[14038-85-8] · C4N4Na2Ni · Disodium Tetracyanonickelate(II) · (MW 208.75)
(catalyst for hydrocyanation of alkynes1)
Physical Data: yellow solid.
Solubility: sol water, ethylene glycol.
Preparative Method: prepared by first precipitating and isolating nickel dicyanide from an aqueous nickel nitrate solution,2 followed by dissolution with a stoichiometric quantity of aqueous sodium cyanide.3 Yellow needle-like crystals of disodium tetracyanonickelate crystallize from water with three molecules of water of recrystallization. Anhydrous material can be prepared by drying at 100 °C.
Handling, Storage, and Precautions: cyanides are highly toxic and appropriate precautions should be taken.
Treatment of alkynes with catalytic amounts of Na2Ni(CN)4 along with excess cyanide ion (in the form of Potassium Cyanide) and either Sodium Borohydride (in ethylene glycol) or Zinc (in water) as the reducing agent leads to saturated secondary nitriles. The advantages of using this reagent is that it avoids the use of toxic HCN and can be performed under mild conditions (45 °C). Terminal alkynes give exclusively secondary nitriles in good yields (eq 1), while internal alkynes lead to mixtures of products (eq 2).1
Aromatic nitriles can also be prepared from aromatic amines by initial conversion to the corresponding diazonium tetrafluoroborates, followed by treatment with Na2Ni(CN)4 in the presence of Sodium Carbonate or sodium phosphate at a pH of around 10 (eq 3).4
Lawrence B. Fertel
Occidental Chemical Corporation, Grand Island, NY, USA