The issue with crystallization
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Is it true that the higher the production temperature, the less likely solvation crystallization will occur? The products manufactured by our company contain antioxidant 1010, which does not crystallize when cooled. Could someone help analyze this? Ethanol is added before cooling to facilitate crystallization of antioxidant 1010, serving as a solvent for it.
Has the ethanol solvent been completely removed before crystallization? If ethanol is still present, it will lower the melting point of the solution, making crystallization more difficult.
Impurities have an impact on the crystallization process, and the speed at which the temperature is reduced also affects the quality of crystallization as well as the size of the crystals
Antioxidant 1010 is presumably a pentaerythritol ester; its solubility in alcoholic solvents increases as the temperature rises. It tends to crystallize easily when the temperature drops. Perhaps there is too much solvent present – in that case, considering concentrating it or using some seed crystals to induce crystallization might be an option. Mixed solvents such as methanol, methanol-water, ethanol-water, isopropanol-water, or ethanol-ethylene glycol could also be used, with the principle being that the greater the increase in solubility as temperature rises, the better.
When selecting a solvent for recrystallization, it is preferable to choose one whose solubility changes significantly with temperature – that is, a solvent with high solubility at high temperatures and low solubility at low temperatures, as this facilitates good crystallization. In the owner’s case, it’s possible that the saturation level is not sufficient. I’m not aware of the specific circumstances and procedures you used; you could try carrying out the process under reflux conditions, using just enough solvent to dissolve antioxidant 1010, and then proceed with cooling for crystallization. Do you also have the data on the solubility of the impurities that need to be removed?
Are there any data on the solubility of the impurities that have been removed? What does that mean? I’m not quite sure. The solvent we use is distilled; could it be because there are too many impurities in it?
There are several reasons for non-crystallization. 1. The low 1010 content results in an increased solvent:solute ratio, making it difficult for crystals to form. 2. The rapid cooling rate prevents the formation of a large number of crystal nuclei, causing the solution to enter a supercooled and supersaturated state directly. 3. There is a problem with the solvent; usually, the water content is too high, which results in disordered crystal formation of 1010 and makes the material sticky, making centrifugation and drying very difficult. 4. The effect of rotation speed: it is possible to consider adding seeds at an appropriate speed to induce crystallization.
The failure to obtain crystals is likely related to the yield of your reaction. Crystallization is a purely physical process; certainly, using ethanol as a solvent has some effect on crystallization, but that effect is minimal. I think the cause lies in your previous reaction processes
It is likely that the solubility of your product in the current solvent is too high, which makes crystallization difficult; evaporate some of the solvent first to facilitate crystallization! ! !