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In general, what is the best type of column used for fractional distillation?

  1. Nov 24, 2006 #1

    jzq

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    Many university organic course laboratories use Liebig columns packed with glass beads. This is what I use, but I would like to know if there are better columns that can be used instead of this. I had a problem with this type of apparatuse before. The glass beads shot right through the $30 adapter and broke it. Of course, its my fault since I did not secure the glass beads with a copper scrub but I would like to avoid something like this from happening again so I would prefer to use a different and more efficient column. I know there are other types of columns such as the Vigreux column, Snyder column, and etc. So what is the best column to use for general fractional distillation?
     
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  3. Nov 28, 2006 #2

    chemisttree

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    I have found that vacuum-jacketed vigreux columns work well but the snyder column is supposed to be more efficient. Never actually measured effeciency for a "general" fractional distillation but I believe that the vigreux column will have less holdup and would be better for smaller distillation volumns (50 mL or less). It can also be used for vacuum distilling wheras the snyder column is very difficult to use under vacuum.
    I've never had a packed column shoot packing up into the head. Stationary packings (like the vigreux) would avoid that but the reason for the pressure surge should definitely be addressed regardless of the column. Bumping can be addressed by adding boiling sticks or stones but don't work well under vacuum. Rapid stirring works the best with vacuum distillation.
    That's my experience... hope it helps.
     
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