1
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Skarmoutsos I. Substantial breakdown of the hydrogen-bonding network, local density inhomogeneities and fluid-liquid structural transitions in supercritical octanol-1: A molecular dynamics investigation. J Chem Phys 2024; 161:044506. [PMID: 39056384 DOI: 10.1063/5.0219417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Accepted: 07/11/2024] [Indexed: 07/28/2024] Open
Abstract
Molecular dynamics simulations have been employed to explore the hydrogen-bonding structure and dynamics in supercritical octanol-1 at a near-critical temperature and up to high densities and pressures. A substantial breakdown of the hydrogen-bonding network when going from ambient-liquid to supercritical conditions is revealed. The fraction of the non-hydrogen bonded molecules significantly increases in supercritical octanol-1, and a substantial decrease in the intermittent hydrogen-bond lifetime is observed. This behavior is also reflected on the maximum local density augmentation, which is comparable to the values obtained for non-polar and non-hydrogen bonded fluids. The existence of a structural transition from an inhomogeneous fluid phase to a soft-liquid one at densities higher than 2.0 ρc is also revealed. At higher densities, a significant change in the reorientational relaxation process is observed, reflected on the significant increase in the ratio of the Legendre reorientational times τ1R/τ2R. The latter becomes much higher than the value predicted by the Debye model of diffusive reorientation and the corresponding ratio for ambient liquid octanol-1. The non-polar tail of octanol-1 under supercritical conditions reorients more slowly in comparison with the polar tail. Interestingly, the opposite behavior is observed for the ambient liquid, further verifying the strong effect of the breakdown of the hydrogen bonding network on the properties of supercritical octanol-1. In accordance with the above-mentioned findings, the static dielectric constant of supercritical octanol-1 is very low even at high densities and pressures, comparable to the values obtained for non-polar and non-hydrogen bonded fluids.
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Affiliation(s)
- Ioannis Skarmoutsos
- Laboratory of Physical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece
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2
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Killian WG, Bala AM, Norfleet AT, Peereboom L, Jackson JE, Lira CT. Infrared quantification of ethanol and 1-butanol hydrogen bonded hydroxyl distributions in cyclohexane. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 285:121837. [PMID: 36137499 DOI: 10.1016/j.saa.2022.121837] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 08/31/2022] [Accepted: 09/02/2022] [Indexed: 06/16/2023]
Abstract
Quantifying the mid-range infrared hydroxyl stretch absorbance region has traditionally been a challenge due to the wavenumber dependence of the attenuation coefficient. Interpretation often assigns a single attenuation coefficient to each type of hydrogen-bonded aggregate. This work leverages a recently developed technique of scaling hydroxyl stretching absorbances in the mid-infrared region with a continuous attenuation coefficient function that produces integrated areas which directly correlate to hydroxyl concentrations. After scaling, the hydroxyl absorbance is fitted with five curves, of which four are dominant. These four curves represent unique hydroxyl configurations and translate to specific aggregate structures. The technique is applied to ethanol and 1-butanol. The resulting population distributions of hydrogen-bonded hydroxyl configurations are compared with the resummed thermodynamic perturbation theory (RTPT) model for linear chains as a function of concentration and temperature. The model is demonstrated to capture the critical features of the distributions.
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Affiliation(s)
- William G Killian
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA
| | - Aseel M Bala
- Department of Chemical and Biomolecular Engineering, Lafayette College, Easton, PA 18042, USA
| | - Andrew T Norfleet
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA
| | - Lars Peereboom
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA
| | - James E Jackson
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Carl T Lira
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA.
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3
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Grelska J, Jurkiewicz K, Burian A, Pawlus S. Supramolecular Structure of Phenyl Derivatives of Butanol Isomers. J Phys Chem B 2022; 126:3563-3571. [PMID: 35522735 PMCID: PMC9125557 DOI: 10.1021/acs.jpcb.2c01269] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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Wide-angle X-ray
scattering patterns were recorded for a series
of aliphatic butanol isomers (n-, iso-, sec-, tert-butanol) and their
phenyl derivatives (4-phenyl-1-butanol, 2-methyl-3-phenyl-1-propanol,
4-phenyl-2-butanol, and 2-methyl-1-phenyl-2-propanol, respectively)
to determine their atomic-scale structure with particular emphasis
on the formation of supramolecular clusters. In addition, molecular
dynamics simulations were carried out and yielded good agreement with
experimental data. The combination of experimental and theoretical
results allowed clarification of the origin of the pre-peak appearing
at low scattering angles for the aliphatic butanols and its absence
for their phenyl counterparts. It was demonstrated that the location
of the hydroxyl group in the molecule of alkyl butanol, its geometry,
and rigidity determine the morphology of the supramolecular clusters,
while the addition of the aromatic moiety causes more disordered organization
of molecules. The phenyl group significantly decreases the number
of hydrogen bonds and size of the supramolecular clusters formed via
the O–H···O scheme. The lower association ability
of phenyl alcohols via H-bonds is additionally attenuated by the appearance
of competing π–π configurations evidenced by the
structural models.
