Sulfite, formation from sulfide oxidation

The average concentrations of reduced inorganic sulfur species in the anoxic zone of the Black Sea measured using a new colorimetric method developed by Volkov [61,62] are summarized in Table 3. Presented elemental sulfur data refer to the stun of elemental sulfur allotropes (zero-valent sulfur) and the zero-valent sulfur derived from some fraction (n - 1) of the original polysulfide S 2. Thiosulfate data in the table represent the total amount of thiosulfate, sulfite, and polythionates. At some stations in the Black Sea, Volkov [61] observed a concentration maximum of elemental sulfur at the oxic/anoxic interface associated with sulfide oxidation by dissolved oxygen and/or Mn oxyhydroxides. Increasing with depth, elemental sulfur concentrations are probably explained by the ongoing process of polysulfide formation... 

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)... 

Barium sulfide solutions undergo slow oxidation in air, forming elemental sulfur and a family of oxidized sulfur species including the sulfite, thiosulfate, polythionates, and sulfate. The elemental sulfur is retained in the dissolved bquor in the form of polysulfide ions, which are responsible for the yellow color of most BaS solutions. Some of the mote highly oxidized sulfur species also enter the solution. Sulfur compound formation should be minimized to prevent the compounds made from BaS, such as barium carbonate, from becoming contaminated with sulfur. 

The typical S-oxidation with BVMOs allows the formation of chiral sulfoxides from organic sulfides. This oxidation has received much interest in organic chemistry due to its use in the synthesis of enantiomerically enriched materials as chiral auxiliaries or directly as biologically active ingredients. This reaction has been studied extensively with CHMO from Adnetohacter showing high enantioselectivi-ties in the sulfoxidation of alkyl aryl sulfides, disulfides, dialkyl sulfides, and cychc and acyclic 1,3-dithioacetals [90]. CHMO also catalyzes the enantioselective oxida-hon of organic cyclic sulfites to sulfates [91]. 

The reaction of polysulfides with peroxide depends on the polysulfide ion present (see above). Once higher polysulfides are produced, the reaction should result in a peroxide-polysulfide intermediate (similar to II) that transfers two electrons from the polysulfide ion to the peroxide as readily as the sulfide and peroxide reaction. At low peroxide levels, partial oxidation of the polysulfide ions should result in the direct formation of sulfate (through thiosulfate and perhaps sulfite) and S ... 

The mechanism of thiosulfate formation in animals is still obscure. Three theories can actually be proposed for this problem according to one by Medes and Floyd (86), thiosulfate would be formed from sulfoxylic acid according to one by Fromageot and Royer (51), it would be formed by oxidation of hydrogen sulfide and finally one may think thiosulfate would result froifi the reaction between free sulfur and sulfite. 

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