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Kazunari Ohgaki - One of the best experts on this subject based on the ideXlab platform.
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Storage capacity of hydrogen in tetrahydrofuran hydrate
Chemical Engineering Science, 2008Co-Authors: Kyohei Ogata, Shunsuke Hashimoto, Takeshi Sugahara, Masato Moritoki, Hiroshi Sato, Kazunari OhgakiAbstract:Abstract The storage capacity of hydrogen in tetrahydrofuran hydrate was investigated by means of pressure–volume–temperature ( p – V – T ) measurement and Raman spectroscopic analysis. We carried out two measurement strategies using Raman spectroscopic analysis. One was isothermal pressure-swing absorption using tetrahydrofuran hydrate at 277.15 K, and the other was the preparation of a single crystal of hydrogen+tetrahydrofuran mixed gas hydrate from compressed hydrogen and tetrahydrofuran aqueous solutions along the stability boundary. The storage amount of hydrogen at 277.15 K obtained from the p – V – T measurement is about 1.6 mol (hydrogen)/mol (tetrahydrofuran) (about 0.8 mass%) at 70 MPa, and isothermal Raman spectroscopic measurement reveals that it reaches the maximum value of 2.0 mol (hydrogen)/mol (tetrahydrofuran) at about 85 MPa. These results agree well with those for a single crystal of hydrogen+tetrahydrofuran hydrate.
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thermodynamic stability of h2 tetrahydrofuran mixed gas hydrate in nonstoichiometric aqueous solutions
Journal of Chemical & Engineering Data, 2007Co-Authors: Shunsuke Hashimoto, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibria (pressure−temperature relations) of the H2 + tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2 + tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2 and tetrahydrofuran for the H2 + tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution.
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Thermodynamic Stability of H2 + Tetrahydrofuran Mixed Gas Hydrate in Nonstoichiometric Aqueous Solutions
Journal of Chemical & Engineering Data, 2007Co-Authors: Shunsuke Hashimoto, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibria (pressure−temperature relations) of the H2 + tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2 + tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2 and tetrahydrofuran for the H2 + tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution.
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thermodynamic and raman spectroscopic studies on h2 tetrahydrofuran water and h2 tetra n butyl ammonium bromide water mixtures containing gas hydrates
Chemical Engineering Science, 2006Co-Authors: Shunsuke Hashimoto, Shu Murayama, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibrium curves of H2+H2+ tetrahydrofuran and H2+H2+ tetra-n-butyl ammonium bromide mixed gas hydrates were measured in a pressure range from 0.1 to 13.6 MPa. Each three-phase equilibrium curve converges at the maximum temperature point of pure tetrahydrofuran and tetra-n-butyl ammonium bromide hydrates, respectively. The difference of maximum temperatures is about 8 K, that is, the equilibrium curve of H2+H2+ tetra-n -butyl ammonium bromide mixed gas hydrate shifts to the high-temperature side from that of H2+H2+ tetrahydrofuran mixed gas hydrate. It is directly confirmed by use of Raman spectroscopy that H2H2 is enclathrated in the hydrate cages by adding a small amount of tetrahydrofuran or tetra-n -butyl ammonium bromide. In both mixed hydrates, H2H2 is enclathrated in only the small cage while tetrahydrofuran or tetra-n-butyl ammonium bromide occupies the large cages of each mixed hydrate.
