Reaction with ammonium thiocyanate

Schlack-Kumpf method, also called the isothiocyanate method, a method for C-terminal sequence analysis of peptides and proteins. The C-terminus is converted with acetic anhydride into a 5(4H) oxa-zolone. Upon reaction with ammonium thiocyanate or with the new derivatizing reagent triphenylgermanyl isothiocyanate (TPG-ITC), Tacyl-2-thiohydantoins are formed, with the peptidyl residue being the acyl group. The peptidyl residue is then cleaved to give the 2-thiohydantoin derived from the C-terminal amino acid, which is subsequently analyzed [P. Schlack,... 

Hantzsch and Weber began their description with the compound which led them indirectly to the discovery of the thiazoles the a-thiocyanoacetone imine ( Rhodanpropimin ) of J. Tcherniac and C. H. Norton. C4H6N2S. obtained by reaction of ammonium thiocyanate with chloroacetone. After Tcherniac and Norton (18), the a thiocyanoacetone... 

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. 

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 ... 

N-(2,6-dichiorophenyl)thiourea (MP 149°C) was prepared in customary manner from 2,6-dichloroaniline (Organic Synthesis lil, 262-263) and ammonium thiocyanate. 16.0 g of this thiourea derivative were refiuxed for 2 A hours together with 16 g of methyl iodide in 150 cc of methanol. Thereafter, the methanol was evaporated out of the reaction mixture in vacuo, leaving as a residue 22 g of N-(2,6-dichlorophenyl)-S-methyl-isothiouronium hydroiodide of the formuia... 

The following sections are concerned with the use of standard solutions of reagents such as silver nitrate, sodium chloride, potassium (or ammonium) thiocyanate, and potassium cyanide. Some of the determinations which will be considered strictly involve complex formation rather than precipitation reactions, but it is convenient to group them here as reactions involving the use of standard silver nitrate solutions. Before commencing the experimental work, the theoretical Sections 10.74 and 10.75 should be studied. 

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). 

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 reactions of potassium thiocyanate in aqueous solution are essentially those of the thiocyanate anion. Its reaction with ferric ammonium sulfate, apphed in Volhard titration, results in the formation of ferric thiocyanate, Fe(SCN)3. Similarly, in titration against shver nitrate, it forms insoluble silver thiocyanate, AgSCN. 

Zinc thiocyante is prepared by the reaction of ammonium thiocyanate with zinc hydroxide... 

The amount of ammonia volatilized was determined from the amount of standard sulfuric acid consumed in the traps. Ethylenediamine was determined by the salicylaldehyde method (14). The sample for cobalt(II) determination was made slightly acidic with hydrochloric acid immediately upon removal of the sample from the reaction flask, in order to prevent further oxidation of the cobalt (18). The carbon was removed by filtration, and the cobalt (II) concentration was determined spectrophotometrically as the cobalt-ammonium thiocyanate complex, (NH4)2Co(NCS)4 (28). 

Reaction of Iron(III) Chloride with Ammonium Thiocyanate. 

Another method of preparation consists in heating carbon disulphide with ammonium carbonate in a sealed tube. The other product of this reaction is ammonium thiocyanate. The yield of thiocarbamide by this method is stated to be much below the theoretical value.6... 

Several methods have been introduced which express the degree of oxidation deterioration in terms of hydroperoxides per unit weight of fat. The modified Stamm method (Hamm et at 1965), the most sensitive of the peroxide determinations, is based on the reaction of oxidized fat and 1,5-diphenyl-carbohydrazide to yield a red color. The Lea method (American Oil Chemists Society 1971) depends on the liberation of iodine from potassium iodide, wherein the amount of iodine liberated by the hydroperoxides is used as the measure of the extent of oxidative deterioration. The colorimetric ferric thiocyanate procedure adapted to dairy products by Loftus Hills and Thiel (1946), with modifications by various workers (Pont 1955 Stine et at 1954), involves conversion of the ferrous ion to the ferric state in the presence of ammonium thiocyanate, presumably by the hydroperoxides present, to yield the red pigment ferric thiocyanate. Newstead and Headifen (1981), who reexamined this method, recommend that the extraction of the fat from whole milk powder be carried out in complete darkness to avoid elevated peroxide values. Hamm and Hammond (1967) have shown that the results of these three methods can be interrelated by the use of the proper correction factors. However, those methods based on the direct or indirect determination of hydroperoxides which do not consider previous dismutations of these primary reaction products are not necessarily indicative of the extent of the reaction, nor do they correlate well with the degree of off-flavors in the product (Kliman et at. 1962). 

In organo-fluorine compounds fluorine atoms can be eliminated by nucleophilic sulfur species to form C —S bonds. In principle, the fluorine to be eliminated can be bonded to aliphatic or araliphatic compounds, as well as to aromatic or heterocyclic compounds however, the replacement proceeds more efficiently the more the fluorine is activated. Therefore, the synthetic usefulness of these reactions is the broadest with fluoroaromatic compounds, including heteroaromatics, with which the reactions often proceed smoothly under mild conditions. The nucleophilic sulfur compound to be reacted is. in most cases, an aliphatic or aromatic thiol or a metal sulfide, but reactions with, for example, thiourea or ammonium thiocyanate have also been described. The sulfur introduced this way can be either oxidized or removed by reduction, opening additional possibilities for modifications of the original fluoro compounds. 

In the second stage of a representative aqueous process, an aqueous solution of polytyinyl alcohol) is heated with butyraldehyde and an acid catalyst. PVB precipitates from solution as il forms. Because PVB resin precipitates early in the reaction there is a tendency toward high levels of intennolecular acetalization. Cross-linking can be minimized by adding emulsifiers to control particle size or substances like ammonium thiocyanate or urea to improve the solubility of PVB in the aqueous phase. 

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