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Ryo Ohmura - One of the best experts on this subject based on the ideXlab platform.
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Phase equilibrium for structure II clathrate hydrates formed with (Fluoromethane + propan-2-ol, 2-methyl-2-propanol, or 2-propanone)
The Journal of Chemical Thermodynamics, 2012Co-Authors: Masatoshi Imai, Shinnosuke Nitta, Satoshi Takeya, Ryo OhmuraAbstract:Abstract This paper presents phase-equilibrium pressure–temperature data for the clathrate hydrates formed in the three component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are {Fluoromethane (CH 3 F) + propan-2-ol + water}, (Fluoromethane + 2-methyl-2-propanol + water), and (Fluoromethane + 2-propanone + water). The mole ratio of water and the water-soluble material (papan-2-ol, 2-methyl-2-propanol, or 2-propanone) was 17:1. The temperature range over which the phase-equilibrium measurements were performed extended to 267.6 K on the lower side and 295.8 K on the higher side. The phase-equilibrium pressures in these three systems were found to be lower than that in the binary (Fluoromethane + water) system at a given system temperature. The crystallographic structure of the hydrates formed in the systems with 2-methyl-2-propanol and 2-propanone was determined to be structure II based on the powder X-ray diffraction measurements.
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phase equilibrium for structure ii clathrate hydrates formed with Fluoromethane propan 2 ol 2 methyl 2 propanol or 2 propanone
The Journal of Chemical Thermodynamics, 2012Co-Authors: Masatoshi Imai, Shinnosuke Nitta, Satoshi Takeya, Ryo OhmuraAbstract:Abstract This paper presents phase-equilibrium pressure–temperature data for the clathrate hydrates formed in the three component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are {Fluoromethane (CH 3 F) + propan-2-ol + water}, (Fluoromethane + 2-methyl-2-propanol + water), and (Fluoromethane + 2-propanone + water). The mole ratio of water and the water-soluble material (papan-2-ol, 2-methyl-2-propanol, or 2-propanone) was 17:1. The temperature range over which the phase-equilibrium measurements were performed extended to 267.6 K on the lower side and 295.8 K on the higher side. The phase-equilibrium pressures in these three systems were found to be lower than that in the binary (Fluoromethane + water) system at a given system temperature. The crystallographic structure of the hydrates formed in the systems with 2-methyl-2-propanol and 2-propanone was determined to be structure II based on the powder X-ray diffraction measurements.
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raman peak frequencies of Fluoromethane molecules measured in clathrate hydrate crystals experimental investigations and density functional theory calculations
Journal of Physical Chemistry A, 2010Co-Authors: Tsutomu Uchida, Ryo Ohmura, Akira HoriAbstract:Systematic observations of Fluoromethane clathrate hydrates were carried out by Raman spectroscopy. The series of Fluoromethanes, i.e., methane (CH4), Fluoromethane (CH3F), diFluoromethane (CH2F2), triFluoromethane (CHF3), and tetraFluoromethane (CF4), were used as standard guest molecules to investigate the vibration modes of the guest molecules in the hydrate phase, since all of these Fluoromethanes are included in the same crystal structure and share similar functional groups. In this study, both the C−H and C−F vibration modes of the guest molecules were systematically collected and assigned each peak based on the density functional theory (DFT) calculations. The Raman peak table obtained by the DFT calculations was useful for assigning the Raman peaks measured by the experiments. The assignment of the Raman peaks of the C−H stretching mode of each Fluoromethane hydrate coincided well with those estimated both experimentally and theoretically in previous studies. The empirical “loose cage−tight cage” ...
Masatoshi Imai - One of the best experts on this subject based on the ideXlab platform.
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phase equilibrium for structure ii clathrate hydrates formed with Fluoromethane propan 2 ol 2 methyl 2 propanol or 2 propanone
The Journal of Chemical Thermodynamics, 2012Co-Authors: Masatoshi Imai, Shinnosuke Nitta, Satoshi Takeya, Ryo OhmuraAbstract:Abstract This paper presents phase-equilibrium pressure–temperature data for the clathrate hydrates formed in the three component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are {Fluoromethane (CH 3 F) + propan-2-ol + water}, (Fluoromethane + 2-methyl-2-propanol + water), and (Fluoromethane + 2-propanone + water). The mole ratio of water and the water-soluble material (papan-2-ol, 2-methyl-2-propanol, or 2-propanone) was 17:1. The temperature range over which the phase-equilibrium measurements were performed extended to 267.6 K on the lower side and 295.8 K on the higher side. The phase-equilibrium pressures in these three systems were found to be lower than that in the binary (Fluoromethane + water) system at a given system temperature. The crystallographic structure of the hydrates formed in the systems with 2-methyl-2-propanol and 2-propanone was determined to be structure II based on the powder X-ray diffraction measurements.