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Affiliation(s)
- Joanna Grelska
- A. Chełkowski Institute of Physics, University of Silesia in Katowice, ul. 75 Pułku Piechoty 1, 41-500 Chorzów, Poland.,Silesian Center for Education and Interdisciplinary Research, ul. 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
| | - Karolina Jurkiewicz
- A. Chełkowski Institute of Physics, University of Silesia in Katowice, ul. 75 Pułku Piechoty 1, 41-500 Chorzów, Poland.,Silesian Center for Education and Interdisciplinary Research, ul. 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
| | - Andrzej Burian
- A. Chełkowski Institute of Physics, University of Silesia in Katowice, ul. 75 Pułku Piechoty 1, 41-500 Chorzów, Poland.,Silesian Center for Education and Interdisciplinary Research, ul. 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
| | - Sebastian Pawlus
- A. Chełkowski Institute of Physics, University of Silesia in Katowice, ul. 75 Pułku Piechoty 1, 41-500 Chorzów, Poland.,Silesian Center for Education and Interdisciplinary Research, ul. 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
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4
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Cabaço MI, Besnard M, Cruz C, Morgado P, Silva GC, Filipe EJM, Coutinho JA, Danten Y. Breaking the Structure of Liquid Hydrogenated Alcohols Using Perfluorinated tert-Butanol: A Multitechnique Approach (Infrared, Raman, and X-ray Scattering) Analyzed by DFT and Molecular Dynamics Calculations. J Phys Chem B 2022; 126:1992-2004. [PMID: 35230118 PMCID: PMC9776561 DOI: 10.1021/acs.jpcb.1c10776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The state of aggregation at room temperature of tert-butanol (TBH) and perfluoro tert-butanol (TBF) liquid mixtures is assessed by vibrational spectroscopy (Raman and infrared) and X-ray diffraction and analyzed using density functional theory (DFT) and molecular dynamics (MD) simulations. It is shown that larger clusters (mostly tetramers) of TBH are destroyed upon dilution with TBF. Small oligomers, monomers, and mainly heterodimers are present at the equimolar concentration. At variance with slightly interacting solvents, the signature of hetero-oligomers is shown by the appearance of a new broad band detected in the infrared region. The same spectral observation is detected for mixtures of other hydrogenated alcohols (methanol and 1-butanol). The new infrared feature is unaffected by dilution in a polar solvent (CDCl3) in a high-concentration domain, allowing us to assign it to the signature of small hetero-oligomers. MD simulations are used to assess the nature of the species present in the mixture (monomers and small hetero-oligomers) and to follow the evolution of their population upon the dilution. Combining MD simulations with DFT calculations, the infrared spectral profile is successfully analyzed in equimolecular mixtures. This study shows that TBF is a structure breaker of hydrogen-bonded alcohol networks and that the TBF (donor)-TBH (acceptor) heterodimer is the dominant species in an extended range of concentration, centered in the vicinity of the equimolar fraction.
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Affiliation(s)
- M. Isabel Cabaço
- CeFEMA,
Centro de Física e Engenharia de Materiais Avançados,
Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Laboratory
of Instrumentation, Biomedical Engineering and Radiation Physics (LIBPhys-UNL),
Department of Physics, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
| | - Marcel Besnard
- CeFEMA,
Centro de Física e Engenharia de Materiais Avançados,
Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- GSM
Institut des Sciences Moléculaires, CNRS (UMR 5255), Université Bordeaux I, 351, Cours de la Libération, 33405 Talence Cedex, France
| | - Carlos Cruz
- CeFEMA,
Centro de Física e Engenharia de Materiais Avançados,
Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Pedro Morgado
- Centro
de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
| | - Gonçalo
M. C. Silva
- Centro
de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
| | - Eduardo J. M. Filipe
- Centro
de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
| | - João A.
