Ammonia/ammonium thiocyanate solution

Chen, Y.S. Cuculo, J.A. Lyotropic mesophase of cellulose in ammonia/ammonium thiocyanate solution. J. Polym. Sci. A Polym. Chem. 1986, 24 (9), 2075-2084. 

Only a few solvents are known to dissolve cellulose completely, and solid cellulose decomposes before melting. Therefore, it is difficult to study the mesophase behavior of cellulose. Chanzy et al. [32] reported lyotropic mesophases of cellulose in a mixture of jV-methyl-morpholine-Af-oxide and water (20-50%), but were unable to determine the nature of the mesophase. Lyotropic cholesteric mesophase formation in highly concentrated mixtures of cellulose in trifluoroa-cetic acid + chlorinated-alkane solvent [33] and in ammonia/ammonium thiocyanate solutions [34] has been studied, and although poor textures were obtained in the polarizing microscope, high optical rotatory power has been measured in an optical rotation (ORD) experiment, which could be fitted to the de Vries equation [Eq. (3)] for selective reflection beyond the visible wavelength region and was taken as proof of a lyotropic chiral nematic phase. 

Cellulose in liquid ammonia/ammonium thiocyanate solutions... 

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. 

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. 

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. 

Ammonium Chromithiocyanate, (NH4)3[Cr(SCN)6].4H20, is formed by dissolving freshly precipitated hydroxide in ammonium-thiocyanate solution, or by reducing ammonium dichromate wth alcohol and sulphuric acid, neutralising the solution with ammonia, adding ammonium thiocyanate, and boiling for a short time. ... 

Yang, K.S. Cuculo, J.A. Formation and characterization of the fibers and films from mesophase solutions of cellulose in ammonia/ammonium thiocyanate solvent. Polymer 1992,33 (1), 170-174. 

Gadamer i-ecommends the following process. The mustard oil is dissolved in alcohol to form an exactly 2 per cent, solution. Five c.c. (4 2 gi-ams) of this solution are allowed to remain with 25 c.c. of deci-noi-mal solution of silver nitrate and 5 c.c. of ammonia for twenty-four hours in a well-stoppei-ed 50 c.c. flask. It is then made up to 50 c.c. with water and filtered from the precipitated silver sulphide 25 c.c. of the filtrate are mixed with 4 c.c. of nitric acid and a few drops of ferric sulphate solution, and titrated with deci-normal ammonium thiocyanate solution, until the characteristic red colour of the ferric thiocyanate appears. 

Five c.c. of the alcoholic solution of mustard oil are mixed in a graduated tube of 100 0.0. capacity with 10 c.c. of solution of ammonia and 50 c.c. >deci-normal silver nitrate solution, and the whole is immediately heated for one hour on a briskly boiling water-bath under a reflux condenser. After cooling to 15 , and filling up to the mark with distilled water, adding nitric acid until a feeble acid reaction takes place, and 1 c.c. ferri-ammonium sulphate solution, deci-normal ammonium thiocyanate solution should be added to the clear filtrate, until a red coloration is produced. 

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. 

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, 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. 

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. 

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. ... 

Fusion of ammonium thiocyanate,6,6 either alone or in the presence of heavy metal salts, at 180°C., gives guanidine thiocyanate. This procedure has been modified by heating lead nitrate with a solution of ammonium thiocyanate in liquid ammonia at 120°.7 Lead sulfide is formed, and guanidine nitrate recovered. Other methods of formation involve the hydrolysis of dicyandiamide8-10 and the nitridation11 of methyl amine by means of ammonium azide in liquid ammonia. 

The 10-mlnute Co82 produced by the Ni82(n,p) reaction has been extracted as the thiocyanate into an organic layer of amyl alcohol-ethyl ether (l l) from a weak hydrochloric acid solution saturated with ammonium thiocyanate and then back-extracted with 6 N ammonia solution (156,208). The 5-2-minute W17 produced by a Ta (p,3n) reaction has also been extracted as the thiocyanate of W(lV) Into ethyl acetate (268). 

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). 

Urea-Ammonium Nitrate Solutions. An important fertilizer is the urea-ammonium nitrate solution which makes up 20% of the nitrogen fertilizer market. This fertilizer utilizes the unusually high solubility between urea and ammonium nitrate (Table 3.15), which allows for a high nitrogen content, low nitrogen cost, and ease of handling. The solution also can contain herbicides since they can be easily added to the solution. However, these solutions are corrosive, so corrosion inhibitors are added such as ammonium thiocyanate, sodium arsenite, sulfonate OA5, or trace ammonia. 

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