Disulfides to sulfonic acids

Wallace and Schriesheim dried the solvent by distillation under nitrogen over Linde I3X molecular sieve (calcined under N at 350° for 4 hrs.) and stored it in a dry box equipped with a moisture conductivity cell. They found it superior to DMF or tetramethylurea as solvent for base-catalyzed (KOH or NaOH) autoxidation of thiols and disulfides to sulfonic acids. It is superior also for base-catalyzed autoxidation of alkylthiophenes and toluene, and of 5-0,2 cyclic ketones to the corresponding dibasic acids."... 

The sulfur-sulfur bridges can be destroyed oxidatively or reductively. Treatment of the protein containing such disulfide bridges with perforinic acid [(HC0)20] (Equation 12.11) converts both sulfur atoms of the disulfide to sulfonic acids. 

Oxidation of Thiols and Disulfides to Sulfonic Acids. Sulfonic acids have been prepared from the corresponding thiols with MTO/H2O2 as the oxidizing system. The protocol is simple, eco-triendly, and produces high yields (eq 60). The same catalytic system was satisfactorily employed in the oxidation of diaryl- and dialkyl disulfides, in acetonitrile at 20 °C with high yields in short... 

When exposed to air, mercaptans are oxidized to yield disulfides and sulfonic acids. 

Thiols, sulfoxides, sulfones, disulfides,407 and other sulfur compounds can be oxidized to sulfonic acids with many oxidizing agents, though for synthetic purposes the reaction is most important for thiols.408 Among oxidizing agents used are boiling nitric acid and barium... 

Further oxidation and hydrolysis of diethyl disulfide to sulfonic and sulfinic acids do not occur when the reaction proceeds in aqueous solvents (13,22). 

Alkyl and aryl sulfides (i.e. thioethers) are readily oxygenated to sulfoxides and sulfones (equation 4), whereas thiol groups can be converted to either disulfides or to sulfonic acids (equation 5). 

Disulfides are generally oxidized by H202 to produce unstable sulfenic acid (RSOH) which then disproportionates (by unknown path) to sulfonic acid (46) ... 

Thiazolyl sulfamic acids, rearrangement of sulfonic acid, 70 rearrangement to sulfonic acid, 75 by sulfonation, 75 2-Thiazolyl sulfenyl chloride, transformation to, thiazolyl disulfides. 412 2-Thiazolyl sulfide, in hydrocarbon synthesis, 406 oxidation of, with m-chloroperbenzoic acid, 415 with CrOj, 415 with Hj02,405,415 with KMn04,415 physical properties, infrared, 405 NMR, 404 pKa, 404 ultraviolet, 404 preparation of, from 2-halothiazoles and 5-Thiazolyl sulfides, bis-5-thiazolyl sulfide, oxidation of, 415 general, 418 5-(2-hydroxythiazolyl)phenyl sulfide case, 418 physical properties, 418 preparation of, 417-418 table of compounds, 493-496 uses of. 442 2-Thiazolyl sulfinic acid, decomposition of, 413 preparation of, from 2-acetamidothiazole sulfonyl chloride, 413 from A-4-thiazoline-2-thione and H, 0, 393,413 table of compounds, 472-473 5-Thiazolyl sulfinic add, preparation of,... 

Hydrogen peroxide commonly is used to oxidize sulfhydryls in proteins to disulfides or, on more extensive treatment, to sulfonic acids (1). However, under certain conditions reacting hydrogen peroxide with protein sulfhydryls may lead to the formation of sulfenic acids (21). The inactivation of highly purified papain by stoichiometric amounts of hydrogen peroxide appears to be due almost exclusively to the formation of papain sulfenic acid (22). The formation and reactions of sulfenic acids in proteins have been reviewed elsewhere by Allison (21). 

Just as mild oxidation converts thiols to disulfides, vigorous oxidation converts them to sulfonic acids. KMn04 or nitric acid (HN03), or even bleach (NaOCl), can be used as the oxidant for this reaction. Any Lewis structure of a sulfonic acid requires either separation of formal charges or more than 8 electrons around sulfur. Sulfur can have an expanded octet, as it does in SF4 (10 electrons) and SF6 (12 electrons). The three resonance forms shown here are most commonly used. Organic chemists tend to use the form with an expanded octet, and inorganic chemists tend to use the forms with charge separation. 

Disulfides have been oxidized to sulfonic acids with hydrogen peroxide in the presence of tungstic acid.401 Whilst sulfonic acids are the normal oxidation product, intermediates of the structure RSS(0)R have been isolated.402... 

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... 

Imidazole- and benzimidazole-2-thiols usually exist largely as the thione tautomers. The thiol (thione) group is susceptible to alkylation (especially in alkaline media), and can be oxidized to sulfide, disulfide and sulfonic acid. This oxidation can often be carried out quite selectively by careful choice of oxidizing agent. The sulfur function can be removed with nitric acid, iron(III) chloride, hydrogen peroxide or, most commonly, Raney nickel. Alkyl- and arylthio groups can be oxidized to sulfoxide or sulfone. 

Beef insulin appears to have a molecular weight of about 6000 and to consist of two polypeptide chains linked by disulfide bridges of cystine residues. The chains can be separated by oxidation, which changes any CyS—SCy or CySH residues to sulfonic acids (CySO H). 

Thiol compounds can be oxidized to sulfenic acids (reaction 1-A), then to sulfmic acids (reaction 1-E), and finally to sulfonic acids (reaction 1-F). Depending on the substrate, the pathway is mediated by cytochrome P450 and/or flavin-containing monooxygenases. Another route of oxidationof thiols is to disulfides either directly (reaction 1-C through thiyl radicals) or by dehy-... 

Oxidative reactions of pteridinethiones can lead to pteridinyl disulfides, pteridinesulfenic, -sulfinic, and to -sulfonic acids. However, there do not seem to be generally applicable synthetic methods for such transformations, and particular methods are used for particular cases. 

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