From: Matthew Orr (reddevil$##$chem.duke.edu)
Date: Thu Jul 22 1999 - 13:36:14 EDT
There's been a great deal of discussion about drying THF lately. Just to
contribute my two cents, we use freshly opened anhydrous THF, to which we
add hot 4A mol sieves. After 1 hour or so, we add it to the stills with
finely cut and mashed sodium chunks plus a pinch of benzophenone.
Our still is almost always a deep royal purple color, occassionally
turning dark blue. Once a month, we change the still head and start over
with fresh solvent and drying agent. This method seems to work very well.
Recently, we have been discussing the possibility of eliminating stills
altogether. I have heard of a couple of industrial systems where columns
are used to dry common solvents, rather than distillation. I don't know
how effective this would be at removing oxygen or other impurities. The
system is rumored to be fairly good and obviously much safer.
Does anyone have any thoughts on the subject? I would be interested in
hearing opinions on the matter. If anyone knows the specifics of the
process, any info you could provide would be appreciated.
Matt Orr
reddevil$##$chem.duke.edu
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