Thiocyanate formation

Antidotes used time to autopsy, with marked loss documented from simple evaporation, thiocyanate formation, hydrolysis, and polymerization... 

The direct-oxidation systems are specific to hydrogen sulfide other sulfur species are apparently not attacked. Solution degradation problems may be caused by thiosulfate formation as well as thiocyanate formation (if HCN is present in the gas to be treated). Solution regeneration techniques have been developed to attempt to minimize the impact of these effects. The systems must be operated with caution, in some cases, the solutions contain species that are considered toxic or environmentally hazardous. 

Write balanced equations to describe the oxidation of the following substances with strongly alkaline permanganate in the presence of barium ion (Stamm reaction) iodide, phosphite (HP03 ), hypophosphite (H2PO2 ), cyanide, thiocyanate, formate. 

Bourdoux, P., F. Delange, M. Gerard, M. Mafuta, A. Hanson and A.M. Ennans. Evidence that cassava ingestion increases thiocyanate formation a possible etiologic factor in endemic goiter. J. Clin. Endocrinol. Metab. 46 613-621, 1978. 

An interesting application of the electrochemical oxidation of thiocyanate ion is the preparation of alkyl and aryl thiocyanates via anodically generated thiocyanogen. Alcohols have been converted to the corresponding thiocyanates by constant current electrolysis of NaSCN in CH2CI2 containing triphenylphosphite and 2,6-lutidinium perchlorate. The yields were fair to good for the primary and secondary alcohols, but no thiocyanate formation was observed with tertiary ones. Similarly, various aromatic amines and phenols were thiocyanated in a two-step procedure, namely electrochemical preparation of (SCN)2 and subsequent reaction with the substrates k... 

Table VIII. Thiocyanate Formation from Ferredoxin ...

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

Reeves and coworkers have recently published examples of tertiary amine catalyzed nitrile formation [29], thiocyanate formation [30], alkylation [31], and carbene formation [31 ]. These reactions almost certainly involve catalysis by quaternary ammonium ions generated in situ. 

Table I. Thiocyanate formation from thiocystine and cyanide catalyzed by rhodanese .

Figure 1 shows the time course of the reaction at pH 7.4 and at pH 9. Turbidity reached a maximum at 4-5 min at pH 9 and then declined as settling of elemental sulfur and slow formation of thiocyanate proceeded (Curve A). There was no thiocyanate formation at pH 7.4 indicating the absence of cyanolysis (Curve B). It is apparent that the catalysis of the decomposition by cyanide was a result of an initial scission of the trisulfide bond by cyanide to form a sulf-hydryl compound. 

Ermans, Evidence that cassava ingestion increased thiocyanate formation, a possible etiologic factor in endemic goiter, J Clin Endocrinol Metab. 46 613 (1978). 

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