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Phase equilibrium for structure II clathrate hydrates formed with (Fluoromethane + propan-2-ol, 2-methyl-2-propanol, or 2-propanone)
The Journal of Chemical Thermodynamics, 2012Co-Authors: Masatoshi Imai, Shinnosuke Nitta, Satoshi Takeya, Ryo OhmuraAbstract:Abstract This paper presents phase-equilibrium pressure–temperature data for the clathrate hydrates formed in the three component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are {Fluoromethane (CH 3 F) + propan-2-ol + water}, (Fluoromethane + 2-methyl-2-propanol + water), and (Fluoromethane + 2-propanone + water). The mole ratio of water and the water-soluble material (papan-2-ol, 2-methyl-2-propanol, or 2-propanone) was 17:1. The temperature range over which the phase-equilibrium measurements were performed extended to 267.6 K on the lower side and 295.8 K on the higher side. The phase-equilibrium pressures in these three systems were found to be lower than that in the binary (Fluoromethane + water) system at a given system temperature. The crystallographic structure of the hydrates formed in the systems with 2-methyl-2-propanol and 2-propanone was determined to be structure II based on the powder X-ray diffraction measurements.
Leticia Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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h abstraction is more efficient than cis trans isomerization in 4 methylcyclohexylidene Fluoromethane an ab initio molecular dynamics study
Physical Chemistry Chemical Physics, 2012Co-Authors: Daniel Kinzel, Jesus Gonzalezvazquez, Leticia GonzalezAbstract:Non-adiabatic molecular dynamics simulations have been performed in the fluoro-olefin (4-methylcyclohexylidene) Fluoromethane (4MCF) using multiconfigurational CASSCF (complete active space self-consistent field) on-the-fly calculations. As an olefin containing a CC double bond, 4MCF is expected to undergo cis–trans isomerization after light irradiation. However, ab initio molecular dynamics shows that a preferential dissociation of atomic hydrogen is taking place after population transfer to the bright ππ* state. This state is strongly mixed with πσ* states allowing dissociation in the electronic excited state before deactivation to the ground state occurs. A minor amount of trajectories experiences F-dissociation, followed by pyramidalization at the sp2 carbons and CHF dissociation. In contrast, the amount of trajectories undergoing torsion around the double bond, and therefore cis–trans isomerization, is marginal. The H-abstraction reaction is ultrafast, taking place in less than 60 fs.
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the role of πσ states in the photochemistry of the chiral fluoroethylene derivative 4 methylcyclohexylidene Fluoromethane
International Journal of Quantum Chemistry, 2011Co-Authors: Daniel Kinzel, Jesus Gonzalezvazquez, Leticia GonzalezAbstract:Multiconfigurational ab initio calculations of the excited states and potential energy curves of the chiral fluoroethylene derivative (4-methylcyclohexylidene)Fluoromethane provide evidence that πσ* states play an important role in the abstraction of HF. We show that more than the ground and valence ππ* states are necessary to correctly describe the relaxation of the title molecule upon excitation to the bright valence ππ* state. A conical intersection between the πσ* and ππ* states has been identified at the FC geometry which makes dissociation of HF in the electronic excited state possible. This conclusion is different from all the previous studies on ethylenic systems where dissociation is postulated as a ground state reaction. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem 111:3394–3404, 2011
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H-abstraction is more efficient than cis–trans isomerization in (4-methylcyclohexylidene) Fluoromethane. An ab initio molecular dynamics study
Physical Chemistry Chemical Physics, 2011Co-Authors: Daniel Kinzel, Jesús González-vázquez, Leticia GonzalezAbstract:Non-adiabatic molecular dynamics simulations have been performed in the fluoro-olefin (4-methylcyclohexylidene) Fluoromethane (4MCF) using multiconfigurational CASSCF (complete active space self-consistent field) on-the-fly calculations. As an olefin containing a CC double bond, 4MCF is expected to undergo cis–trans isomerization after light irradiation. However, ab initio molecular dynamics shows that a preferential dissociation of atomic hydrogen is taking place after population transfer to the bright ππ* state. This state is strongly mixed with πσ* states allowing dissociation in the electronic excited state before deactivation to the ground state occurs. A minor amount of trajectories experiences F-dissociation, followed by pyramidalization at the sp2 carbons and CHF dissociation. In contrast, the amount of trajectories undergoing torsion around the double bond, and therefore cis–trans isomerization, is marginal. The H-abstraction reaction is ultrafast, taking place in less than 60 fs.
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non adiabatic photoisomerization versus photodissociation dynamics of the chiral fluoroethylene derivative 4 methylcyclohexylidene Fluoromethane
Chemical Physics, 2010Co-Authors: Sherin Alfalah, Daniel Kinzel, Jesus Gonzalezvazquez, Leticia GonzalezAbstract:Abstract The photoisomerization around the C C double bond and the competing elimination of hydrogen fluoride (HF) are studied in (4-methylcyclohexylidene) Fluoromethane. Both reactions are mediated by twisted conical intersections (CI) around the C C bond. Potential energy surfaces (PES) for the electronic ground state and first bright excited state of π π ∗ character are calculated using the CASSCF method along two reaction coordinates: the torsion around the C C bond and the distance between the center of masses of the hydrocarbon moiety and the HF fragment. Non-adiabatic couplings between both PES are obtained at the same level of theory. Wavepacket dynamics on the coupled surfaces show that after light irradiation torsion in the π π ∗ state dominates over HF dissociation, although the system starts with enough kinetic energy to reach the CI leading to HF-elimination.
