Examination of viscosities for fluids in the system H2O--NaCl predicted by the commonly-used model of Palliser and McKibbin has identified regions of pressure-temperature-salinity (PTx) space in ...which the model delivers values that are inconsistent with some experimental data and exhibits discontinuities and trends that are unexpected. Here, we describe a revised empirical model to calculate viscosity of H2O--NaCl fluids that shows good correlation with experimental values and shows trends that are consistent with known or expected behavior outside of the region where experimental data are available. The model described here is valid over the temperature range from the H2O solidus (0 degree C) to 1000 degree C, from 0.1 MPa to less than or equal to 500 MPa, and for salinities from 0 to 100 wt % NaCl.
Various thermodynamic properties of H2O that are defined as pressure or temperature derivatives of some other variable, such as isothermal compressibility (β, pressure derivative of density), ...isobaric thermal expansion (α, temperature derivative of density), and specific isobaric heat capacity (cf, temperature derivative of enthalpy), all show large magnitudes near the critical point, reflecting large variations in fluid density and specific enthalpy with small changes in temperature and pressure. As a result, mass (related to fluid density) and energy (related to fluid enthalpy) transport in this PT region are sensitive to changing PT conditions. Addition of NaCl to H2O causes the region of anomalous behavior, here defined as the critical region, to migrate to higher temperatures and pressures. The critical region is defined as that region of PT space in which the dimensionless reduced susceptibility χ~ ≥ 0.5. When NaCl is added to H2O, the critical region migrates to higher temperature and pressure. However, the absolute magnitudes of thermodynamic properties that are defined as temperature and/or pressure derivatives (α, β, and cf) all decrease with increasing salinity. Thus, the mass and energy transporting capacities of hydrothermal fluids in the critical region become less sensitive to changing PT conditions as the salinity increases. For example, quartz solubility can be described as a function of fluid density, and because density becomes less sensitive to changing PT conditions as salinity increases, quartz solubility also becomes less sensitive to changing PT conditions as fluid salinity increases. Similarly, fluxibility describes the ability of a fluid to transport heat by buoyancy‐driven convection, and fluxibility decreases with increasing salinity. Results of this study show that the mass and energy transport capacity of fluids in the Earth's crust are maximized in the critical region and that the sensitivity to changing PT conditions decreases with increasing salinity.
Pure H2O exhibits anomalous behavior in the vicinity of the critical point, reflected by large variations in density and specific enthalpy with small changes in temperature and pressure. Mass and energy transport properties that are temperature or pressure derivatives of density and specific enthalpy thus show large variability near the critical point. Addition of NaCl to H2O causes the critical region in which fluid properties exhibit anomalous behavior to migrate to higher temperatures and pressures.
General characteristics of fluids, which were responsible for formation of zwitters within Severny massif, were constrained on the basis of fluid inclusion research of zwitter quartz. Fluid ...inclusions, which contain Bi oxyhalogenide crystalline phases, are discussed in details. These data provide insights into the speciation of bismuth in the course of its transport by postmagmatic fluids related to Li-F granites.
Abstract
Various thermodynamic properties of H
2
O that are defined as pressure or temperature derivatives of some other variable, such as isothermal compressibility (β, pressure derivative of ...density), isobaric thermal expansion (α, temperature derivative of density), and specific isobaric heat capacity (
c
f
, temperature derivative of enthalpy), all show large magnitudes near the critical point, reflecting large variations in fluid density and specific enthalpy with small changes in temperature and pressure. As a result, mass (related to fluid density) and energy (related to fluid enthalpy) transport in this
PT
region are sensitive to changing
PT
conditions. Addition of NaCl to H
2
O causes the region of anomalous behavior, here defined as the critical region, to migrate to higher temperatures and pressures. The critical region is defined as that region of
PT
space in which the dimensionless reduced susceptibility
≥ 0.5. When NaCl is added to H
2
O, the critical region migrates to higher temperature and pressure. However, the absolute magnitudes of thermodynamic properties that are defined as temperature and/or pressure derivatives (α, β, and
c
f
) all decrease with increasing salinity. Thus, the mass and energy transporting capacities of hydrothermal fluids in the critical region become less sensitive to changing
PT
conditions as the salinity increases. For example, quartz solubility can be described as a function of fluid density, and because density becomes less sensitive to changing
PT
conditions as salinity increases, quartz solubility also becomes less sensitive to changing
PT
conditions as fluid salinity increases. Similarly, fluxibility describes the ability of a fluid to transport heat by buoyancy‐driven convection, and fluxibility decreases with increasing salinity. Results of this study show that the mass and energy transport capacity of fluids in the Earth's crust are maximized in the critical region and that the sensitivity to changing
PT
conditions decreases with increasing salinity.
In the present work, a convenient and straightforward approach to the preparation of borylated amidines based on the
-dodecaborate anion B
H
NCCH
NHR-, R=H, Alk, Ar was developed. This method has two ...stages. A nitrile derivative of the general form B
H
NCCH
was obtained, using a modified technique, in the first stage. On the second stage the resulting molecular system interacted with primary amines to form the target amidine products. This approach is characterised by a simple chemical apparatus, mild conditions and high yields of the final products. The mechanism of the addition of amine to the nitrile derivative of the
-dodecaborate anion was studied, using quantum-chemical methods. The interaction between NH
and B
H
NCCH
ammonia was chosen as an example. It was found that the structure of the transition state determines the stereo-selectivity of the process. A study of the biological properties of borylated amidine sodium salts indicated that the substances had low toxicity and could accumulate in cancer cells in significant amounts.
