flakten
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Vacuum Desiccator vs Rotary Evaporator
This question will probably seem foolish to you experienced chemists, that's why I posted it in "Beginnings".
The question is simple: What are the different advantages ad disadvantages of a rotovap and a vacuum desiccator?
Temperature control? But with a bit of craftsmanship you can control the temperature in the desiccator too.
So why do some chemists spend £1-2.000 on a rotovap?
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Sulaiman
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I believe that when a rotovap is used, the solvent is condensed and recovered,
A vacuum dessicator removes but can not recover the solvent due to the vacuum.
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flakten
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So solvent recovery would be the only advantage?
But I use a vacuum desiccator an I have solvent trap so that the solvents don't damage my precious pumps.
But either way the solvent can only be reused for identical experiments since it will now contain trace elements of chemicals, products and side
reactions.
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NitreRat
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Rotovaps are capable of removing much more solvent than most vacuum desiccators are capable of. Vacuum desiccators are normally just used for drying
solids which still contain small amounts of solvent and are too temperature sensitive for lab ovens. Rotovaps also have the advantage (over normal
vacuum distillation) that they rotate, which greatly increases the rate of solvent evaporation. More expensive models also have many adjustable
settings tailored for specific solvents so you can safely leave your experiment for long durations of time. In a professional lab you can't afford to
be constantly carefully controlling your vacuum desiccator's temperature. Another advantage I can think of is that they fit ground-glass jointed
glassware so you can use the same flask used in the reaction, reducing transfer loss.
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beerwiz
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Rotavaps remove the solvent much faster than regular distillation or a vacuum dessicator. But I've found that if you do a regular distillation but use
a magnetic stirrer, the speed of the vacuum distillation is comparable to the rotavap.
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Sulaiman
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Nero-post to leave this thread with a good answer,
posted due to new video https://www.youtube.com/watch?v=uTwjlMA-e8I
Summary : quick and nice but expensive, solvent rarely re-used.
(so I was exactly wrong in my post above 
CAUTION : Hobby Chemist, not Professional or even Amateur
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Texium
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You can certainly re-use the solvent recovered in a rotovap, so long as you clean the receiving flask between runs and haven’t bumped stuff into
your condenser. It’s just a highly optimized low-vacuum distillation apparatus. NitreRat already provided a thorough and accurate answer.
Also, I’ve never seen that air-inlet tube that NurdRage uses. I don’t think those are particularly common. I’ve always used rotovaps with bump
traps placed between the boiling flask and the rotary joint. They won’t prevent bumping, but they do prevent you ruining your day by having stuff
bump into your condenser, and they allow you to recover whatever was ejected by the bumping. Seeing his setup with no bump trap is very odd to me.
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