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Larry King

Dean Stark v/s Packed Reflux column

Larry Rafey  Follow
Thanks all, the solvent is water miscible, n-butanol. As both water and butanol rise in the reflux column, it was envisaged that the water would be adsorbed by the eg 3A molecular sieve ( granules ) leaving the n-butanol to trickle back into the reaction flask. Other desiccants like MgSO4 can adversely affect the outcome due to probable ion participation.
Molecular sieves have a water adsorption capacity of approx 20% w/w, retain water upto 200 deg c fluid temps, unreactive neutral conditions, 3A does not adsorb large molecules like n-butanol, can be recycled.

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Aileen Sotin  Follow
The apparatus is not complex.  It is one piece, the trap.  Then a condenser is attached above it.  As long as water is not free to react in the reaction and the equilibrium is shifted to products, it does not matter.  I have no comment on sieves since I have never done that.  What solvent are you trying to use.  Water usually needs to form an azeotrope.

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Christopher Patterson  Follow
DS is always way easier and less expensive.
           -Z

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Catherine Salierno  Follow
Also, sieves are available either balled or as a powder; there's no need for the cartridge apparatus you describe, just filter them off at the end of the reaction. Or use MgSO4 instead, it's a good dessicant and a Lewis acid so good for e.g. imine formations (sieves are generally a bit basic).

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