Ammonium thiocyanate/ammonia

Aqueous salt solutions such as saturated zinc chloride or calcium thiocyanate can dissolve limited amounts of cellulose [131]. Two nonaqueous salt solutions with a lengthy history are ammonium thiocyanate/ammonia and dimethylacetamide/lithium chloride (DMAc/LiCl). Solutions up to about 15% can be prepared with these solvents. DMAc-LiCl has been used for molecular weight determinations of cotton [135] (see Section 1.5.2). 

The reaction is carried out at low temperature in aqueous medium and then allowed to stand overnight (221). Ammonium thiocarbamate is prepared from a cold saturated solution of ammonium thiocyanate, which is gradually added to dilute sulfuric acid at 25°C. The liberated carbonyl sulfide is passed into a saturated solution of alcoholic ammonia at about 10°C (221). The fairly low yield indicates that the reaction has not been greatly developed. 

Physical Properties. Ammonium thiocyanate [1762-95-4] NH SCN, is a hygroscopic crystalline soHd which deHquesces at high humidities (375,376). It melts at 149°C with partial isomerization to thiourea. It is soluble in water to the extent of 65 wt % at 25°C and 77 wt % at 60°C. It is also soluble to 35 wt % in methanol and 20 wt % in ethanol at 25°C. It is highly soluble in Hquid ammonia and Hquid sulfur dioxide, and moderately soluble in acetonitrile. 

Chemical Properties. Ammonium thiocyanate rearranges upon heating to an equiHbrium mixture with thiourea 30.3 wt % thiourea at 150°C, 25.3 wt % thiourea at 180°C (373,375). At 190—200°C, dry ammonium thiocyanate decomposes to hydrogen sulfide, ammonia, and carbon disulfide, leaving guanidine thiocyanate [56960-89-5] as a residue. Aqueous solutions of ammonium thiocyanate are weakly acidic a 5 wt % solution has a pH of 4—6. 

Manufacture. An extensive technology was developed initially ia the 1930s for isolation of ammonium thiocyanate from coke-oven gases, but this technology is no longer practiced ia the United States (372). However, such thiocyanate recovery processes are used iadustrially ia Europe. Likewise, the direct sulfurization of cyanides to thiocyanates is not practiced commercially ia the United States. The principal route used ia the United States is the reaction of carbon disulfide with aqueous ammonia, which proceeds by way of ammonium dithiocarbamate [513-74-6]. Upon heatiag, the ammonium dithiocarbamate decomposes to ammonium thiocyanate and hydrogen sulfide. 

This reaction can also be mn in a continuous fashion. In the initial reactor, agitation is needed until the carbon disulfide Hquid phase reacts fully. The solution can then be vented to a tower where ammonia and hydrogen sulfide are stripped countercurrendy by a flow of steam from boiling ammonium thiocyanate solution. Ammonium sulfide solution is made as a by-product. The stripped ammonium thiocyanate solution is normally boiled to a strength of 55—60 wt %, and much of it is sold at this concentration. The balance is concentrated and cooled to produce crystals, which are removed by centrifiigation. 

Manufacture, Shipment, and Analysis. In the United States, sodium and potassium thiocyanates are made by adding caustic soda or potash to ammonium thiocyanate, followed by evaporation of the ammonia and water. The products are sold either as 50—55 wt % aqueous solutions, in the case of sodium thiocyanate, or as the crystalline soHds with one grade containing 5 wt % water and a higher assay grade containing a maximum of 2 wt % water. In Europe, the thiocyanates may be made by direct sulfurization of the corresponding cyanide. The acute LD q (rat, oral) of sodium thiocyanate is 764 mg/kg, accompanied by convulsions and respiratory failure LD q (mouse, oral) is 362 mg/kg. The lowest pubhshed toxic dose for potassium thiocyanate is 80—428 mg/kg, with hallucinations, convulsions, or muscular weakness. The acute LD q (rat, oral) for potassium thiocyanate is 854 mg/kg, with convulsions and respiratory failure. 

Carbon disulfide reacts with concentrated ammonia to give ammonium thiocyanate [1762-95-4] and ammonium trithiocarbonate [13453-08-2] in a reaction promoted by alumina catalysts ... 

At approximately 160°C, some of the ammonium thiocyanate is converted to thiourea [62-56-6] H2NCSNH2, iulow yield. With alcohoHc ammonia, ammonium dithiocarbamate [513-74-6] forms ... 

Guanidine Nitrate (Coll. Vol. i, 293) From ammonium thiocyanate, lead nitrate, and ammonia at 120°. Gockel, Z. angew. Chem. 48, 430 (1935). 

Ammonium-ferrisulfat, n. ammonium iron(III). sulfate, ferric ammonium sulfate, -ferro-sulfat, n. ammonium iron(II) sulfate, ferrous ammonium sulfate, -jodat, n. ammonium iodate. -jodid, n. ammonium iodide, -platinchlorid, n. ammonium platinichloride (chloroplatinate). -rest, m. ammonium radical. rhodanid, -rhodantir, n. ammonium thiocyanate, -salpeter, m. ammonium nitrate, -salz, n. ammonium s t. -selfe,/. ammonia soap, -sulfhydrat, n. ammonium hydrosulfide, -sulfocyanid, n. ammonium thiocyanate, -verbindung,/. ammonium compound, -zinn-chlorid, n. ammonium chlorostannate, pink salt. 

