What solvent should I pick for recrystallization to improve yield?

[Paul_T]

I’m trying to purify a solid I synthesized using recrystallization from ethanol, but my yield is dropping way more than expected. I’m worried my solvent choice might be wrong because the compound seems too soluble even when the solution cools in an ice bath.

[MatthewER]

I’ve done the same thing with a solid that looked fine when hot but stayed stubbornly soluble in ethanol as it cooled. The yield would crater even though I clearly saw some crystals start to form. I keep thinking the solvent is pulling too much of the compound back into solution at low temperature. I seeded the solution and gave it a long nap on the ice bath, but the overall amount attracted into the mother liquor stayed higher than I expected. Maybe there’s a small impurity that’s staying dissolved with the solvent.

[BrianD]

Could the real issue be decomposition or a solvated form with ethanol rather than simple solubility?

[Madison_B]

I keep drifting back to that thought about drying the starting material and the solvent. I once forgot to dry the solid and the recrystallization behaved completely differently; the crystals were cloudy and the yield was lousy. Then I checked the powder under light and it looked a bit oily, which makes me wonder if I’m chasing the wrong problem. Anyway, maybe a quick sanity check on moisture content could save time before you chase solvent tricks.

[SofiaZR]

I did try changing the solvent vibe a little by mixing in a bit of water with ethanol to cut the solubility at cold and it helped the crystals form, though not perfectly. The yield bounced around and I wasn’t fully confident in the purity, so I stopped there and kept notes rather than repeating. It felt like the right move to test a different polarity, but I can’t say it fixed the root cause. If you have a melting point or a simple impurity check, that might tell you whether the low yield is really the solubility problem or something else.