Thiocyanic acid, ammonium salt

Ammonium Thiocyanate. Thiocyanic acid ammonium salt ammonium rhodanide ammonium sulfocyanate ammonium sulfocyanide. CH4N3S mol wt 76,12, C 15.73%, H 5.30% N 36.80%, S 42.12%. NH4SCN. The usual grade is 98-99% pure. Prepn Gmetin s. Ammonium (8th ed ) 23, pp 372-383 (1936). 

Synonyms Ammonium rhodanate Ammonium rhodanide Ammonium sulfocyanate Ammonium sulfocyanide Thiocyanic acid ammonium salt... 

Thiocyanic acid ammonium salt. See Ammonium thiocyanate Thiocyanic acid, 2-(benzothiazolylthio) methyl ester. See2-... 

Therefore the extent of extraction or back-extraction is governed by the concentration of X ia the aqueous phase, the distribution coefficients, and selectivities depending on the anion. In nitrate solutions, the distribution coefficient decreases as the atomic number of the REE increases, whereas ia thiocyanate solutions, the distribution coefficient roughly increases as the atomic number of the REE increases. The position of yttrium in the lanthanide series is not the same in nitrate and thiocyanate solutions, and this phenomenon has been used for high purity yttrium manufacture in the past. A combination of extraction by carboxyUc acids then by ammonium salts is also utilized for production of high purity yttrium. 

Care must be exercised in using sodium nitrite near other chemicals. It is incompatible with ammonium salts, thiocyanates, thiosulfates, and strong reducing agents. In acid solutions, sodium nitrite evolves toxic NO in the presence of secondary amines it can form nitrosamines which are suspected carcinogens. 

Free thiocyanic acid [463-56-9] HSCN, can be isolated from its salts, but is not an article of commerce because of its instabiHty, although dilute solutions can be stored briefly. Commercial derivatives of thiocyanic acid are principally ammonium, sodium, and potassium thiocyanates, as weU as several organic thiocyanates. The chemistry and biochemistry of thiocyanic acid and its derivatives have been reviewed extensively (372—374). 

Determination of copper as copper(I) thiocyanate Discussion. This is an excellent method, since most thiocyanates of other metals are soluble. Separation may thus be effected from bismuth, cadmium, arsenic, antimony, tin, iron, nickel, cobalt, manganese, and zinc. The addition of 2-3 g of tartaric acid is desirable for the prevention of hydrolysis when bismuth, antimony, or tin is present. Excessive amounts of ammonium salts or of the thiocyanate precipitant should be absent, as should also oxidising agents the solution should only be slightly acidic, since the solubility of the precipitate increases with decreasing pH. Lead, mercury, the precious metals, selenium, and tellurium interfere and contaminate the precipitate. 

Alternatively, the reaction of 93c (R = n-Bu) with ammonium thiocyanate in refluxing acetic acid gave the ammonium salt of N-phosphonomethylthiohydantoin 99 in moderate isolated yield (2). 

The thiocyanates are generally soluble in water, the exceptions being those of lead, silver, mercury and copper. Most of them dissolve also in alcohol and ether. Aqueous solutions of the alkali thiocyanates undergo atmospheric oxidation under the influence of sunlight with solutions of medium concentration this change takes place rapidly, with separation of a yellow, amorphous precipitate consisting of pseudocyanogen sulphide, (CNS)3 (cf. p. 236). The concentration of thiocyanate most favourable to the separation of this sulphide is about 50 per cent, in summer and 10 per cent, in winter. In addition to this substance the products of the photochemical oxidation of potassium thiocyanate include hydrocyanic acid, sulphate, carbon dioxide, ammonia and ammonium salts ... 

Guanidine salts have been prepared by heating ammonium thiocyanate,1 by hydrolysis of dicyanodiamide by acids,2 (whereby one molecule of the guanidine salt is produced), and by the action of ammonium salts on dicyanodiamide,3 from which two molecules of guanidine salt result. The nitrate has been prepared from the thiocyanate by the action of nitric acid.4... 

The formula of carbon dioxide is C02, that of carbon disulphide CS2 and it is evident that an intermediate substance should exist of the formula COS. This substance is carbon oxysulphide. It is a gas, prepared by heating thiocyanic acid, HSCN, the ammonium salt of il which is produced when ammonia is passed through a mixture of carbon disulphide and alcohol CS2 + 2NHg.Alc = H2S + (NH4) SCN.Alc. On evaporation of the alcohol the ammonium thiocyanate crystallises out. This salt, distilled with sulphuric acid, yields in passing the acid HSCN, which, on account of the high temperature, reacts with water, forming ammonia (which yields ammonium sulphate with the sulphuric acid) and carbon oxysulphide, COS HSCN + H20 = NHS + COS. 

Cuprous thiocyanate, CuCNS.—The thiocyanate is produced by dissolving cuprous oxide or carbonate in thiocyanic acid, and by the interaction of solutions of potassium thiocyanate and a cupric salt in presence of a reducer, such as ferrous sulphate or sulphurous acid.2 It is a white substance, its solubility at 18° C. being 0 23 mg. in 1 litre of water.3 It dissolves in ammonium hydroxide and concentrated hydrochloric acid, and also in concentrated nitric acid with formation of cupric sulphate. It is employed in the preparation of aromatic thiocyanates.4... 

Cupric thiocyanate, Cu(CNS)2.—The thiocyanate is formed as a velvet-black precipitate by adding basic cupric carbonate or cupric hydroxide to a solution of thiocyanic acid, and by the interaction of potassium thiocyanate and concentrated solutions of cupric salts.8 It is very unstable, being transformed by contact with water into cuprous thiocyanate.9 With ammonium hydroxide it yields blue, aeicular crystals of ammonio-cupric ihiocyanaie, Cu(CNS)2,2NHs, also produced by dissolving cupric hydroxide in ammonium thiocyanate.10... 

Certain nitriles add amines to form N-substituted amidines. This reaction has been modified and extended through the use of ammonia and alkyl- or aryl-ammonium salts of sulfonic acids. Many amidines have been prepared in yields ranging from 13% to 86%. Some amidines are obtained in better yields by heating a cyanide with ammonium thiocyanate or an alkylammonium thiocyanate."... 

Triazines are one of the oldest known compound classes in organic chemistry. First reports date back to 1776 when cyanuric acid (l,3,5-triazine-2,4,6-triol 1,3,5-triazine-2,4,6(l//,3//,5f/)-trione) was obtained by the pyrolysis of uric acid.1 The same method was also utilized in 1820 2 however, triazine compounds were probably first prepared in 1704 upon trimerization of cyanide derivatives when the Berlinerblau -complex salt, the first known cyano compound, was discovered.468 Cyanuric chloride was synthesized in 1828 from hydrogen cyanide and chlorine.3 Another method, discovered in 1834, involves treatment of potassium thiocyanate with chlorine. When heated, cyanuric chloride is obtained.4 Melamine (1,3,5-triazine-2,4,6-triamine) was also prepared in 1834 by heating potassium thiocyanate with ammonium chloride.5 Although 2,4,6-substituted 1,3,5-triazine derivatives were identified very early, the unsubstituted parent compound was not synthesized before 1895.6 At that time, however, the isolated compound was assigned to a dimeric species and not to the trimeric hydrogen cyanide. This was finally proven much later."... 

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