- Redox Properties of Diaryl Chalcogenides and Their Oxides
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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.
- Engman, Lars,Lind, Johan,Merenyi, Gabor
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Read Online
- Robust and fast oxidation of sulfides by immobilized Mo(VI) complex on magnetic nanoparticles in solvent-free condition
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In this research, a heterogeneous catalyst by modifying the magnetically reusable manganese ferrite nanomaterials with oxo-peroxomolybdenum (VI) Schiff base complex was prepared. The prepared catalyst was characterized completely using different physicochemical methods. The recoverable heterogeneous catalyst was tested with different sulfides for the sulfoxidation process under solvent-free situation. The significant and superior turnover frequency (TOF) of the nanocatalyst was acquired to oxidize C7H8S compound (9408 h?1). The offered nanocatalyst has been shown catalytic selectivity, activity, and reusability in a short time. Furthermore, the heterogeneous catalyst has good recoverability at least five consecutive cycles without losing its selectivity towards products in the oxidation reaction.
- Babaei, Behnam,Basharnavaz, Hadi,Bezaatpour, Abolfazl
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Read Online
- 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
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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.
- Bezaatpour, Abolfazl,Payami, Fatemeh,Eskandari, Habibollah
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- Fe(III)-salen complex supported on dendrimer functionalized magnetite nanoparticles as a highly active and selective catalyst for the green oxidation of sulfides
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In this study, we reported the preparation of polyamidoamine-modified magnetite nanoparticles and their use for the immobilization of Fe(III)-salen complex to form a novel magnetic catalyst. The prepared catalyst was characterized by some modern techniques i.e. Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), N2 adsorption-desorption analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), and inductively couple plasma atomic emission spectroscopy (ICP-AES). The catalyst showed excellent activity and selectivity for the oxidation of sulfides to sulfoxides (conversion 87–100percent, selectivity 82–100percent) using H2O2 (30percent w/w) as oxidant in aqueous medium at 50 °C. Furthermore, the catalyst could be recovered in a facile manner from the reaction mixture by using a magnet and reused for five cycles with high catalytic stability.
- Asadi, Zahra,Masteri-Farahani, Majid,Niakan, Mahsa
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- Deep eutectic solvent-assisted synthesis of highly efficient nanocatalyst (n-TiO2@TDI@DES (ZnCl2:urea)) for chemoselective oxidation of sulfides to sulfoxides
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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.
- Taghavi, Shaghayegh,Amoozadeh, Ali,Nemati, Firouzeh
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- Selective synthesis of sulfoxides and sulfonesviacontrollable oxidation of sulfides withN-fluorobenzenesulfonimide
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A practical and mild method for the switchable synthesis of sulfoxides or sulfonesviaselective oxidation of sulfides using cheapN-fluorobenzenesulfonimide (NFSI) as the oxidant has been developed. These highly chemoselective transformations were simply achieved by varying the NFSI loading with H2O as the green solvent and oxygen source without any additives. The good functional group tolerance makes the strategy valuable.
- Cao, Zhong-Yan,Li, Xiaolong,Lu, Hao,Wang, Panpan,Wang, Shengqiang,Xu, Xiaobo,Yan, Leyu,Yang, A-Xiu
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supporting information
p. 8691 - 8695
(2021/10/22)
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- Modification of MnFe2O4 surface by Mo (VI) pyridylimine complex as an efficient nanocatalyst for (ep)oxidation of alkenes and sulfides
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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.
