RE: ORGLIST:problem of reduction

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From: Maringanti Krishna (maringanti9$##$yahoo.com)
Date: Sat Jun 05 2004 - 01:25:24 EDT


Stef"
Alternatively, you can also try a normal work-up..(addition of a cold, saturated aq. sodium sulfate solution to your LAH reaction mixture) that leaves you a granular precipitate. Dump your solids into boiling water and filter them hot. You should get your compound more or less pure with trace Aluminium impurity.
If you want further purification, and if you are convinced that your alcohol is soluble in Methyl or Ethyl alcohols (even very little solubility is fine), then go for a Soxhlette extraction. Aluminum salts remain in the thimble, you get your compound nicely into methanol (though it might take some 24 hours, and several cycles, you can leave the set up alone, as Soxhlette does its work).
Gooz luck!
PS: If your alcohol is so insoluble, how do you check its purity anyway? How do you check its NMR spectra for example?
Or, Can you sublime your alcohol?
What is the parameter for checking its purity? If HPLC what is the solvent system?
Also, if you find that your compound is forming an intractable gel, there are ways to break the gels! For example try to filter your substance through three or four Whatman filter papers under high vacuum. (you may have to cool the flask where you collect the filtrate).
If nothing else works, make your solid absolutely dry and derivetize it to a methyl ether. You can always remove methyl ethers with HBr in dichloromethane!

                
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