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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: g-bones on November 11, 2008, 08:41:34 PM

Title: getting rid of bromoform...?
Post by: g-bones on November 11, 2008, 08:41:34 PM

I am currently using bromoform as a solvent in a carbene (base + CHBr3 = :CBr2) addition across an alkene to form a halocyclopropane.  The problem is, once the reaction is complete getting rid of the bromoform is a total pain (bp is about 150 and it is not very volatile at all).  I columned out some of it, but still some remains.  I would use a kughelror but this still does not result in a complete removal and always gives a mixture of decomposition of my product and bromoform in my product.  I have been azeotroping it with CH2Cl2 and it is coming out but is taking a very very long time.
Does anybody have a suggestion for removing this dreadful solvent?

Title: Re: getting rid of bromoform...?
Post by: Two00proof on November 12, 2008, 10:45:12 AM

I've only used bromoform once, but if I remember correctly, what I did was adsorbed the product onto silica gel, then ran a column on it with an initial flush of ether or maybe hexane.  This effectively washed out the bromoform leaving my product at the top of the column, then I ran the column as you normally would.  Of course, this may not work for all compounds.