[eb51111]

Hi,

I'm setting up a rotary evaporation system to routinely remove chloroform. It's a pretty basic setup - i.e. without digital vacuum control.
My question is with a water bath temp of 40°C, CHCl₃ should come off OK - however with just tap temperature water running through the condenser (no chiller unit) - will the pump be OK without a secondary trap inbetween condenser and pump, as I know chloroform could have detrimental effect on pump oil/seals?

I'd be very grateful for any suggestions on how to ensure we don't damage the pump.

Thanks

[rolnor]

You will get most of the chloroform in the pump. Can you use hotter bath and aspirator?

[eb51111]

You will get most of the chloroform in the pump. Can you use hotter bath and aspirator?

Potentially yes. But given the choice I'd rather use a pump as it should be quicker - what about a Buchner flask with ice in between the condenser and the pump? Something along those lines... or how effective would a chiller unit be (to cool water to approx. 5°C) with chloroform?

Thanks

[OrganicDan96]

i would use a trap with dry ice and acetone

[eb51111]

i would use a trap with dry ice and acetone

Yes that is an option, but I need it to be used 24hr's a day all year round and dry ice would be too expensive - I need a permanent solution.

[OrganicDan96]

could you have a trap with a cryocooler setup if you have access to one?

[rolnor]

Aspirator and chloroform is fast, pump will be full of solvent.

[wildfyr]

At room temp chloroform in the trap will go into the pump. 0C will dramatically slow down but not totally prevent it from going through.

[eb51111]

At room temp chloroform in the trap will go into the pump. 0C will dramatically slow down but not totally prevent it from going through.

But I understand there are pumps available that are solvent resistant - ones where the internal components are all PTFE?
This needs to be something that can be run very often and therefore cold finger (with dry ice or other) is not really viable.
Thanks for all the suggestions though - the aspirator might have to be the solution if no pump can take CHCl₃.

[wildfyr]

You can get a chiller and fill it with isopropanol/water which gets down under the freezing point of water to put on the rotovap and this should protect most pumps during controlled rotary evaporation.

If a pump is running all the time it will also stay pretty hot, so the chloroform will just boil out the top. The thing is, a "good" pump like an Edwards rotary vein pump is probably too strong and will just blast your liquid into the trap at room temp as soon as the vacuum is opened.

You want a small pump that is kind of moderate vacuum like this https://www.grainger.com/product/3KYY6?gclid=Cj0KCQjw5J so you can maintain control. Also if you break it you won't feel so bad.

I have virtually same pump I linked to, and while I don't leave it on all the time, I'm sure I've sucked plenty of solvent into it and it seems OK.