POTASSIUM SODIUM ALLOY

Uses

Alternative to other reagents for desulfurizations, dehalogenations(as Wurtz coupling reactions), and Birch reductions.

Additionally can be used as:

• A reducing agent for aliphatic ester substrates
• A deprotectant in place of the typical heavy metal deprotectant

Application

Sodium-Potassium Alloy is used for preparation of organopotassium compounds; in combination with TMSCl, greatly enhances acyloin condensations; dehalogenation of dihalides; preparation of γ, δ-unsaturated alcohols via fragmentation of γ-halo ketones; in combination with crown ethers is a useful reducing agent for alkynes and alkyl fluorides.

Preparation

Sodium-Potassium Alloy can be prepared by mixing 1 part Sodium and 5 parts Potassium (by weight) in refluxing xylene until melted. The melt is then carefully mixed with a glass stirring rod, keeping the alloy in one large globule. Upon cooling to room temperature, the alloy will remain liquid and can easily be transferred via a glass pipet.^[1]

reaction suitability

reagent type: reductant

Safety Profile

A low-melting alloy of Na and K. Its toxicity is due to either Na or K alone. Corrosive to the eyes, skin, and mucous membranes. Upon contact with moisture it reacts violently to evolve H2; much heat; and a highly caustic residue of NaOH or KOH. Oxidation forms Na2O and K2O, whch are powerful caustics. A dangerous fire and explosion hazard. Violent or explosive reaction with O2, water, moisture, steam, halogens, oxidzers, acids or acid fumes, gving off much heat, hydrogen, toxic and corrosive fumes, often spattering either red-hot particles or actually flaming particles. A severe explosion hazard, wiU react explosively under the appropriate condtions with moisture, acids, acid fumes, solid CO2, carbon disulfide, halocarbons (e.g., CH3Cl, carbon tetrachloride, chloroform, bromoform,1,1,1- trichloroethane, 1,1,2- trichlorotrifluoroethane, tetrachloroethane, CH2Cl2, CH2l2), ammonium sulfate + NH4 + No3, HgO, metal halides (e.g., silver halides, zinc chloride, iron(Ⅲ) chloride), metal oxides (e.g., silver oxide, mercury oxide), nitrogen-containing explosives (e.g., ammonium nitrate, ammonium sulfate, picric acid, nitrobenzene), oxalyl bromide, oxalyl chloride, pentachloroethane, K oxides, KO2, Si, NaHCO3, polytetrafluoroethylene. Reacts vigorously with oxidizing materials. To fight fire, use G-1 powder, dry sodum chloride, dry sodium carbonate, dry calcium carbonate, dry sand, resin-coated sodium chloride, or dry soda ash. Never use water, graphite, carbon dioxide, halocarbons, or foam. Dangerous; when heated it emits highly toxic fumes of Na2O and K2O. Used as a liquid coolant for nuclear reactor cores. See also SODIUM and POTASSIUM.

storage

Sodium-Potassium Alloy is a flammable solid; handle under inert atmosphere.

References

1. Gilman, H.; Young, R. V. JOC 1936, 1, 315.