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991.
992.
A mathematical framework for applying a density-and-temperature-dependent volume translation in a thermodynamically consistent manner was developed. Volumetric equations of state (EOS)s that incorporate this translation procedure can be used to generate derived properties, such as fugacity and enthalpy departure, that are based on isothermal departure or residuals from ideal gas state conditions. This kind of translation serves to improve the original EOS and not simply act as a correlation for molar volumes. A density-and-temperature-modified translation of this type was applied to the Soave–Redlich–Kwong EOS and was shown to possess accuracy for saturation pressure predictions equivalent to the untranslated EOS, as well as greatly improved density predictions compared to what is available when using only constant valued translation. The EOS translated in this manner retains many of the important features of the untranslated EOS, such as explicit calculation of volume roots, while having the representation capabilities of substantially more complicated models, such as the extended virial equation of Benedict, Webb, Rubin, and Starling. 相似文献
993.
Patricia Lara Margarita Paneque Prof. Dr. Manuel L. Poveda Prof. Dr. Laura L. Santos Dr. José E. V. Valpuesta Verónica Salazar Dr. Ernesto Carmona Prof. Dr. Salvador Moncho Gregori Ujaque Dr. Agustí Lledós Prof. Dr. Celia Maya Dr. Kurt Mereiter Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(36):9046-9057
Experimental and theoretical studies on equilibria between iridium hydride alkylidene structures, [(TpMe2)Ir(H){?C(CH2R)ArO }] (TpMe2=hydrotris(3,5‐dimethylpyrazolyl)borate; R=H, Me; Ar=substituted C6H4 group), and their corresponding hydride olefin isomers, [(TpMe2)Ir(H){R(H)C? C(H)OAr}], have been carried out. Compounds of these types are obtained either by reaction of the unsaturated fragment [(TpMe2)Ir(C6H5)2] with o‐C6H4(OH)CH2R, or with the substituted anisoles 2,6‐Me2C6H3OMe, 2,4,6‐Me3C6H2OMe, and 4‐Br‐2,6‐Me2C6H2OMe. The reactions with the substituted anisoles require not only multiple C? H bond activation but also cleavage of the Me? OAr bond and the reversible formation of a C? C bond (as revealed by 13C labeling studies). Equilibria between the two tautomeric structures of these complexes were achieved by prolonged heating at temperatures between 100 and 140 °C, with interconversion of isomeric complexes requiring inversion of the metal configuration, as well as the expected migratory insertion and hydrogen‐elimination reactions. This proposal is supported by a detailed computational exploration of the mechanism at the quantum mechanics (QM) level in the real system. For all compounds investigated, the equilibria favor the alkylidene structure over the olefinic isomer by a factor of between approximately 1 and 25. Calculations demonstrate that the main reason for this preference is the strong Ir–carbene interactions in the carbene isomers, rather than steric destabilization of the olefinic tautomers. 相似文献
994.
Yusuf Erdogdu M. Tahir Güllüoğlu Mustafa Kurt Şenay Yurdakul 《Journal of inclusion phenomena and macrocyclic chemistry》2009,64(3-4):341-355
We report the results of detailed experimental and theoretical studies on the molecular structure and vibrational spectra of metal(II) halide complexes of 1,3-bis(4-pyridyl)propane [M(N2C13H14)X2, where M represents Zn or Hg, and X represents Cl, Br, or I]. The FT–infrared spectra (FT-IR) and FT-Raman spectra of the metal complexes of the 1,3-bis(4-pyridyl)propane molecule in the powder form were recorded between the 400–4000 and 5–3500 cm?1 regions, respectively. The molecular geometry and vibrational frequencies of the metal complexes of 1,3-bis(4-pyridyl)propane in the ground state were calculated using density functional theory (B3LYP functional) with LANL2DZ and SDD as basis sets. The total energy distributions (TED) among the symmetry coordinates of the normal modes were computed for the low-energy structure of the molecules. Complete vibrational assignments based on the calculated TED values are given. 相似文献
995.
Marko P. Sušnik Michael Schnürch Marko D. Mihovilovic Kurt Mereiter Peter Stanetty 《Monatshefte für Chemie / Chemical Monthly》2009,140(4):423-430
Abstract A short and efficient sequence for the synthesis of a series of 4-(2-amino-5-thiazolyl)-pyrimidine-2-amines was developed.
1-Phenyl-2-(6-pyrimidinyl)-ethanones, obtained via Weinreb’s methodology, were used in a Hantzsch thiazole cyclization reaction,
followed by introduction of the aniline moieties via nucleophilic substitution.
Graphical abstract
相似文献
996.
Kurt Kalcher Ivan Svancara Marijo Buzuk Karel Vytras Alain Walcarius 《Monatshefte für Chemie / Chemical Monthly》2009,140(8):861-889
Abstract An overview of the use of electrochemical sensors made from heterogeneous carbon materials (carbon paste electrodes, screen-printed
carbon electrodes) in the field of food analysis is presented. Sensors for inorganic and organic analytes as well as biosensors
are summarized.
Graphical abstract
相似文献
997.