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Thermodynamic and Raman spectroscopic studies on H2+tetrahydrofuran+water and H2+ tetra-n-butyl ammonium bromide+water mixtures containing gas hydrates
Chemical Engineering Science, 2006Co-Authors: Shunsuke Hashimoto, Shu Murayama, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibrium curves of H2+H2+ tetrahydrofuran and H2+H2+ tetra-n-butyl ammonium bromide mixed gas hydrates were measured in a pressure range from 0.1 to 13.6 MPa. Each three-phase equilibrium curve converges at the maximum temperature point of pure tetrahydrofuran and tetra-n-butyl ammonium bromide hydrates, respectively. The difference of maximum temperatures is about 8 K, that is, the equilibrium curve of H2+H2+ tetra-n -butyl ammonium bromide mixed gas hydrate shifts to the high-temperature side from that of H2+H2+ tetrahydrofuran mixed gas hydrate. It is directly confirmed by use of Raman spectroscopy that H2H2 is enclathrated in the hydrate cages by adding a small amount of tetrahydrofuran or tetra-n -butyl ammonium bromide. In both mixed hydrates, H2H2 is enclathrated in only the small cage while tetrahydrofuran or tetra-n-butyl ammonium bromide occupies the large cages of each mixed hydrate.
Shunsuke Hashimoto - One of the best experts on this subject based on the ideXlab platform.
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Storage capacity of hydrogen in tetrahydrofuran hydrate
Chemical Engineering Science, 2008Co-Authors: Kyohei Ogata, Shunsuke Hashimoto, Takeshi Sugahara, Masato Moritoki, Hiroshi Sato, Kazunari OhgakiAbstract:Abstract The storage capacity of hydrogen in tetrahydrofuran hydrate was investigated by means of pressure–volume–temperature ( p – V – T ) measurement and Raman spectroscopic analysis. We carried out two measurement strategies using Raman spectroscopic analysis. One was isothermal pressure-swing absorption using tetrahydrofuran hydrate at 277.15 K, and the other was the preparation of a single crystal of hydrogen+tetrahydrofuran mixed gas hydrate from compressed hydrogen and tetrahydrofuran aqueous solutions along the stability boundary. The storage amount of hydrogen at 277.15 K obtained from the p – V – T measurement is about 1.6 mol (hydrogen)/mol (tetrahydrofuran) (about 0.8 mass%) at 70 MPa, and isothermal Raman spectroscopic measurement reveals that it reaches the maximum value of 2.0 mol (hydrogen)/mol (tetrahydrofuran) at about 85 MPa. These results agree well with those for a single crystal of hydrogen+tetrahydrofuran hydrate.
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thermodynamic stability of h2 tetrahydrofuran mixed gas hydrate in nonstoichiometric aqueous solutions
Journal of Chemical & Engineering Data, 2007Co-Authors: Shunsuke Hashimoto, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibria (pressure−temperature relations) of the H2 + tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2 + tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2 and tetrahydrofuran for the H2 + tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution.
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Thermodynamic Stability of H2 + Tetrahydrofuran Mixed Gas Hydrate in Nonstoichiometric Aqueous Solutions
Journal of Chemical & Engineering Data, 2007Co-Authors: Shunsuke Hashimoto, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibria (pressure−temperature relations) of the H2 + tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2 + tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2 and tetrahydrofuran for the H2 + tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution.
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thermodynamic and raman spectroscopic studies on h2 tetrahydrofuran water and h2 tetra n butyl ammonium bromide water mixtures containing gas hydrates
Chemical Engineering Science, 2006Co-Authors: Shunsuke Hashimoto, Shu Murayama, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibrium curves of H2+H2+ tetrahydrofuran and H2+H2+ tetra-n-butyl ammonium bromide mixed gas hydrates were measured in a pressure range from 0.1 to 13.6 MPa. Each three-phase equilibrium curve converges at the maximum temperature point of pure tetrahydrofuran and tetra-n-butyl ammonium bromide hydrates, respectively. The difference of maximum temperatures is about 8 K, that is, the equilibrium curve of H2+H2+ tetra-n -butyl ammonium bromide mixed gas hydrate shifts to the high-temperature side from that of H2+H2+ tetrahydrofuran mixed gas hydrate. It is directly confirmed by use of Raman spectroscopy that H2H2 is enclathrated in the hydrate cages by adding a small amount of tetrahydrofuran or tetra-n -butyl ammonium bromide. In both mixed hydrates, H2H2 is enclathrated in only the small cage while tetrahydrofuran or tetra-n-butyl ammonium bromide occupies the large cages of each mixed hydrate.
