Catalytic hydrocyanatton of acetylenes by cyanonickelate avoiding use of hydrogen cyanide

Abstract Acetylenes are readily hydrocyanated by cyanonickelate to give nitriles without the use of hydrogen cyanide. The catalyst is prepared in situ in water or ethylene glycol by reduction of [Ni(CN)4]2− with NaBH4 or Zn powder in the presence of excess KCN. The hydrocyanation produces acrylonitriles, which are hydrogenated to saturated secondary nitriles. The reaction is applicable to both terminal and internal acetylenes, and α.ω-diynes yield dinitriles. The hydrocyanation proceeds regioselectively and in the fashion of cis-1,2-addition of HCN. A deuterium tracer study using NaBD4 or D2O has clearly shown that the hydrogen source NaBH4 in the hydrocyanation step and is solvent in the hydrogenation step, indicating that the hydrogen transfer process differs between hydrocyanation and hydrogenation. Probable processes, including σ-vinylcyanonickelate as an intermediate species, are discussed.