Diethyl sulphide, oxidation

In the dehalogenation of 4-chlorobiphenyl, 1-chloro- and 1-bromonaphthalene, 9-chloro- and 9-bromoanthracene and 4-chlorobenzonitrile, diethyl sulphide has been used as electron donor397. The involvement of radical anions in these reactions is evidenced by the incorporation of deuterium into the products when the reactions were performed in acetonitrile-deuterium oxide. Lithium diisopropylamide in hexane or tetrahydrofuran398 and sodium methyl siliconate (MeSi03Na3)399 have also been used as electron transfer reagents in the photodehalogenation of 4-chlorobiphenyl. 

Diphenyl sulphoxide, thiodiglycol sulphoxide, and diethyl sulphoxide are oxidised to the corresponding sulphones. Howard and Levitt studied the kinetics of oxidation of these compounds at pH 8 in a phosphate buffer (aqueous solution) and found the rates to be first-order with respect to peroxodisulphate and independent of the substrate concentration over the limited range employed (0.01-0.02 M). The removal of oxygen had no effect on the rate. Diethyl sulphide is oxidised very rapidly initially, then at the same rate as diethyl sulphoxide. Howard and Levitt concluded that the sulphide is first oxidised to the sulphoxide which in turn is oxidised to the sulphone, but Wilmarth and Haim point out that this interpretation cannot be correct, and conclude that the reaction must be more complex. 

The micelle-bound carboxylate-catalysed iodine oxidation of diethyl sulphide shows a decrease in the free energy of activation of 0.55 kcal mol per additional methylene in the carboxylate. This represents 80% of the available hydrophobic binding energy. By contrast, the micelle-catalysed oxidation of ketones shows an energy decrease of 0.16 kcal mol per methylene in the ketone. ... 

Micellar Efllecls on Inorganic Reactions.—Electron transfer between ferric ion and phenothiazine is inhibited by cationic micelles and accelerated by up to 10 -fold in anionic micelles of sodium lauryl sulphate. " In both cases the rate-surfactant concentration profile can be simulated accurately. Anionic micelles only cause a small effect on the reactivity of ruthenium(iii) tris(bipyridyl) with molybdenum(iv) octacyanide but accelerate the reaction between ferrous ion and tris(tetramethylphenanthroline)iron(ra). In the latter case a plot of surfactant concentration is linear with the reciprocal of the observed rate constant. Fast outer-sphere electron-transfer reactions may decrease in rate constant by up to four orders of magnitude when one of the reactants is solubilized in an anionic micelle. When this partner is neutral the inhibition is reduced somewhat by added salt, but when it is cationic the effect may be attenuated by competitive binding of Na or HsO and exclusion of reactant from the micelle. Oxidation of diethyl sulphide is catalysed by micelles of sodium lauryl sulphate containing carboxylate-ions by the mechanism shown. (Scheme 3). The rate advantage is quantitatively accounted for by the entropy term, and hexanoate is forty-fold more effective than acetate. Electron-transfer between the anionic trans-1,2-diaminocyclohexane... 

The standard Sharpless reagent [Ti(OPr-i)4/(R, R)-diethyl tartrate (DET)/t-BuOOH] oxidizes methyl p-tolyl sulphide into a mixture of racemic sulphoxide and sulphone286. 

A closely related asymmetric synthesis of chiral sulphoxides, which involves a direct oxidation of the parent sulphides by t-butylhydroperoxide in the presence of metal catalyst and diethyl tartrate, was also reported by Modena and Di Furia and their coworkers-28-7,288 jjje effect 0f the reaction parameters such as metal catalyst, chiral tartrate and solvent on the optical yield does not follow a simple pattern. Generally, the highest optical purities (up to 88%) were observed when reactions were carried out using Ti(OPr-i)4 as a metal catalyst in 1,2-dichloroethane. 

Photochemical irradiation of dimethyl and diethyl sulphoxides yields the corresponding sulphone in the presence of air and a photosensitizer such as methylene blue in yields up to 99% . Sulphoxides are also oxidized when they act as traps for persulphoxides, the intermediate formed on reaction of a sulphide with photochemically generated singlet oxygen - , equation (9). Isotope studies have shown that such reactions proceed through a linear sulphurane intermediate . Persulphones also react with sulphoxides in a similar manner , equation (10). 

Preparation of Sodium Sulphide. Assemble an apparatus as shown in Fig. 67. Put 0.2 g of finely triturated highly pure sulphur into test tube 1 with a ground-glass joint, and lower the tube into a beaker with a mixture of dry ice and acetone. Connect a source of dry ammonia (see Fig. 62a) to cock 3 of the apparatus, open cock 4, and fill the apparatus with ammonia. Put 2 g of metallic sodium thoroughly purified of oxide films and washed with benzene and diethyl ether onto filter 2. Pass ammonia through the apparatus until test tube 1 is filled with liquid ammonia up to one-third of its volume, after which disconnect the apparatus for preparing ammonia. 

Simple optically active phosphines can be converted back into phosphonium salts without any change of configuration if benzyl or alkyl halides are used (reversal of Equation 13.57). Oxidation to phosphine oxides with hydrogen peroxide or sulphurisation to phosphine sulphides with elemental sulphur also proceeds with retention of configuration. On the other hand, racemisation or complete inversion occurs if oxidation is carried out with diethyl peroxide. Halogenation to a phosphonium compound followed by hydrolysis results in inversion (13.63). 

Corey has reported a novel method for the introduction of two alkyl appendages at the carbonyl carbon of ketones. Ketones react with the anion of diethyl allylthiomethylphosphonate (155) to give vinyl allyl sulphides such as (156) heating in the presence of mercury(ii) oxide induces a thio-Claisen rearrangement to yield the aldehyde (157), which can be further elaborated by various oxidation-reduction sequences to give, for example, the spiro-enone (158). 

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