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- Author or Editor: A. Markin x
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Oxidation mechanism of ferrocene with molecular oxygen
Kinetic and thermodynamic aspects
Abstract
The present work is devoted to the thermodynamic and kinetic analysis of literature data on the oxidation of ferrocene in the presence of Bronsted acids, since up to now the mechanism of this reaction is still not explained
Abstract
By adiabatic vacuum and dynamic calorimetry, heat capacity for poly[bis(trifluoroethoxy)phosphazene] has been determined over the 6–620 K range. Physical transformations of the polymer on its heating and cooling have been detected and characterized. Smoothed heat capacity C p 0(T) and standard thermodynamic functions (H 0(T)-H 0(0), S 0(T) and G 0(T)-H 0(0)) of poly[bis(trifluoroethoxy)phosphazene] have been evaluated for the temperature range from T→0 to 560 K. The standard entropy of formation Δf S 0 at T=298.15 K has been also determined. Fractal dimensions D in the heat capacity function of the multifractal variant of Debye’s theory of heat capacity of solids characterizing the heterodynamics of the tested polymer have been determined.
Abstract
Data on synthesis, thermal behavior and thermodynamic properties for the NZP phosphates NaMe2(PO4)3 and Na5Me(PO4)3 (Me=Ti, Zr, Hf) are reported. The compounds were synthesized by sol-gel method and solid-state reactions and characterized by X-ray powder diffraction, IR spectroscopy, electron microprobe and chemical analysis. Their thermal behavior was studied by the DTA measurements. The heat capacities of the phosphates were measured between temperatures 7 and 650 K. The fractal dimensions for the phosphates were calculated. The obtained thermodynamic characteristics of these phosphates and also literature data for the compounds of NZP type structure are summarized.
Abstract
In this study, the temperature dependence of heat capacity C p° = f(T) of crystalline bis-(η6-m-xylene)molybdenum fulleride between T = (8 and 320) K was measured by precision adiabatic vacuum calorimetry. Also the temperature dependence of EPR signal parameters of bis-(η6-m-xylene)molybdenum fulleride in the range from 120 to 300 K was investigated by electron paramagnetic resonance. In the interval 175–220 K the reversible endothermic transformation was detected and its thermodynamic characteristics were estimated. This transformation was caused by the dissociation of the (C60 −)2 dimer in the [(η6-(m-xylene))2Mo]•+[C60]•− fulleride during heating. Based on the experimental data, the standard (p° = 0.1 MPa) thermodynamic functions, namely, the heat capacity, enthalpy, entropy, and Gibbs function were calculated for dimeric fulleride in the interval from T → 0 to 175 K as well as for monomeric [(η6-(m-xylene))2Mo]•+[C60]•− complex between 220 and 320 K. The standard thermodynamic properties of tested fulleride and previously studied C60 fullerite and neutral dimer (C60)2 were compared.
Abstract
In this study for the first time the temperature dependences of the heat capacity C p 0 and enthalpies of physical transitions of carbosilane dendrimers with diundecylsilyl and diundecylsiloxane terminal groups of the fifth generation have been measured using the methods of precision adiabatic vacuum calorimetry and differential scanning calorimetry over the range from 6 to 580 K. In the above temperature ranges the physical transformations have been detected and their thermodynamic characteristics were estimated and analyzed. The standard thermodynamic functions: heat capacity C p 0(T), enthalpy H°(T) − H°(0), entropy S°(T) − S°(0), and free Gibbs energy G°(T) − H°(0) and standard entropies of formation of dendrimers at T = 298.15 K have been calculated over the range from T → 0 K to 580 K. The thermodynamic properties of studied dendrimers have been compared.
Abstract
In the present research for the first time, the heat capacity 
of crystalline tetraphenylantimony acetophenoneoxymate Ph4SbONCPhMe has been measured using the methods of precision adiabatic vacuum calorimetry over the range from 6 to 350 K, the standard thermodynamic functions: heat capacity 
, enthalpy H°(T) − H°(0), entropy S°(T), and Gibbs function G°(T) − H°(0) have been calculated over the range from T → 0 K to 350 K. Low-temperature (20 K ≤ T ≤ 50 K) heat capacity data have shown a chain-layered structure topology of the compound under study. The energy of combustion of the compound has been determined in the isothermal combustion calorimeter with a stationary bomb. The standard thermodynamic functions of formation of crystalline Ph4SbONCPhMe at 298.15 K have been calculated. The differential scanning calorimetry and thermogravimetric analysis studies have shown the compound melts with decomposition and its melting temperature has been estimated. Thermodynamic properties of Ph4SbONCPhMe, Ph5Sb and Ph4SbONCPh2 have been compared.
Abstract
The temperature dependence of the heat capacity of crystalline barium zirconium phosphate C p o = f(T) was measured over the temperature range 6–612 K. The experimental data obtained were used to calculate the standard thermodynamic functions C p o(T), H°(T) − H°(0), S°(T), G°(T) − H°(0) over the temperature range from T → 0 to 610 K and standard entropy of formation at 298.15 K. The data on the low-temperature (6 ≤ T/K ≤ 50) heat capacity were used to determine the fractal dimension of Ba0.5Zr2(PO4)3. Conclusions concerning the topology of the structure of phosphate were drawn. Thermodynamic properties of M0.5Zr2(PO4)3 (M = Ca, Sr, Ba) were compared.
Summary The thermodynamic data for NZP compounds MZr2(PO4)3 (M=Na, K, Rb, Cs, Zr0.25) and Na5D(PO4)3 (D=Ti, Zr) are reported. The heat capacities of the phosphates were measured between T=7 and T=640 K. The standard enthalpies entropies, and Gibbs functions of formation at T=298.15 K were derived. The obtained thermodynamic characteristics of phosphates of the NZP type structure and literature data are summarized. Thermodynamic functions of reactions of solid-state synthesis were calculated and the usability of ceramic technology for obtaining NZP compounds was proved.
