Running Reactions Unattended!!
[....if you must.....]
Organic reactions have never been famous for their speed - in fact,
they are among the slowest reactions in the chemical world. It is
common to reflux a reaction for 12 or more hours, heat a flask in an
oil or sand bath for three days (stirring the whole time), and otherwise
consume huge amounts of time and energy waiting for a reaction to reach
What if a reaction needs to be heated all night?
If it appears that a reaction must be allowed to proceed overnight, verify that it really needs to be heated/refluxed. Reactions with no running water almost never cause problems. If your reaction must be refluxed all night, here's a set of guidelines for doing this with a minimal chance of drowning our downstairs neighbors.
Instead of using a faucet for the cooling water source and the sink for the drain, use one of our submersible water pumps in a 5-gal bucket obtained for the purpose. Fill the bucket full of ice-water, and the submersible pump will keep the condenser very cold for quite a long time. Also, there's no chance of the sink's drain becoming plugged. Ask a senior researcher how to set this up.
Make sure all rubber tubing is new-looking, supple, and free of cracks and other signs of wear that could turn into a tear, if the building's water pressure were to increase suddenly and without warning (which happens depressingly often).
Use the small metal clip-type clamps made for the purpose to clamp each hose end to the nipple in the glassware to which it's attached. It doesn't make the hose popping off *impossible*, but it's pretty close.
Run the cooing water at the slowest practical speed. Don't have it so slow that it may shut off if the building's pressure changes (vide supra), but not so fast that it may pop off all by itself.
Make sure to use a magnetic stirrer to aid stirring, NOT boiling chips. These become clogged and useless incredible quickly, then one good bump can send your reaction mixture all over the place.
What if it doesn't need to be heated, but still must run all night,
What if a reaction needs to be cooled all night?
Clearly, by taking the right precautions, setting things up slowly and carefully, you can put the hours of the night to work for you. But, PLEASE, be sure to be meticulous in your setup, double check everything, ask someone to look over your setup to be certain, and if you have the slightest doubt as to the safety or wisdom of running a reaction all night, DON'T DO IT!!
To get permission to run a questionable reaction, make sure and ask ME - not a senior researcher, not a postdoc, not another faculty member - just me!
It's amazing how
often people stir reactions that do not need it! If the reaction
is a solution; that it, if there are no solids present, and no solids
are expected to form, why stir it?