Is the impact of purification that significant?
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The content of the crude product is 95%; why then, after purification to achieve a content of 99%, the yield is less than 70% of that of the crude product? I use DMF as a solvent to dissolve the crude product and then recrystallize it with ethanol. Could anyone with experience give me some advice? Thank you all
The crystallization mother liquor contains some substances that have not yet crystallized, possibly because these substances have a certain solubility in the DMF-ethanol mixture. It is difficult to give accurate advice since the properties of these substances are unknown. You can try recrystallization using water as the anti-solvent. Additionally, considering lowering the temperature at the crystallization endpoint for cooled crystallization is also an option.
Try using other solvents to see if you can purify it. It may also be related to the amount of ethanol you add