P. Coutinho
- CICECO,
Departamento de Química, Universidade
de Aveiro, 3810-193 Aveiro, Portugal
| | - Yann Danten
- GSM
Institut des Sciences Moléculaires, CNRS (UMR 5255), Université Bordeaux I, 351, Cours de la Libération, 33405 Talence Cedex, France
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5
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Isabel Cabaço M, Besnard M, Cruz C, Morgado P, Silva GM, Filipe EJ, Coutinho JA, Danten Y. The structure of liquid perfluoro Tert-Butanol using Infrared, Raman and X-Ray scattering analyzed by quantum DFT calculations and molecular Dynamics. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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6
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Gaseous hetero dimers of perfluoro tert-butyl alcohol with hydrogenated alcohols by infrared spectroscopy and quantum DFT calculations. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2021.111110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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7
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Nowok A, Jurkiewicz K, Dulski M, Hellwig H, Małecki JG, Grzybowska K, Grelska J, Pawlus S. Influence of molecular geometry on the formation, architecture and dynamics of H-bonded supramolecular associates in 1-phenyl alcohols. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115349] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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8
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Engelbrecht LDV, Farris R, Vasiliu T, Demurtas M, Piras A, Cesare Marincola F, Laaksonen A, Porcedda S, Mocci F. Theoretical and Experimental Study of the Excess Thermodynamic Properties of Highly Nonideal Liquid Mixtures of Butanol Isomers + DBE. J Phys Chem B 2021; 125:587-600. [PMID: 33428423 DOI: 10.1021/acs.jpcb.0c10076] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Binary alcohol + ether liquid mixtures are of significant importance as potential biofuels or additives for internal combustion engines and attract considerable fundamental interest as model systems containing one strongly H-bonded self-associating component (alcohol) and one that is unable to do so (ether), but that can interact strongly as a H-bond acceptor. In this context, the excess thermodynamic properties of these mixtures, specifically the excess molar enthalpies and volumes (HE and VE), have been extensively measured. Butanol isomer + di-n-butyl ether (DBE) mixtures received significant attention because of interesting differences in their VE, changing from negative (1- and isobutanol) to positive (2- and tert-butanol) with increasing alkyl group branching. With the aim of shedding light on the differences in alcohol self-association and cross-species H-bonding, considered responsible for the observed differences, we studied representative 1- and 2-butanol + DBE mixtures by molecular dynamics simulations and experimental excess property measurements. The simulations reveal marked differences in the self-association of the two isomers and, while supporting the existing interpretations of the HE and VE in a general sense, our results suggest, for the first time, that subtle changes in H-bonded topologies may contribute significantly to the anomalous volumetric properties of these mixtures.
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Affiliation(s)
- Leon de Villiers Engelbrecht
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio Sestu, Monserrato, 09042 Cagliari, Italy
| | - Riccardo Farris
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio Sestu, Monserrato, 09042 Cagliari, Italy
| | - Tudor Vasiliu
- Centre of Advanced Research in Bio-nanoconjugates and Biopolymers, Romanian Academy-Petru Poni (PP) Institute of Macromolecular Chemistry, 00487 Iasi, Romania
| | - Monica Demurtas
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio Sestu, Monserrato, 09042 Cagliari, Italy
| | - Alessandra Piras
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio Sestu, Monserrato, 09042 Cagliari, Italy
| | - Flaminia Cesare Marincola
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio Sestu, Monserrato, 09042 Cagliari, Italy
| | - Aatto Laaksonen
- Centre of Advanced Research in Bio-nanoconjugates and Biopolymers, Romanian Academy-Petru Poni (PP) Institute of Macromolecular Chemistry, 00487 Iasi, Romania.,Department of Materials and Environmental Chemistry, Division of Physical Chemistry, Arrhenius Laboratory, Stockholm University (SU), 106 91 Stockholm, Sweden.,State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University (NTU), 210009 Nanjing, China.,Department of Engineering Sciences and Mathematics, Division of Energy Science, Luleå University of Technology, SE-97187 Luleå, Sweden
| | - Silvia Porcedda
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio Sestu, Monserrato, 09042 Cagliari, Italy
| | - Francesca Mocci
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio Sestu, Monserrato, 09042 Cagliari, Italy
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9
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10
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Kalhor P, Li QZ, Zheng YZ, Yu ZW. Is the Fourier Transform Infrared Free-OH Band of t-Butanol Only from Free OHs? Case Studies on the Binary Systems of the Alcohol with CCl 4 and CHCl 3. J Phys Chem A 2020; 124:6177-6185. [PMID: 32623889 DOI: 10.1021/acs.jpca.0c03463] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Attenuated total reflection-Fourier transform infrared spectroscopy and quantum chemical calculations were performed on tert-butyl alcohol (t-BuOH) and its binary solutions with CCl4 and CHCl3. The study was focused on the free-OH stretching bands. Two resolution-enhancing methods, excess spectroscopy and two-dimensional correlation spectroscopy, were employed to examine the structural heterogeneity and search for the detailed contributors to the free-OH bands. Unexpectedly, CCl4 was found not to be an inert solvent and, similar to CHCl3, formed hydrogen/halogen bonds (H-/X-bond) with t-BuOH. It was observed that the free-OH band in the t-BuOH-CHCl3 system is larger and more red-shifted than that in the t-BuOH-CCl4 system, indicating the stronger intermolecular interactions in the former system. Furthermore, in the t-BuOH-CHCl3 system, the H-bonds are stronger than the X-bonds, while in the t-BuOH-CCl4 system, both interactions are similar in strength. To assign the free-OH bands, it was found that they are not only from the free OH of the t-BuOH monomer, but they are also contributed by the quasi-free OH with the oxygen bonded to H or Cl and even the weakly H-bonded OH of t-BuOH molecules. Finally, all the identified species increased simultaneously via cosolvent addition, suggestive of the destabilization of the highly associated t-BuOH clusters.
