Guidelines for care & Use of Dry Solvent Stills [Example]

5. Laboratory Specific SOPs
Guidelines for care & Use of Dry Solvent Stills [Example]
(Procedure formerly used in Dr. Davies’ Lab, written by Nick Huby, grad student)
It is my hope that by requiring each person in the lab to be personally responsible for the upkeep of
the solvent stills the burden that effort this entails will be equally shared throughout the lab community.
Somewhat optimistically I also hope that this will also engender a greater sense of responsibility by people
at all times when using these pieces of communal apparatus.
I have decided quite arbitrarily and of my accord that each person's period of responsibility will
run from twelve noon Wednesday through to twelve noon the following Wednesday. During this time it is
their responsibility to:
i) ensure that the stills are being used in a responsible manner
ii) ensure that the stills do not get dangerously low, i.e. they are filled up as required
iii) ensure that there is an adequate supply of pre-dried solvent available to fill the stills with when
required
iv) ensure that the pre-dried solvent bottles contain an adequate amount of sodium ribbon
v) ensure that the stills are kept in a usable state, i.e. diethyl ether, tetrahydrofuran, and hexane
stills retain the blue color of sodium benzophenone ketyl
vi) ensure that water tubing to condensers and argon tubing does not leak
vii) ensure that argon cylinder is not empty
viii) ensure that there is mineral oil in both bubblers
Their period of responsibility for a still will be extended, as necessary, until that still is in a usable
condition.
Ether
Diethylether for use in the still is pre-dried over sodium ribbon and is kept in a bottle in the solvent
cupboard under the oven. Only fill this bottle with anhydrous ether, since anesthesia and
chromatography/extraction grade ether both contain ethanol which reacts with sodium. Sodium ribbon is
used as it has a large surface-to-volume ratio and it can be added directly to the solvent before the sodium
surface can be tarnished by atmospheric moisture. It will at times be necessary to add further sodium ribbon
to the bottle as old sodium ribbon is consumed. If the build up of junk in the bottles becomes too great
most of the ether will have to be decanted off, the bottle cleaned, and fresh sodium added to the ether which
was decanted off (follow instructions given for starting still from scratch.)
Once pre-dried the ether can be added directly to the ether still. The still also contains sodium
ribbon, the blue color is due to sodium benzophenone ketyl. Provided that the ether is dry it is only
necessary to add a spatula or so of benzophenone to obtain this blue color.
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