Nuclear magnetic resonance measurement of spin-lattice relaxation and self-diffusion in supercritical CO<sub>2</sub>-<i>n</i>-hexadecane mixtures

Etesse, Patrick; Chapman, Walter G.; Kobayashi, Riki

doi:10.1080/00268979300102941

Cited by 11 publications

(7 citation statements)

References 22 publications

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“…Nuclear spin−lattice relaxation rates have been measured under SCF conditions by Jonas et al . and Kobayashi et al . − for various SCF mixtures. NMR chemical shift measurements were also used to relate 129 Xe chemical shift data to the local solvent structures of SCF Xe.…”

Section: Introductionmentioning

confidence: 99%

“…13 One of the advantages of utilizing NMR relaxation data is that they provide not only information, similar to optical methods, on overall molecular motions but also site-specific information on intramolecular motions. Nuclear spin-lattice relaxation rates have been measured under SCF conditions by Jonas et al 14 and Kobayashi et al [15][16][17] for various SCF mixtures. NMR chemical shift measurements 18 were also used to relate 129 Xe chemical shift data to the local solvent structures of SCF Xe.…”

Section: Introductionmentioning

confidence: 99%

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CO₂ Clustering of 1-Decanol and Methanol in Supercritical Fluids by ¹³C Nuclear Spin−Lattice Relaxation

et al. 1997

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A sapphire high-pressure NMR cell, capable of independently controlling sample pressure, temperature, and concentration, is used to measure 13 C spin-lattice relaxation times for carbons 1, 5, and 9 of 1-decanol in dense carbon dioxide at pressure between 80 and 200 atm. These NMR experiments, carried out along four isotherms between 288 and 348 K, provide relaxation data for 1-decanol in liquid and supercritical fluid CO 2 . The nuclear spin-lattice relaxation mechanisms for carbons 1, 5, and 9 of 1-decanol as well as for the carbon nucleus in carbon dioxide of this mixture are discussed. The relaxation data are analyzed using a modified Stokes-Einstein-Debye equation, together with an AK model, that postulates the formation of CO 2 clusters with the 1-decanol molecule in CO 2 -decanol mixture at supercritical and near-critical liquid densities. Such CO 2 cluster formation with methanol molecules was also detected in earlier relaxation measurements in CO 2 -methanol mixtures at the comparable densities. Possible solvent clustering gradients along the aliphatic chain in 1-decanol in dense CO 2 are also suggested.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

CO₂ Clustering of 1-Decanol and Methanol in Supercritical Fluids by ¹³C Nuclear Spin−Lattice Relaxation

et al. 1997

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“…In eq 18, R SR may be obtained from experimental measurements; R m and R cl may be calculated using eqs 5, 8, and 14. The three variables y 1 , y 4 , and K 4 may be obtained by solving the three eqs (16)(17)(18) simultaneously. Similar equations could be written for the trimer (n ) 3) and the pentamer (n ) 5).…”

Section: Resultsmentioning

confidence: 99%

“…NMR nuclear relaxation measurements have been shown to be an effective experimental method for studying important molecular interactions that influence fluid dynamics . This method has been used to study molecular motions under SCF conditions by Jonas et al , and Kobayashi et al. − for a variety of SCF mixtures. Studies in our laboratory have recently explored SCF structures in CO 2 −CH 4 mixtures and local solvent density enhancement in the vicinity of alcohol solute molecules in SCF CO 2 …”

Section: Introductionmentioning

confidence: 99%

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Hydrogen Bonding of Methanol in Supercritical CO₂ Studied by ¹³C Nuclear Spin−Lattice Relaxation

et al. 1997

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A sapphire high-pressure NMR cell, capable of independently controlling sample pressure, temperature, and concentration, is used to measure 13 C spin-lattice relaxation times for dilute methanol in dense carbon dioxide at pressures from 80 to 220 atm and temperatures from 287 to 334 K. These ranges of temperature and pressure provide relaxation data for methanol in both the liquid and supercritical fluid phases of CO 2 . The nuclear Overhauser effect (NOE), used for separating the contributions of the dipolar and spin-rotation mechanisms, has also been measured. Spin-rotation relaxation theory, together with proposed hydrogenbonding models, is used to interpret the experimental data. The partial molar enthalpy changes for hydrogen bond formation agree well with those reported by Smith et al. using FTIR (J. Am. Chem. Soc. 1991, 113, 8327-8334) and commonly accepted hydrogen bond energies. A large negative change in the partial molar volume arising from hydrogen bond formation in methanol is observed near the critical temperature of the CO 2 -methanol mixture.

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Supercritical Fluids

Taylor¹,

Jacobson²

2007

Encyclopedia of Magnetic Resonance

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Nuclear magnetic resonance measurement of spin-lattice relaxation and self-diffusion in supercritical CO₂-n-hexadecane mixtures

Cited by 11 publications

References 22 publications

CO₂ Clustering of 1-Decanol and Methanol in Supercritical Fluids by ¹³C Nuclear Spin−Lattice Relaxation

CO₂ Clustering of 1-Decanol and Methanol in Supercritical Fluids by ¹³C Nuclear Spin−Lattice Relaxation

Hydrogen Bonding of Methanol in Supercritical CO₂ Studied by ¹³C Nuclear Spin−Lattice Relaxation

Supercritical Fluids

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Nuclear magnetic resonance measurement of spin-lattice relaxation and self-diffusion in supercritical CO2-n-hexadecane mixtures

Cited by 11 publications

References 22 publications

CO2 Clustering of 1-Decanol and Methanol in Supercritical Fluids by 13C Nuclear Spin−Lattice Relaxation

CO2 Clustering of 1-Decanol and Methanol in Supercritical Fluids by 13C Nuclear Spin−Lattice Relaxation

Hydrogen Bonding of Methanol in Supercritical CO2 Studied by 13C Nuclear Spin−Lattice Relaxation

Supercritical Fluids

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Nuclear magnetic resonance measurement of spin-lattice relaxation and self-diffusion in supercritical CO₂-n-hexadecane mixtures

CO₂ Clustering of 1-Decanol and Methanol in Supercritical Fluids by ¹³C Nuclear Spin−Lattice Relaxation

CO₂ Clustering of 1-Decanol and Methanol in Supercritical Fluids by ¹³C Nuclear Spin−Lattice Relaxation

Hydrogen Bonding of Methanol in Supercritical CO₂ Studied by ¹³C Nuclear Spin−Lattice Relaxation