Standard Operating Procedure (SOP) for solvent stills
Carlier Group
3/9/12
Introduction
The Carlier Group currently has three solvent stills in operation: tetrahydrofuran, diethyl ether, and
toluene (or heptane). These are located in the back left hood of Room 3019 HHS.
Each of the stills contains Na metal as the drying and deoxygenating agent, and the THF and Et2O stills
contain benzophenone, which forms a blue/purple ketyl radical ion when the solvent is H2O- and oxygenfree. The stills are under a slow constant nitrogen stream to help maintain this environment.
The heating mantle of each still is powered by a variac, which has markings corresponding to the settings
at which the solvent will reflux. DO NOT exceed the setting given for reflux, or the temperature will rise
more than necessary and the solvent could start to evaporate. A lower setting is also given, at which the
still should “simmer” or “idle” when not being actively used.
Operation
1.
When ready to collect, turn the variac to the reflux setting. and “tag” the still with your name.
2.
It’s good practice to let the solvent reflux for a few minutes in the open stopcock position before
collection, so as to “flush” the system. You should also wait until the collected solvent has cooled
somewhat before using a syringe to remove it from the reservoir. Open the needle stopcock and pierce
the septum in the same position each time (in the center). Flush your syringe with nitrogen once or twice
before drawing up solvent, which should be done slowly. Be sure to close the needle stopcock once you
have completed using the still.
3.
When transferring solvent via syringe to your reaction, make sure to “protect” the tip of your
needle (with a rubber stopper or something similar) when transporting it between the stills room and your
lab.
4.
When you are done, cautiously open the stopcock to allow solvent to slowly flow back into the
pot flask; watch the bubbler to ensure that you do not suck air through the bubbler into the still apparatus.
Then turn the variac down to the “simmer” setting. Check the apparatus 10 minutes later to ensure the
reflux has abated. Do not leave the 3rd Floor of HHS until the reflux has stopped. Remove the tag with
your name on it.
Contact the Group Member responsible for Solvent Stills when:
- solvent is running low, or you need a lot of solvent
- the still has changed color and needs attention (ESPECIALLY important with THF)
- nitrogen is not flowing
- water is not flowing
- water is leaking
- a still is leaking
- a septum needs to be changed
- an unattended still is refluxing without a tag