The molecule I am trying to crystallize is an indole based alkaloid that I used a liquid-liquid extraction process to extract. The organic solvent that I use is d-limonene, so there is a lot of non-alkaloid "stuff" in solution. I am not exactly using a reactor vessel, I have steel buckets that are seal in 130F temps. I have used a sonicator probe to induce crystallization before. The solution was 172F and the precipitate was 55F. The liquid is seeded with a 99% pure crystal that I have crystallized in the past and it was confirmed by HPLC from a 3rd party lab. I do not have control of the crystallization vessel as far as temp, pressure, etc. We're working on getting a reactor, as well as a particle viewer. The alkaloid is poorly water soluble, but is acid soluble (labile at pH below 2 and temps above 80C for a longer period of time). The solubility of the acid is due to the a hydrogen addition on a nitrogen that exists in one of the rings (this I am getting from MD software and Avogadro. I am assuming it is correct).
As far as "the devil is in the details" what else would you like? I provided the pKa of the alkaloid in question, I can't really go into the non alkaloid components of the solution as I have not been able to get an exploratory test run to know exactly what they are. However, I am fairly sure they are common plant starches/waxes/carbohydrates/polymers. Polymers can be used to prevent crystallization, and I've done some experiments in the past to be relatively sure that this is the case (I took a solution that normally would crystalize well, reduced the volume with evaporation, no crystallization, replaced the volume with water, got it to crystallize. to me this indicates the concentration of non-alkaloid constituent is important). The volumes of liquids I am dealing with vary between 3 liters and 50 gallons.
The alkaloid has 3 diasteromers, as well as 3 or 4 other closely related indole-based alkaloids that tend to be present. The acid I'm using is acetic acid, and the base I use to increase the pH of the solution is calcium, sodium, potassium, or ammonium hydroxide.
I guess my main question, isn't so much to do with my process, and more the fact that there are crystallization/precipitations that are heat catalyzed, which I was always taught to be the opposite, however, as i've recently learned, calcium hydroxide is less soluble with warmer temperatures. So there are some substances that
