Sulfide thiocyanate formation from

Table IX. Thiocyanate Formation from Apoferredoxin and Sulfide"...

The fate of thiocyanate in soil is largely uncharacterized. Early studies have shown that thiocyanate can undergo both aerobic (Betts et al. 1979) and anaerobic microbial degradation (Betts et al. 1979 Stafford and Callely 1969 Youatt 1954) however, the degradation pathway has not been defined (Brown and Morra 1993). Saturated soils treated with thiocyanate were found to emit carbonyl sulfide (COS) (Minami 1982 Minami and Fukushi 1981). Katayama et al. (1992, 1993) have reported the formation of carbonyl sulfide from the biodegradation of thiocyanate by pure and mixed cultures of Thiobacillus thioparus. 

Katayama Y, Narahara Y, Inoue Y, et al. 1992. A thiocyanate hydrolase of Thiobacillus thioparus. A novel enzyme catalyzing the formation of carbonyl sulfide from thiocyanate. J Biol Chem 267(13) 9170-9175. 

More decisive evidence is provided by the interconvertibility of N-aryl-JV-arylamidinothioureas (28) and Hector s bases by oxidation-reduction.63, B4,67b The former compounds are accessible (as salts) (i) by the condensation of arylthioureas (24) with arylcyanamides (23),63 (ii) by the extrusion of sulfur from the recently described40,41 s-diaryldithioformamidine hydrobromidesB4a (22), (tit) by the oxidation of arylthioureas (24) with 0.5 moles of hydrogen peroxide in the presence of mineral acids,B4a and (iv) by the mild reduction of Hector s bases by hydrogen sulfide in acid media.B4a The first of these four reactions limitB the structure of the products to the three alternatives 25, 28, and 30. Of these, 25 is excluded by the non-identity of the product with authentic67 N-phenyl-i -phenylamidinothiourea (25 R = Ph). The monosulfide structure (30) is not reconciled as readily with the observedB4a hydrolytic fission of the products into diaryl-guanidines (29) and thiocyanic acid as is structure 28. Indeed, as in the case of thioamides and nitriles (see Section II, C, 1), the present condensation may involve the primary formation of an intermediate diimido-monosulfide (30) and its isomerization to 28. 

These reactions support the postulated reaction mechanism for formation of cyclohexane sulfide from cyclohoxono oxide and potassium thiocyanate (Eq. 2). 

Sodium, potassium, barium, or calcium thiocyanate may be made by reaction of sulfur and the corresponding cyanide by heating to fusion. Ammonium thiocyanate (plus ammonium sulfide) may be made by reaction of ammonia and carbon disulfide, a reaction which probably accounts for tlie presence of ammonium thiocyanate in the products of the destructive distillation of coal. This reaction corresponds to the formation of ammonium evanate from ammonia and carbon dioxide. 

Aqueous sodium sulfide reduced the aryl thiocyanate 85, prepared from ethidium bromide, affording the air-sensitive dithiol 86 in 63% yield381 (equation 92). Also, Nicolaou s group has reported on the cleavage of dithiatopazine 87, a stable 1,2-dithietane system with loss of one sulfur atom and formation of a rearranged thioketone 88382 (equation 93). 

The formation of desaurins from ketones, carbon disulfide, and base 1275,1281,1282,1285-1290 believed to involve nucleophilic attack on a thioketene by the dianion of a 1,1-dimercaptoalkene, as shown for the synthesis of 572. Related syntheses involve the use of thiophosgene instead of carbon disulfide and the use of diazoalkanes or phosphonium and sulfonium ylides instead of a ketone and base. Treatment of perfluoroiso-butylene with fluoride ion and elemental sulfur in a dipolar, aprotic solvent ° °° or with sources of anionic sulfur (potassium sulfide, sodium hydrosulfide,potassium thiocyanate,sodium thiosulfate, dithiocarbamate salts, dithiophosphate salts ) give the dimer (573) of bis(trifIuoromethyl)-thioketene. Similarly, other 2,4-bis(methylene)-l,4-dithietanes are obtained by treating 2,2-dichlorovinyl ketones with anionic sulfur re-... 

Gas chromatography (GC) with an infrared (IR) detector was introduced as a method to detect volatile radiolytic products, some of which were hypothesized to be responsible for the bad smells emanating from irradiated drugs. Thiocyanic acid was held responsible, for example, for the sulfurous smell in irradiated ampicillin. The head-space (HS) injection technique for GC and the on-line MS detection allowed new approaches to detect radiosterilization [12]. Many volatile radiolytic products were identified from the mass spectral libraries. Some ofthe compounds identified such as aldehydes, esters and sulfides were quite malodorous. A few of the volatile radiolytic products came from the degradation of drug molecules by the ionizing radiation, whereas residual solvents played a key role in the formation of other volatile radiolytic products. 

The formation of trifluoromethyl sulfides (and other chalcogenides) from thiocyanates or disulfides, CF SiMej, and Bu NF is possible. The combination of sulfenyl chlorides. 

Whatever the explanation for the color change, the interesting fact remains that in molten potassium or sodium thiocyanate the sulphur is highly reactive and displays reactions which are not realizable in aqueous solutions of alkali thiocyanates. Among such reactions are formation of silver sulfide from metallic silver formation of sodium thiosulfate with sodium sulfite conversion of metal oxides and sulfates (even lead sulfate)... 

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