542-84-7 cobalt cyanide

Cyan-kalium, n. potassium cyanide, -kalium-losung, /. potassium cyanide solution, -ko-balt, m. cobalt cyanide, -kohlensaure, / cyanocarbonic acid. -kupfer, n. copper cyanide, -laugerei, -laugung, /. cyaniding. cyanidation. -losung, / cyanide solution, -metall, n. metallic methyl cyanide, -natrium, n. sodium cyanide. -platin, n. platinum cyanide. 

A. Homogeneous Hydrogenation Catalyzed by Cobalt Cyanide Complexes. 433... 

By studying the NMR spectra of the products, Jensen and co-workers were able to establish that the alkylation of (the presumed) [Co (DMG)2py] in methanol by cyclohexene oxide and by various substituted cyclohexyl bromides and tosylates occurred primarily with inversion of configuration at carbon i.e., by an 8 2 mechanism. A small amount of a second isomer, which must have been formed by another minor pathway, was observed in one case (95). Both the alkylation of [Co (DMG)2py] by asymmetric epoxides 129, 142) and the reduction of epoxides to alcohols by cobalt cyanide complexes 105, 103) show preferential formation of one isomer. In addition, the ratio of ketone to alcohol obtained in the reaction of epoxides with [Co(CN)5H] increases with pH and this has been ascribed to differing reactions with the hydride (reduction to alcohol) and Co(I) (isomerization to ketone) 103) (see also Section VII,C). 

Most organopentacyanides are stable towards [Co(CN)jH], with the exception of allyl complexes which react to liberate propylene derivatives (105). This is one of the steps in the homogeneous hydrogenation of butadienes catalyzed by cobalt cyanide complexes (see Section VII,A). 

The cobalt cyanide complexes are excellent catalysts for the homogeneous hydrogenation at room temperature of a variety of organic (and inorganic)... 

Many of these cobalt complexes will catalyze the reduction of organic compounds by borohydride, hydrazine, thiols, etc. Cobalt cyanide complexes will catalyze the reduction of a,j8-unsaturated acids by borohydride (105) DMG complexes the reduction of butadiene and isoprene by borohydride, but not by H2 (124) Co(II) salen, the reduction of CHCI3 and CH3CCI3 to the dichloro compounds by borohydride (116) and cyanocobalamin, the selective reduction of -CCI2- by borohydride to -CHCl- in compounds such as aldrin, isodrin, dieldrin, and endrin without... 

Isomerization has been observed with many a,j3-unsaturated carboxylic acids such as w-cinnamic 10), angelic, maleic, and itaconic acids (94). The possibility of catalyzing the interconversion of, for example, 2-ethyl-butadiene and 3-methylpenta-l,3-diene has not apparently been explored. The cobalt cyanide hydride will also catalyze the isomerization of epoxides to ketones (even terminal epoxides give ketones, not aldehydes) as well as their reduction to alcohols. Since the yield of ketone increases with pH, it was suggested that reduction involved reaction with the hydride [Co" (CN)jH] and isomerization reaction with [Co (CN)j] 103). A related reaction is the decomposition of 2-bromoethanol to acetaldehyde... 

The system of cobalt cyanide com- 32 plexes and its position in homo- (144) geneous catalysis... 

Magnesium reacts with incandescence on heating with cadmium cyanide, cobalt cyanide, copper cyanide, lead cyanide, nickel cyanide and zinc cyanide. With gold... 

The major distinction between the two classes of catalysts is that the members of the former group are olefin isomerization catalysts, while the cobalt cyanide and the chromium catalysts are not23-25. 

Cobaltous Cyanide, The behavior of this catalyst system is very com-... 

Aqueous solutions containing cobaltous cyanide complexes (the prevalent complex in a freshly prepared solution is believed to be Co(CN)6 ) absorb hydrogen rapidly ( 5 min.) at temperatures as low as 0°, the total uptake corresponding to that required to reduce all the cobalt to the +1 state. It has been suggested (Mills et al., 50) that the mechanism of the reaction involves the heterolytic splitting of hydrogen, i.e.. 

Alkali metal 1-methyl- and 1-phenyl-borinates are also available from bis(borinato)cobalt complexes (see below) on treatment with sodium or potassium cyanide in an aprotic solvent like acetonitrile. Cobalt cyanide precipitates and the alkali borinate remains in solution. After addition of thallium(I) chloride to some complexes, thallium 1-methyl- or 1-phenyl-borinate could be isolated as pale yellow solids, the only main group borinates isolated hitherto. They are insoluble in most organic solvents but readily soluble in pyridine and DMSO. The solids are stable on treatment with water and aqueous potassium hydride, but are decomposed by acids <78JOM(153)265). 

The cyanide ion in inorganic cyanides can be present as both complexed and free cyanide. In order to study the chromatography of metal cyanides, Rocklin and Johnson [48] prepared and assayed solutions of cadmium, zinc, copper, nickel, gold, iron and cobalt cyanides. Table 2.6 lists the percentage of total cyanide detected. 

Fig. 9.3. Adsorption of cobalt cyanide ions on Y-AI2Q3 as a function of surface protonation. ( addition of HN03 O, addition of KOH.

Cobaltous Cyanide, Co(CN)2.3H20, may be precipitated from a solution of the chloride by addition of potassium cyanide. The precipitate, which has a reddish colour, becomes violet at 100° C. It still retains its combined water even at 200° C., but at 250° C. becomes incandescent in air and leaves a black carburised residue.3 The original precipitate is soluble in excess of potassium cyanide in consequence of the formation of soluble potassium cobalto-cyamde, K4Co(CN)6. Addition of dilute hydrochloric acid causes the reprecipitation of the cobaltous cyanide unless, in the meantime, the solution has been wanned, thereby oxidising the eobalto-eyanide to eobalti-eyanide, which is more stable (vide infra). 

Potassium Ccbalto-cyanide, Iy4Co(CN)6, as mentioned above, is produced when cobaltous cyanide is dissolved in excess of potassium cyanide solution. It may be precipitated from solution by the addition of alcohol.4 Its aqueous solution contains the ion Co(CN)6"", so that the formula for the salt is K4Co(CN)6 rather than 4KCN.Co(CN)2.s... 

The chemistry of cobalt cyanide complexes has been extensively reviewed by Sharpe. ... 

---