Development of the AVEC model for associating mixtures using NMR spectroscopy

Karachewski, Anne M.; Howell, Wayne J.; Eckert, Charles A.

doi:10.1002/aic.690370106

Cited by 38 publications

(29 citation statements)

References 46 publications

(41 reference statements)

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“…More recently the self association of alcohols mixed with saturated hydrocarbons has been studied based on different association models using NMR spectroscopy. Karachewski et al 5,6 have tested 1-3-1 association models for propan-2-ol + cyclohexane and n-butanol + cyclohexane mixtures, while Liu et al 7 prefer a continuous association model with association constants depending on the chain length of the associated species by passing a maximal value for tetrameric species in ethanol + cyclohexane mixtures. Rappon and Johns 8 have applied the linear continuous association model with association constants independent of the chain length to their 1 H NMR data of pentanol + heptane mixtures.…”

Section: Introductionmentioning

confidence: 99%

¹H NMR spectroscopic and thermodynamic studies of hydrogen bonding in liquid n-butanol + cyclohexane, tert-butanol + cyclohexane, and n-butanol + pyridine mixtures

Bich

Hensen

Michalik

et al. 2002

Phys. Chem. Chem. Phys.

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H NMR chemical shifts d OH of the proton in the hydroxyl group of n-butanol and tert-butanol have been measured as function of mixture composition in the binary mixtures n-butanol + cyclohexane, tertbutanol + cyclohexane, and n-butanol + pyridine at 303, 313 and 323 K. In addition the molar excess enthalpy H E of n-butanol + pyridine has been determined as a function of the mixture composition at 298 K using a flow calorimeter. The ERAS (extended real associated solution) model has been applied for describing simultaneously the data of d OH and H E for n-butanol + cyclohexane accounting for self association of n-butanol via hydrogen bonding. The mixture of n-butanol + pyridine was treated similarly using the ERAS model considering self association of n-butanol as well as cross association of n-butanol with pyridine. The results obtained indicate that self association in n-butanol and tert-butanol as well as cross association between n-butanol and pyridine play an important role in these mixtures. The ERAS model is able to describe the dependence of d OH and H E on mixture composition and temperature for all mixtures with a minimum of adjustable parameters providing a realistic insight into the liquid structure of these systems.y Electronic supplementary information (ESI) available: Experimental chemical shifts d OH of alcohol mixtures referred to TMS (Table S1) and molar excess enthalpies H E of n-butanol(1) + pyridine(2) mixtures at 298 K (Table S2). See

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Section: Introductionmentioning

confidence: 99%

¹H NMR spectroscopic and thermodynamic studies of hydrogen bonding in liquid n-butanol + cyclohexane, tert-butanol + cyclohexane, and n-butanol + pyridine mixtures

Bich

Hensen

Michalik

et al. 2002

Phys. Chem. Chem. Phys.

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“…The understanding of intermolecular interactions in such a solvent at supercritical conditions has become important . Various spectroscopic studies, such as NMR, , IR, − Raman, X-ray, neutron diffraction, and dielectric measurement, have been performed on liquid methanol. Theoretical molecular simulation studies , on hydrogen-bonding structures in methanol have been reported.…”

Section: Introductionmentioning

confidence: 99%

Pressure and Temperature Effects on the Hydrogen-Bond Structures of Liquid and Supercritical Fluid Methanol

Bai

Yonker

1998

J. Phys. Chem. A

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The proton spin-lattice relaxation times and proton chemical shifts for the hydroxyl and methyl protons in methanol were measured at liquid and supercritical densities using capillary high-pressure NMR spectroscopy. The pressure range for the proton nuclear relaxation measurements was between 50 and 3500 bar over a temperature range of 298-573 K. The proton chemical shifts of methanol were investigated for a pressure range of 50-3500 bar and a temperature range of 298-773 K. Attempts were made to separate the contributions of the dipolar and spin-rotation interactions to the spin-relaxation processes at each thermodynamic condition over methanol densities ranging from liquid to supercritical fluid. An average number of hydrogen bonds per molecule in methanol and the apparent activation energy of the methyl group internal rotation have been extracted from the experimental relaxation data. The extracted quantities show a moderate pressure dependence in addition to temperature effects, which suggest that molecular packing effects on hydrogen-bonded methanol are important at higher pressures. A comparison between methanol and water at similar thermodynamic conditions was also made to obtain new insight into these two important supercritical solvents.

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“…Most theoretical treatments of hydrogen bonding postulate the existence of distinct molecular species in solution, resulting from chemical reactions described by equilibrium constants (Heidemann and Prausnitz, 1976;Ikonomou and Donohue, 1986;Anderko, 1991;Karachewski et al, 1991). Levin and Perram (1968) presented an alternative treatment based on statistical mechanics, in which the focus is on the counting of the number of arrangements of hydrogen bonds, not on the distribution of particular complexes.…”

Section: Introductionmentioning

confidence: 99%

Theory of hydrogen bonding in supercritical fluids

et al. 1992

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The degree of hydrogen bonding and macroscopic thermodynamic properties for pure and mixed fluids are predicted with the hydrogen bonding lattice fluid (LFHB) equation of state over a wide range in density encompassing the gas, liquid and supercritical states. The model is successful for molecules forming complex seuassociated networks, in this case pure methanol, ethanol, and water, and the mixture I-hexanol-SF6. In supercritical wafer, significant hydrogen bonding is still present despite all the thermal energy and is highly pressure-and temperature-dependent. A fundamental description of pressure and temperature effects on hydrogen bonding is presented for a well-defined case, the formation of a complex between a donor and acceptor in an inert solvent, where no selfassociation is present. The partial molar enthalpy and volume change on complexation both become pronounced near the critical point, where the density is highly variable with temperature and pressure.

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Development of the AVEC model for associating mixtures using NMR spectroscopy

Cited by 38 publications

References 46 publications

¹H NMR spectroscopic and thermodynamic studies of hydrogen bonding in liquid n-butanol + cyclohexane, tert-butanol + cyclohexane, and n-butanol + pyridine mixtures

¹H NMR spectroscopic and thermodynamic studies of hydrogen bonding in liquid n-butanol + cyclohexane, tert-butanol + cyclohexane, and n-butanol + pyridine mixtures

Pressure and Temperature Effects on the Hydrogen-Bond Structures of Liquid and Supercritical Fluid Methanol

Theory of hydrogen bonding in supercritical fluids

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Development of the AVEC model for associating mixtures using NMR spectroscopy

Cited by 38 publications

References 46 publications

1H NMR spectroscopic and thermodynamic studies of hydrogen bonding in liquid n-butanol + cyclohexane, tert-butanol + cyclohexane, and n-butanol + pyridine mixtures

1H NMR spectroscopic and thermodynamic studies of hydrogen bonding in liquid n-butanol + cyclohexane, tert-butanol + cyclohexane, and n-butanol + pyridine mixtures

Pressure and Temperature Effects on the Hydrogen-Bond Structures of Liquid and Supercritical Fluid Methanol

Theory of hydrogen bonding in supercritical fluids

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¹H NMR spectroscopic and thermodynamic studies of hydrogen bonding in liquid n-butanol + cyclohexane, tert-butanol + cyclohexane, and n-butanol + pyridine mixtures

¹H NMR spectroscopic and thermodynamic studies of hydrogen bonding in liquid n-butanol + cyclohexane, tert-butanol + cyclohexane, and n-butanol + pyridine mixtures