Satoshi Takeya - One of the best experts on this subject based on the ideXlab platform.
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phase equilibrium for structure ii clathrate hydrates formed with Fluoromethane propan 2 ol 2 methyl 2 propanol or 2 propanone
The Journal of Chemical Thermodynamics, 2012Co-Authors: Masatoshi Imai, Shinnosuke Nitta, Satoshi Takeya, Ryo OhmuraAbstract:Abstract This paper presents phase-equilibrium pressure–temperature data for the clathrate hydrates formed in the three component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are {Fluoromethane (CH 3 F) + propan-2-ol + water}, (Fluoromethane + 2-methyl-2-propanol + water), and (Fluoromethane + 2-propanone + water). The mole ratio of water and the water-soluble material (papan-2-ol, 2-methyl-2-propanol, or 2-propanone) was 17:1. The temperature range over which the phase-equilibrium measurements were performed extended to 267.6 K on the lower side and 295.8 K on the higher side. The phase-equilibrium pressures in these three systems were found to be lower than that in the binary (Fluoromethane + water) system at a given system temperature. The crystallographic structure of the hydrates formed in the systems with 2-methyl-2-propanol and 2-propanone was determined to be structure II based on the powder X-ray diffraction measurements.
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Phase equilibrium for structure II clathrate hydrates formed with (Fluoromethane + propan-2-ol, 2-methyl-2-propanol, or 2-propanone)
The Journal of Chemical Thermodynamics, 2012Co-Authors: Masatoshi Imai, Shinnosuke Nitta, Satoshi Takeya, Ryo OhmuraAbstract:Abstract This paper presents phase-equilibrium pressure–temperature data for the clathrate hydrates formed in the three component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are {Fluoromethane (CH 3 F) + propan-2-ol + water}, (Fluoromethane + 2-methyl-2-propanol + water), and (Fluoromethane + 2-propanone + water). The mole ratio of water and the water-soluble material (papan-2-ol, 2-methyl-2-propanol, or 2-propanone) was 17:1. The temperature range over which the phase-equilibrium measurements were performed extended to 267.6 K on the lower side and 295.8 K on the higher side. The phase-equilibrium pressures in these three systems were found to be lower than that in the binary (Fluoromethane + water) system at a given system temperature. The crystallographic structure of the hydrates formed in the systems with 2-methyl-2-propanol and 2-propanone was determined to be structure II based on the powder X-ray diffraction measurements.
Shinnosuke Nitta - One of the best experts on this subject based on the ideXlab platform.
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phase equilibrium for structure ii clathrate hydrates formed with Fluoromethane propan 2 ol 2 methyl 2 propanol or 2 propanone
The Journal of Chemical Thermodynamics, 2012Co-Authors: Masatoshi Imai, Shinnosuke Nitta, Satoshi Takeya, Ryo OhmuraAbstract:Abstract This paper presents phase-equilibrium pressure–temperature data for the clathrate hydrates formed in the three component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are {Fluoromethane (CH 3 F) + propan-2-ol + water}, (Fluoromethane + 2-methyl-2-propanol + water), and (Fluoromethane + 2-propanone + water). The mole ratio of water and the water-soluble material (papan-2-ol, 2-methyl-2-propanol, or 2-propanone) was 17:1. The temperature range over which the phase-equilibrium measurements were performed extended to 267.6 K on the lower side and 295.8 K on the higher side. The phase-equilibrium pressures in these three systems were found to be lower than that in the binary (Fluoromethane + water) system at a given system temperature. The crystallographic structure of the hydrates formed in the systems with 2-methyl-2-propanol and 2-propanone was determined to be structure II based on the powder X-ray diffraction measurements.
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Phase equilibrium for structure II clathrate hydrates formed with (Fluoromethane + propan-2-ol, 2-methyl-2-propanol, or 2-propanone)
The Journal of Chemical Thermodynamics, 2012Co-Authors: Masatoshi Imai, Shinnosuke Nitta, Satoshi Takeya, Ryo OhmuraAbstract:Abstract This paper presents phase-equilibrium pressure–temperature data for the clathrate hydrates formed in the three component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are {Fluoromethane (CH 3 F) + propan-2-ol + water}, (Fluoromethane + 2-methyl-2-propanol + water), and (Fluoromethane + 2-propanone + water). The mole ratio of water and the water-soluble material (papan-2-ol, 2-methyl-2-propanol, or 2-propanone) was 17:1. The temperature range over which the phase-equilibrium measurements were performed extended to 267.6 K on the lower side and 295.8 K on the higher side. The phase-equilibrium pressures in these three systems were found to be lower than that in the binary (Fluoromethane + water) system at a given system temperature. The crystallographic structure of the hydrates formed in the systems with 2-methyl-2-propanol and 2-propanone was determined to be structure II based on the powder X-ray diffraction measurements.