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Affiliation(s)
- Payam Kalhor
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Qing-Zhong Li
- The Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Yantai University, Yantai 264005, China
| | - Yan-Zhen Zheng
- College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zhi-Wu Yu
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
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11
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Bala AM, Killian WG, Plascencia C, Storer JA, Norfleet AT, Peereboom L, Jackson JE, Lira CT. Quantitative Analysis of Infrared Spectra of Binary Alcohol + Cyclohexane Solutions with Quantum Chemical Calculations. J Phys Chem A 2020; 124:3077-3089. [PMID: 32181659 DOI: 10.1021/acs.jpca.9b11245] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hydrogen bonding has profound effects on the behavior of molecules. Fourier-transform infrared spectroscopy is the technique most commonly used to qualitatively identify hydrogen-bonding moieties present in a chemical sample. However, quantitative analysis of infrared (IR) spectra is nontrivial for the hydroxyl stretching region where hydrogen bonding is most prominently expressed in organic alcohols and water. Specifically, the breadth and extreme overlap of the O-H stretching bands, and the order of magnitude variability of their IR attenuation coefficients complicates the analysis. In the present work, sequential molecular dynamics simulations and quantum mechanical calculations are used to develop a function to relate the integrated IR attenuation coefficient to the vibrational frequencies of hydroxyl bands across the O-H stretching region. This relationship is then used as a guide to develop an attenuation coefficient scaling function to quantitatively determine concentrations of alcohols in a hydrocarbon solution from experimental IR spectra by integration across the entire hydroxyl frequency range.
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Affiliation(s)
- Aseel M Bala
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, United States
| | - William G Killian
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, United States
| | - Cesar Plascencia
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Jackson A Storer
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, United States
| | - Andrew T Norfleet
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, United States
| | - Lars Peereboom
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, United States
| | - James E Jackson
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Carl T Lira
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, United States
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12
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Structural, rheological and dynamic aspects of hydrogen-bonding molecular liquids: Aqueous solutions of hydrotropic tert-butyl alcohol. J Colloid Interface Sci 2020; 560:730-742. [DOI: 10.1016/j.jcis.2019.10.094] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/23/2019] [Accepted: 10/24/2019] [Indexed: 11/23/2022]
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13
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14
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Mesele OO, Vartia AA, Laage D, Thompson WH. Reorientation of Isomeric Butanols: The Multiple Effects of Steric Bulk Arrangement on Hydrogen-Bond Dynamics. J Phys Chem B 2015; 120:1546-59. [DOI: 10.1021/acs.jpcb.5b07692] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Oluwaseun O. Mesele
- Department
of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Anthony A. Vartia
- Department
of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Damien Laage
- Department
of Chemistry, Ecole Normale Supérieure, UMR ENS-CNRS-UPMC 8640, 24 rue Lhmond, 75005 Paris, France
| | - Ward H. Thompson
- Department
of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
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15
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Soetens JC, Bopp PA. Water-Methanol Mixtures: Simulations of Mixing Properties over the Entire Range of Mole Fractions. J Phys Chem B 2015; 119:8593-9. [PMID: 26082996 DOI: 10.1021/acs.jpcb.5b03344] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Numerous experimental and theoretical investigations have been devoted to the hydrogen bond in pure liquids and mixtures. Among the different theoretical approaches, molecular dynamics (MD) simulations are predominant in obtaining detailed information, on the molecular level, simultaneously on the structure and the dynamics. Water and methanol are the two most prominent hydrogen-bonded liquids, and they and their mixtures have consequently been the subject of many studies; we revisit here the problem of the mixtures. An important first step is to check whether a classical potential model, the components of which are deemed to be satisfactory for the pure liquids, is able to reproduce the known thermodynamic excess properties of the mixtures sufficiently well. We have used the available BJH (water) and PHH (methanol) flexible models because they are by construction mutually compatible and also well suited to study, in a second step, some dynamic property characteristic of hydrogen-bonded liquids. In this article we show that these models, after a slight reparametrization for use in NpT simulations, reproduce the essential features of the excess mixing and molar properties of water-methanol mixtures. Furthermore, in the pure liquids, the agreement of the radial distribution functions with experiment remains as satisfactory as before. Similarly, the translation self-diffusion coefficients D are modified by less than 10%. In the mixtures, they evolve nonmonotonously as a function of mole fraction.
