Sulfoxidation of thioethers using titanium silicate molecular sieve catalysts

Reddy, Ranga; Reddy, J. Sudhakar; Kumar, Rajiv; Kumar, Pradeep

doi:10.1039/c39920000084

Cited by 96 publications

(27 citation statements)

References 6 publications

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“…[8] In many of these studies, the properties of the solvent used were found to be important, for example, a strong correlation between molar transition energy e T (30) and initial oxidation rate was observed. [5] In all these reactions the foremost criterion is that the oxidation is selective, with the rate of reaction being of secondary importance. It has recently been shown that ionic liquids can provide a medium in which to perform reactions without over-oxidation, [10] and therefore the effect of ionic liquids on the selective oxidation of thioethers was investigated.…”

Section: Introductionmentioning

confidence: 99%

“…[3][4][5][6][7][8][9] For example, Reddy et al used molecular sieves containing titanium to achieve chemoselectivities of between 75 and 97 % for dialkyl and alkyl-aryl thioethers. [5] Hulea et al also reported the selective oxidation of dialkyl thioethers over various zeolites. [6] Robinson et al investigated the rates of sulfoxide and sulfone formation following the oxidation of alkyl and allyl thioethers using TS-1/H 2 O 2 and demonstrated that shape-selective catalysis could occur for the more bulky thioethers studied.…”

Section: Introductionmentioning

confidence: 99%

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Heterogeneous Oxidation of Pyrimidine and Alkyl Thioethers in Ionic Liquids over Mesoporous Ti or Ti/Ge Catalysts

Cimpeanu

Pârvulescu

Amorós

et al. 2004

Chemistry A European J

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Heterogeneous catalytic oxidation of a series of thioethers (2-thiomethylpyrimidine, 2-thiomethyl-4,6-dimethyl-pyrimidine, 2-thiobenzylpyrimidine, 2-thiobenzyl-4,6-dimethylpyrimidine, thioanisole, and n-heptyl methyl sulfide) was performed in ionic liquids by using MCM-41 and UVM-type mesoporous catalysts containing Ti, or Ti and Ge. A range of triflate, tetrafluoroborate, trifluoroacetate, lactate and bis(trifluoromethanesulfonyl)imide-based ionic liquids were used. The oxidations were carried out by using anhydrous hydrogen peroxide or the urea-hydrogen peroxide adduct and showed that ionic liquids are very effective solvents, achieving greater reactivity and selectivity than reactions performed in dioxane. The effects of halide and acid impurities on the reactions were also investigated. Recycling experiments on catalysts were carried out in order to evaluate Ti leaching and its effect on activity and selectivity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Heterogeneous Oxidation of Pyrimidine and Alkyl Thioethers in Ionic Liquids over Mesoporous Ti or Ti/Ge Catalysts

Cimpeanu

Pârvulescu

Amorós

et al. 2004

Chemistry A European J

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“…[10,15] The structure of the zeolite (MFI, BEA, MEL) [16][17][18] and the nature of the solvent [19,20] influence oxidation rates. Hulea et al [21] reported that H 2 O 2 reacts with ethylsulfide on Ti-BEA and TS-1 (Ti-MFI), but only Ti-BEA catalyzed the oxidation of larger thiophenic molecules, because of difussional constraints prevalent in TS-1.…”

Section: Introductionmentioning

confidence: 99%

Selective Catalytic Oxidation of Organosulfur Compounds with tert‐Butyl Hydroperoxide

Chica¹,

Gatti²,

Modén³

et al. 2006

Chemistry A European J

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Rates and selectivities for the oxidation of various organosulfur compounds with tert-butyl hydroperoxide were measured on CoAPO-5 (APO = aluminophosphate; Co/P = 0.05), Co/H-Y (Co/Al = 0.15), and MoO(x)/Al2O3 (15 % wt MoO3). Rates increased with increasing electron density at the sulfur atom (methyl phenyl sulfide>diphenyl sulfide>4-methyldibenzothiophene>2,5-dimethyl thiophene). Rates (per metal atom) were significantly higher on CoAPO-5 than on Co/H-Y, MoO(x)/Al2O3, or homogeneous Co acetate catalysts. Small amounts of sulfoxides (1-oxide) were detected on all catalysts at low reactant conversions, together with their corresponding sulfones; at higher conversions, only sulfones (1,1-dioxide) were detected, indicating that the oxidation of sulfoxides is much faster than for organosulfur reactants in the sequential oxidation pathways prevalent on these catalysts. Framework Co cations were not leached from CoAPO-5 during the oxidation of 4-methyldibenzothiophene, but most exchanged Co cations in H-Y and >20 % of Mo cations in MoO(x)/Al2O3 were extracted during these reactions. The fraction of redox-active Co cations in CoAPO-5 and Co/H-Y was measured by reduction-oxidation cycles using H2 and O2 and by UV-visible spectroscopy. This fraction was much larger in CoAPO-5 (0.35) than in Co/H-Y (0.01), consistent with the higher oxidation rates measured on CoAPO-5 and with the involvement of redox-active species in kinetically-relevant steps in catalytic oxidation sequences. Redox-active Co cations at framework positions within accessible channels are required for catalytic activity and structural stability during oxidative desulfurization, whether hydroperoxides are used as reactants or as intermediates (when O2 is used as the oxidant).