- Bouzari, Narges,Bezaatpour, Abolfazl,Babaei, Behnam,Amiri, Mandana,Boukherroub, Rabah,Szunerits, Sabine
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- Sulfoxidation inside a hypercrosslinked microporous network nanotube catalyst
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In the present work, a kind of efficient heterogeneous catalyst was synthesized from amine-functionalized hypercrosslinked bottlebrush copolymers of microporous network nanotubes (amine-MNNs) and Na2WO4. The synthesized tungstate-supported microporous network nanotubes (TMNNs) catalyst was shown to be highly active in the selective H2O2 oxidation of sulfides to sulfoxides or sulfones under mild conditions due to the high specific surface area (800 m2 g-1) and firm structure of the nanotubes. The catalyst was found to be very stable and could be recycled at least 8 times without any significant loss of activity. These results present a new opportunity for the development of efficient green organic catalytic materials with high activity.
- Shi, Zhaocheng,Ying, Zhong,Yang, Liusai,Meng, Xiaoyan,Wu, Lidan,Yu, Leshu,Huang, Sen,Xiong, Linfeng
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supporting information
p. 1542 - 1547
(2020/02/06)
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- Synthesis and nano-Pd catalyzed chemoselective oxidation of symmetrical and unsymmetrical sulfides
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A highly chemoselective, efficient and nano-Pd catalyzed protocol for the rapid construction of sulfoxides and sulfones via the oxidation of symmetrical and unsymmetrical sulfides using H2O2 as an oxidant has been developed, respectively. The ready availability of starting materials, easy recovery and reutilization of the catalyst, wide substrate scope, and high yields make this protocol an attractive alternative. The process also involves the metal-free and microwave-promoted synthesis of symmetrical diarylsulfides, and FeCl3-mediated preparation of symmetrical diaryldisulfides through the reaction of arenediazonium tetrafluoroborates with Na2S·9H2O as a sulfur source. In addition, unsymmetrical sulfides were generated via the K2CO3-mediated reaction of arenediazonium tetrafluoroborates with symmetrical disulfides.
- Li, Xing,Du, Jia,Zhang, Yongli,Chang, Honghong,Gao, Wenchao,Wei, Wenlong
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p. 3048 - 3055
(2019/03/21)
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- Synthesis and characterization of indium and thallium immobilized on isonicotinamide-functionalized mesoporous MCM-41: Two novel and highly active heterogeneous catalysts for selective oxidation of sulfides and thiols to their corresponding sulfoxides and disulfides
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Two highly ordered isonicotinamide (INA)-functionalized mesoporous MCM-41 materials supporting indium and thallium (MCM-41-INA-In and MCM-41-INA-Tl) have been developed using a covalent grafting method. A surface functionalization method has been applied to prepare Cl-modified mesoporous MCM-41 material. Condensation of this Cl-functionalized MCM-41 with INA leads to the formation of MCM-41-INA. The reaction of MCM-41-INA with In(NO3)3 or Tl(NO3)3 leads to the formation of MCM-41-INA-In and MCM-41-INA-Tl catalysts. The resulting materials were characterized using various techniques. These MCM-41-INA-In and MCM-41-INA-Tl catalysts show excellent catalytic performance in the selective oxidation of sulfides and thiols to their corresponding sulfoxides and disulfides. Finally, it is found that the anchored indium and thallium do not leach out from the surface of the mesoporous catalysts during reaction and the catalysts can be reused for seven repeat reaction runs without considerable loss of catalytic performance.
- Molaei, Somayeh,Ghadermazi, Mohammad
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- Oxygenation of sulfides catalysed by SBA-15-immobilized molybdenum(VI) complex of a bis(phenol) diamine ligand using aqueous hydrogen peroxide as a green oxidant
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A highly efficient and reusable molybdenum-based catalyst has been synthesized by covalent grafting of a bis(phenol) diamine ligand, namely 2-(((2-bromoethyl)(2-((3,5-di-tert-butyl-2-hydroxybenzyl)amino)ethyl)amino)methyl)-4,6-di-tert-butylphenol, onto functionalized ordered mesoporous silica (SBA-15) followed by complexation with MoO2(acac)2. The resulting organic–inorganic hybrid material was found to be a highly effective catalyst for oxygenation of various sulfides to their corresponding sulfoxides or sulfones. The catalyst was characterized using transmission and scanning electron microscopies, X-ray photoelectron, Fourier transform infrared and atomic absorption spectroscopies, Brunauer–Emmett–Teller surface area analysis and thermogravimetric analysis. Mild reaction conditions, high selectivity and easy recovery and reusability of the catalyst render the presented protocol very useful for addressing industrial needs and environmental concerns.
