[carrielynn]

What is a good solvent for crystallizing impure fluorene - water, methyl alcohol, or toluene? The experiment did not go well and I didn't get any crystals, so I'm trying to find out which one would have given me crystals so I can figure out where I went wrong.

Also, what melting point should I expect from these crystals?

[macman104]

Which solvent did you choose, can you explain the process you used to try and recrystallize the fluorene?  Which of the structures for those 3 solvents do you think looks most similar to fluorene?

By the way, the wikipedia page has the melting point and structure

http://en.wikipedia.org/wiki/Fluorene

[carrielynn]

Thanks. Well I think toluene looks the most similar, but so much dissolved at room temperature I thought it was too soluble. So I tried heating water and methyl alcohol, and each time there did not appear to be any dissolving. I didn't see the difference between them.

[zhangbo2007]

Thanks. Well I think toluene looks the most similar, but so much dissolved at room temperature I thought it was too soluble. So I tried heating water and methyl alcohol, and each time there did not appear to be any dissolving. I didn't see the difference between them.

Fluorene is soluble in benzene and ether. Why not try either of the two solvents?

[carrielynn]

Just because I'm supposed to determine which of the three is the best.

I read that fluorene is insoluble in water. Toluene dissolved at room temperature, and methanol did not. So I'm guessing methanol is what I should be using?

[pantsboy]

You are correct.  It's too soluble in toluene and insoluble in H₂O so Methanol is your best choice.  Bring the solvent to its boiling point (~65°C) and add just enough to barely cover the sample.  Let it cool to room temperature and crystals should begin to form.  If you still see nothing after about 15 minutes, I would scratch the edge of the glass which will give the fluorene a surface to start recrystallizing on.  Transfer it to an ice bath and let it sit for a while to make sure you get as many crystals out as possible.

if you decide to test its melting point, Fluorene is listed as having a range of 116°-117°C.  Just make sure crystals are nice and dry before you test it otherwise you'll get an inaccurate reading from the moisture depressing and broadening the melting point range.

hope this helps and good luck!