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Affiliation(s)
- Jean-Christophe Soetens
- Institut des Sciences Moléculaires, UMR CNRS no. 5255, and Department of Chemistry, Université de Bordeaux, 351 Cours de la Libération, 33405 Talence, France
| | - Philippe A Bopp
- Institut des Sciences Moléculaires, UMR CNRS no. 5255, and Department of Chemistry, Université de Bordeaux, 351 Cours de la Libération, 33405 Talence, France
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16
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Abdel Hamid AR, Lefort R, Lechaux Y, Moréac A, Ghoufi A, Alba-Simionesco C, Morineau D. Solvation Effects on Self-Association and Segregation Processes in tert-Butanol–Aprotic Solvent Binary Mixtures. J Phys Chem B 2013; 117:10221-30. [DOI: 10.1021/jp402380f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- A. R. Abdel Hamid
- Institute
of Physics of Rennes, CNRS-University of Rennes 1, UMR 6251, F-35042 Rennes,
France
| | - R. Lefort
- Institute
of Physics of Rennes, CNRS-University of Rennes 1, UMR 6251, F-35042 Rennes,
France
| | - Y. Lechaux
- Institute
of Physics of Rennes, CNRS-University of Rennes 1, UMR 6251, F-35042 Rennes,
France
| | - A. Moréac
- Institute
of Physics of Rennes, CNRS-University of Rennes 1, UMR 6251, F-35042 Rennes,
France
| | - A. Ghoufi
- Institute
of Physics of Rennes, CNRS-University of Rennes 1, UMR 6251, F-35042 Rennes,
France
| | - C. Alba-Simionesco
- Laboratoire Léon
Brillouin,
UMR 12, CEA-CNRS, F-91191 Gif-sur-Yvette,
France
| | - D. Morineau
- Institute
of Physics of Rennes, CNRS-University of Rennes 1, UMR 6251, F-35042 Rennes,
France
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17
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Idrissi A, Oparin RD, Krishtal SP, Krupin SV, Vorobiev EA, Frolov AI, Dubois L, Kiselev MG. The study of correlations between hydrogen bonding characteristics in liquid, sub- and supercritical methanol. Molecular dynamics simulations and Raman spectroscopy analysis. Faraday Discuss 2013; 167:551-66. [DOI: 10.1039/c3fd00103b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Tassaing T, Soetens JC, Vyalov I, Kiselev M, Idrissi A. Supercritical ammonia: A molecular dynamics simulation and vibrational spectroscopic investigation. J Chem Phys 2010; 133:214505. [PMID: 21142306 DOI: 10.1063/1.3506868] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- T Tassaing
- Institut des Sciences Moléculaires, Université Bordeaux 1, UMR-CNRS 5255, 351 cours de la Libération, 33405 Talence Cedex, France
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19
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Tassaing T, Garrain PA, Bégué D, Baraille I. On the cluster composition of supercritical water combining molecular modeling and vibrational spectroscopic data. J Chem Phys 2010; 133:034103. [PMID: 20649304 DOI: 10.1063/1.3457483] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The present study is aimed at a detailed analysis of supercritical water structure based on the combination of experimental vibrational spectra as well as molecular modeling calculations of isolated water clusters. We propose an equilibrium cluster composition model where supercritical water is considered as an ideal mixture of small water clusters (n=1-3) at the chemical equilibrium and the vibrational spectra are expected to result from the superposition of the spectra of the individual clusters, Thus, it was possible to extract from the decomposition of the midinfrared spectra the evolution of the partition of clusters in supercritical water as a function of density. The cluster composition predicted by this model was found to be quantitatively consistent with the near infrared and Raman spectra of supercritical water analyzed using the same procedure. We emphasize that such methodology could be applied to determine the portion of cluster in water in a wider thermodynamic range as well as in more complex aqueous supercritical solutions.
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Affiliation(s)
- T Tassaing
- Institut des Sciences Moléculaires (ISM), UMR 5255, CNRS-Université Bordeaux I, 351, Cours de la Libération, Talence Cedex 33405, France.
