1992 Fiscal Year Final Research Report Summary
Clustering Phenomena in Supercritical Fluids
| Project/Area Number |
03453121
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
化学工学
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| Research Institution | Tohoku University |
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Principal Investigator |
SAITO Shozaburo Tohoku University,Department of Molecular Chemistry & Engineering,Professor, 工学部, 教授 (00005224)
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| Co-Investigator(Kenkyū-buntansha) |
INOMATA Hiroshi Tohoku University,Research center of Supercritical Fluid Technology,Associate Pr, 工学部, 助教授 (10168479)
OSAWA Masatoshi Tohoku University,Department of Molecular Chemistry & Engineering,Associate Prof, 工学部, 助教授 (00108466)
KONNO Mikio Tohoku University,Department of Molecular Chemistry & Engineering,Associate Prof, 工学部, 助教授 (40125547)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Supercritical Fluid / Spectroscopy / Solvation / FTIR / Fluorescence spectra / MD Simulation / LJ fluid |
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| Research Abstract |
Infrared absorption spectra of naphthalene in supercritical carbon dioxide (CO2) solution of various concentrations were measured at 318.15 K and various pressures. The molar absorption coefficient of naphthalene in supercritical CO_2 was found to be dependent on the density of CO_2. As the density of CO_2 increased, a red shift of peak wavenumber of C-C vibration (quadrant stretching) and decrease in FWHM (full width at half maximum)of infrared absorption spectra were observed. This suggests that the molecular motion (vibration and rotation) of naphthalene in supercritical CO_2 was affected by the fluid density.
Dimerization of Benzoic acid and tautomerization of 2,4-pemtanedione via hydrogen bonding in supercritical CO2 was also measured using FTIR spectroscopy. The concentrations of monomer and dimer of benzoic acid were determined from absorbance data and Beer-Lambert's law. It was found that the equilibrium constants were dependent on the density and the dimerization equilibrium was shifted to monomeric form at higher densities. The tautomeric equilibrium between keto form (dipole moment: 4D) and enol form (dipole moment: 3D) of 2,4-pentanedione (acetylacetone) was shifted to polar keto form as the density of CO_2 increased, which indicated that the quadrupole moment of CO_2 provided slight polarity and played an important role in the tautomerization of 2,4-pentanedione in supercritical CO_2.
MD simulation for LJ fluids indicated that the stability of clusters was strongly influenced be the parameter-epsilon and cluster size was by the parameter-sigma.
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