- Saberikia, Iraj,Safaei, Elham,Karimi, Babak,Lee, Yong-Iii
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- Applications of iron and nickel immobilized on hydroxyapatite-core-shell γ-Fe2O3 as a nanomagnetic catalyst for the chemoselective oxidation of sulfides to sulfoxides under solvent-free conditions
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In the present study, Fe2+ and Ni2+ immobilized on hydroxyapatite-core-shell γ-Fe2O3 (γ-Fe2O3@HAp-Fe2+ and γ-Fe2O3@HAp-Ni2+) with a high surface area has been synthesized and characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), and scanning electron microscope (SEM) techniques. Then, γ-Fe2O3@HAp-Fe2+ and γ-Fe2O3@HAp-Ni2+ were used as a new and magnetically recoverable nano catalyst for the selective oxidation of sulfides to sulfoxides with 33% aqueous H2O2 (0.5 mL) as an oxidant at room temperature in good to excellent yields and short reaction time. Nontoxicity of reagent, mild reaction condition, inexpensive and high catalytic activity, simple experimental procedure, short period of conversion and excellent yields, and ease of recovery from the reaction mixture using an external magnet are the advantages of the present method.
- Sajjadifar, Sami,Rezayati, Sobhan,Arzehgar, Zeinab,Abbaspour, Sima,Torabi Jafroudi, Mogharab
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p. 960 - 969
(2018/03/29)
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- Synthesis and characterization of oxo-vanadium complex anchored onto SBA-15 as a green, novel and reusable nanocatalyst for the oxidation of sulfides and oxidative coupling of thiols
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Abstract: The present work describes the synthesis of a new oxo-vanadium complex immobilized on SBA-15 nanostructure as an efficient catalyst for oxidation of sulfides and oxidative coupling of thiols. Characterization of the resultant AMPD@SBA-15 nanostructure was performed by various physico-chemical techniques such as Fourier transform infrared spectroscopy, transmission and scanning electron microscopies, energy-dispersive X-ray spectroscopy, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, thermal gravimetric analysis, and N2 adsorption and desorption. The results of the developed procedure bring several benefits such as the use of commercially available, ecologically benign, operational simplicity, and cheap and chemically inert reagents. It shows good reaction times, practicability and high efficiency, and is easily recovered from the reaction mixture by simple filtration and reused for several consecutive cycles without noticeable change in its catalytic activity. More importantly, high efficiency, simple and an inexpensive procedure, commercially available materials, easy separation, and an eco-friendly procedure are the several advantages of the currently employed heterogeneous catalytic system.
- Tamoradi, Taiebeh,Ghadermazi, Mohammad,Ghorbani-Choghamarani, Arash,Molaei, Somayeh
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p. 4259 - 4276
(2018/03/21)
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- Selective oxidation method of thioether
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The invention relates to a selective oxidation method of thioether, and discloses a novel synthesis method of a single sulfone compound shown as a formula (I). According to the invention, thioether shown in a formula (II) is taken as a raw material, under existence of tert-butyl hydroperoxide, an oxidation reaction is carried out in a solvent, after the reaction is completed, and through post-treatment, the single sulfone compound shown as the formula (I) is obtained. Compared with the prior art, an oxidizing agent tert-butyl hydroperoxide which is friendly to environment is employed, usage ofa metal catalyst is avoided, the reaction condition is mild, selectivity is high, the operation is simple, the applicability is wide, and the reaction yield is high.