In the biopharmaceutical industry, column chromatography residuals are routinely assessed by the direct measurement of mock eluates. In this study, we evaluated virus and other impurity carryover between protein A cycles and the feasibility of using a total organic carbon (TOC) analyzer to monitor for column impurity leakage as a correlate for actual measured carryover in mock eluates. Commercial process intermediates were used in scaled down studies of two protein A media, ProSep A (Millipore, Bedford, MA, USA) and MabSelect SuRe (GE Healthcare, Uppsala, Sweden). The chromatography system was programmed to run up to 200 normal load/elution cycles with periodic blank cycles to measure protein and phage carryover, and water flush cycles to measure TOC release. Sustained phage carryover was evident in each study. Carryover and TOC release was lowest in the case where cleaning was most stringent (50 mM NaOH/0.5 M Na2SO4 with MabSelect SuRe). The TOC analysis at this time does not appear to be a viable practical means of measuring impurity carryover; direct measurements in mock eluates appears to be more predictive of column performance. 相似文献
998.
Mouhssin Oufir Nadine Schulz Patan Shaik Sha Vallikhan Eva Wilhelm Kornel Burg Jean-Francois Hausman Lucien Hoffmann Cedric Guignard 《Journal of chromatography. A》2009,1216(7):1094-1099
A mass spectrometer was coupled to high-performance ligand-exchange liquid chromatography (HPLEC) for simultaneous analysis of stress associated solutes such as proline, hydroxyproline, methylproline, glycine betaine and trigonelline extracted from leaves of drought stressed oaks and an internal standard namely N-acetylproline. Methanol/chloroform/water extracts were analyzed using an Aminex HPX-87C column and specifically quantified by the positive ion mode of an electrospray ionisation-mass spectrometry (ESI-MS) in single ion monitoring (SIM) mode. The recovery of N-acetyl proline added to oak leaf extracts ranged from 85.2 to 122.1% for an intra-day study. Standard calibration curves showed good linearity in the measured range from 0.3125 to 10 μmol L−1 with the lowest correlation coefficient of 0.99961 for trigonelline. The advantages of this alternative procedure, compared to previously published methods using fluorescence or amperometric detections, are the simultaneous and direct detection of osmoprotectants in a single chromatographic run, a minimal sample preparation, a good specificity and reduced limits of quantification, ranging from 0.1 to 0.6 μmol L−1. Fifty-six days of water deficit exposure resulted in increased foliar free proline levels (2.4-fold, P < 0.001, 155 μmol g−1 FW) and glycine betaine contents (2.5-fold, P < 0.05, 175 μmol g−1 FW) of drought stressed oak compared to control. 相似文献
999.
Volodymyr Babizhetskyy Kurt Hiebl Hansjürgen Mattausch Arndt Simon 《Solid State Sciences》2009,11(2):501-506
The ternary rare-earth metal boride carbides REBC (RE = Ce, Pr, Nd) were prepared by melting mixtures of the elements and subsequent annealing at temperatures between 1270 K and 1570 K. Their crystal structures were refined from single crystal X-ray diffraction data. They crystallize in the LaBC-type structure (space group P212121, Z = 20); CeBC: a = 8.5021(5) Å, b = 8.5217(7) Å, c = 12.3834(7) Å, R1 = 0.033 (wR2 = 0.059) for 2838 reflections with Io > 2σ(Io); PrBC: a = 8.4478(5) Å, b = 8.4719(8) Å, c = 12.325(1) Å, R1 = 0.031 (wR2 = 0.063) for 2564 reflections with Io > 2σ(Io); NdBC: a = 8.370(1) Å, b = 8.392(1) Å, c = 12.253(3) Å, R1 = 0.035 (wR2 = 0.086) for 4275 reflections with Io > 2σ(Io). The structure consists of a three-dimensional framework of rare-earth metal atoms resulting from the stacking of slightly corrugated two-dimensional square nets, leading to voids filled with B5C5 finite chains. The magnetism of the compounds PrBC and NdBC is characterized by the onset of ferromagnetism with Curie temperatures around 10 K and 8 K, respectively. The reduced effective paramagnetic moment μeff ≈ 1.8 μB as well as the weak magnetization at 6 K, 5 T is discussed. 相似文献
1000.
Bardak F Atac A Kurt M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,71(5):1896-1900
In this study the M(IN)(2)Ni(CN)(4) [where M: Co, Ni, and Cd, and IN: isonicotinic acid, abbreviated to M-Ni-IN] tetracyanonickelate and some metal halide complexes with the following stoichiometries: M(IN)(6)X(2) (M: Co; X: Cl and Br, and M: Ni; X: Cl, Br and I) and Hg(IN)X(2) (X: Cl, Br, and I) were synthesized for the first time. Certain chemical formulas were determined using elemental analysis results. The FT-IR and Raman spectra of the metal halide complexes were reported in the 4000-0 cm(-1) region. The FT-IR spectra of tetracyanonickelate complexes were also reported in the 4000-400 cm(-1) region. Vibrational assignments were given for all the observed bands. For a given series of isomorphous complexes, the sum of the difference between the values of the vibrational modes of the free isonicotinic acid and coordinated ligand was found to increase in the order of the second ionization potentials of metals. The frequency shifts were also found to be depending on the halogen. The proposed structure of tetracyanonickelate complexes consists of polymeric layers of /M-Ni(CN)(4)/(infinity) with the isonicotinic acid molecules bound directly to the metal atom. 相似文献