@article {2475, title = {High Temperature End of the So-Called "Koga Line": Anomalies in Temperature Derivatives of Heat Capacities}, journal = {Journal of Physical Chemistry B}, volume = {113}, number = {17}, year = {2009}, note = {ISI Document Delivery No.: 438BCTimes Cited: 0Cited Reference Count: 24Koga, Yoshikata Westh, Peter Moriya, Yosuke Kawasaki, Koji Atake, Tooru}, month = {Apr}, pages = {5885-5890}, type = {Article}, abstract = {The so-called "Koga line" is a collection of the loci of anomalies in various third derivatives of the Gibbs function, G, in the temperature-mole fraction field for aqueous solutions of nonelectrolytes. This splits the H2O-rich region into two, in each of which the molecular organization and interactions-we call it mixing scheme-is qualitatively different. In this work, we attempt to locate the high temperature end of the Koga line. This is a particularly interesting range of the boundary, since its extrapolation to zero Solute concentration provides information on possible temperature induced changes in the properties of pure water. To this end, we determine semi-isobaric heat capacities of aqueous 2-butoxyethanol by adiabatic calorimetry up to a maximum of 95 degrees C. The corrections due to vaporization were not applied due to the lack of required vapor pressure and thermal expansivity data. Furthermore, we measured directly the isobaric heat capacities per molar volume for aqueous I-propanol as well as 2-butoxyethanol by differential scanning calorimetry up to 120 degrees C at 3 atm. We then took one more temperature derivative of the respective heat capacity data. The resulting third derivative quantities from the former data showed step-type anomalies, while those from the latter negative peak-type anomalies. The loci of these anomalous points seem to point to about 70 degrees C at infinite dilution.}, keywords = {25-DEGREES-C, AQUEOUS 2-BUTOXYETHANOL, density, FLUCTUATION, METHANOL, MIXING SCHEME, PARTIAL MOLAR VOLUMES, pressure, TRANSITION, WATER-RICH REGION}, isbn = {1520-6106}, url = {://000265529900029}, author = {Koga,Yoshikata and Westh, P. and Moriya, Y. and Kawasaki, K. and Atake, T.} } @article {1237, title = {Effects of solvent flow, dopant flow, and lamp current on dopant-assisted atmospheric pressure photoionization (DA-APPI) for LC-MS. Ionization via proton transfer}, journal = {Journal of the American Society for Mass Spectrometry}, volume = {16}, number = {8}, year = {2005}, note = {ISI Document Delivery No.: 952BFTimes Cited: 42Cited Reference Count: 37}, month = {Aug}, pages = {1275-1290}, type = {Article}, abstract = {In this paper, the effects of solvent flow, dopant flow, and lamp power on proton transfer ionization in dopant-assisted (DA) atmospheric pressure photoionization (APPI) are investigated. A broad theoretical framework is presented, describing the primary photoionization process, the formation of protonated-solvent cluster ions, and the balance between analyte ion creation via proton transfer and loss via recombination. The principal experimental test system utilized methanol as the solvent, toluene as the dopant, and acridine as the analyte. Comparisons are made between acridine and a less basic compound, 9-methylanthracene (9-MA). Experimental determinations of the trends in the analyte MH+ signal and the total ion current (TIC) with variations in the subject parameters are provided. Experimental results and theory demonstrate that both the analyte signal and the TIC approach asymptotic limits with increases in dopant flow and/or lamp current (two factors which dictate the rate of photoion generation). The data show that these limits are lowered at higher solvent flow rates. These results are attributed to the recombination loss process, the rate of which increases with the second power of ion concentration. We deduce that the recombination rate constant increases with solvent flow rate, a consequence of the growth of ion-solvent clusters. Cluster growth is also believed to be a factor in the dramatic loss of sensitivity for 9-MA that occurs as the solvent flow is raised, because larger protonated-solvent cluster ions have greater solvation energies and may be unreactive with compounds having low gas-phase basicity and/or low solvation energy.}, keywords = {DETECTOR, GAS-PHASE, ION-SOURCE, LIQUID-CHROMATOGRAPHY, MASS-SPECTROMETRY, METHANOL, PLASMA, SENSITIVITY, SOLVATION, SYSTEM}, isbn = {1044-0305}, url = {://000230975700009}, author = {Robb, D. B. and Blades, M. W.