Disulfide, oxidation

Hot surfaces and electric sparks are potential ignition sources for carbon disulfide. The ignition temperature depends on specific conditions, and values from 90 to 120°C in air have been reported (2,22). Data on carbon disulfide oxidation and combustion have been summarized (18). Oxidation products ate generally sulfur dioxide [7446-09-5] and carbon dioxide [124-58-9J ... 

If sulfur is present, another iadustrially important compound results, 2-mercaptoben2othia2ole (2-ben2othia2olethiol [149-30-4]). Carbonyl sulfide is a coproduct of many carbon disulfide oxidation reactions. Some examples are... 

Diphenylcyclopropenone, 47, 62 Dii henyldiacetylene, 45, 39 Diphenyl disulfide, oxidation to methyl benzenesulfinate, 46, 62 1,1-Diphenylethylene, reaction with N,or diphenylmtrone, 46,129 N,N -Diphi iiyli tiiyleni diamine, condensation with triethyl orthoformate, 47, 14... 

Methyl disulfide, oxidation to methane-sulfinyl chloride by chlorine, 40, 62... 

Diphenylcyclopropane, 48, 75 Diphenylcyclopropenone, 47, 62 Diphenyldiacetylene, 46,39 Diphenyl disulfide, oxidation to methyl... 

Diborneo-l,2-dithiin 25 was synthesized from (R)-thiocamphor 212 via disulfide oxidation (of the enethiol form) and Cope rearrangement to the bis-thiocamphor, which was deprotonated employing NaH/DMF to form the dienolate and then finally oxidized with K3[Ee(CN)6] (Scheme 58) <1995T13247, 1994TL1973> only the racemic dithiin derivative 25 was obtained. 

E3 catalyzes the regeneration of the disulfide (oxidized) form of lipoate electrons pass first to FAD, then to NAD+. 

The conversion of thiols into disulfides (oxidative S—S coupling) is an important reaction in synthetic organic chemistry and many stoichiometric and catalytic metal reagents have been reported as oxidants for this transformation. However, there are only few reports on the oxidation of thiols using iron-based systems. 

Susceptibility to oxidation of disulfides built into proteins is strongly dependent on their location in the protein molecule (G3). Since the disulfides have a crucial role in maintaining protein tertiary structure, oxidation of certain —S—S— bridges may expose further disulfides and cause unfolding of the protein molcule. The final disulfide oxidation is a sulfone residue, which is stable and does not tend to reverse to sulfide. Therefore oxidative breakage of disulfides is irreversible. The spatial location of disulfides inside protein molecules influences their susceptibility to oxidation. The ribonuclease molecule has four —S—S— bonds, and at least three correctly located disulfide bonds are necessary to retain the ribonuclease enzyme properties. The compact ribonuclease molecule is relatively resistant to HOC1 oxidation (D18). 

The most common reaction of this group is a reversible oxidation that forms a disulfide. Oxidation of two molecules of cysteine forms cystine, a molecule that contains a disulfide bond (Figure 5.14). When two cysteine residues form such... 

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