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Thermodynamic and Raman spectroscopic studies on H2+tetrahydrofuran+water and H2+ tetra-n-butyl ammonium bromide+water mixtures containing gas hydrates
Chemical Engineering Science, 2006Co-Authors: Shunsuke Hashimoto, Shu Murayama, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibrium curves of H2+H2+ tetrahydrofuran and H2+H2+ tetra-n-butyl ammonium bromide mixed gas hydrates were measured in a pressure range from 0.1 to 13.6 MPa. Each three-phase equilibrium curve converges at the maximum temperature point of pure tetrahydrofuran and tetra-n-butyl ammonium bromide hydrates, respectively. The difference of maximum temperatures is about 8 K, that is, the equilibrium curve of H2+H2+ tetra-n -butyl ammonium bromide mixed gas hydrate shifts to the high-temperature side from that of H2+H2+ tetrahydrofuran mixed gas hydrate. It is directly confirmed by use of Raman spectroscopy that H2H2 is enclathrated in the hydrate cages by adding a small amount of tetrahydrofuran or tetra-n -butyl ammonium bromide. In both mixed hydrates, H2H2 is enclathrated in only the small cage while tetrahydrofuran or tetra-n-butyl ammonium bromide occupies the large cages of each mixed hydrate.
Hiroshi Sato - One of the best experts on this subject based on the ideXlab platform.
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Storage capacity of hydrogen in tetrahydrofuran hydrate
Chemical Engineering Science, 2008Co-Authors: Kyohei Ogata, Shunsuke Hashimoto, Takeshi Sugahara, Masato Moritoki, Hiroshi Sato, Kazunari OhgakiAbstract:Abstract The storage capacity of hydrogen in tetrahydrofuran hydrate was investigated by means of pressure–volume–temperature ( p – V – T ) measurement and Raman spectroscopic analysis. We carried out two measurement strategies using Raman spectroscopic analysis. One was isothermal pressure-swing absorption using tetrahydrofuran hydrate at 277.15 K, and the other was the preparation of a single crystal of hydrogen+tetrahydrofuran mixed gas hydrate from compressed hydrogen and tetrahydrofuran aqueous solutions along the stability boundary. The storage amount of hydrogen at 277.15 K obtained from the p – V – T measurement is about 1.6 mol (hydrogen)/mol (tetrahydrofuran) (about 0.8 mass%) at 70 MPa, and isothermal Raman spectroscopic measurement reveals that it reaches the maximum value of 2.0 mol (hydrogen)/mol (tetrahydrofuran) at about 85 MPa. These results agree well with those for a single crystal of hydrogen+tetrahydrofuran hydrate.
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thermodynamic stability of h2 tetrahydrofuran mixed gas hydrate in nonstoichiometric aqueous solutions
Journal of Chemical & Engineering Data, 2007Co-Authors: Shunsuke Hashimoto, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibria (pressure−temperature relations) of the H2 + tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2 + tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2 and tetrahydrofuran for the H2 + tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution.
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Thermodynamic Stability of H2 + Tetrahydrofuran Mixed Gas Hydrate in Nonstoichiometric Aqueous Solutions
Journal of Chemical & Engineering Data, 2007Co-Authors: Shunsuke Hashimoto, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibria (pressure−temperature relations) of the H2 + tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2 + tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2 and tetrahydrofuran for the H2 + tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution.