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“…We selected titanosilicate as the catalyst for oxidation by hydrogen peroxide since the effective catalytic ability of titanosilicate to form sulfoxide from a simple structural sulfide (thioether) in the presence of hydrogen peroxide has been reported. [16][17][18] Titanosilicate has been used in the field of chemical industry as a catalyst for hydrogen peroxide. 19) This article deals with the search for the optimal reaction conditions of reaction to form the oxide of each drug using hydrogen peroxide and titanosilicate in a small scale reaction (0.1 mmol).…”

Section: Introductionmentioning

confidence: 99%

Preparation of Metabolites by Chemical Reaction: Conversion of Antipsychotic Phenothiazines to their Sulfoxides and Tertiary Amino Cyclic Antidepressants to their N-Oxide with Hydrogen Peroxide Using Titanosilicate Catalyst

Ogamo

Fukumoto

2004

JOURNAL OF HEALTH SCIENCE

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The aim of this study was to establish a preparation method needed to analyze the metabolites of an analytical procedure for antipsychotic phenothiazines and tertiary amino cyclic antidepressants by chemical reaction. These drugs were oxidized to their sulfoxide and N-oxide, respectively, with hydrogen peroxide using titanosilicate as the catalyst. An acidic medium (pH 3.0) containing 20% methanol was found to be optimal for the preparation of phenothiazine sulfoxide, and an alkaline medium (pH 10.5) containing 50% methanol was optimal for the preparation of the Noxide of tertiary amino cyclic antidepressants. Each preparative scale reaction (2 mmol) was carried out and the crystallized product of each oxide was obtained. The amount of hydrogen peroxide needed to obtain the best yields of sulfoxide was 1.3-2.0 times the molar equivalent of the phenothiazines. The purities of the prepared crystallized product of the phenothiazine sulfoxides were good except for periciazine sulfoxide. The amounts of hydrogen peroxide needed to obtain the best yields of N-oxide were 4-5 times the molar equivalent of tertiary amino cyclic antidepressants. The purities of the crystals of each N-oxide were 99.5-100%. The characteristic mass fragment ions of each prepared oxide that were distinguishable as the N-oxides from parent drug could be confirmed when the collisional energy was decreased to 10 eV. 1 H-and 13 C-NMR spectral data confirmed the structure of the prepared mianserin N-oxide to be 2-oxide. In conclusion, a simple and rapid preparation method for oxide metabolites of phenothiazines and tertiary amino cyclic antidepressants available as analytical standards was established.

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Sulfoxidation of thioethers using titanium silicate molecular sieve catalysts

Abstract: Titanium silicate molecular sieves having MEL (TS-2) or MFI (TS-1) topology efficiently catalyse the oxidation of various thioethers to the corresponding sulfoxides and sulfones using dilute hydrogen peroxide (26 wt%) as an oxidising agent.

Cited by 96 publications

References 6 publications

Heterogeneous Oxidation of Pyrimidine and Alkyl Thioethers in Ionic Liquids over Mesoporous Ti or Ti/Ge Catalysts

Heterogeneous Oxidation of Pyrimidine and Alkyl Thioethers in Ionic Liquids over Mesoporous Ti or Ti/Ge Catalysts

Selective Catalytic Oxidation of Organosulfur Compounds with tert‐Butyl Hydroperoxide

Preparation of Metabolites by Chemical Reaction: Conversion of Antipsychotic Phenothiazines to their Sulfoxides and Tertiary Amino Cyclic Antidepressants to their N-Oxide with Hydrogen Peroxide Using Titanosilicate Catalyst

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