} } @article {901, title = {Mixing schemes in ionic liquid-H2O systems: A thermodynamic study}, journal = {Journal of Physical Chemistry B}, volume = {108}, number = {50}, year = {2004}, note = {ISI Document Delivery No.: 879CXTimes Cited: 78Cited Reference Count: 33}, month = {Dec}, pages = {19451-19457}, type = {Article}, abstract = {We studied the hydration characteristics of room-temperature ionic liquids (IL). We experimentally determined the excess chemical potentials, mu(i)(E), the excess partial molar enthalpies, H-i(E), and the excess partial molar entropies S-i(E) in IL-H2O systems at 25 degreesC. The ionic liquids studied were 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) and the iodide ([bmim]l). From these data, the excess (integral) molar enthalpy and entropy, H-m(E) and S-m(E), and the IL-IL enthalpic interaction, H-IL-IL(E), were calculated. Using these thermodynamic data, we deduced the mixing schemes, or the "solution structures", of IL-H2O systems. At infinite dilution IL dissociates in H2O, but the subsequent hydration is much weaker than for NaCl. As the concentration of IL increases, [bmim]l ions and the counteranions begin to attract each other up to a threshold mole fraction, x(IL) = 0.015 for [bmim]BF4 and 0.013 for [bmim]l. At still higher mole fractions, IL ions start to organize themselves, directly or in an H2O-Mediated manner. Eventually for x(IL) > 0.5-0.6, IL molecules form clusters of their own kind, as in their pure states. We show tha HI-L-IL, a third derivative of G, provided finer details than H-i(E) and S-i(E) second derivatives, which in turn gave more detailed information than H-m(E) and S-m(E), first derivative quantities.}, keywords = {25-DEGREES-C, AQUEOUS SODIUM-CHLORIDE, ENTHALPIES, GLYCEROL, H2O, METHANOL, MIXTURES, MOLECULAR-ORGANIZATION, SOLVENTS, WATER}, isbn = {1520-6106}, url = {://000225695100058}, author = {Katayanagi, H. and Nishikawa, K. and Shimozaki, H. and Miki, K. and Westh, P. and Koga,Yoshikata} } @article {3939, title = {Ion solvation dynamics in binary mixtures}, journal = {Journal of Chemical Physics}, volume = {106}, number = {7}, year = {1997}, note = {ISI Document Delivery No.: WH024Times Cited: 37Cited Reference Count: 21}, month = {Feb}, pages = {2782-2791}, type = {Article}, abstract = {The dynamics of selective ion solvation in binary Stockmayer solvents is investigated using molecular dynamics simulations. The dependence of the usual solvation response function, S(t), on solvent composition and on the relative polarity of the solvent species is examined and discussed. We also introduce particle solvation response functions which describe the compositional relaxation of the first solvation shell. It is shown that the selective solvation process can be well described by a simple phenomenological model based on the ideas of elementary chemical kinetics. This model is useful and helps in the identification of two distinct time scales present in the selective solvation process. These are associated with a rapid electrostriction step during which the total number of particles in the first shell increases to its equilibrium value, and a slower spatial redistribution process during which the composition of the first shell achieves equilibrium. The redistribution phase depends on the rate of mutual ion-solvent diffusion and also on the rate of particle exchange between the first and second shells. A detailed analysis of the exchange process indicates that exchanges occur on virtually a one-to-one basis with the insertion of a stronger dipole into the first shell being mirrored by an almost immediate ejection of a weaker one. (C) 1997 American Institute of Physics.}, keywords = {DIPOLAR LIQUIDS, ELECTRON-TRANSFER, METHANOL, SIMULATIONS}, isbn = {0021-9606}, url = {://A1997WH02400027}, author = {Day, T. J. F. and Patey, G. N.