1774-34-1Relevant articles and documents
Redox Properties of Diaryl Chalcogenides and Their Oxides
Engman, Lars,Lind, Johan,Merenyi, Gabor
, p. 3174 - 3182 (1994)
The redox proeprties of diaryl chalcogenides and their corresponding oxides were studied by means of pulse radiolysis.Diaryl sulfides, selenides, and tellurides were found to be readily (k = 109 - 1010 M-1 s-1) oxidized to the corresponding radical cations by a variety of one-electron oxidants (Tl2+, OH., Br.-, N3.).None of the radical cations appeared to form three-elecron-bonded dimers with their corresponding chalcogenides.The radical cations of diaryl chalcogenides were also formed by one-electron reduction of their respective oxides.Among one-electron reductants tested, only the solvated electron was able to rapidly (k = (0.9 - 2) x 1010 M-1 s-1) reduce diphenyl sulfoxide and diphenyl selenoxide between pH 3 and 13.Diphenyl telluroxide is present predominantly as a hydrate, (C6H5)2Te(OH)2, which undergoes protonation/dehydration below pH 5.3 to yield (C6H5)2TeOH+.Both of these species react rapidly with the solvated electron to yield the radical cation, but only (C6H5)2TeOH+ reacts with CO2.- with measurably fast rate (k = 6 x 109 M-1 s-1).Upon one-electron oxidation, bis(4-hydroxymethyl) sulfide (pH > 0.5) and bis(4-hydroxyphenyl) telluride (pH > 2.5) were found to readily deprotonate to form phenoxyl radicals.Below pH 2.5, it was also possible to observe the radical cation spectrum of the organotellurium compound.One-electron reduction potentials of a variety of diaryl chalcogenide observing their redox equilibria by pulse radiolysis.The following E0 values versus NHE were determined E0 ((C6H5)2S.+/(C6H5)2S) = 1.54 V; E0 ((C6H5)2Se.+/(C6H5)2Se) = 1.37 V; E0 ((C6H5)2Te.+/(C6H)2Te) = 1.14 V; E0 ((4-HO-C6H4)2Te.+/(4-OH-C6H4)2Te) = 0.95 V; E0 ((4-H2N-C6H4)2Te.+/(4-H2N-C6H4)2Te) = 0.80 V; E0 ((4-OOCCH2O-C6H4)2S.+/(4-OOCCH2O-C6H4)2S) = 1.21 V.The two-electron redox potentials of the telluroxide/telluride redox couple were determined by means of EMF titration as a function of the pH.A value of 0.65 V was obtained for both the ((4-HO-C6H4)2Te(OH)2,2H+)/(4-HO-C6H4)2Te,2H2O) and the ((4-H2N-C6H4)2Te(OH)2,2H+)/((4-H2N-C6H4)2Te,2H2O) couples.The chalcogen-oxygen single-bond strengths in the OH adducts to diaryl chalcogenides were found to increase as one traverses the chalcogens from sulfur to tellurium.This is in contrast to the trend for the corresponding chalcogen-oxygen double bond strengths.A dissociation enthalpy of 84 kcal/mol was estimated for the Te=O bond in diaryl telluroxides.Calculated one-electron reduction potentials for diphenyl sulfoxide and dimethyl sulfoxide did not provide a thermodynamic rationale for the low reactivity of dialkyl sulfoxides toward the hydrated electron.Finally, the (C6H5)2S.+ radical cation was produced by reduction of (C6H5)2SO in a 50/50 v/v water/tert-butyl alcohol mixture.We thus propose (C6H5)2S.+ as a useful one-electron oxidant in mixed solvents.
Green, inexpensive, and fast conversion of sulfides to sulfoxides by multiusable Mo(VI) macrocyclic Schiff base complex supported on Fe3O4 nanoparticles in solvent-free conditions
Bezaatpour, Abolfazl,Payami, Fatemeh,Eskandari, Habibollah
, p. 910 - 920 (2017)
In the present study, the macrocyclic-based Mo(VI) Schiff base complex was harbored on Fe3O4 nanoparticles and characterized by X-ray powder diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy, infrared spectroscopy, transmission electron microscopy, vibrating sample magnetometry, diffuse reflectance spectra, and atomic absorption spectroscopy. Separable nanocatalyst was tested under solvent-free conditions for the oxidation of methyl phenyl sulfide, diphenyl sulfide, benzyl phenyl sulfide, dipropyl sulfide, dibutyl sulfide, dimethyl sulfide, bis (4-hydroxyphenyl) sulfide, diallyl sulfide, and benzothiophene using H2O2 (30% in water) as green oxidant. This catalyst is very efficient for thioanisole oxidation with 100% conversion in 3 min. We were able to separate the nanocatalyst magnetically using external magnetic field and to apply the catalyst at least six consecutive times without a significant decrease in conversion. Remarkable and excellent turnover frequency of the catalyst was obtained to oxidize the thioanisole (526,000 h?1), dimethyl sulfide (526,000 h?1), diallyl sulfide (526,000 h?1), dibutyl sulfide (521,000 h?1), and dipropyl sulfide (500,000 h?1). The prepared nanocatalyst has been beneficial in catalytic activity, selectivity, reaction time, and reusability with easy separation.
Deep eutectic solvent-assisted synthesis of highly efficient nanocatalyst (n-TiO2@TDI@DES (ZnCl2:urea)) for chemoselective oxidation of sulfides to sulfoxides
Taghavi, Shaghayegh,Amoozadeh, Ali,Nemati, Firouzeh
, (2020/12/21)
This study proposed a straightforward process to synthesize 2,4-toluene diisocyanate (TDI)-functionalized TiO2 nanoparticles in which a cost-effective linker (TDI) with high reactivity was employed to couple nano-TiO2 through covalent bonding to a deep eutectic solvent (DES). By this method, DES was successfully immobilized on the TiO2@TDI surface as an adsorbent and stabilizer. The structural, morphological, and physicochemical characteristics of the synthesized nanocatalysts were evaluated using various analytical methods including Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM–EDX), and elemental analysis. The heterogeneity of the catalyst was also examined by a hot filtration test. The obtained TiO2@TDI@DES nanoparticles offered superior catalytic behavior and excellent yield as well as recyclability for the chemoselective oxidation of sulfide into sulfoxide using a green oxidant (hydrogen peroxide). This catalyst exhibited excellent reusability as it can be recovered for six successive cycles with no significant leach or reduction of catalytic efficiency.
Modification of MnFe2O4 surface by Mo (VI) pyridylimine complex as an efficient nanocatalyst for (ep)oxidation of alkenes and sulfides
Bouzari, Narges,Bezaatpour, Abolfazl,Babaei, Behnam,Amiri, Mandana,Boukherroub, Rabah,Szunerits, Sabine
, (2021/03/04)
In this current paper, we report a new type of heterogeneous molybdenum (+6) complex, prepared by covalent grafting of cis-dioxo?molybdenum (VI) pyridylimine complex on the surface of MnFe2O4 nanoparticles (NP) and characterized using various physicochemical techniques. The recyclable prepared nanocatalyst was tested for sulfoxidation of sulfides and epoxidation of alkenes under solvent-free condition. The catalyst exhibited high turnover frequency for the oxidization of cyclooctene and cyclohexene (10,850 h?1) and thioanisole and dimethyl sulfide (41,250 h?1). The synthesized catalyst was found highly efficient, retrievable and eco-friendly catalyst for the (ep)oxidation of alkenes and sulfides in excellent yields in a short time. Furthermore, the synthesized nanocatalyst can be reused for four runs without apparent loss of its catalytic activity in the oxidation reaction.
