Potassium Ferrocyanide Hydrogen Carbonate

When distilled with potassium cyanide, potassium ferrocyanide, hydrogen cyanide, and ammonium carbonate are produced —4... 

Ferrocyanide-hydrogen peroxide Ammonium chloride (0.5 g) is added to a 0.1% potassium ferro-cyanide solution in 0.2% hydrochloric acid, and the resulting solution is sprayed on the plate, which is then dried (100°C). The chromatogram is further sprayed with 30% hydrogen peroxide, heated (150°C, 30 min), and sprayed with 10% potassium carbonate to yield yellow/red spots. 

From 1885 to 1895 potassium ferrocyanide w as manufactured very largely from spent oxide of iron, used in purifying coal gas from hydrogen sulphide. Coal gas, as it leaves the retorts, contains hydrogen cyanide, formed by the action of ammonia on red-hot carbon. Thus —... 

Carbon dioxide decomposes potassium ferrocyanide solution at 72° to 74° C., liberating hydrogen cyanide and precipitating ferrous potassium ferrocyanide.2 Continued passage of carbon dioxide through a boiling solution of potassium ferrocyanide results in the precipitation of ferric hydroxide and the formation of potassium carbonate and hydrogen cyanide, or its decomposition products, ammonia and formaldehyde.3... 

Analytical Characters.—(1.) K, Na or NH hydroxid white ppt., soluble in excess.- (2.) Carbonate of K or Na white ppt., in absence of NH< salts. (3.) Hydrogen sulfld, in neutral solution white ppt. In presence of an excess of a mineral acid, the formation of this ppt. is prevented, unless sodium acetate be also present. (4.) Ammonium sulfhydrate white ppt., insoluble in excess, in KHO, NHtHO, or acetic acid soluble in dilute mineral acids. (5.) Ammonium carbonate white ppt., soluble in excess. (6.) Disodic phosphate, in absence of NHj salts white ppt., soluble in acids or alkalies. (7.) Potassium ferrocyanid white ppt., insoluble in HCl. 

The detection of cations on chromatoplates is performed by spraying the solutions of the detection reagents at an appropriate concentration level, followed by visualization of the separated zones. The spraying reagents used as detectors include, 0.04-1 % dithizone in chloroform or carbon tetrachloride, 1% ethanolic solution of dimethylglyoxime, 1% aqueous solution of potassium ferrocyanide, 1% aqueous aluminon containing sufficient amount of ammonium acetate, 1% alcoholic solution of alizarine Red S, freshly prepared 0.1% solution of stannous chloride in 2 M HCl, hydrogen sulfide gas, aqueous saturated solution of ammonium sulfide, aqueous solution of ammonium thiocyanate and dilute solutions of diphenylcarbazide, p-nitroso-yV,A -dimethylaniline and sodium rhodizonate. 

This process, which was developed and commercialized at the gas works at Hamburg, Germany, and patented by Fischer (1932), utilizes an aqueous solution containing about 20% potassium ferrocyanide and 6% potassium bicarbonate. The solution is subjected to electrolysis, which converts a portion of the ferrocyanide to ferricyanide and an equivalent amount of the bicarbonate to carbonate, releasing at the same time a proportionate volume of hydrogen. The presence of both ferricyanide and carbonate enables the solution to absorb H2S rapidly and to convert it immediately to elemental sulfur. The reactions involved can be expressed by the following equations ... 

Potassium Acetate Potassium Acid Sulfate Potassium Acid Tartrate Potassium Antimonate Potassium Bicarbonate Potassium Bichromate Potassium Bisulfate Potassium Bisulfite Potassium Bitartrate Potassium Borate Potassium Bromate Potassium Bromide Potassium Carbonate Potassium Chlorate Potassium Chloride Potassium Chromate Potassium Cyanide Potassium Dichromate Potassium Ferricyanide Potassium Ferrocyanide Potassium Fluoride Potassium Hexacyanoferrate (III) Potassium Hydrogen Carbonate Potassium Hydrogen Sulfate Potassium Hydrogen Sulfite Potassium Hydroxide Potassium Hypochlorite Potassium Hyposulfite Potassium lodate Potassium Iodide Potassium Manganate Potassium Nitrate Potassium Perborate Potassium Perchlorate Potassium Permanganate Potassium Peroxydisulfate Potassium Persulfate... 

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. 

There are several salts that behave in this way at atmospheric temperatures, the more important being ammonium acetate potassium bromate, carbonate, cyanide, ferricyanide, ferrocyanide, iodate, and permanganate disodium hydrogen phosphate and sodium borate and carbonate.4 In the case of potassium chlorate the points L and S appear to be practically coincident, whilst for the majority of salts the point S lies somewhere to the left of L, namely at S —that is to say, saturation occurs before the limiting concentration is reached. Generally speaking, at the ordinary temperature, concentrated solutions of salts are less corrosive than distilled water—that is, the point S lies below the level of A, exceptions being 5 ammonium sulphate, aluminium... 

Addition of ferric chloride to certain liquors produced in the manufacture of Prussian blue in a French factory by the methylamine method (see p. 213) resulted in the precipitation of a violet compound.1 Several hundred grams of this were isolated by Muller, warmed with potassium carbonate and hydroxide successively, and the filtered solution allowed to crystallise. The product thus isolated crystallised in thin scales and rectangular prisms, and proved to be the potassium salt of an entirely new acid, namely hydrogen carbonyl ferrocyanide, H3Fe(CN)5.CO. Following up this discovery, Muller succeeded in preparing a series of well-defined salts. 

Solutions of oxide of zinc are recognised by the following characters. Caustic alkalies produce a bulky white precipitate of hydrate, soluble in an excess of the alkali. The alkaline carbonates precipitate a bulky white carbonate of zinc, permanent when carbonate of soda or potash is employed, but soluble in excess of carbonate of ammonia. Sulphuretted hydrogen has no action if the solution be acid but if it be quite neutral forms a white precipitate of hydrated sulphuret of zinc, which is best formed by hydrosulphuret of ammonia. Ferrocyanide of potassium also causes a white precipitate. 

---