- Metal and solvent free selective oxidation of sulfides to sulfone using bifunctional ionic liquid [pmim]IO4
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The oxidation of organo-sulfides to sulfones has been accomplished using an easily accessible bifunctional ionic liquid, [pmim]IO4 in the absence of any other oxidants, metal and organic solvent at ambient temperature. A variety of sulfides including dialkyl, aryl-alkyl, diaryl, and aryl-hetero aryl have been oxidized to the corresponding functionalized sulfones in high yields by this procedure.
- Ahammed, Sabir,Kundu, Debasish,Siddiqui, Mohammad Nahid,Ranu, Brindaban C.
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p. 335 - 337
(2015/03/18)
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- Chromium(VI) oxide catalyzed oxidation of sulfides to sulfones with periodic acid
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A highly efficient and selective oxidation of sulfides to sulfones with periodic acid catalyzed by CrO3 is described. A variety of electron-rich and electron-deficient sulfides were oxidized to sulfones with 2 mol% CrO3 in acetonitrile at room temperature in excellent yields. Sulfides with other readily oxidized functional groups were selectively oxidized to sulfones in high yields with 10 mol% CrO3 in ethyl acetate/acetonitrile at -35 °C.
- Xu, Liang,Cheng, Jie,Trudell, Mark L.
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p. 5388 - 5391
(2007/10/03)
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- The Relative Reactivity of Thioethers and Sulfoxides toward Oxygen Transfer Reagents: The Oxidation of Thianthrene 5-Oxide and Related Compounds by MoO5HMPT
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The oxidation of thianthrene 5-oxide (SSO) by MoO5HMPT has been studied in 1,2-dichloroethane at 40 deg C.Under conditions of excess substrate over the oxidant, three products are formed, i.e., two isomeric cis and trans bissulfoxides (SOSO) and sulfide-sulfone (SSO2) which quantitatively account for the active oxygen of MoO5HMPT consumed.The rates of appearance of the products at different reactant concentrations have been measured.A second-order rate law has been established.The ratios of the rate constants and of the final concentrations of the three products, i.e., k2(cis-SOSO):k2(trans-SOSO):k2(SSO2) = 1.0:4.0:1.0; infinite:infinite:infinite = 1.0:4.5:1.2, are in good agreement.The trans-SOSO-forming reaction is only 4-fold faster than that leading to SSO2. cis-SOSO and SSO2 are produced at almost the same rate.Evidence is presented that all the oxidation reactions are electrophilic processes taking place via a simple bimolecular mechanism not involving the coordination of the substrate to the metal.The low selectivity is due to the scarce reactivity of the thioether center in thianthrene 5-oxide.The investigation of the oxidative behavior of structurally related compounds reveals that such a low reactivity results from a combination of stereoelectronic effects.These findings provide a rationale to some ambiguous results obtained when thianthrene 5-oxide is employed as a mechanistic probe of the electronic character of the oxidants.
- Bonchio, Marcella,Conte, Valeria,Conciliis, Maria Assunta De,Furia, Fulvio Di,Ballistreri, Francesco Paolo,et al.
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p. 4475 - 4480
(2007/10/02)
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- Oxygen transfer reactions. 2. A comparison of the reactions of ruthenium tetroxide, chromyl chloride, and permanganate with thianthrene 5-oxide
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Products obtained from the oxidation of thianthrene 5-oxide, SSO, have been used to compare oxygen transfer mechanisms for three high-valent transition metals. Oxidation of SSO by benzyltriethylammonium permanganate in methylene chloride gives the corresponding sulfone, thianthrene 5,5-dioxide (SSO2), as the exclusive product. Oxidation of SSO by ruthenium tetroxide also gives SSO2 as the predominant product along with minor amounts of the disulfoxide, thianthrene 5,10-dioxide (SOSO). However, the converse is observed when chromyl chloride is used as the oxidant; SOSO is the major product. It is suggested that oxygen transfers from permanganate and ruthenium tetroxide are initiated by complexation between the central metal atom and the oxygen end of the S=O dipole, while oxidation by chromyl chloride is likely initiated by an alternative mechanism, possibly a single electron transfer.
- May,Yee,Lee
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p. 2249 - 2254
(2007/10/02)
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- FURTHER FUNCTIONAL GROUP OXIDATIONS USING SODIUM PERBORATE
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Sodium perborate in acetic acid is an effective reagent for the oxidation of aromatic aldehydes to carboxylic acids, iodoarenes to (diacetoxyiodo)arenes, azines to N-oxides, and various types of sulfur heterocycles to S,S-dioxides.Nitriles are unaffected by the reagent in acetic acid, but undergo smooth hydration to amides when aqueous methanol is employed as solvent.
- McKillop, Alexander,Kemp, Duncan
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p. 3299 - 3306
(2007/10/02)
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- Oxidation of Organic Sulphides by Chlorine and lodosylbenzene Diacetate: Kinetics and Mechanism
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Chlorine oxidises diphenyl sulphide and a range of cyclic analogues, and also the corresponding sulphoxides, in a reaction which is first order with respect to both chlorine and substrate; the order with respect to chloride ion is -1.These results are consistent with a mechanism similar to that usually accepted for oxidation by bromine or iodine.Oxidation of the same substrates by iodosylbenzene diacetate is acid catalysed, but zero order with respect to oxidant.A mechanism is proposed, involving rate-determining rehybridisation of a tetrahedral protonated sulphide, or sulphoxide, to a trigonal pyramidal form from which the oxidant abstracts a hydride ion simultaneously with nucleophilic attack by water.The same mechanism can account for the formation of sulphonium salts as by-products from the more reactive sulphides.Structural influences on reactivity can be rationalised in terms of electronic and steric effects.
- Humffray, Alan A.,Imberger, Helmut E.
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p. 382 - 387
(2007/10/02)
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