} } @article {3830, title = {Excess partial molar enthalpies of alkane-mono-ols in aqueous solutions}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {74}, number = {5}, year = {1996}, note = {ISI Document Delivery No.: UP791Times Cited: 50Cited Reference Count: 29}, month = {May}, pages = {713-721}, type = {Article}, abstract = {Excess partial molar enthalpies, H-A(E), of methanol, ethanol, and 1- and 2-propanols in aqueous solutions were measured directly, accurately, and in small increments in mole fraction at 25 degrees C. From these data, the solute-solute enthalpic interactions, H-AA(E) = N(partial derivative H-A(E)/partial derivative n(A)), were evaluated for each alcohol. These data indicate that three distinctively different mixing schemes, I, II, and III exist, as was the case for aqueous 2-butoxyethanol previously studied in our laboratory. The transition from mixing scheme I to II appears to take place gradually within a small composition range. As the hydrophobic moiety becomes smaller from 2-butoxyethanol to methanol, the locus of the transition moves to a higher value in mole fraction of the alcohol. At the same time, the range of transition becomes wider and the solute-solute enthalpic interaction weaker.}, keywords = {1-PROPANOL, 2-BUTOXYETHANOL, 2-PROPANOL, 25-DEGREES-C, BUTYL ALCOHOL-SOLUTIONS, CONCENTRATION FLUCTUATIONS, enthalpic interaction, ENTROPIES, ETHANOL, excess partial molar enthalpies in aqueous solutions, FREE-ENERGIES, METHANOL, MIXING SCHEME, TERT-BUTANOL MIXTURES, TRANSITION, transition of, WATER-RICH REGION}, isbn = {0008-4042}, url = {://A1996UP79100011}, author = {Tanaka, S. H. and Yoshihara, H. I. and Ho, A. W. C. and Lau, F. W. and Westh, P. and Koga,Yoshikata} } @article {3642, title = {Reaction of methanol with perfluorotetracyclobuta-1,3,5,7-cyclooctatetraene}, journal = {Journal of Fluorine Chemistry}, volume = {76}, number = {2}, year = {1996}, note = {ISI Document Delivery No.: UA116Times Cited: 4Cited Reference Count: 13}, month = {Feb}, pages = {121-124}, type = {Article}, abstract = {Perfluorotetracyclobuteno-1,3,5,7-cyclooctatetraene (PCOT) is a planar and centrosymmetric molecule which possesses an extraordinary electron affinity due to the planarity of the eight pi-electron system and the cumulative electron-withdrawing effects of the 16 fluorine atoms. An improved method for the synthesis of PCOT and the product resulting from the spontaneous reaction of PCOT with excess alcohol is reported. Crystal structures of the methyl (1) and ethyl (2) derivatives are described.}, keywords = {CRYSTAL, IR spectroscopy, MASS SPECTROMETRY, METHANOL, NMR spectroscopy, perfluorotetracyclobutacyclo-octatetraene, reaction, STRUCTURE}, isbn = {0022-1139}, url = {://A1996UA11600002}, author = {Cullen, W. R. and Rettig, S. J. and Moore, A. E. and Soulen, R. L.} } @article {3585, title = {FOURIER-TRANSFORM SPECTROSCOPY OF (CH3OH)-O-18 - THE INPLANE CH3-ROCKING BAND}, journal = {Journal of Molecular Spectroscopy}, volume = {172}, number = {1}, year = {1995}, note = {ISI Document Delivery No.: RG022Times Cited: 15Cited Reference Count: 25}, month = {Jul}, pages = {153-175}, type = {Article}, abstract = {The infrared Fourier transform spectrum of (CH3OH)-O-18 has been recorded in the region from 1020 to 1620 cm(-1) at high resolution in order to study the low-lying bending modes, including the CH3-rocking, OH-bending, and CH3-deformation fundamental bands. More than 10 000 lines have now been assigned in this region. The present paper focuses on the n = 0 ground torsional subbands of the in-plane CH3-rocking fundamental. This band is principally of parallel a-type character, due to mixing of the predominantly parallel CO-stretching and OH-bending coordinates with the perpendicular rocking coordinate. Some b-type character was also observed, with partial assignments of a number of weak perpendicular subbands. The parallel subbands have been fitted to J(J + 1) power-series expansions to obtain the subband origins, as well as compact representations of the data in terms of phenomenological state-specific expansion coefficients. The n = 0 excited state energies calculated from the subband origins follow a similar oscillatory pattern with K to that of the ground vibrational state but with significantly reduced amplitude. Analysis with our basic torsion-rotation Hamiltonian yields an effective torsional barrier height for the rocking state of 474.5 +/- 2.8 cm(-1), a 27\% increase over the ground state value. The vibrational energy is found to be 1058.46 +/- 0.62 cm(-1). An interesting J-localized level-crossing resonance between the CH3-rocking and CO-stretching modes has also been observed through perturbations in the spectrum. (C) 1995 Academic Press, Inc.}, keywords = {CH3OH, METHANOL, MICROWAVE, MOLECULES, ROTATION, SPECTRUM}, isbn = {0022-2852}, url = {://A1995RG02200013}, author = {Zhao, S. B. and Lees, R. M. and Johns, J. W. C. and Chan, C. P. and Gerry, M. C. L.} }