The dry solid is stable thermally and to light at room temperature, and is only oxidised slowly in air. In solution the compound slowly decomposes in the presence of oxygen.
Fill the flask with nitrogen, remove the stopper and, lightly greasing the ground glass joint with silicone grease, replace it with a sublimation probe or "finger". The apparatus setup should look something like this.
Evacuate the flask, close the side-arm tap and immerse the flask as fully as possible in a warm water bath maintained at 70 - 75°C.
Now put crushed ice into the sublimation finger and let the sublimation proceed for one hour.
Replenish the crushed ice when necessary and occasionally open the flask briefly to vacuum. In due course remove the flask from the bath and support the joint of the sublimation finger with a rubber band. (This will prevent accidental opening by the nitrogen pressure).
Fill the flask with nitrogen and close the sidearm tap. Turn off the nitrogen supply and remove the hose.
To shut down the apparatus, turn off the nitrogen supply. Remove the Dewar carefully. Open Tap 1 and immediately switch off the pump. This is a suitable point to end the first day's work. On the following day, proceed to Part Two.