Re: ORGLIST:problem of reduction

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From: Norwid-Rasmus Behrnd (behrndnr$##$yahoo.de)
Date: Thu Jun 03 2004 - 13:33:49 EDT


Dear Stephanie,

one alternative thought could be a purification of your alcohol via a derivative which
could be less polar - by this better soluble in organic solvents - to seperate by this
remaining starting material and after that, in a secound step, to come back to the
initial envisaged product. What about an ester like obtained with p-Nitrobenzylchloride ;
but maybe your compound is not only polar due to a Hydroxyl group but possesses amines,
too. Is this the case ? Alternativemt, it could be an ether instead of an esther, as
silyl ethers, for example are known as "trick" to mobilizing preparation of polar
substances for gas chromatography.

Norwid

 --- stephanie <roulle.stephanie$##$wanadoo.fr> schrieb: > Hello everybody,
> I have a problem with a reduction. I want to reduce an ester to an alcohol with LiAlH4
> / THF. The reaction is perfect but my problem is the treatment. The alcohol obtained is
> very cristalline and insoluble in all solvant. It precipitate when I treat my reaction.
> I tried to hydrolyse with HCl and extract with dichloromethane and there is
> precipitation. I also tried to hydrolyse with Na2SO4 with water and also precipitation
> and I cannot separate Na2SO4 and the obtained alcohol. I tried at last to hydrolyse
> with THF/water, there is also precipitation, I evaporate the THF and put isopropanol
> and filtrate. The problem is that my yield is over 100% because I have also aluminium
> hydroxyde and I cannot separate them of my product.
> Can anybody help me please ???
>
>
> stephanie

        

        
                
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