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Ivlev DV, Dyshin AA, Kiselev MG, Kolker AM. Topology of hydrogen-bonded clusters in sub- and supercritical n-buthanol. Molecular dynamics simulation. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2010. [DOI: 10.1134/s0036024410120125] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Kajiya D, Saitow KI. Site-Selective Solvation in Supercritical CO2Observed by Raman Spectroscopy: Phenyl Group Leads to Greater Attractive Energy than Chloro Group. J Phys Chem B 2010; 114:16832-7. [DOI: 10.1021/jp107820j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Daisuke Kajiya
- Natural Science Center for Basic Research and Development (N-BARD) and Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan
| | - Ken-ichi Saitow
- Natural Science Center for Basic Research and Development (N-BARD) and Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan
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22
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Andanson JM, Jutz F, Baiker A. Simple in situ monitoring of a complex catalytic reaction network at high pressure by attenuated total reflection Fourier transform infrared spectroscopy. APPLIED SPECTROSCOPY 2010; 64:286-292. [PMID: 20223063 DOI: 10.1366/000370210790918436] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Attenuated total reflection (ATR) Fourier transform infrared (FT-IR) in situ measurements were performed during the catalytic hydrogenation of acetophenone under high pressure (5.0 MPa). The catalyst used was a suspension of rhodium nanoparticles in an ionic liquid. At the highest temperature used (80 degrees C), the selectivity of the hydrogenation to 1-phenylethanol dropped from 80% in the beginning of the reaction, when acetylcyclohexane was the main side product, to less than 50% after a few hours of experiment because of the consecutive hydrogenation of 1-phenylethanol to ethylcyclohexane. The evolution of the concentrations of reactant and products was quantified using flawless spectra of pure components with a classical least squares (CLS) multivariate method applied to several ranges of the mid-infrared spectra. The only variable parameters of the analysis are the concentrations of each component themselves and the baseline shift of the spectrum during the reaction. The advantage of using multivariate analysis over the analysis of a single vibrational band, as well as the limitations of this type of spectral analysis, are discussed.
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Affiliation(s)
- Jean-Michel Andanson
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Hönggerberg, HCI, CH-8093 Zürich, Switzerland
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Skarmoutsos I, Guardia E. Local Structural Effects and Related Dynamics in Supercritical Ethanol. 2. Hydrogen-Bonding Network and Its Effect on Single Reorientational Dynamics. J Phys Chem B 2009; 113:8898-910. [DOI: 10.1021/jp901489c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Ioannis Skarmoutsos
- Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, B4−B5 Campus Nord UPC, 08034 Barcelona, Catalonia, Spain
| | - Elvira Guardia
- Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, B4−B5 Campus Nord UPC, 08034 Barcelona, Catalonia, Spain
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Danten Y, Cabaço MI, Besnard M. Interaction of Water Highly Diluted in 1-Alkyl-3-methyl Imidazolium Ionic Liquids with the PF6− and BF4− Anions. J Phys Chem A 2009; 113:2873-89. [DOI: 10.1021/jp8108368] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Y. Danten
- Institut des Sciences Moléculaires, CNRS (UMR 5255), Université Bordeaux, 351, Cours de la Libération 33405 Talence Cedex, France, and Centro de Física Atómica da UL, Av. Prof. Gama Pinto 2, 1694-003 Lisboa Codex and Departamento de Física, Instituto Superior Técnico, UTL, Av. Rovisco Pais 1049-001 Lisboa, Portugal
| | - M. I. Cabaço
- Institut des Sciences Moléculaires, CNRS (UMR 5255), Université Bordeaux, 351, Cours de la Libération 33405 Talence Cedex, France, and Centro de Física Atómica da UL, Av. Prof. Gama Pinto 2, 1694-003 Lisboa Codex and Departamento de Física, Instituto Superior Técnico, UTL, Av. Rovisco Pais 1049-001 Lisboa, Portugal
| | - M. Besnard
- Institut des Sciences Moléculaires, CNRS (UMR 5255), Université Bordeaux, 351, Cours de la Libération 33405 Talence Cedex, France, and Centro de Física Atómica da UL, Av. Prof. Gama Pinto 2, 1694-003 Lisboa Codex and Departamento de Física, Instituto Superior Técnico, UTL, Av. Rovisco Pais 1049-001 Lisboa, Portugal
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25
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26
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Durov VA, Shilov IY, Tereshin OG. Modeling of Supramolecular Structure and Dielectric Properties of Butanols from Melting Point to Supercritical State. J Phys Chem B 2008; 112:8076-83. [DOI: 10.1021/jp710428n] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Vladimir A. Durov
- Faculty of Chemistry, Moscow State University, Vorobyevy Gory, Moscow 119899, Russia
| | - Ignat Yu. Shilov
- Faculty of Chemistry, Moscow State University, Vorobyevy Gory, Moscow 119899, Russia
| | - Oleg G. Tereshin
- Faculty of Chemistry, Moscow State University, Vorobyevy Gory, Moscow 119899, Russia
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Kajiya D, Mouri Y, Saitow KI. Difference of Solute−Solvent Interactions of cis- and trans-1,2-Dichloroethylene in Supercritical CO2 Investigated by Raman Spectroscopy. J Phys Chem B 2008; 112:7980-3. [DOI: 10.1021/jp803875x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Daisuke Kajiya
- Natural Science Center for Basic Research and Development (N-BARD), Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan, and PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Yutaka Mouri
- Natural Science Center for Basic Research and Development (N-BARD), Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan, and PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Ken-ichi Saitow
- Natural Science Center for Basic Research and Development (N-BARD), Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan, and PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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Andanson JM, Kazarian SG. In situ ATR-FTIR Spectroscopy of Poly(ethylene terephthalate) Subjected to High-Temperature Methanol. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/masy.200850521] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kosower EM, Markovich G, Borz G. Molecule-enhanced surface-enhanced infrared absorption spectroscopy (MOSEIRA). Chemphyschem 2007; 8:2506-12. [PMID: 17955505 DOI: 10.1002/cphc.200700462] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Surface-enhanced infrared absorption spectroscopy (SEIRA) of methanol, ethanol, 1-propanol, and 2-propanol in thin films on planar silver halide (AgX) fibers under slow N(2) flow using 1 sec scans reveals structure in absorbance-time plots. The absorption intensities show extra enhancements (3x) in the absorbance (O--H stretch) ascribed to oligomers present at the AgX surface (molecule enhanced, thus MOSEIRA). This is above those due to amplification (40x, 20 reflections) and enhancement (30x, image dipoles or surface phonon polaritons). In the case of ethanol an excellent initial pentamer spectrum evolves over 8-10 min to a mixture of pentamer, tetramer, and trimer spectra that within another minute forms small oligomers and monomers. We use a new type of cell for infrared spectroscopy containing an AgX planar fiber. The optical configuration leads to a vicinal region at the surface defined by evanescent waves. Within this region are surface-induced organized species such as ethanol oligomers. The planar AgX fiber supports 20 reflections and transmits light over a wide visible-infrared wavelength range. Short scan times permit the study of volatile substrates or solvents, including the effects of solvent polarity.
