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Eiichi Nakamura - One of the best experts on this subject based on the ideXlab platform.
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synthesis of esomeprazole and related proton pump inhibitors through Iron catalyzed enantioselective sulfoxidation
ACS Catalysis, 2018Co-Authors: Shigenobu Nishiguchi, Laurean Ilies, Takuhiro Izumi, Takayoshi Kouno, Junpei Sukegawa, Eiichi NakamuraAbstract:We report here an application of Iron catalysis for the kilogram scale asymmetric synthesis of a proton pump inhibitor, esomeprazole, in 87% yield and 99.4% ee by catalytic sulfoxidation with hydrogen peroxide using an Iron Salt/chiral Schiff base in combination with a carboxylate Salt. Under similar reaction conditions, other proton pump inhibitors such as (S)-lansoprazole, (S)-rabeprazole, and (S)-pantoprazole, were also synthesized in high yield and ee. A carboxylate additive was crucial for the success of this reaction, and we consider that it coordinates to the active Iron species, and it also acts as a hydrogen-bond acceptor to coordinate to the substrate through the imidazole NH.
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Synthesis of Esomeprazole and Related Proton Pump Inhibitors through Iron-Catalyzed Enantioselective Sulfoxidation
2018Co-Authors: Shigenobu Nishiguchi, Laurean Ilies, Takuhiro Izumi, Takayoshi Kouno, Junpei Sukegawa, Eiichi NakamuraAbstract:We report here an application of Iron catalysis for the kilogram scale asymmetric synthesis of a proton pump inhibitor, esomeprazole, in 87% yield and 99.4% ee by catalytic sulfoxidation with hydrogen peroxide using an Iron Salt/chiral Schiff base in combination with a carboxylate Salt. Under similar reaction conditions, other proton pump inhibitors such as (S)-lansoprazole, (S)-rabeprazole, and (S)-pantoprazole, were also synthesized in high yield and ee. A carboxylate additive was crucial for the success of this reaction, and we consider that it coordinates to the active Iron species, and it also acts as a hydrogen-bond acceptor to coordinate to the substrate through the imidazole NH
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Iron catalyzed borylation of aryl chlorides in the presence of potassium t butoxide
ACS Catalysis, 2017Co-Authors: Takumi Yoshida, Laurean Ilies, Eiichi NakamuraAbstract:A catalytic amount of an inorganic Iron Salt such as Fe(acac)3 catalyzes borylation of various aryl and heteroaryl chlorides with bis(pinacolato)diboron, where the presence of potassium t-butoxide is crucially important. The alkoxide is considered to produce in situ an electron-rich Iron alkoxide complex as the active species. The reaction requires only an Iron Salt and potassium t-butoxide as promoters and is easily scalable. The arylboron compound prepared by this reaction can be further coupled in situ with an aryl halide under the Suzuki–Miyaura conditions.
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β arylation of carboxamides via Iron catalyzed c sp3 h bond activation
Journal of the American Chemical Society, 2013Co-Authors: Rui Shang, Laurean Ilies, Arimasa Matsumoto, Eiichi NakamuraAbstract:A 2,2-disubstituted propionamide bearing an 8-aminoquinolinyl group as the amide moiety can be arylated at the β-methyl position with an organozinc reagent in the presence of an organic oxidant, a catalytic amount of an Iron Salt, and a biphosphine ligand at 50 °C. Various features of selectivity and reactivity suggest the formation of an organometallic intermediate via rate-determining C–H bond cleavage rather than a free-radical-type reaction pathway.
Olivier Piva - One of the best experts on this subject based on the ideXlab platform.
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sequential oxidation prins reaction processes induced by the same Iron Salt direct access to 2 aryl 4 chloro tetrahydropyrans from benzyl alcohols
ChemInform, 2014Co-Authors: Fabienne Fache, Mickael Muselli, Olivier PivaAbstract:Iron nitrate supported on bentonite K10 is used to oxidize benzylic alcohols to the corresponding aldehydes.
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sequential oxidation prins reaction processes induced by the same Iron Salt direct access to 2 aryl 4 chloro tetrahydropyrans from benzyl alcohols
Synlett, 2013Co-Authors: Fabienne Fache, Mickael Muselli, Olivier PivaAbstract:A clay-supported Iron(III) nitrate (Clayfen) was used as a stoichiometric reagent to first oxidize benzylic alcohols. The aldehydes thus obtained were converted in situ into tetrahydropyrans by way of a Prins cyclization induced by Iron species already present in the media.
Zhiguo Yuan - One of the best experts on this subject based on the ideXlab platform.
