Potassium nitroprusside

Sodium Nitroprusside, Na2Fe(CN)5NO (22.6.7) It is synthesized by successive reactions including the reaction of potassium ferrocyanide with nitric acid, which forms potassium nitroprusside (22.6.5), which is further transformed to copper nitroprusside (22.6.6), and reaction of this with sodium carbonate gives sodium nitroprusside (22.6.7). 

The monohydrate has been obtained in crystalline form in several ways, such as, for example, by the action of concentrated potassium hydroxide solution upon potassium nitroprusside.2... 

When potassium ferricyanide is warmed with a solution of bleaching powder to 70° C. a considerable evolution of gas takes place, and a reddish deposit of ferric oxide and calcium carbonate is formed. The filtered solution is concentrated and the potassium nitroprusside extracted with alcohol, and converted into the insoluble copper salt by addition of cupric chloride. This latter is decomposed with sodium hydroxide, yielding the sodium salt, which may be further purified by dissolving in a little water, addition of alcohol, and subsequent evaporation after filtering off any insoluble material.2 The constitution to be assigned to sodium nitroprusside in particular, and hence to nitro-prussides in general, has been a subject of debate, Browning s3 formula is —... 

Potassium nitroprusside, K2[Fe(CN)6NO], may be obtained by the interaction of a ferrous salt with the nitrite and cyanide of potash —9... 

Nantokite, see Copper(I) chloride Natron, see Sodium carbonate Naumannite, see Silver selenide Neutral verdigris, see Copper(H) acetate Nitre (niter), see Potassium nitrate Nitric oxide, see Nitrogen(II) oxide Nitrobarite, see Barium nitrate Nitromagnesite, see Magnesium nitrate 6-water Nitroprusside, see Sodium pentacyanonitrosylfer-rate(II) 2-water... 

Sulphur.—The presence of sulphur in organic compounds may be detected by heating the substance with a little metallic sodium or potassium. The alkaline sulphide, when dissolved in water, gives a violet colouration with a solution of sodium nitro-prusside. Heat a fragment of gelatine with a small piece of potassium in a test-tube until the bottom of the tube is red hot, and place it m a small beaker of water as described in the test for nitrogen (p. 2). Filter the liquid and add a few drops of sodium nitroprusside solution. 

Detection.—Sulphur in the free state is readily recognisable by its general appearance and characteristics, and especially by its combustion to sulphur dioxide. Both in mixtures and compounds the presence of the element can be demonstrated by heating with charcoal and an alkali carbonate,2 or even better, on a small scale, by heating with an equal bulk of sodium or potassium,3 or with powdered iron 4 in each case some of the sulphur is converted into sulphide, which may be detected by the action of an aqueous extract on mercury or silver, or on sodium nitroprusside the metals are blackened, whilst the nitro-prusside is very sensitive in giving a purple coloration (see p. 62). Alternatively, the solution of the alkali sulphide may be acidified and tests applied for hydrogen sulphide to the vapours evolved on warming. 

Solutions of the alkali sulphides give a deep violet to purple coloration with a solution of sodium nitroprusside, and as mentioned on p. t. J, this may be used as a test for sulphides. By the interaction of the nitroprusside with the sulphides of lithium, sodium, potassium and rubidium, stable crystalline compounds of the type M4[Fc(CN)BNOS] have been obtained. From eleetrotitrimetric evidence the reaction appears to proceed in two stages 7... 

After this operation, the liquid is evaporated to dryness and the residue taken up in a mixture of 2 vols. of absolute alcohol and 1 vol. of anhydrous ether. The solution is filtered, the solvent evaporated and the new residue heated with potassium bisulphate in presence of glycerine (from the saponification of the acetins) an odour of acrolein is emitted and the vapours impart a dark blue colour to a paper steeped in a fresh solution of sodium nitroprusside and piperidine. 