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thermodynamic and raman spectroscopic studies on h2 tetrahydrofuran water and h2 tetra n butyl ammonium bromide water mixtures containing gas hydrates
Chemical Engineering Science, 2006Co-Authors: Shunsuke Hashimoto, Shu Murayama, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibrium curves of H2+H2+ tetrahydrofuran and H2+H2+ tetra-n-butyl ammonium bromide mixed gas hydrates were measured in a pressure range from 0.1 to 13.6 MPa. Each three-phase equilibrium curve converges at the maximum temperature point of pure tetrahydrofuran and tetra-n-butyl ammonium bromide hydrates, respectively. The difference of maximum temperatures is about 8 K, that is, the equilibrium curve of H2+H2+ tetra-n -butyl ammonium bromide mixed gas hydrate shifts to the high-temperature side from that of H2+H2+ tetrahydrofuran mixed gas hydrate. It is directly confirmed by use of Raman spectroscopy that H2H2 is enclathrated in the hydrate cages by adding a small amount of tetrahydrofuran or tetra-n -butyl ammonium bromide. In both mixed hydrates, H2H2 is enclathrated in only the small cage while tetrahydrofuran or tetra-n-butyl ammonium bromide occupies the large cages of each mixed hydrate.
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Thermodynamic and Raman spectroscopic studies on H2+tetrahydrofuran+water and H2+ tetra-n-butyl ammonium bromide+water mixtures containing gas hydrates
Chemical Engineering Science, 2006Co-Authors: Shunsuke Hashimoto, Shu Murayama, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibrium curves of H2+H2+ tetrahydrofuran and H2+H2+ tetra-n-butyl ammonium bromide mixed gas hydrates were measured in a pressure range from 0.1 to 13.6 MPa. Each three-phase equilibrium curve converges at the maximum temperature point of pure tetrahydrofuran and tetra-n-butyl ammonium bromide hydrates, respectively. The difference of maximum temperatures is about 8 K, that is, the equilibrium curve of H2+H2+ tetra-n -butyl ammonium bromide mixed gas hydrate shifts to the high-temperature side from that of H2+H2+ tetrahydrofuran mixed gas hydrate. It is directly confirmed by use of Raman spectroscopy that H2H2 is enclathrated in the hydrate cages by adding a small amount of tetrahydrofuran or tetra-n -butyl ammonium bromide. In both mixed hydrates, H2H2 is enclathrated in only the small cage while tetrahydrofuran or tetra-n-butyl ammonium bromide occupies the large cages of each mixed hydrate.
Takeshi Sugahara - One of the best experts on this subject based on the ideXlab platform.
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Storage capacity of hydrogen in tetrahydrofuran hydrate
Chemical Engineering Science, 2008Co-Authors: Kyohei Ogata, Shunsuke Hashimoto, Takeshi Sugahara, Masato Moritoki, Hiroshi Sato, Kazunari OhgakiAbstract:Abstract The storage capacity of hydrogen in tetrahydrofuran hydrate was investigated by means of pressure–volume–temperature ( p – V – T ) measurement and Raman spectroscopic analysis. We carried out two measurement strategies using Raman spectroscopic analysis. One was isothermal pressure-swing absorption using tetrahydrofuran hydrate at 277.15 K, and the other was the preparation of a single crystal of hydrogen+tetrahydrofuran mixed gas hydrate from compressed hydrogen and tetrahydrofuran aqueous solutions along the stability boundary. The storage amount of hydrogen at 277.15 K obtained from the p – V – T measurement is about 1.6 mol (hydrogen)/mol (tetrahydrofuran) (about 0.8 mass%) at 70 MPa, and isothermal Raman spectroscopic measurement reveals that it reaches the maximum value of 2.0 mol (hydrogen)/mol (tetrahydrofuran) at about 85 MPa. These results agree well with those for a single crystal of hydrogen+tetrahydrofuran hydrate.
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thermodynamic stability of h2 tetrahydrofuran mixed gas hydrate in nonstoichiometric aqueous solutions
Journal of Chemical & Engineering Data, 2007Co-Authors: Shunsuke Hashimoto, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibria (pressure−temperature relations) of the H2 + tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2 + tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2 and tetrahydrofuran for the H2 + tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution.
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Thermodynamic Stability of H2 + Tetrahydrofuran Mixed Gas Hydrate in Nonstoichiometric Aqueous Solutions
Journal of Chemical & Engineering Data, 2007Co-Authors: Shunsuke Hashimoto, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibria (pressure−temperature relations) of the H2 + tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2 + tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2 and tetrahydrofuran for the H2 + tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution.