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Affiliation(s)
- Edward M Kosower
- School of Chemistry, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel.
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Yasaka Y, Kubo M, Matubayasi N, Nakahara M. High-Sensitivity Raman Spectroscopy of Supercritical Water and Methanol over a Wide Range of Density. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2007. [DOI: 10.1246/bcsj.80.1764] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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32
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Sassi P, Palombo F, Cataliotti RS, Paolantoni M, Morresi A. Distributions of H-Bonding Aggregates in tert-Butyl Alcohol: The Pure Liquid and Its Alkane Mixtures. J Phys Chem A 2007; 111:6020-7. [PMID: 17579375 DOI: 10.1021/jp071609q] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A vibrational analysis using FTIR and Raman spectroscopies was carried out on pure liquid t-butyl alcohol (TBA) in the range of temperatures 15 < or = t < or = 70 degrees C. The whole range of molar fractions for TBA in 2,2'dimethylbutane (2,2'DMB) was also explored and compared with the t dependence of pure alcohol properties. Temperature and composition dependence of vibrational spectra were reproduced by simultaneous fitting of IR and Raman OH-stretching band contours by using harmonic frequencies and intensities derived from ab initio calculations for the various hydrogen-bonded structures. Adopting this fitting procedure, size and shape distributions of H-bonding aggregates have been derived, thus giving a quantitative description of balancing factors between hydrophilic and hydrophobic interactions in this liquid system.
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Affiliation(s)
- Paola Sassi
- Dipartimento di Chimica, Sezione di Chimica Fisica, Università di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy.
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Cataliotti RS, Palombo F, Paolantoni M, Sassi P, Raudino A. Concentration fluctuations and collective properties in mixed liquid systems: Rayleigh-Brillouin spectra oftert-butyl alcohol/ 2,2′-dimethylbutane liquid mixture. J Chem Phys 2007; 126:044505. [PMID: 17286485 DOI: 10.1063/1.2431170] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Rayleigh-Brillouin spectra have been measured in a range of temperatures and compositions of t-butyl alcohol/2,2(')-dimethylbutane liquid mixture. The mixture mole fraction has been varied from pure alkane (x(TBA)=0) to pure alcohol (x(TBA)=1) at temperatures between 283 and 323 K. In the same composition and temperature ranges the authors also executed measurements of mass density, shear viscosity, and refractive index. From light scattering spectra the authors have extracted the hypersound velocities and adiabatic compressibilities and evaluated their excess values. Moreover, the authors attempted to evaluate the isothermal (40 degrees C) Landau-Placzek ratios at various mole fractions, but these values proved to be subject to significant errors due to great uncertainty in the central component intensity measurements. Thus, in discussing the results, this latter quantity was considered only from a qualitative point of view. These results highlight a nonideal behavior of the studied liquid mixture with a probable azeotropic composition around x(TBA)=0.7 due to formation of small clusters of hydrogen-bonded alcohol tetramers that are completely surrounded by solvent molecules and analogous or smaller clusters. These clusters, shaped as inverse micelles, offer their hydrophobic moiety towards the molecules that constitute the solvation shell, resulting in a low polarity solution structure that minimizes the solute-solvent interactions. Differences in thermal and compositional behavior of excess molar volumes and adiabatic compressibilities have been interpreted by attributing different weights to the solute-solvent interaction forces and to the hydrogen bond connectivity effects.