A more efficient method for decomposing most sulphur compounds is to heat them with sodium or potassium, and then test the solution of the product for sulphide. The test is rendered sensitive by heating the substance with potassium in an ignition tube, dissolving the melt in water, and testing for sulphide by the nitroprusside or methylene blue reactions (see under Sulphides, Section IV.6, reactions 6 and 7). 

Sodium nitroprusside,5 Na2[Fe(CN)6N0]2H20, which is usually obtained by decomposing the potassium salt with sodium carbonate. Potassium carbonate is exceedingly soluble in water, so that sodium nitroprusside is readily obtained in pure form by crystallisation. 

Cobalt nitroprusside, Co[Fe(CN)6NO], obtained by double decomposition of a soluble cobalt salt with sodium nitroprusside, is a red salt, possessing an appreciable solubility in water. It dissolves in acids, but is insoluble in potassium hydroxide or ammonia solution. This latter property enables it to be separated from the corresponding nickel salt, which readily dissolves in ammonia.7... 

Nickel nitroprusside, Ni[Fe(CN)5NO], obtained in a similar manner to the preceding salt,8 is dark green when anhydrous, but upon exposure to moist air becomes ashen grey. It is insoluble in acids, but readily dissolves in ammonia to a brownish yellow liquid. Potassium hydroxide turns it lemon-yellow. 

Sodium aquo ferrocyanide,2 Na3Fe(CN)s.H20, results when sodium nitroprusside reacts with hydroxylamine, etc., or when the salt is oxidised by potassium hypobromite or hydrogen peroxide. 

Colour Tests. Potassium Dichromate (Method 2)—green SchifTs Reagent—violet Sodium Nitroprusside (Method 2)— red. 

The single-line absorber is generally potassium (or sodium) nitroprusside, K4Fe(CN)g,3H20, enriched with Fe. 

Hg(N03)2]iH20, 8.5 grams, plus 5 ml 6M nitric acid, is dissolved in water and made up to 500 ml. This solution must he standard-ized. (b) Potassium chloride, O.IN. Dry this salt at 110° for several hours and cool in a desiccator, and weigh out accurately the appropriate amount to prepare 250 or 500 ml of solution dissolve in water, transfer to the volumetric flask, make up to the mark, (c) Sodium nitroprusside, 10 per cent. This solution should be fresh that is, it should not be kept for more than a week, (d) Hexamminecobaltic chloride. Weigh out accurately about 0.9 gram of salt, dissolve in water, and make up to 100 ml in a volumetric flask. 

To standardize the mercuric nitrate, pipette 10 ml of O.lN potassium chloride into a 250-ml Erlenmeyer flask then add 40 ml of water (measured with a graduate) and 3 drops of 10 per cent sodium nitroprusside. Titrate with mercuric nitrate, shaking well between additions as the end point is neared. The end point is marked by a permanent white turbidity and is quite sharp. When the mercuric nitrate has been standardized, titrate the hexamminecobaltic chloride solution by the same procedure, taking care to have the volume of solution in the titration flask the same as in the standardization. The end point arrives somewhat early because of the reaction HgCh + Hg++—> 2HgCl+ but by performing the standardization and titration under similar conditions, with the final mercuric chloride concentrations almost the same, this error, which is small in any case, becomes quite negligible. 

Ensure that the high-alert medications such as heparin, potassium chloride, and nitroprusside are premixed in the pharmacy. 

Exposure to NO donors, S-nitrosoglutathione (250 pM) or sodium nitroprusside (500 pM) induced lipid peroxidation in primary cultures of cerebellar granule cells of 7-day-old Wistar rats as indicated by the significant increase in thiobarbituric acid reactive substances (Wei et al. 1999). In cells pre-treated with L-ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-l-benzopyran-6-yl-hydrogen phosphate] potassium salt (EPC-Kl), superoxide dismutase or NO scavenger haemoglobin, the formation of thiobarbituric acid reactive substances was markedly suppressed. 

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