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thermodynamic and raman spectroscopic studies on h2 tetrahydrofuran water and h2 tetra n butyl ammonium bromide water mixtures containing gas hydrates
Chemical Engineering Science, 2006Co-Authors: Shunsuke Hashimoto, Shu Murayama, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibrium curves of H2+H2+ tetrahydrofuran and H2+H2+ tetra-n-butyl ammonium bromide mixed gas hydrates were measured in a pressure range from 0.1 to 13.6 MPa. Each three-phase equilibrium curve converges at the maximum temperature point of pure tetrahydrofuran and tetra-n-butyl ammonium bromide hydrates, respectively. The difference of maximum temperatures is about 8 K, that is, the equilibrium curve of H2+H2+ tetra-n -butyl ammonium bromide mixed gas hydrate shifts to the high-temperature side from that of H2+H2+ tetrahydrofuran mixed gas hydrate. It is directly confirmed by use of Raman spectroscopy that H2H2 is enclathrated in the hydrate cages by adding a small amount of tetrahydrofuran or tetra-n -butyl ammonium bromide. In both mixed hydrates, H2H2 is enclathrated in only the small cage while tetrahydrofuran or tetra-n-butyl ammonium bromide occupies the large cages of each mixed hydrate.
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Thermodynamic and Raman spectroscopic studies on H2+tetrahydrofuran+water and H2+ tetra-n-butyl ammonium bromide+water mixtures containing gas hydrates
Chemical Engineering Science, 2006Co-Authors: Shunsuke Hashimoto, Shu Murayama, Takeshi Sugahara, Hiroshi Sato, Kazunari OhgakiAbstract:Phase equilibrium curves of H2+H2+ tetrahydrofuran and H2+H2+ tetra-n-butyl ammonium bromide mixed gas hydrates were measured in a pressure range from 0.1 to 13.6 MPa. Each three-phase equilibrium curve converges at the maximum temperature point of pure tetrahydrofuran and tetra-n-butyl ammonium bromide hydrates, respectively. The difference of maximum temperatures is about 8 K, that is, the equilibrium curve of H2+H2+ tetra-n -butyl ammonium bromide mixed gas hydrate shifts to the high-temperature side from that of H2+H2+ tetrahydrofuran mixed gas hydrate. It is directly confirmed by use of Raman spectroscopy that H2H2 is enclathrated in the hydrate cages by adding a small amount of tetrahydrofuran or tetra-n -butyl ammonium bromide. In both mixed hydrates, H2H2 is enclathrated in only the small cage while tetrahydrofuran or tetra-n-butyl ammonium bromide occupies the large cages of each mixed hydrate.
John P Wolfe - One of the best experts on this subject based on the ideXlab platform.
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stereoselective synthesis of saturated heterocycles via palladium catalyzed alkene carboetherification and carboamination reactions
Synlett, 2008Co-Authors: John P WolfeAbstract:The development of palladium-catalyzed carboetherification andcarboamination reactions between aryl or alkenyl halides and alkenesbearing pendant heteroatoms is described. These transformationseffect the stereoselective construction of useful heterocycles,such as Tetrahydrofurans, pyrrolidines, imidazolidin-2-ones, isoxazolidines,and piperazines. The scope, limitations, and applications of thesereactions are presented, and current stereochemical models are described.The mechanism of the product formation, which involves an unusualintramolecular SYN-insertion of an alkene intoa palladium-heteroatom bond, is also discussed in detail. 1 Introduction 2 Palladium-Catalyzed Synthesis of Tetrahydrofurans from γ-Hydroxyalkenesand Aryl or Alkenyl Halides 2.1 Mechanism of the Tetrahydrofuran Formation 3 Palladium-Catalyzed Synthesis of Pyrrolidines from γ-Aminoalkenesand Aryl or Alkenyl Halides 3.1 Tandem Palladium-Catalyzed N-Arylation-CarboaminationReactions of Primary Amines 3.2 Palladium-Catalyzed Carboamination Reactions of N-Protected γ-Aminoalkenes 3.3 Mechanism of the Palladium-Catalyzed Carboamination Reactions:Surprises and Utility 3.4 Application of the Palladium-Catalyzed Carboamination of N-Protected γ-Aminoalkenesto the Stereoselective Synthesis of (+)-Preussin and ItsAnalogues 4 Synthesis of Imidazolidin-2-ones via Palladium-Catalyzed CarboaminationReactions 5 Synthesis of Isoxazolidines via Palladium-Catalyzed CarboetherificationReactions 6 Synthesis of Piperazines via Palladium-Catalyzed CarboaminationReactions 7 Summary and Future Outlook
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Recent Advances in the Stereoselective Synthesis of Tetrahydrofurans.
