature that won't result in excess amounts of oils getting into the NP, but will still be hot enough to maximise the DMT base solubility in the NP
unless of course you are evaporating to recover product
but with the advantage of freeze precipitation.. why would you do such a thing?
