[Reddart]

Hi,

I was wanting to help semi automate a particular reaction by replacing an addition funnel with a pump to meter in reagent. One of the problems with this particular reaction is I am adding reagent solution while vacuum distilling off solvent. The reaction requires an overhead stirrer for thorough mixing, otherwise I would try to do this on a rotovap.

The scale I am running this requires ~ 1mL/min of almost 1L of solution (so a ~10hr procedure), hence desiring to get away from the addition funnel (and fiddling with the valve every 15 minutes or so to keep the correct addition rate).

I was thinking peristaltic pump since the reaction vessel is under vacuum and the volumes being pumped. Any other solutions that come to mind?

[Reddart]

Since this topic is initiating so much conversation, I wanted to add this possible solution, a metered valve:
https://us.vwr.com/store/item/NA5132641/masterflex-metal-metering-valves-avantor

Since it is under vacuum, something like this should work. I just don't know how consistent it meters. I suppose it can't be worse than attempting to meter a tiny flow on an addition funnel, and possibly a lot better if it is sized close to my desired rate.

[wildfyr]

I like the peristaltic pump better. It will "pinch" off with each rotation, so extra liquid won't be sucked through by the vacuum. With a metering valve, that is all based on STP and gravity. Its just a hole.

[rolnor]

I question if you can do the reaction via another route that dont needs the slow addition, this is complicated. A peristalitic pump has a tube, and this tube can collapse under vacuum.