Tetrahedron, 2007Co-Authors: John P WolfeAbstract:Substituted Tetrahydrofurans are commonly occurring substructures found in a broad array of natural products and other biologically active molecules. For example, the annonaceous acetogenins are a large family of natural products bearing tetrahydrofuran cores.1 Tetrahydrofuran moieties are also found in many other classes of natural products including lignans,2 polyether ionophores3 and macrodiolides.4 These substances exhibit a diverse range of biological activities including antitumor, antihelmic, antimalarial, antimicrobial, and antiprotozoal. Due to the importance of these molecules, considerable effort has been devoted towards the development of methods for the stereoselective construction of substituted Tetrahydrofurans.5 This review covers the important transformations that have been used in the stereoselective synthesis of Tetrahydrofurans, with emphasis placed on literature published between 1993–2005. A broad array of new methods developed over the past twelve years are described, as well as recent advances in older reactions that are widely used. The coverage of this review is limited to the synthesis of Tetrahydrofurans; methods that generate furans, dihydrofurans, and benzofurans are not discussed.
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palladium catalyzed synthesis of 2 1 disubstituted Tetrahydrofurans from γ hydroxy internal alkenes evidence for alkene insertion into a pd o bond and stereochemical scrambling via β hydride elimination
Journal of the American Chemical Society, 2005Co-Authors: Michael B Hay, John P WolfeAbstract:Palladium-catalyzed reactions of γ-hydroxy internal acyclic alkenes with aryl bromides afford 2,1‘-disubstituted Tetrahydrofurans in good yields with diastereoselectivities of 3−5:1. The analogous transformations of substrates bearing internal cyclic alkenes afford fused bicyclic and spirocyclic tetrahydrofuran derivatives in good yields with excellent diastereoselectivities (>20:1). A series of deuterium labeling experiments indicate that the origin of the modest diastereoselectivity in reactions of acyclic internal alkene substrates likely derives from a series of reversible β-hydride elimination and σ-bond rotation processes that occur following a rare intramolecular alkene syn-insertion into an intermediate Pd(Ar)(OR) complex. In addition, these studies shed light on the chemoselectivity of insertion, suggesting that the alkene inserts into the Pd−O bond in preference to the Pd−C bond.
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palladium catalyzed synthesis of Tetrahydrofurans from γ hydroxy terminal alkenes scope limitations and stereoselectivity
Journal of Organic Chemistry, 2005Co-Authors: Michael B Hay, And Alison R Hardin, John P WolfeAbstract:A new, stereoselective synthesis of substituted Tetrahydrofurans via Pd-catalyzed reactions of aryl and vinyl bromides with γ-hydroxy terminal alkenes is described. This transformation affords trans-2,5- and trans-2,3-disubstituted Tetrahydrofurans with up to >20:1 dr. This methodology also provides access to bicyclic and spirocyclic tetrahydrofuran derivatives in good yield with 10−20:1 dr. The scope and limitations of these transformations are discussed in detail, as are the effect of substrate sterics and electronics on yield and stereoselectivity. A proposed mechanism of these transformations is presented along with a model that rationalizes the stereochemical outcome of the reactions.
