Oxidation of organic sulphides—XVI

Synthesis and electrochemical characterisation of some long chain 1,4,8,11,15,18,22,25-octa-alkylated metal-free and zinc phthalocyanines possessing discotic liquid crystalline properties

“…The poor solubility of the dialkylated thiophenes, 3, with the longer alkyl chains in the solvent of choice for sodium perborate-induced oxidations, glacial acetic acid, probably contributes much to the observed decrease in yields. When oxidation of series 3 was performed with m-chloroperoxybenzoic acid, MCPBA, in dichloromethane 18 the yield of 2,5-bis(dodecyl)thiophene 1,1-dioxide was increased to 41% after 18 hours, but yields for the C 18 H 37 derivative remained unsatisfactory. However, when oxidation of series 3 was performed with dimethyldioxirane, 19 near quantitative oxidation was observed for all dialkylated thiophenes provided stirring of the heterogeneous reaction mixture was ef®cient.…”

“…Phthalocyanines have been investigated inter alia for applications such as dyestuffs, 1 blue and green pigments, 2 chemical sensors, 1,3 photodynamic cancer drugs, 4 non-linear optical materials, 5 converters of visible light energy (from solar radiation) into various other forms of energy including chemical 6 and electrical energy, 7 catalysts in a variety of chemical reactions including hydrogenation of multiple bonds 8 and oxidation of thiols, 9 and as liquid crystals. 10 One of our groups has reported wide ranging investigations of non-peripherally substituted 1,4,8,11,15,18,22,25-octakisalkylphthalocyanines. These have been obtained as metal-free, copper, cobalt, nickel 11 and zinc 12 derivatives and homologous series have been synthesized in which the length of the alkyl chains has been varied from methyl through to decyl.…”

Mechanism for the Oxidation of Sulfides and Sulfoxides with Periodates: Reactivity of the Oxidizing Species

“…Sulfoxides are also oxidized to sulfones with IO 4 -in a one-step oxygen-transfer reaction, and the structures of the TSs and the ∆G ‡ data are similar to those obtained for the reactions of sulfides. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) and sulfoxides were suggested to proceed by a one-step oxygen-transfer mechanism in the reactions initiated by peroxides, [17][18][19][20] percarboxylic acids, [17,[21][22][23] peroxomonophosphoric acid, [24] as well as by permanganate [25] and peroxomolybdate ions [26] and several metal complexes. [27][28][29][30][31][32][33] A mechanism involving oxygen-atom transfer steps has also been proposed for the periodate oxidation of the iodide ion.…”

An investigation by means of correlation analysis into the mechanisms of oxidation of aryl methyl sulfides and sulfoxides by dimethyldioxirane in various solvents

“…Numerous oxidations of organosulfur compounds by hydroperoxidic reagents have been studied over the past five decades. [1][2][3][4][5][6][7][8][9][10][11][12][13] The early expectation was that the oxidation of sulfides would involve the formation of a sulfonium intermediate by S N 2 displacement of nucleophilic S upon the peroxo bond (Scheme 1a); 1 however, inconsistencies with this assumption became apparent. For example, reaction rates are strongly dependent neither on the relative permittivity of the solvent 2 nor on the ionic strength 3 as would be expected for a reaction involving a large separation of charge; on the other hand, reaction rates are strongly dependent on the protic nature of the solvent 4 and, if an aprotic solvent is used, the order of reaction in the hydroperoxide may increase from one to two.…”