The solubilities of phenylboronic acid, its pinacol ester and azaester in organic solvents (chloroform, 3-pentanone, acetone, dipropyl ether and methylcyclohexane) have been determined experimentally by a dynamic method, in which the disappearance of turbidity was determined by measuring of light intensity using a luminance probe. Phenylboronic acid has high solubility in ether and ketones, moderate in chloroform and very low in hydrocarbon. Pinacol ester and azaester show better solubility than the parent acid in all tested solvents. For pinacol ester differences between particular solvents are small, while for azaester the differences are significant. For both esters the highest solubility is observed in chloroform and the lowest in the hydrocarbon. The results have been correlated by the Wilson, NRTL and Redlich-Kister equations. For the phenylboronic acid better correlation of the data is obtained by polynomials in comparison with the above equations. It is connected with additional acid-anhydride equilibrium in the system. The influence of polarity of the solvents on the solubility is discussed.
Solubility of six phenylboronic compounds in water was investigated using different methods. The results are consistent with each other, although for particular compounds selected methods should be preferred. The solubility of the investigated compounds is low, with the value of ca. 2 g/100 cm 3 H2O at 20°C for unsubstituted phenylboronic acid. The unsubstituted benzoxaborole is less soluble than phenylboronic acid. Introduction of OiBu, COOH and CF3 groups into the phenyl ring decreases solubility in comparison with unsubstituted phenylboronic acid, especially for the alkoxy substituent.
Solubility of six phenylboronic compounds in water was investigated using different methods. The results are consistent with each other, although for particular compounds selected methods should be preferred. The solubility of the investigated compounds is low, with the value of ca. 2 g/100 cm3 H2O at 20°C for unsubstituted phenylboronic acid. The unsubstituted benzoxaborole is less soluble than phenylboronic acid. Introduction of OiBu, COOH and CF3 groups into the phenyl ring decreases solubility in comparison with unsubstituted phenylboronic acid, especially for the alkoxy substituent.
The
solubility of three isomers of isobutoxyphenylboronic acid
in several organic solvents (chloroform, 3-pentanone, acetone, dipropyl
ether, and methylcyclohexane) has been determined experimentally by
a dynamic method, in which the disappearance of turbidity was determined
by light intensity measurements using a luminance probe. The solubility
of the ortho-isobutoxyphenylboronic acid is significantly
higher than that of other isomers for all of the tested solvents.
It can be explained by the differences in the structures of ortho
compared with meta and para isomers. Introduction of the isobutoxy
group into the phenylboronic acid ring generally increases the solubility
in most solvents: it is higher for all of the investigated compounds
in comparison with phenylboronic acid for all investigated solvents,
except dipropyl ether. Experimental data were correlated by the λh-equation, which gave better results than other models.
Magnetic materials in the form of magnetic rings are widely used in power engineering products. In many cases, they operate in high frequency and in nonlinear conditions, e.g., as damping elements in electrical power substations equipped with Gas-Insulated Switchgear (GIS) where they provide suppression of Very Fast Transient Overvoltages (VFTOs). To model phenomena in GIS with magnetic rings it is required to have realistic time-dependent models of magnetic materials operating in a wide frequency range and nonlinear conditions. Nowadays, this has become even more relevant due to the actual trend in the industry to create digital twins of physical devices. Models composed of high-precise discrete lumped nonlinear elements are in demand in circuit simulators like SPICE. This work introduces a method based on classical algorithms that find equivalent lumped models of magnetic cores based on frequency-dependent measurements of impedance under DC-bias current. The model is specifically designed to achieve numerically stable simulations.
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