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improved sulfide mitigation in sewers through on line control of ferrous Salt dosing
Water Research, 2018Co-Authors: Guangming Jiang, Keshab Sharma, Yuecong Wang, Jose Gonzalez, Ramon Ganigué, Tung Nguyen, Zhiguo YuanAbstract:Abstract Water utilities worldwide spend annually billions of dollars to control sulfide-induced corrosion in sewers. Iron Salts chemically oxidize and/or precipitate dissolved sulfide in sewage and are especially used in medium- and large-size sewers. Iron Salt dosing rates are defined ad hoc, ignoring variation in sewage flows and sulfide levels. This often results in Iron overdosing or poor sulfide control. Online dosing control can adjust the chemical dosing rates to current (and future) state of the sewer system, allowing high-precision, stable and cost-effective sulfide control. In this paper, we report a novel and robust online control strategy for the dosing of ferrous Salt in sewers. The control considers the fluctuation of sewage flow, pH, sulfide levels and also the perturbation from rainfall. Sulfide production in the pipe is predicted using auto–regressive models (AR) based on current flow measurements, which in turn can be used to determine the dose of ferrous Salt required for cost-effective sulfide control. Following comprehensive model-based assesment, the control was successfully validated and its effectiveness demonstrated in a 3-week field trial. The online control algorithm controlled sulfide below the target level (0.5 mg S/L) while reducing chemical dosing up to 30%.
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electrochemical oxidation of Iron and alkalinity generation for efficient sulfide control in sewers
Water Research, 2017Co-Authors: Zhiguo Yuan, Caroline Kustermans, Eleni Vaiopoulou, Antonin Prevoteau, Korneel Rabaey, Ilje PikaarAbstract:Abstract The addition of Iron Salts is one of the most commonly used dosing strategies for sulfide control in sewers. However, Iron Salts decrease the sewage pH which not only reduces the effectiveness of sulfide precipitation but also enhances the release of residual sulfide to the sewer atmosphere. Equally important, concentrated Iron Salt solutions are corrosive and their frequent transport, handling, and on-site storage often come with Occupational Health and Safety (OH&S) concerns. Here, we experimentally demonstrated a novel sulfide control approach using electrochemical systems with parallel placed Iron electrodes. This enabled combining anodic dissolved Iron species release with cathodic hydroxyl anion production, which alleviates all the aforementioned concerns. A long-term experiment was successfully carried out achieving an average sulfide removal efficiency of 95.4 ± 4.4% at low voltage input of 2.90 ± 0.54 V over the course of 8 weeks. This electrochemical method was demonstrated to successfully achieve efficient sulfide control. In addition, it increases the sewage pH, thereby overcoming the drawbacks associated with the pH decrease in the case of conventional Iron Salt dosing. Ferrous ions were produced at an overall coulombic efficiency (CE) of 98.2 ± 1.2%, whereas oxygen evolution and direct sulfide oxidation were not observed. Short-term experiments showed that increasing either inter-electrode gap or current density increased the cell voltage associated with the increase in the ohmic drop of the system. Overall, this study highlights the practical potential of in-situ generation of dissolved Iron species and simultaneous hydroxyl anion generation for efficient sulfide control in sewers.
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impact of Iron Salt dosage to sewers on downstream anaerobic sludge digesters sulfide control and methane production
Journal of Environmental Engineering, 2013Co-Authors: Huoqing Ge, Jurg Keller, Lishan Zhang, Damien J Batstone, Zhiguo YuanAbstract:The addition of Iron Salts to sewers for sulfide control has a significant impact on downstream wastewater-treatment performance, in which Iron ions can be resolubilized from Iron sulfide precipitates in aeration tanks to precipitate phosphate, thus enhancing phosphorus removal from the wastewater. In this study, the impact of Iron Salt dosage to sewers on the performance of anaerobic sludge digesters was investigated at bench scale. Anaerobic digesters were fed with mixed primary sludge, activated sludge, and sludge that contained ferric phosphate precipitates, formed by aerating Iron sulfide- and phosphate-containing wastewater with activated sludge. In anaerobic conditions, ferric ions were released from ferric phosphate precipitates and utilized for a third time to precipitate sulfide that formed during sludge digestion, which ultimately resulted in complete control of H2S emissions from digesters. The results indicate that Iron Salt addition to sewers at typical dosing rates (e.g., 5-20 mgFeL −1 ) would provide an excessive quantity of Iron Salts for sulfide control in sludge digesters. Methane production and other digestion processes were not negatively impacted by Iron addition to the wastewater. DOI: 10.1061/(ASCE) EE.1943-7870.0000650. © 2013 American Society of Civil Engineers. CE Database subject headings: Hydrogen sulfides; Anaerobic treatment; Sewers; Iron compounds; Methane; Sludge. Author keywords: Hydrogen sulfide; Anaerobic sludge digestion; Sewers; Iron addition; Methane production.
