Oxidation of organic sulfides

Sodium chlorite reacts very violently with organic compounds of divalent sulfur, or with free sulfur (which may ignite), even in presence of water. Contact of the chlorite with rubber vulcanised with sulfur or a divalent sulfur compound should therefore be avoided [1]. Application of factorial design techniques to experimental planning gave specific conditions for the safe oxidation of organic sulfides to sulfoxides using sodium chlorite or calcium hypochlorite [2],... 

The assistance of some electron-rich groups [94-96], heteroatoms [90, 97, 98] or filled cr-orbitals [99,100] in the oxidation of organic sulfides was studied in a series of papers (Scheme 24). Since the 3p orbitals of sulfur are quite compact compared to those of Se, the mentioned electronic and stereoelectronic effects are rather remarkable. These interactions (discussed in terms of a trans-annular... 

The pyridine-catalysed Cr(V) oxidation of organic sulfides to sulfoxides may be explained by Michaelis-Menten (MM) kinetics between intermediate Cr(V)-catalyst and Cr(V)-catalyst-substrate complexes.14... 

Bloodworth AJ, Courtneidge JL, Davies AG (1984) Rate constants for the formation of oxiranes by y-scission in secondary p-t-butylperoxyalkyl radicals. J Chem Soc Perkin Trans 2 523-527 Bohr V (2002) Repair of oxidative DNA damage in nuclear and mitochondrial DNA, and some changes with aging in mammalian cell. Free Rad Biol Med 32 804-812 Bonifacic M, Stefanic I (2000) Oxidation of organic sulfides by peroxyl radicals search for an adduct intermediate. Nukleonika 45 39-44... 

Schmidt KH, Flan P, Bartels DM (1995) Radiolytic yields of the hydrated electron from transient conductivity improved calculation of the hydrated electron diffusion coefficient and analysis of some diffusion-limited (e )aq reaction rates. J Phys Chem 99 10530-10539 Schoneich C, Aced A, Asmus K-D (1991) Halogenated peroxyl radicals as two-electron-transfer agents. Oxidation of organic sulfides to sulfoxides. J Am Chem Soc 113 375-376 Schuchmann Fl-P, von Sonntag C (1981) Photolysis at 185 nm of dimethyl ether in aqueous solution Involvement of the hydroxymethyl radical. J Photochem 16 289-295 Schuchmann Fl-P, von Sonntag C (1984) Methylperoxyl radicals a study ofthey-radiolysis of methane in oxygenated aqueous solutions. Z Naturforsch 39b 217-221 Schuchmann Fl-P, von Sonntag C (1997) Heteroatom peroxyl radicals. In Alfassi ZB (ed) Peroxyl radicals. Wiley, Chichester, pp 439-455... 

Studies of the oxidation of organic sulfides with amino acid-derived ligands in acetonitrile revealed very little difference between the mechanism of their oxidation and that of halides, except for one major exception. Despite the fact that acid conditions are still required for the catalytic cycle, hydroxide or an equivalent is not produced in the catalytic cycle, so no proton is consumed [48], As a consequence, there is no requirement for maintenance of acid levels during a catalyzed reaction. Peroxo complexes of vanadium are well known to be potent insulin-mimetic compounds [49,50], Their efficacy arises, at least in part, from an oxidative mechanism that enhances insulin receptor activity, and possibly the activity of other protein tyrosine kinases activity [51]. With peroxovanadates, this is an irreversible function. Apparently, there is no direct effect on the function of the kinase, but rather there is inhibition of protein tyrosine phosphatase activity. The phosphatase regulates kinase activity by dephosphorylating the kinase. Oxidation of an active site thiol in the phosphatase prevents this down-regulation of kinase activity. Presumably, this sulfide oxidation proceeds by the process outlined above. 

Smith, T.S. and V.L. Pecoraro. 2002. Oxidation of organic sulfides by vanadium haloperoxidase model complexes. Inorg. Chem. 41 6754—6760. 

Figure 8 Examples of oxygen transfer to different substrates using hydroperoxo or alkylperoxo species A, the epoxidation of olefins catalyzed by Mo (VI) complexes as in the Oxirane process B, the Baeyer-Villiger oxidation of ketones catalyzed by Pt(II) complexes C, the epoxidation of olefins catalyzed by Ti(IV) silicates D, the oxidation of organic sulfides catalyzed by V(V) complexes.

One-electxon oxidation of organic sulfides (thioethers) leads primarily to a sulfur-centered radical cation, R2S, which is stabilized either by resonance (e.g. if R = Aryl) or interaction with a free electron pair provided by a second sulfur atom (typically in the case of aliphatic sulfides). The latter stabilization occurs inter- or intm-molecularly with the former depending on the sulfide concentration, while the intramolecular process requires a geometry of the two interacting p orbitals which is favorable for overlap. This concept has been verified in numerous experiments and supported by theoretical calculations. ... 

Schoneich C, Aced A, Asmus KD. (1991) Halogenated peroxyl radicals as two-electron transfer agents. Oxidation of organic sulfides to sulfoxides. Chem Soc 113 375-376. 

The stepwise oxidation of organic sulfides to sulfoxides and sulfones with ozone is reported, in the case of carboxymethyimercaptosuccinic acid, it is the only successful oxidation to the sulfoxide known. The yields in most cases are essentially quantitative with respect to both the sulfur compound and ozone. 

Chellamani, A., Harikengaram, S. Kinetics and mechanism of (salen)Mn" -catalysed oxidation of organic sulfides with sodium hypochlorite. J. Phys. Org. Chem. 2003, 16, 589-597. 

Oxidation of organic sulfides with hydrogen peroxide, over Ti-containing zeolites, may be a selective, mild and facile method for preparing sulfoxides. The reactivity of thioethers is in... 

The one-electron oxidation of organic sulfides yields sulfide radicals cations (Reaction (3.36)) [104]. 

Depending on the enzyme used for oxidation of organic sulfides, sulfoxides with S- or R-configuration can be obtained with high ee, whereas at present there is only one chemical oxidation method which leads to high ee in alkyl aryl sulfoxides. This method uses chiral titanium complexes and cumene hydroperoxide for the oxidation of organic sulfides[26]. 

Osmium tetroxide also catalyzes the oxidation of organic sulfides to sulfones with NMO or trimethylamine iV-oxide (see Osmium Tetroxide-N-MethylmorphoUne N-Oxide). In contrast, most sulfides are not oxidized with stoichiometric amounts of OSO4. Oxidations of alkynes and alcohols with OSO4 without and in the presence of cooxidants have also been reported. However, these reactions have not found wide synthetic applications because of the availability of other methods. 

Hypervalent iodine reagents are commonly used for the oxidation of organosulfiir compounds. Applications of hypervalent iodine reagents for the preparation of sulfoxides, including enantioselective oxidations of organic sulfides, have been summarized in reviews [519,520]. 

For the enantioselective oxidations of organic sulfides to chiral sulfoxides using iodine(V) reagents, also see Section 3.2. 

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