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Paragraph 0066; 0067; 0068
(2018/09/20)
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- Schiff base complex of Mo supported on iron oxide magnetic nanoparticles (Fe3O4) as recoverable nanocatalyst for the selective oxidation of sulfides
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In this work, a new tridentate Schiff base dioxo-molybdenum(VI) complex immobilized on silica-coated magnetic nanoparticles (MoO25CML–Fe3O4@SiO2) has been synthesized and characterized using different techniques such as FTIR, TGA, AAS, ICP–AES, XRD, VSM, EDX and SEM analyses. The catalytic activity of synthesized complex was examined in the oxidation of various sulfides in the presence of H2O2 as cheap, green and eco-friendly oxidant. This catalytic system provides high conversion and selectivity toward either sulfoxides or sulfones under different conditions. Also, the nanocatalyst could be easily separated and regenerated from reaction media by external magnet and could be reused for ten times without significant loss of the activity and selectivity.
- Aghajani, Milad,Monadi, Niaz
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p. 963 - 975
(2017/03/11)
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- Nano-sized glass as an economically viable and eco-benign support to anchor heteropolyacids for green and sustainable chemoselective oxidation of sulfides to sulfoxides
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Abstract: In this work, glass wastes were employed as cost-effective supports for the immobilization of phosphomolybdic acid (5–25 wt.% PMA) through an impregnation method. The highly efficient and retrievable nanocatalyst named nano-glass waste-supported phosphomolybdic acid (n-GW/PMA) was fully characterized by several techniques such as: XRD, FE-SEM, EDX, FT-IR and TGA. The catalytic performance of the as-synthesized heterogeneous nanocatalyst was effectively investigated for the chemoselective oxidation of sulfides to sulfoxides in the presence of 30% H 2O 2 as an oxidant at room temperature under solvent-free condition. Optimization of the reaction conditions was performed by means of central composite design (CCD), which is one of the powerful response surface methodologies. Based on the results obtained under the optimum condition, the sample of 16 wt.% of PMA loading offered high conversion rates and yields (97%). Besides, the beneficial points of the prepared catalyst were its recoverability and reusability for several reaction cycles, low-cost and toxicity, easy availability and facile production. Graphical abstract: Nano-glass waste-supported phosphomolybdic acid (n-GW/PMA) was synthesized as a novel, highly efficient and retrievable nanocatalyst for the chemoselective, green and rapid oxidation of sulfides to sulfoxides through an experimental design (CCD) approach. The prepared catalyst was characterized by FT-IR, TGA, XRD, FE-SEM and EDX techniques. [Figure not available: see fulltext.].
- Zolfagharinia, Somayeh,Kolvari, Eskandar,Koukabi, Nadiya,Hosseini, Maliheh M
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p. 1411 - 1421
(2017/09/25)
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- Sulfamic acid-functionalized nano-titanium dioxide as an efficient, mild and highly recyclable solid acid nanocatalyst for chemoselective oxidation of sulfides and thiols
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A highly efficient and retrievable titanium dioxide-based nanocatalyst has been synthesized by covalent grafting of chlorosulfonic acid on amine-functionalized titania as a novel inorganic-organic hybrid heterogeneous nanocatalyst, which was characterized by Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The acid strength of the catalyst was determined by pH analysis and the Hammett acidity function. The potential of the resultant nanocatalyst was effectively evaluated for the chemoselective oxidation of sulfides to sulfoxides and thiols to disulfides using 30% H2O2 as an oxidant at room temperature under solvent-free conditions, which led to high conversion rates and yields. Optimization of the reaction conditions was studied by central composite design (CCD), which is one of the most widely used response surface methodologies. The catalyst can be easily recycled up to 10 times without significant decrease in catalytic activity, which makes it a promising catalyst for practical and large-scale applications. This work is the first report that uses 2,4-toluene diisocyanate as a linker for immobilizing liquid acid on a support.