According to REM, hydrazine hydrate Is reacted with 2 mols of ammonium thiocyanate to produce 1,2-bislthlocarbamoyl) hydrazine which by loss of ammonia and rearrangement produces 5-amino-2-mercapto-1,3,4-thiadiazole. That compound is acetyied with acetic anhydride. 

Carbon disulfide is also used to produce xanthates ROC(S)SNa as an ore flotation agent and ammonium thiocyanate as a corrosion inhibitor in ammonia handling systems. 

Aminotrimethylenephosphonic acid 172 Ammonia 86,87 -, dipole moment 97 -, reagent 166 Ammonium cations 144 Ammonium rhodanide see Ammonium thiocyanate... 

When hot, ammonia and compounds, which contain nitrogen-hydrogen bonds eg ammonium salts and cyanides react violently with chlorates and alkaline perchlorates. Diammonlum sulphate, ammonium chloride, hydroxyl-amine, hydrazine, sodamide, sodium cyanide and ammonium thiocyanate have been cited. So far as hydrazine is concerned, the danger comes from the formation of a complex with sodium or lithium perchlorate, which is explosive when ground. Many of these interactions are explosive but the factors which determine the seriousness of the accident are not known. 

According to an O.S. amendment sheet, the procedure as described [1] is dangerous because the reaction mixture (dicyanodiamide and ammonium nitrate) is similar in composition to commercial blasting explosives. This probably also applies to similar earlier preparations [2]. An earlier procedure which involved heating ammonium thiocyanate, lead nitrate and ammonia demolished a 50 bar autoclave [3], TGA and DTA studies show that air is not involved in the thermal decomposition [4], Explosive properties of the nitrate are detailed [5], An improved process involves catalytic conversion at 90-200°C of a molten mixture of urea and ammonium nitrate to give 92% conversion (on urea) of guanidinium nitrate, recovered by crystallisation. Hazards of alternative processes are listed [6],... 

Materials Required Ethionamide 0.3 g dilute sulphuric acid (10% w/w) 10 ml dilute ammonia solution (4.25 ml of strong ammonia solution in 100 ml of water) 0.1 N silver nitrate 50 ml dilute nitric acid (10.6 ml of nitric acid to 100 ml of water) 60 ml ferric ammonium sulphate solution (10% w/v in water) 5 ml and 0.1 N ammonium thiocyanate solution. 

Procedure Weigh accurately about 0.3 g of ethionamide in a flask and dissolve in 10 ml of dilute sulphuric acid. Add to it 100 ml of water, 20 ml of dilute ammonia solution and rapidly 50 ml of 0.1 N silver nitrate solution. Allow the resulting mixture to stand for a few minutes, filter and wash the filter paper with three successive quantities, each of 10 ml of DW. To the combined filtrate and washings, add 60 ml of dilute nitric acid, cool and titrate with 0.1 N ammonium thiocyanate employing 5 ml of ferric ammonium sulphate solution as an indicator. Each ml of 0.1 N silver nitrate is equivalent to 0.008312 g of C8H1QN2S. 

A favourable endothermic reaction occurs when barium hydroxide is mixed with ammonium thiocyanate. If you removed the stopper in photograph (B), you would detect the characteristic odour of ammonia. 

Cyclohexylurea has been prepared by the reaction of cyclo-hexyl isocyanate with gaseous ammonia or ammonium hydroxide, by thermal decomposition of cyclohexyl allophanamide, by treating cyclohexylamine hydrochloride with an aqueous solution of potassium cyanate," by heating nitrosomethylurea with cyclohexylamine, and by heating an ethanolic solution of cyclohexylamine and 3,5-dimethyl-l-carbamylpyrazole. 2,6-DimethyIphenyIthiourea has been synthesized by allowing 2,6-dimethylaniline hydrochloride to react with ammonium thiocyanate. ... 

Acetazolamide Acetazolamide is 5-acetamido-l,3,4-thiadiazole-2-sulfonamide (9.7.5). The synthesis of acetazolamide is based on the production of 2-amino-5-mercapto-l,3, 4-thiadiazole (9.7.2), which is synthesized by the reaction of ammonium thiocyanate and hydrazine, forming hydrazino-N,N -( ji-(thiourea) (9.7.1), which cycles into thiazole (9.7.2) upon reaction with phosgene. Acylation of (9.7.2) with acetic anhydride gives 2-acetylamino-5-mercapto-l,3,4-thiadiazol (9.7.3). The obtained product is chlorinated to give 2-acetylamino-5-mercapto-l,3,4-thiadiazol-5-sulfonylchloride (9.7.4), which is transformed into acetazolamide upon reaction with ammonia (9.7.5) [24,25]. 

Ammonium thiocyanate is made in the United States by the reaction of carbon disulfide with aqueous ammonia. Ammonium dithiocarbamate is formed as an intermediate in this reaction, which upon heating, decomposes to ammonium thiocyanate and hydrogen sulfide. 

The crude tetrachloride mixture of zirconium and hafnium is dissolved in ammonium thiocyanate solution. The solution is extracted with methyl isobutyl ketone (MIBK). MIBK is passed countercurrent to aqueous mixture of tetrachloride in the extraction column. Halhium is preferentially extracted into MIBK leaving zirconium in the aqueous phase. Simultaneously, zirconium tetrachloride oxidizes to zirconyl chloride, ZrOCb. When sulfuric acid is added to aqueous solution of zirconyl chloride, the chloride precipitates as a basic zirconium sulfate. On treatment with ammonia solution the basic sulfate is converted into zirconium hydroxide, Zr(OH)4. Zirconium hydroxide is washed, dried, and calcined to form zirconium oxide, Zr02. 

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