Calcium cyanide

Sodium thiosulfate and sodium sulfate have shown antidotal properties toward KCN toxicity. Certain compounds and enzymes may exhibit similar action (see Sections 14.2 and 14.3). Ohkawa et al. (1972) reported that j5flra-aminopropiophenone [70-69-9] protected mice against lethal doses of KCN. 

Potassium cyanide is a noncombustible solid vapor pressure is 0 at 20°C (68°F) and does not present any fire or explosion hazard at ambient temperature. It liberates dangerously toxic HCN when it comes in contact with acid  

Powdered metals, magnesium, calcium, beryllium, boron, and aluminum reduce KCN on heating in the absence of air, forming potassium (highly reactive)  

It forms highly toxic cyanogen gas on reacting with copper sulfate or chloride  

Small amounts of KCN can be destroyed in the laboratory by treating with sodium hypochlorite. Laundry bleach containing about 5% NaOCl is added dropwise to cyanide solution maintained at a constant temperature of 45-50°C (113-122°F). Nontoxic potassium cyanate formed according to the reaction 

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In cyanidation, the ground ore is leached with a solution of sodium cyanide (0.02—0.05%) or an equivalent of calcium cyanide together with some lime. The leaching solution is aerated to provide oxygen and gold is dissolved with formation of sodium dicyanoauratae(-l) [15280-09-8] 5 2l(J u(C2>5)[) (see... 

Tetrasodium hexakiscyanoferrate decahydrate [14434-22-1], Na4[Fe(CN)g] IOH2O, or yellow pmssiate of soda, forms yellow monoclinic crystals that are soluble in water but insoluble in alcohol. It is slightly efflorescent at room temperature, but the anhydrous material, tetrasodium hexakiscyanoferrate [13601 -19-9], Na4[Fe(CN)J, is obtained at 100°C. The decahydrate is produced from calcium cyanide, iron(II) sulfate, and sodium carbonate in a process similar to that for the production of K4[Fe(CN)g] 3H2O. It is used in the manufacture of trisodium hexakiscyanoferrate, black and blue dyes, as a metal surface coating, and in photographic processing. 

Calcium cyanamide can be converted to calcium cyanide [592-01-8], used ia cyanidation of metallic ores and production of sodium cyanide and ferrocyanides (11) (see Cyanides). Calcium cyanamide has also been used to make cyanamide which ia turn is the starting material for important iadustrial organic syntheses. 

In North America, calcium cyanamide is no longer used as fertiliser, but it has limited use in special agricultural appHcations for defoHants, fungicides, herbicides, and as a weed killer. The primary industrial use is as a chemical intermediate for the manufacture of calcium cyanide, hydrogen cyanamide solution, and dicyandiamide. Calcium cyanamide is also used to add nitrogen to steel. 

Industrial uses make up most of the market for cyanamide. Calcium cyanamide is used directly for steel nitridation (34) and to some extent for desulfurization (36) (see Steel). Cyanamide is used to produce cationic starch (36) and calcium cyanide. Cyanamide is, of course, the raw material for dicyandiamide and melamine. New uses include intermediates for pesticides, detergents (37), medicines such as antihistamines, hypertension, sedatives, contraceptives, etc (38), the photography industry (39), as an additive for fuels and lubricants, as a paper preservative, and as a cement additive. 

Ammonium cyanide may be prepared in solution by passing hydrogen cyanide into aqueous ammonia at low temperatures. It may also be prepared from barium cyanide and ammonium sulfate, or calcium cyanide with ammonium carbonate. It may be prepared in the dry state by gentiy heating a mixture of potassium cyanide or ferrocyanide and ammonium chloride, and condensing the vapor in a cooled receiver. Ammonium cyanide is soluble in water or alcohol. The vapor above soHd NH CN contains free NH and HCN, a very toxic mixture. 

Cmde calcium cyanide [592-01-8] about 48 to 50 eq % sodium cyanide, is the only commercially important alkaline-earth metal cyanide, and output toimage has been greatiy reduced. This product, commonly called black cyanide, is marketed in flake form as a powder or as cast blocks under the trademarks Aero and Cyanogas of the American Cyanamid Co. 

Physical and Chemical Properties. Because of decomposition, the melting point of calcium cyanide can only be estimated by extrapolation to be 640°C (70). 

Aqueous solutions of calcium cyanide prepared even at low temperature turn yellow or brown owing to the formation of HCN polymer. Calcium cyanide hydroly2es readily. 

The presence of brown polymer in soHd form is sometimes noted even in dry calcium cyanide that has been stored for long periods. Calcium cyanide is decomposed by carbon dioxide, acids, and acidic salts Hberating hydrogen cyanide. 

With sulfur in aqueous medium, calcium cyanide forms calcium thiocyanate [2092-16-2]... 

Manufacture. Calcium cyanide is made commercially from lime [1305-78-3], CaO, coke, and nitrogen. The reactions are carried out in an electric furnace (69). 

Hexacyanobenzene [1217-44-33] benzenehexacarbonitnle, is prepared from 2,4,6-tnfluorobenzene-l,3,5-tricarbonitrile [3638-97-9] by substitution with calcium cyanide (48,49). It forms colored TT-complexes with aromatic hydrocarbons. 

Calcium cyanide Ca(CN)2 Reacts with air moisture to release HCN. If finely ground and the relative humidity of the air is >35%, this can occur fairly rapidly Releases HCN slowly on contact with water or CO2, or rapidly with acids Do not handle with bare hands Nonflammable white powder or crystals... 

Hydrogen cyanide Calcium cyanide Potassium cyanide Sodium cyanide Hydrogen fluoride as F Hydrogen peroxide Hydrogen selenide as Se Hydrogen sulphide Hydroquinone... 

Aero Agro Chemical hidustries Ltd., 168 AERO , calcium cyanide, 9 Aerojet Fine Chemicals, 215, 229 AEROPHINE , phosphine, 9 AEROTHENE MM , methylene chloride, 9 AFFLAIR , luster pigments, 9 Aflatoxins, 9... 

Cyan-Mthert m. cyanic ester. -Mthyl, n. ethyl cyanide, -bad, n. cyanide bath. -baryum,n. barium cyanide, -benzol, n. cyanobenzene. -bromid, n. cyanogen bromide, -calcium, n. calcium cyanide, -chlorid, n. cyanogen chloride. -doppelsalZt n. double cyanide. 

J.5 Select an acid and a base for a neutralization reaction that results in the formation of (a) potassium bromide (b) zinc nitrite (c) calcium cyanide, Ca(CN)2 (d) potassium phosphate. Write the balanced equation for each reaction. 

Wade, O. 1924. The effectiveness of calcium cyanide in the extermination of the black tail prairie dog, Cynomys ludovicianus (Ord.). Jour. Econ. Entomol. 17 339-342. 

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