- Tabrizian, Elham,Amoozadeh, Ali,Rahmani, Salman
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p. 21854 - 21864
(2016/03/08)
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- Magnetic nanoparticle-supported imidazole tribromide: a green, mild, recyclable and metal-free catalyst for the oxidation of sulfides to sulfoxides in the presence of aqueous hydrogen peroxide
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Imidazole tribromide immobilized on magnetic nanoparticles as a bromine source was prepared and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) techniques. The high catalytic activity of this novel catalyst was investigated in the oxidation of sulfides to sulfoxides using aqueous hydrogen peroxide as an oxidant at room temperature under solvent-free conditions. More importantly, the catalyst could be easily recovered by an external magnet and reused five times without any significant loss of catalytic activity.
- Otokesh, Somayeh,Kolvari, Eskandar,Amoozadeh, Ali,Koukabi, Nadiya
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p. 53749 - 53756
(2015/06/30)
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- Tungstate supported on periodic mesoporous organosilica with imidazolium framework as an efficient and recyclable catalyst for the selective oxidation of sulfides
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Abstract A catalyst based on immobilization of tungstate ions (WO42-) inside the mesochannels of periodic mesoporous organosilica comprising bridged ionic liquid (1,3-bis(3-trimethoxysilylpropyl)imidazolium chloride) has been synthesized and characterized. This catalyst was then employed for the selective oxidation of organic sulfides to the corresponding sulfoxides or sulfones. The final synthesized catalyst was characterized by various techniques such as nitrogen sorption analysis, transmission electron microscopy, and thermogravimetric analysis. The catalyst was also applied to the selective oxidation of sulfides containing readily oxidizable functional groups such as hydroxyl, allylic, and even challenging aliphatic sulfides. Interestingly, it was found that on changing the reaction medium from aqueous methanol to aqueous acetonitrile, the product selectivity was changed successfully from sulfoxide to sulfone with good to excellent yields. Moreover, the catalyst can also be recovered and reused efficiently in nine subsequent reaction cycles without any remarkable decrease in the catalyst activity and selectivity.
- Karimi, Babak,Khorasani, Mojtaba,Bakhshandeh Rostami, Fatemeh,Elhamifar, Dawood,Vali, Hojatollah
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p. 990 - 999
(2015/06/08)
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- Selective synthesis of sulfoxides and sulfones from sulfides using silica bromide as the heterogeneous promoter and hydrogen peroxide as the terminal oxidant
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Silica bromide as a heterogeneous promoter and reagent is prepared from the reaction of silica gel with PBr3as a non-hydroscopic, filterable, cheap, and stable yellowish powder that can be stored for months. The results show that silica bromide is a suitable and efficient promoter for the chemoselective oxidation of sulfides to the corresponding sulfoxides or sulfones in the presence of 30% H2O2in acetonitrile. The excellent yields, heterogeneous conditions, simplicity, compatibility with a variety of functionalities, and ease of isolation of the products make our procedure a practical alternative.
- Maleki, Behrooz,Hemmati, Saba,Sedrpoushan, Alireza,Ashrafi, Samaneh Sedigh,Veisi, Hojat
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p. 40505 - 40510
(2015/02/03)
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- Selectivity adjustment of SBA-15 based tungstate catalyst in oxidation of sulfides by incorporating a hydrophobic organic group inside the mesochannels
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A novel heterogeneous catalyst system comprising tungstate ions embedded into the hydrophobic mesochannels of SBA-15 was found to exhibit significant selectivity enhancement in oxidation of sulfides in water or water/CH 3CN using 30% H2O2. Our studies demonstrated that the presence of an n-octyl group in the interior of nanospaces of our catalyst system provides a hydrophobic/hydrophilic region in the mesochannels of the catalyst where the active tungstate species are located and in turn results in at least three distinct important features. First of all, the catalyst comprising the n-octyl group shows much better water tolerance than the catalysts not having hydrophobic organic moieties. Moreover, the nonproductive decomposition of H2O2 was significantly inhibited in the present catalyst system. The present catalyst system also offers an unprecedented selectivity changeover depending on the hydrophobic nature of the initial sulfides and/or the utilized solvent mixture. While high yields and excellent selectivities toward the corresponding sulfoxide were obtained in the oxidation of less hydrophobic sulfides in H2O as a reaction solvent, the selectivity pattern was shifted toward sulfones in the case of using more hydrophobic sulfides as substrates. On the other hand, in CH3CN/ H2O (1:1) as the reaction solvent, almost all of the studied sulfides were selectively oxidized to the corresponding sulfoxide in high yields. On the basis of several compelling observations, we have proposed a synergistic model to explain the origin of the observed selectivities. The catalyst was respectively recovered and reused in five and seven successive reaction runs in water and water/CH3CN, respectively, with only a slight decrease of reactivity.