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Iron Salts dosage for sulfide control in sewers induces chemical phosphorus removal during wastewater treatment
Water Research, 2010Co-Authors: Oriol Gutierrez, Keshab Sharma, Donghee Park, Zhiguo YuanAbstract:Chemical phosphorus (P) removal during aerobic wastewater treatment induced by Iron Salt addition in sewer systems for sulfide control is investigated. Aerobic batch tests with activated sludge fed with wastewater containing Iron sulfide precipitates showed that Iron sulfide was rapidly reoxidised in aerobic conditions, resulting in phosphate precipitation. The amount of P removed was proportional to the amount of Iron Salts added, and for the sludge used, ratios of 0.44 and 0.37 mgP/mgFe were obtained for ferric and ferrous dosages, respectively. The hydraulic retention time (HRT) of Iron sulfide in sewers was found to have a crucial impact on the settling of Iron sulfide precipitates during primary settling, with a shorter HRT resulting in a higher concentration of Iron sulfide in the primary effluent and thus enabling higher P removal. A mathematical model was developed to describe Iron sulfide oxidation in aerated activated sludge and the subsequent Iron phosphate precipitation. The model was used to optimise FeCl(3) dosing in a real wastewater collection and treatment system. Simulation studies revealed that, by moving FeCl(3) dosing from the WWTP, which is the current practice, to a sewer location upstream of the plant, both sulfide control and phosphate removal could be achieved with the current ferric Salt consumption. This work highlights the importance of integrated management of sewer networks and wastewater treatment plants. (C) 2010 Elsevier Ltd. All rights reserved.
John Philip - One of the best experts on this subject based on the ideXlab platform.
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effect of initial ph and temperature of Iron Salt solutions on formation of magnetite nanoparticles
Materials Chemistry and Physics, 2007Co-Authors: G Gnanaprakash, S Mahadevan, T Jayakumar, P Kalyanasundaram, John PhilipAbstract:Abstract We report the effect of initial pH and temperature of Iron Salt solutions on formation of magnetite (Fe3O4) nanoparticles during co-precipitation. We synthesized nanoparticles by keeping the initial pH at 0.7, 1.5, 3.0, 4.7, 5.7, 6.7 for two different temperatures of 30 and 60 °C. When the initial pH (prior to alkali addition) of the Salt solution was below 5, the nanoparticles formed were 100% spinel Iron oxide. Average size of the magnetite particles increases with initial pH until ferrihydrite is formed at a pH of 3 and the size remains the same till 4.7 pH. The percentage of goethite formed along with non-stoichiometric magnetite was 35 and 78%, respectively, when the initial pH of the solution was 5.7 and 6.7. As the reaction temperature was increased to 60 °C, maintaining a pH of 6.7, the amount of goethite increased from 78 to 100%. These results show that the initial pH and temperature of the ferrous and ferric Salt solution before initiation of the precipitation reaction are critical parameters controlling the composition and size of nanoparticles formed. We characterize the samples using X-ray diffraction, transmission electron microscopy and vibrating sample magnetometer. The results of the present work provide the right conditions to synthesis pure magnetite nanoparticles, without goethite impurities, through co-precipitation technique for ferrofluid applications.
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effect of initial ph and temperature of Iron Salt solutions on formation of magnetite nanoparticles
Materials Chemistry and Physics, 2007Co-Authors: G Gnanaprakash, S Mahadevan, T Jayakumar, P Kalyanasundaram, John Philip, Baldev RajAbstract:We report the effect of initial pH and temperature of Iron Salt solutions on formation of magnetite (Fe3O4) nanoparticles during co-precipitation. We synthesized nanoparticles by keeping the initial pH at 0.7, 1.5, 3.0, 4.7, 5.7, 6.7 for two different temperatures of 30 and 60 ◦ C. When the initial pH (prior to alkali addition) of the Salt solution was below 5, the nanoparticles formed were 100% spinel Iron oxide. Average size of the magnetite particles increases with initial pH until ferrihydrite is formed at a pH of 3 and the size remains the same till 4.7 pH. The percentage of goethite formed along with non-stoichiometric magnetite was 35 and 78%, respectively, when the initial pH of the solution was 5.7 and 6.7. As the reaction temperature was increased to 60 ◦ C, maintaining a pH of 6.7, the amount of goethite increased from 78 to 100%. These results show that the initial pH and temperature of the ferrous and ferric Salt solution before initiation of the precipitation reaction are critical parameters controlling the composition and size of nanoparticles formed. We characterize the samples using X-ray diffraction, transmission electron microscopy and vibrating sample magnetometer. The results of the present work provide the right conditions to synthesis pure magnetite nanoparticles, without goethite impurities, through co-precipitation technique for ferrofluid applications. © 2007 Elsevier B.V. All rights reserved.
Fabienne Fache - One of the best experts on this subject based on the ideXlab platform.
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sequential oxidation prins reaction processes induced by the same Iron Salt direct access to 2 aryl 4 chloro tetrahydropyrans from benzyl alcohols
ChemInform, 2014Co-Authors: Fabienne Fache, Mickael Muselli, Olivier PivaAbstract:Iron nitrate supported on bentonite K10 is used to oxidize benzylic alcohols to the corresponding aldehydes.
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sequential oxidation prins reaction processes induced by the same Iron Salt direct access to 2 aryl 4 chloro tetrahydropyrans from benzyl alcohols
Synlett, 2013Co-Authors: Fabienne Fache, Mickael Muselli, Olivier PivaAbstract:A clay-supported Iron(III) nitrate (Clayfen) was used as a stoichiometric reagent to first oxidize benzylic alcohols. The aldehydes thus obtained were converted in situ into tetrahydropyrans by way of a Prins cyclization induced by Iron species already present in the media.
