Oxidation of disulfides

Disulfides are oxidized to rtionosulfoxides (alkyl thiohulfinates) with peroxybenzoic acid (equation 585) [308], 

Under anhydrous conditions, chlorine converts dimethyl disulfide into methanesulfinyl chloride by a sequence of reactions (equation 586) [687], 

The oxidation of disulfides with oxygen in solutions of potassium hydroxide in dimethylformamide at 23.5 °C gives sulfonic acids in 90% yields (equation 587) [53], 

2 -Diaminodiphenyl disulfide, when treated with peroxysulfuric acid, is oxidized to o-aniiinesulfonic acid in 80% yield (equation 588) [187.  

Chlorine in the presence of water converts disulfides into sulfonyl chlorides 

Disulfides can be oxidized to sulfonic acids in the same way as thiols 589-593 

In laboratory work the oxidation of disulfides has been applied particularly to the preparation of thiosulfinic and thiosulfonic esters  

Oxidation to thiosulfinic esters is best effected by an equivalent amount of perbenzoic acid or peracetic acid in chloroform,594 and the preparation of thiosulfonic esters by a slight excess of hydrogen peroxide in acetic acid or by chlorine in the presence of glacial acetic acid with subsequent treatment by water.595-597 

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Sulfinic esters, aromatic, by oxidation of disulfides in alcohols, 46, 64 Sulfonation ot d,l camphor to d,l-10-camphorsulfomc acid, 45,12 Sulfoxides, table of examples of preparation from sulfides with sodium metapenodate, 46,79 Sulfur dioxide, reaction with styrene phosphorus pentachlonde to give styrylphosphomc diclilonde, 46,... 

Electrochemical oxidation of disulfides and trapping of intermediately formed sulfmates by alkylation yields sulfones in good yields494. 

Gilbert and coworkers18 were able to detect ESR spectra of sulfinyl radicals together with other sulfur-centered radicals during the oxidation of disulfides and thiols with a titanium(III)-peroxide couple reaction mechanisms involving sulfenic acids as intermediates have been discussed. 

For a review of the oxidation of disulfides, see Savige Maclaren. in Kharasch Meyers Organic Sulfur Compounds, vol. 2 pp. 367-402. Pergamon, New York. 1966. 

R. C. Pitkethly Yes, our experience and that of others (I, 2, 3) would indicate that the oxidation of disulfides in alkaline media involves... 

Possible reaction mechanisms postulated by Mockel et al. (51) for the oxidation of disulfides by OH radicals are as follows ... 

A more feasible route for the formation of these sulfonic acids would be via the oxidation of disulfides. Under peroxide oxidation the disulfide bond is ruptured giving rise to two sulfonic acid groups. Thus the presence of methyldisulfide, ethyldisulfide and... 

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). 

Alternatively, the episulfonium37-39,177 178 and episelenonium ions40 formed by anodic oxidation of disulfides or diselenides in the presence of an alkene react with acetonitrile to give, after pyrolysis, the corresponding acetamides 12 with total trans stereoselectivity. 

The oxidation of thiophene sulfides combined with a selective separation process of oxidized products, for example by adsorption on inert materials, might offer an alternative to deep hydrotreating for desulfurization of oil fractions. On these grounds, the oxidation of disulfides has gained considerable interest [149]. Owing to the nature of sulfur impurities, large-pore and even more mesoporous Ti-silicates would be appropriate catalysts. 

A third possibility, in which a highly favorable outer-sphere oxidation of disulfide radical anions to neutral disulfides, Eq. (38), becomes ratedetermining, will yield... 

Oxidation of disulfides with halogens may lead to sulfonyl chlorides or the much less stable bromides which afford sulfonamides. However, replacement of the sulfur function by halogen or complete desulfurization may also occur. Treatment of the sulfonyl chloride does not yield the expected esters but is the best way to prepare the sulfonic acids. Electrolytic oxidation of thiones affords a mixture of sulfonic acids and desulfurized compounds. The action of ozone on disulfides is a feasible but not very convenient reaction leading to sulfonic acids. Scheme 54 summarizes some of these relationships and the unusual nitration of the sulfonamide (147) (62BEp619423) for convenience the generalized triazole Tr is shown in... 

Anodic oxidation of disulfides usually gives the equivalent of RS, which may add to double bonds [99] oxidation of (XXXII) in the presence of HX (X = halogen) gives (XXXIII) [100] it is interesting that a five-membered, rather than a six-membered ring is formed, as in Eq. (17) the reaction is proposed to pass through an episulfonium ion [100]. 

N.B. Similarly, useful electrophiles can be to a large palette of amides, readily generated from the anodic oxidation of disulfides. 

Oxidation of disulfides.1 A simple alkyl disulfide is oxidized by the reagent at — 78°... 

D Fukshima, YH Kim, T Iyanagi, S Oae. Enzymatic oxidation of disulfides and thiolsulfinates by both rabbit liver microsomes and a reconsituted system with purified cytochrome P-450. J Biochem 83(4) 1019—1027, 1978. 

Redox reactions, which take advantage of the ease of reduction and oxidation of disulfides, are rarely used for the conjugation. 

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