A comprehensive study focused on the preparation of disubstituted carboxonium derivatives of
-decaborate anion 2,6-B
H
O
CC
H
was carried out. The proposed synthesis of the target product was based ...on the interaction between the anion B
H
and benzoic acid C
H
COOH. It was shown that the formation of this product proceeds stepwise through the formation of a mono-substituted product B
H
OC(OH)C
H
. In addition, an alternative one-step approach for obtaining the target derivative is postulated. The structure of tetrabutylammonium salts of carboxonium derivative ((C
H
)
N)2,6-B
H
O
CC
H
was established with the help of X-ray structure analysis. The reaction pathway for the formation of 2,6-B
H
O
CC
H
was investigated with the help of density functional theory (DFT) calculations. This process has an electrophile induced nucleophilic substitution (EINS) mechanism, and intermediate anionic species play a key role. Such intermediates have a structure in which one boron atom coordinates two hydrogen atoms. The regioselectivity for the process of formation for the 2,6-isomer was also proved by theoretical calculations. Generally, in the experimental part, the simple and available approach for producing disubstituted carboxonium derivative was introduced, and the mechanism of this process was investigated with the help of theoretical calculations. The proposed approach can be applicable for the preparation of a wide range of disubstituted derivatives of
-borate anions.
The process of protonation of 2,6-B
H
O
CCH
was investigated both theoretically and experimentally. The most suitable conditions for protonation of the derivative 2,6-B
H
O
CCH
were found. The ...process of protonation was carried out in the presence of an excess of trifluoromethanesulfonic acid CF
SO
H at room temperature in dichloromethane solution. The structure of the resulting complex 2,6-B
H
O
CCH
*H
was established using NMR data and the results of DFT calculations. An additional proton atom H
was found to be localized on one of the facets that was opposite the boron atom in a substituted position, and which bonded mainly with one apical boron atom. The main descriptors of the B-H
bond were established theoretically using QTAIM and NBO approaches. In addition, the mechanism of 2,6-B
H
O
CCH
protonation was investigated.
The novel members of the 1,2-diboraoxazoles family have been obtained. In the present work, we have carried out the intramolecular ring-closure reaction of borylated iminols of general type B
H
...N=C(OH)R
(R = Me, Et,
Pr,
Pr,
Bu, Ph, 4-Cl-Ph). This process is conducted in mild conditions with 83-87% yields. The solid-state structures of two salts of 1,2-diboraoxazoles were additionally investigated by X-ray crystallography. In addition, the phenomena of bonding interactions in the 1,2-diboraoxazole cycles have been theoretically studied by the Quantum Theory of Atoms in Molecules analysis. Several local and integral topological properties of the electron density involved in these interactions have been computed.
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•Silver (I) complexes with derivatives of closo-borate anions were synthesized.•The interaction of Ag(Ph3P)3NO3 with derivatives of closo-borate anions was studied.•Methods for ...obtaining boron-containing silver (I) complexes have been developed.
In this work, we synthesized silver(I) complexes with monosubstituted derivatives of the decahydro-closo-decaborate and dodecahydro-closo-dodecaborate anions of the composition Ag(PPh3)4B10H9OC5H10 (1), Ag(PPh3)4B10H9O2C4H8 (2), (Ph3P)2Agμ–B12H11ClAg(Ph3P)2 (3), and (Ph3P)2Agμ–B10H9COOMeAg(Ph3P)2 (4). These compounds were obtained by the interaction between the tetrabutylammonium salts of the corresponding anions B10H9OC5H10−, B10H9O2C4H8−, B10H9Cl2−, and B10H9COOCH32− with tris(triphenylphosphine)silver (I) nitrate in the presence of triphenylphosphine. The complexes synthesized were investigated using elemental analysis, IR, 1H and 13C NMR spectroscopies, and X-ray diffraction.
The preparation of novel nitrilium derivatives of closo-dodecaborate anion B12H11NCR−, R = n-C3H7, i-C3H7, 4-C6H4CH3, 1-C10H7 is described. Target compounds were obtained in good yields (up to 73%). ...The synthesis of target borylated nitrilium derivatives was characterised by the simplicity of the chemical apparatus and the absence of the necessity for the purification of desired compounds. The crystal structures of previously obtained B12H11NCCH3− and novel B12H11NCC3H7− were established with the help of X-ray structure analysis. DFT-analysis of several nitrilium derivatives B12H11NCR−, R = CH3, C3H7, 4-CH3C6H4 was carried out. The main peculiarities of the C≡N bond of the exo-polyhedral substituent were revealed in terms of bond lengths, bond orders and atomic charges. The LUMO orbitals of the systems considered were examined for understanding of the electrophilic nature of the nitrilium derivatives of the closo-dodecaborate anion.
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