- Karimi, Babak,Khorasani, Mojtaba
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p. 1657 - 1664
(2013/07/26)
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- PHOTOACID GENERATORS
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A photoacid generator compound has formula (I): [in-line-formulae]G+Z???(I)[/in-line-formulae] wherein G has formula (II): In formula (II), X is S or I, each R0 is commonly attached to X and is independently C1-30 alkyl; polycyclic or monocyclic C3-30 cycloalkyl; polycyclic or monocyclic C6-30 aryl; or a combination comprising at least one of the foregoing groups. G has a molecular weight greater than 263.4 g/mol, or less than 263.4 g/mol. One or more R0 groups are further attached to an adjacent R0 group, a is 2 or 3, wherein when X is I, a is 2, or when X is S, a is 2 or 3. Z in formula (I) comprises the anion of a sulfonic acid, a sulfonimide, or a sulfonamide. A photoresist and coated film also includes the photoacid generator, and a method of forming an electronic device uses the photoresist.
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- Silver nitrate catalyzed oxidation of sulfides
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A variety of sulfides were converted into the corresponding sulfoxide derivatives with 70% tert-butyl hydroperoxide in water as the oxidant in the presence of catalytic quantity of silver nitrate. The method described has a wide range of application, does not involve cumbersome workup, exhibits chemoselectivity, and proceeds under mild reaction conditions, and the resulting products are obtained in good yields within a reasonable time. Georg Thieme Verlag Stuttgart New York.
- Das, Rima,Chakraborty, Debashis
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supporting information; experimental part
p. 277 - 280
(2011/03/18)
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- Cu(II)-catalyzed oxidation of sulfides
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A variety of sulfides and disulfides were converted into the corresponding sulfoxide derivatives with 70% t-BuOOH (water) as the oxidant in the presence of catalytic quantity of CuBr2. The method described does not involve cumbersome work-up, has wide range of applicabilities, exhibits chemoselectivity, and proceeds under mild reaction conditions, and the resulting products are obtained in good yields within reasonable time.
- Das, Rima,Chakraborty, Debashis
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scheme or table
p. 6255 - 6258
(2011/01/04)
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- Molybdatophosphoric acid as an efficient catalyst for the catalytic and chemoselective oxidation of sulfides to sulfoxides using urea hydrogen peroxide as a commercially available oxidant
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An efficient procedure for the chemoselective oxidation of alkyl (aryl) sulfides to the corresponding sulfoxides using urea hydrogen peroxide (UHP) in the presence of a catalytic amount of molybdatophosphoric acid at room temperature is described. The advantages of described method are: generality, high yield and chemoselectivity, short reaction time, low cost and compliment with green chemistry protocols.
