SUBJECTS thiocyanate

Compounds such as hydrogen sulfide and cyanides are the most common metal surface poisoners occurring in process units subject to aqueous-phase hydrogen attack. In many process units, these compounds can be effectively eliminated and hydrogen diffusion stopped by adding ammonium polysulfides and oxygen to the process streams which converts the compounds to polysulfides and thiocyanates, provided the pH is kept on the alkaline side. 

A decisive solvent effect is also observed with other a,/ -epoxy ketones. Specifically, 3jS-hydroxy-16a,17a-epoxypregn-5-en-20-one and its acetate do not react with thiocyanic acid in ether or chloroform. However, the corresponding thiocyanatohydrins are formed by heating an acetic acid solution of the epoxide and potassium thiocyanate. As expected, the ring opening reaction is subject to steric hindrance. For example, 3j6-acetoxy-14f ,15f5-epoxy-5) -card-20(22)-enoIide is inert to thiocyanic acid in chloroform, whereas the 14a,15a-epoxide reacts readily under these conditions.Reactions of 14a,15a-epoxides in the cardenolide series yields isothiocyanatohydrins, e.g., (135), in addition to the normal thiocyanatohydrin, e.g., (134). 

The majority of the literature reports deal with the reaction of calixarenes with Group I and II cations. Polymeric calixarenes have been the subject of a more recent innovation. Harris et al. [23] have prepared a calix[4]ar-ene methacrylate, its polymerization, and Na complex-ation (Scheme 3). They concluded that both monomers and polymers form stable complexes with sodium thiocyanate. 

The theory of melting continues to be the subject of recent publications, including consideration of vacancy concentrations near the melting point [8,9], lattice vibrations and expansions [8,10—12], Meanwhile, the phenomenon also continues to be the subject of experimental investigations Coker et al. [13], from studies of the fusion of tetra-n-amyl ammonium thiocyanate, identify the greatest structural change as that which... 

Another main subject of research of Garcia Gonzalez, with the collaboration of J. Femandez-Bolanos, was the reaction of amino sugars with isothiocyanic acid derivatives. 2-Amino-2-deoxy-D-glucose hydrochloride and potassium thiocyanate were shown to give rise to 4-(D-arabino-tetritol-l-... 

The subjects of this chapter are the exploration of the scope and hmitations of the new Pd-Sn catalyzed hydrogenolysis route for the synthesis of thiols via 2-(perfluoroalkyl)ethane thiocyanate, the characterization of the surprisingly active and robust Pd-Sn catalysts, and the attempted correlation of the characterization of the catalysts with observed onset of hydrogenolysis reactivity and snrprisingly long lifetime in the presence of known catalyst poisons. ... 

Korpilahde, T. et al. Smoking history and serum cotinine and thiocyanate concentrations as determinants of rheumatoid factor in non-rheumatoid subjects, Rheumatology (Oxford), 43, 1424, 2004. 

Chelate complexes could only be prepared in the case of platinum(II) as the metal ion, while the group V atom alone acted as a donor toward palladium(II) and mercury(II). The coordinated olefin in the chelate complexes was found to be readily displaced by monodentate ligands such as tertiary arsines, -toluidine and the thiocyanate ion. It was suggested by these workers that chelation would take place more readily if the olefinic phosphine or arsine were subject to greater steric restrictions than was the pentenyl ligand. 

Two human subjects inhaled 160 ppm for 4 hours one of them experienced a slight flushing of the face 2 hours later and a slight feeling of bronchial tightness 5 hours later. A week before this, the same two subjects had inhaled 80 ppm with no effects. Blood cyanide and urine thiocyanate levels did not correlate with exposure and, therefore, are not reliable indicators of brief exposure to low concentrations. 

The reaction between ferric salts and alkali thiocyanate, which constitutes the well-known test for ferric iron, has been the subject of much investigation.7 It may be represented simply thus,... 

The preparations of 1,2,4-thiadiazoles and 1,2,4-thiadiazolidines from thioureas are well known and have been summarized in three reviews those of Bambas,188 Sherman,189 and Kurzer.170 Contained in these reviews are discussions of the controversies that surrounded some of the products, notably Hector s bases, which resulted from oxidation of substituted thioureas.171,172 Subjects covered in the above reviews, but too extensive to outline in detail here, are the oxidation of amidinothioureas to 3,5-diamino-1,2,4-thiadiazoles (71),173,174 the oxidation of phenylthiourea175 and of substituted amidinothioureas176 to 3,5-diimino-l,2,4-thiadiazolidines (72, Hector s bases), the reaction of thiopseudoureas with trichloromethanesulfenyl chloride to form 3-alkylthio-5-chloro-l,2,4-thiadiazoles (73),177 the reaction of thiopseudoureas with sodium thiocyanate and bromine178 and the oxidation... 

Numerous additional examples of linkage isomerization in solids have been reported.13 Most studies have focused on elucidating the relative roles played by steric and electronic effects in determining the bonding mode of the nitrite or thiocyanate ligand. Interestingly, the bonding mode of thiocyanate has been found to be subject to counter-ion control in the solid state.20... 

Cyclic derivatives of 1,2- and 1,3-amino alcohols have been trialled as chiral catalysts in the addition of diethylzinc to benzaldehyde.229 Enantioselective addition of diethylzinc to benzaldehyde is the subject of other reports,230,231 including the use of triazinyl-BINOLs as enantioselective catalysts of addition to araldehydes, using Ti(IV) tetraisopropoxide.232 Two optically active amino thiocyanate derivatives (60) of (-)-norephedrine act as aprotic ligands for enantioselective addition of diethylzinc to aldehydes in up to 96% ee.233 The ee drops drastically if the -SCN group is changed to -SR. 

Tressl et all6 11 have isolated some of the oligomers formed in their model systems, based mainly on pyrroles (/V-methyl and A-methyl-2-formyl), and have subjected them to tests for antioxidant activity (DPPH and Fe3+ thiocyanate). Although activity was found, its occurrence seemed somewhat haphazard. 

Cyanide and thiocyanate are normal constituents of blood (77). Sources of cyanide include some foods, for example, cyanogenic glycosides in bitter almonds, fruit seeds, and a number of plants, cigarette smoke, and smoke from fires. The blood concentration of cyanide in healthy subjects was... 

Kage et al. (75) applied their GC/ECD/GC/MS method to the analysis of blood levels in two casualties who died from cyanide poisoning. Blood levels of cyanide and thiocyanate in a subject who died following ingestion of sodium cyanide were 0.52 and 0.10 umol/ml respectively (= 13 and 5.6 xg/ml). Levels determined in a fatal victim of smoke inhalation were 0.28 and 0.13umol respectively (= 7.3 and 7.5 xg/ml). Fatal levels of cyanide are estimated as 0.05-0.1 umol/ml (= 1.3-2.6 xg/ml). The lower levels of thiocyanate in comparison to cyanide in the blood were attributed to the sudden death they were twice the mean levels ( 0.06 pmol/ml) found in cigarette smokers. 2-Aminothiazoline-4-carboxylic acid was detected in the urine of moderate cigarette smokers at concentrations between <0.3-1.1 xM (76). 

Coordination Chemistry of the Cyanate, Thiocyanate, and Selenocyanate Ions A. H. Norhury SUBJECT INDEX... 

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