Saturation molalities and standard molar enthalpies of solution of cytidine(cr), hypoxanthine(cr), thymidine(cr), thymine(cr), uridine(cr), and xanthine(cr) in H2O(l) |
| |
| Institution: | 1. The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland;2. Faculty of Chemistry, University of Wroc?aw, Joliot-Curie 14, 50-383 Wroc?aw, Poland;1. N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation;2. Institute of Problems of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region, Russian Federation;1. Department of Neurosurgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou 350005, China;2. Beijing Key Laboratory of Microanalytical Methods and Instrumentation, Department of Chemistry, Tsinghua University, Beijing 100084, China;3. Department of Bioengineering, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan;1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Sichuan University, Chengdu 610065, China;2. Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China;1. Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Russia;2. Helmholtz Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany;3. Institute Laue Langevin, 71 Avenue des Martyrs, 38042 Grenoble, France;4. Scientific-Practical Materials Research Center of NAS of Belarus, 220072 Minsk, Belarus;5. NRC \"Kurchatov Institute\", Acad. Kurchatov sq. 1, 123182 Moscow, Russia;6. Institute of Crystallography, RWTH Aachen University and JCNS at MLZ, 85747 Garching, Germany |
| |
| Abstract: | Saturation molalities m(sat) in H2O(l) have been measured for the substances cytidine(cr), hypoxanthine(cr), thymidine(cr), thymine(cr), uridine(cr), and xanthine(cr) by using h.p.l.c. The states of hydration were established by performing Karl-Fischer analyses on samples of these substances, which had been allowed to equilibrate with their respective aqueous saturated solutions for several days at T≈298 K and then dried with air at T≈296 K for ≈24 h. The crystalline forms of the substances were identified by comparison of the results of X-ray diffraction measurements with results from the literature. Also, molar enthalpies of solution ΔsolHm(cal) for these substances were measured by using an isoperibol solution calorimeter. A self-association (stacking) model was used to estimate values of the activity coefficients γ and relative apparent molar enthalpies Lφ for these substances. These γ and Lφ values were used to adjust the measured values of m(sat) and ΔsolHm(cal) to the standard state and thus obtain values of the standard molar Gibbs free energy ΔsolG°m and enthalpy changes ΔsolHm° for the dissolution reactions of these substances. The values of the pKs and of the standard molar enthalpies of the ionization reactions were also used to account for speciation of the substances in the calculations of ΔsolGm° and ΔsolHm°. Values of standard molar enthalpies of formation ΔfHm°, standard molar Gibbs free energies of formation ΔfGm°, and standard partial molar entropies S2,m° for the aqueous species of hypoxanthine and xanthine were calculated. A detailed summary and comparison of thermodynamic results from the literature for these substances is presented. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