- Hasaninejad, Alireza,Zolfigol, Mohammad Ali,Chehardoli, Gholamabbas,Mokhlesi, Mohammad
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experimental part
p. 307 - 316
(2010/09/05)
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- Method for manufacturing bisphenol
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A method for manufacturing bisphenol by reacting phenols and ketones, characterized (1) in that an alkali metal compound and/or alkaline earth metal compound is added to bisphenol obtained by reacting a phenol and a ketone, and (2) in that the basicity of the bisphenol is adjusted so as to be equivalent to an amount of 1 × 10-8to 1 × 10-6moles of bisphenol as disodium salt with respect to 1 mole of bisphenol provides a bisphenol in which there is no residue of the organic catalysts ordinarily used in manufacturing bisphenol, so that byproducts are not produced during purification, allowing bisphenol with outstanding color tone, thermal resistance, etc., to be obtained.
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- Process for the purification of bisphenols and preparation of polycarbonates therefrom
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A phenol and a ketone are reacted to form bisphenol, and the liquid bisphenol obtained or a mixed solution of said solution and a phenol is filtered through a calcined metal filter to obtain bisphenol which makes it possible to efficiently obtain bisphenol which either does not contain fine particulate impurities or contains such impurities only in minute amounts, and a method for manufacturing polycarbonate using bisphenol obtained bythis method. The filtration grade of the calcined metal filter should be 1.0 μm or less. After filtering, the calcined metal filter can be backwashed or chemically washed and then reused. The bisphenol should preferably be bisphenol A.
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- Method for preparing aromatic bischloroformate compositions
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Bischloroformate oligomer compositions are prepared by passing phosgene into a heterogeneous aqueous-organic mixture containing at least one dihydroxyaromatic compound, with simultaneous introduction of a base at a rate to maintain a specific pH range and to produce a specific volume ratio of aqueous to organic phase. By this method, it is possible to employ a minimum amount of phosgene. The reaction may be conducted batchwise or continuously. The bischloroformate composition may be employed for the preparation of cyclic polycarbonate oligomers or linear polycarbonate, and linear polycarbonate formation may be integrated with bischloroformate composition formation in a batch or continuous process.
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- Bischoloroformate preparation method with phosgene removal and monochloroformate conversion
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Aqueous bischloroformates are prepared by the reaction of a dihydroxyaromatic compound (e.g., bisphenol A) with phosgene in a substantially inert organic liquid (e.g., methylene chloride) and in the presence of an aqueous alkali metal or alkaline earth metal base, at a pH below about 8. After all solid dihydroxyaromatic compound has been consumed, the pH is raised to a higher value in the range of about 7-12, preferably 9-11, and maintained in said range until a major proportion of the unreacted phosgene has been hydrolyzed. At the same time, any monochloroformate in the product may be converted to bischloroformate.
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- Cyclic monocarbonate bishaloformates
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Cyclic monocarbonate bischloroformates are prepared by the reaction of a carbonyl halide such as phosgene with a bridged substituted resorcinol or hydroquinone such as bis(2,4-dihydroxy-3-methylphenyl)methane or bis(2,5-dihydroxy-3,4,6-trimethylphenyl)methane in the presence of aqueous alkali metal hydroxide. The cyclic monocarbonate bischloroformates may be used for the preparation of linear or cyclic polycarbonates containing cyclic carbonate structural units, which may in turn be converted to crosslinked polycarbonates.
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- Polyetherimide bisphenol compositions
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Polyetherimide bisphenols and bischloroformates are prepared by the reaction of dianhydrides or certain bisimides with aminophenols or mixtures thereof with diamines. They are useful as intermediates for the preparation of cyclic heterocarbonates, which may in turn be converted to linear copolycarbonates. The bisphenols can also be converted to salts which react with cyclic polycarbonate oligomers to form block copolyetherimidecarbonates.
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- Vat dye and sulfur dye compositions
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Specific vatting accelerators according to claims 1 and 2 are described. These can be added to a vat dye or sulfur dye composition, or to a dye bath or printing paste containing a vat dye or sulfur dye, by virtue of which an improvement of dye yield, particularly on cellulose materials, is obtained.
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