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Affiliation(s)
- Rosario Sergio Cataliotti
- Dipartimento di Chimica, Sezione di Chimica Fisica, Università di Perugia, Via Elce di Sotto 8, I-06001 Perugia, Italy.
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Andanson JM, Bopp PA, Soetens JC. Relation between hydrogen bonding and intramolecular motions in liquid and supercritical methanol. J Mol Liq 2006. [DOI: 10.1016/j.molliq.2006.08.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Palombo F, Tassaing T, Danten Y, Besnard M. Hydrogen bonding in liquid and supercritical 1-octanol and 2-octanol assessed by near and midinfrared spectroscopy. J Chem Phys 2006; 125:094503. [PMID: 16965093 DOI: 10.1063/1.2336424] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The near and midinfrared spectra of 1-octanol (and 2-octanol) have been measured along the liquid-gas coexistence curve from room temperature up to the critical point and in the supercritical domain along the isotherm T=385 degrees C (and T=365 degrees C) above the critical point of both 1-octanol and 2-octanol for pressure ranging from 0.5 up to 15 MPa. The density values of SC 1- and 2-octanol have been estimated by analysing the near infrared (NIR) spectra in the 3nu(a)(CH) region. A quantitative analysis of the absorption band associated with the OH stretching vibration [nu(OH)] and its first and second overtones [2nu(OH) and 3nu(OH)] was carried out in order to estimate the percentage of "free" OH groups in both alcohols in the whole thermodynamic domain investigated here. Very consistent results have been obtained from the independent analysis of these three different absorption bands which gave us a good confidence in the degree of hydrogen bonding reported here for 1- and 2-octanol. Thus, the percentage of free OH groups which is around 5% in liquid 1-octanol under ambient conditions strongly increase up to 70%-80% at a temperature of about 340 degrees C. Then, in the supercritical domain, upon a decrease of the density from 0.4 to 0.1 g cm(-3), the fraction of free hydroxyl groups is nearly constant presenting a plateaulike regime around 80%. As the density decreases again, this plateau regime is followed by a further increase of X(nb) which reaches a value of 96% for the system in the gaseous phase (0.01 g cm(-3); P=0.45 MPa). Finally, it comes out from this study that the percentage of free OH groups is always greater in 2-octanol than in 1-octanol at the same density.
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Affiliation(s)
- F Palombo
- Laboratoire de Physico-Chimie Moléculaire, CNRS (UMR 5803), Université Bordeaux I, 351 Cours de Ia Liberation, 33405 Talence Cedex, France
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Besnard M, Tassaing T, Danten Y, Andanson JM, Soetens JC, Cansell F, Loppinet-Serani A, Reveron H, Aymonier C. Bringing together fundamental and applied science: The supercritical fluids route. J Mol Liq 2006. [DOI: 10.1016/j.molliq.2005.05.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Dellis D, Chalaris M, Samios J. Pressure and Temperature Dependence of the Hydrogen Bonding in Supercritical Ethanol: A Computer Simulation Study. J Phys Chem B 2005; 109:18575-90. [PMID: 16853392 DOI: 10.1021/jp051688a] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
As a step toward deeper insight on the "hydrogen bonding" in supercritical ethanol (scEtOH), we carried out NVT molecular dynamics simulations of the fluid over a wide range of temperatures and pressures. The fluid was studied at SC conditions for which thermodynamic and spectroscopic (NMR, infrared, Raman, dielectric) data are available. The various site-site pair distribution functions (pdf's) were calculated, and their temperature and pressure dependence was obtained. It was found that over the thermodynamic conditions investigated here, scEtOH remains highly structured. Moreover, the characteristic behavior of the first peaks in H-H, O-O, and H-O pdf's reveals that hydrogen bonds still exist in scEtOH. The analysis focuses also on the reorientational dynamics of the bond unit vectors O-H, C-O, and of the permanent dipole moment of the molecules as well as the total dipole moment of the sample. The corresponding Legendre time correlation functions were discussed in connection to the "hydrogen bonding" in the fluid and in the context of experimental results. Specifically, the behavior of the O-H dynamics exhibits the well-known associative nature of the molecules in the system. A further analysis of the hydrogen bonds was carried out, and the degree of aggregation (average number of H-bonds per molecule) was obtained and compared with results from NMR chemical shift studies. Also the estimated monomer and free O-H groups in the fluid were compared with results from IR and Raman vibrational spectroscopy. The percentage analysis fi of the liquid and scEtOH molecules, with i = 0, 1, 2, 3, ... hydrogen bonds per molecule, has been obtained. The results show the existence of small, linear-chain oligomers formed mainly by two molecules, whereas the number of the three body oligomers, and specifically that of four body oligomers in the sample, is relatively small.
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Affiliation(s)
- Dimitris Dellis
- Laboratory of Physical Chemistry, Department of Chemistry, University of Athens, Panepistimiopolis, Athens 157-71, Greece
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