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Author: Subject: Is there a way to setup a rotovap so it condenses back into the main flask? An adapter of some kind?
Electra
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[*] posted on 19-4-2016 at 18:30
Is there a way to setup a rotovap so it condenses back into the main flask? An adapter of some kind?


I've been wanting to invest in a rotovap for a while, and lately I've been needing to deal with some reactions that normal stirring(magnetic or mechanical) wouldn't be ideal. As an alternative, if I could find a way to rotate the flask for the reaction I am doing, it would really simplify things.

There are plenty of laboratory flask rollers/rotators, but none of them that I'm aware of enable the attachment of a condenser. If I could find a way to make a rotovap condense back into the main flask, then it could serve a double purpose, reaction followed by solvent removal.

Is there any sort of adapter or attachment that can enable this? I would assume so, I just have no idea what it would be called.
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[*] posted on 19-4-2016 at 19:32


This thread seems to recommend against it, citing that rotovaps are quite delicate and refluxes are easy to perform without one. I'd recommend just taking off the condenser when the reflux is finished and then transitioning to the rotovap: http://www.sciencemadness.org/talk/viewthread.php?tid=18459

That being said, bahamuth does have a nice rotovap reflux setup in the above thread, and this could be the necessary piece: http://www.meadowshplc.com/products/buchi-rotary-evaporators...

Too expensive for me though...




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Electra
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[*] posted on 19-4-2016 at 21:23


The issue I have is that I have a large heterogeneous mass inside of a homogenous solution. I can't reflux it because the mass clumps together and pressure will build up underneath it and then erupt upwards, spewing mess everywhere violently, which I learned the hard way. Stir-bar's wouldn't be effective and a mechanical stirrer would only work if it could scrape the sides of the flask. What would work is if the flask was rotating to prevent pockets of the solution from getting trapped under the mass.


[Edited on 20-4-2016 by Electra]
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Oscilllator
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[*] posted on 19-4-2016 at 23:55


Just tilt the rotavap over until the flask is vertical :)
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[*] posted on 20-4-2016 at 01:00


Quote: Originally posted by Oscilllator  
Just tilt the rotavap over until the flask is vertical :)


LOL nice one! But what happens to the heating bath?

gsd
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[*] posted on 20-4-2016 at 03:26


Get the tiniest flask that will fit on your outlet and pre-filll it with your solvent. On the rotovap models that I have seen when your takeoff flask is full the distillate will shortly (after it fills a few more aberrations) begin flowing back into the flask.



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Ozone
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[*] posted on 20-4-2016 at 04:06


Mine is actually setup for this. There is a valve that shuts off condensate flow to the collection flask (so, it runs back into the pot).

O3




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[*] posted on 20-4-2016 at 04:41


I use a rotovap for mixing and heating solutions occasionally, great for heating recrystallizations to dissolve the material safely. Just don't cool the condenser, and set the water bath temp just below the BP, leave the vacuum off, use a keck or other clip to hold the flask on, and it will act as a rotating heater just fine. As long as the temp is just below the BP and the vacuum is off, the amount of solvent loss is not that much. You really don't need anything special. If you wanted to do this for hours, you could certainly fill the receiver with solvent, and that would work, but I've never done one that needed that type of fix.
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