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Safer Sodium

Metallic sodium and potassium, as well as their alloys,  are useful for their potency in chemical reduction reactions.  However, their instability  when exposed to oxygen is  inconvenient, and their highly exothermic reaction with  water is a severe fire hazard  in the laboratory.

Dye et al. have addressed  this problem by mixing the  metals with silica gel. Liquid  Na-K alloy combines with  silica at room temperature,  producing a black powder  that remains air-sensitive but  is easily handled under nitrogen. Heating the powder to  150oC (or heating a pure  Na/silica mixture to 165oC)  yields a new product, stable  for months, that retains much of its reducing capacity even  on exposure to dry oxygen.  This so-called stage I powder  can be packed in columns  and used for reductions or  dehalogenative couplings  of eluted aromatics. Further  heating of the Na–stage I  powder to 400oC gives a  slightly less powerful stage II  reducing agent that can be  handled in humid air and used  for drying organic solvents  or for controlled reaction  with water to generate  small quantities of hydrogen.  Preliminary experiments suggest that stage II formation  involves chemical decomposition of the silica to produce  Na₄Si₄ particles. — JSY   

J. Am. Chem. Soc. 10.1021/ja051786+ (2005).