[The Guy]

I am working on a reaction between 2-Napthol (or 1-Naphtol) Malononitrile and anisaldehyde to afford the attach molecule (this should be from 2-napthol)
In Lit, they report in several papers that they purify the product by only recrystallization out of EtOH without the need for further workup, I have tried that, with no success. The product have some solubility in EtOH in rt, also the starting material and the other by product have similar property, I don't get how that would work?
I add hot EtOH to the crude, then let it sit overnight, then filter it. Should I add drops of water to enhance the process? I notice that water give me precipitate, but they are fine-solid that wont stay on filter funnel.
Any advice appreciated.

[Babcock_Hall]

I have no specific knowledge of this system.  One thing to try is to recrystallize using as large a change in temperature as possible.  Are you dissolving in the minimum volume of hot (almost boiling) ethanol?  Are you chilling first to room temperature, then to ice-water temperature?  If the solubility in cold ethanol is too great, then a mixed solvent system is a possibility.  After dissolving in hot ethanol, you would add drops of water (where it would seem that your product is less soluble) until you began to see cloudiness, then slowly back off with a few more drops of hot ethanol, just until the cloudiness redissolved.  Then let the solution cool to RT, then to ice-water temperature.  Slow cooling tends to allow larger crystals to form. 

[The Guy]

I have no specific knowledge of this system.  One thing to try is to recrystallize using as large a change in temperature as possible.  Are you dissolving in the minimum volume of hot (almost boiling) ethanol?  Are you chilling first to room temperature, then to ice-water temperature?  If the solubility in cold ethanol is too great, then a mixed solvent system is a possibility.  After dissolving in hot ethanol, you would add drops of water (where it would seem that your product is less soluble) until you began to see cloudiness, then slowly back off with a few more drops of hot ethanol, just until the cloudiness redissolved.  Then let the solution cool to RT, then to ice-water temperature.  Slow cooling tends to allow larger crystals to form.

I've not use cold bath, I was trying to avoid rapid cooling to grow better crystal. I missed the point of the solubility in cold EtOH. I will try to put it in ice bath after it reach room temp. Thank you for the great advice.

About adding water, I didn't get that clearly. Now after adding drops of water the cloudiness will appear, which I think is the begging of the crystal forming, what is the point of adding EtOH again to reverse the effect?

Thanks a lot

[Babcock_Hall]

If you add water and see some small crystals (which might be manifested as turbidity), then you are just past the solubility limit.  Adding a few drops of hot ethanol will redissolve the small crystals and allow large crystals to form slowly upon slow cooling.
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