[Memo. M]

please.... I want your help ASAP..

how can I crystallize:

1- methyl orange

2- alizarin

3-Fluorescein

and what is the suitable solvent for them?

thank you...

[OC pro]

For all three compounds use EtOH/water mixture. Dissolve the compounds in hot ethanol (must be as minimal as possible), then add same amount of water (should see precipitate forming). Put it in the fridge and let the solid crystallize.

[Memo. M]

thank you very very very much for you..oc pro

I do it successfully with methyl orange & alizarin

but when I mix little amount of ethanol with Fluorescein..it dissolved


If I use Petroleum ether or Chloroform..does it work???

[OC pro]

Pet Ether will not work since Fluorescein will not be soluble at all and it will also not be miscible with water.

You can try chloroform, acetonitrile or a Pet ether/ethyl acetate mixture. I always take a small amount of the compound which I want to recrystallize (~5mg), put it in several test tubes and add various solvents (few drops) to the different test tubes. If it will not dissolve at room temperature (this is good) I just heat a bit and have a look what happens. 
Good luck!

[Memo. M]

thank you so much for your help....
I really appreciate it..