Sodium

Only deactivate with surplus ethanol! May be recycled!

a) Options

The pure compound can be disposed in a separate bottle. Ensure a safe packaging. If the metal is covered with deposits there is no need to dispose it but the metal - if performed properly - can be easily separated from the deposits by melting it. This even may be performed in a student's lab course.

On the other hand sodium can be deactivated with alcohols, but you will need lots of the alcohol which at the end is diluted with water. This means that a big volume of solvent mixture has to be disposed at the end.

b) Deactivation of pure sodium

Put the sodium slowly into alcohol.

  • You may slow down the reaction speed if you use iso-propanol first and only later on proceed with ethanol.
  • All the time make sure that there is enough surplus alcohol to ensure that the solution remains thin fluid. If there is not enough of the alcohol sodium alcoholate will precipitate which makes the solution viscous. Then the metal is not cooled any more and it will worm up until it is glowing. If the mixture becomes viscous, add more alcohol. If more than half a teaspoon of sodium has to be deactivated stirr the mixture.
  • To avoid thickening of the mixture it is convenient if it warms a little up. Prevent from boiling. It is careless to cool in an ice bath since there will be a desastrous reaction if the flask breaks and the metal comes into contact with water. Wait until the temperature lowers alone instead.
  • Pass the hydrogen developed into the fume hoods flue. Place low quantities which are deactivated in a beaker direct to the fume hoods flue.
  • If the deactivation is performed in a beaker place it in a plastic bowl. If the beaker breaks or if the mixture boils the bowl will pick up the mixture. With an open beaker allways be aware that the mixture could ignite, because of the oxygen in the atmosphere. Therefore only deactivate small quantities in a beaker. If the mixture ignites the problem often is enlarged because the beaker is tipped over because of a startle response. You may avoid this problem if the beaker is clamped.
  • Monitor the reaction until it is died down. Reserve enough time for this job!!

Final treatment of the mixture see d)

c) Destillation residue if a solvent has been dried over sodium

The sodium should be covered completely with the solvent. Add alcohol to the mixture - at the beginning very slowly and at the end more quantities. Again the mixture has to remain thin fluid. If necessary add more inert solvent (hexane, petrolether, toluene). See hints given in b).

Final treatment of the mixture see d)

d) Ensure that all of the sodium is deactivated

  • Destroy all remaining sodium clusters (for example with a spatula). Check the walls of the reaction bottle, if there are residues of the metal. Stirr thoroughly.
  • If the mixture is cloudy you may not expect that the reaction is finished if you do not see any evolution of gas. It is better to filter these mixtures to detect all remaining solid material. If there is still sodium present, treat with more alcohol as described in b).
  • If the reaction has died down leave the mixture standing alone for several hours - better over night.
  • Dilute the mixture with water - at the beginning slowly. All the time watch for developing of gas. When all the reactions are died down stirr thoroughly and again leave the mixture standing alone for several hours.
  • Filter the mixture. The filtrate is a very useful reagent to deactivate other chemicals like benzyl halogenides or organic acid halogenides. Therefore only dispose as solvent waste, if you do not need the mixture for that purpose.
  • Depending on what is found on the filter treat it either with water or with ethanol.
  • All used equipment is only free of sodium if it has been immersed completely into water and you do not see any reaction. All solutions are only sodium free if they have been filtered.