Search

In this work, a new application of Cu(II) complex with 3-hydroxy-2-naphtoic acid (Cu-HNA) as a reusable heterogeneous catalyst in the synthesis of tetrahydrobenzo[a]xanthene-11-ones via a one-pot three-component condensation of aryl aldehydes, 2-naphthol, and dimedone in solvent-free condition was reported. At the end of the reaction, with a simple filtration, the catalyst was easily recovered and reused at least five times with no significant loss of its catalytic activity. Appropriate activity and efficient of the catalyst, very good yields, short reaction time, mild and simple work-up, and no use of organic solvents are other benefits of this proposed methodology. [ABSTRACT FROM AUTHOR]

Layered magnesium silicate was modified by water-insoluble chlorin e6 derivatives with two and three ethanolamine fragments on the periphery of the macrocycle by introducing chlorin e6 derivatives into the reaction medium as solutions in hydrochloric acid without the use of organic solvents. The modified layered silicates obtained are characterized by intense fluorescence along with photostability and exhibit photochemical activity in reactions of photosensitized oxidation of model pollutants like xanthene (rhodamine 6G) and azo dyes (methyl orange). [ABSTRACT FROM AUTHOR]

The extraction of trace amounts of U(VI), Th(IV), Am(III), and lanthanides(III) from nitric acid solutions with polyphosphinylbenzenes was studied. The stoichiometry of the extracted complexes was determined, and the influence of the extractant structure, the HNO3 concentration in the aqueous phase, and the nature of organic solvents on the efficiency of metal ions extraction into the organic phase was considered. It was found that compounds with diphenylphosphoryl groups attached directly to the benzene ring in the ortho position in their molecules have the highest extraction ability with respect to actinides and lanthanides. [ABSTRACT FROM AUTHOR]

Isocyanates readily reacts with NaN3 in the presence of ZnCl2 in organic solvents to form the corresponding carbamoyl azides. The formation of carbamoyl azides completed in 5–10 min at room temperature, which prevent the risk of release of hydrogen azide. The obtained carbamoyl azides without isolation can be used for the preparation of 1-substituted tetrazol-5-ones. [ABSTRACT FROM AUTHOR]

Isocyanates readily reacts with NaN3 in the presence of ZnCl2 in organic solvents to form the corresponding carbamoyl azides. The formation of carbamoyl azides completed in 5–10 min at room temperature, which prevent the risk of release of hydrogen azide. The obtained carbamoyl azides without isolation can be used for the preparation of 1-substituted tetrazol-5-ones. [ABSTRACT FROM AUTHOR]

The kinetics of the metal exchange reactions of cadmium(II) 5,15-dinitro-2,3,7,8,12,13,17,18-octaethylporphyrinate with copper(II) and zinc(II) chlorides in DMF and DMSO were investigated by the spectrophotometric method. The kinetic parameters of the metal exchange reaction were determined. A possible stoichiometric reaction mechanism was proposed. The effect of the solvent and solvate salt nature on the rate of the metal exchange reaction was revealed. [ABSTRACT FROM AUTHOR]

The reactions of 1-germatranol hydrate with malonic, succinic, maleic, cork, sebacic acids, and bistrimethylsilyl ester of succinic acid, and also of bis(germatran-1-yl)oxane with succinic acid in acetonitrile, water, methanol, and dimethylsulfoxide were studied. In organic solvents, mono- and dicarboxyl-substituted 1-germatranols are formed, which, like 1-germatranol, are reversibly hydrolyzed with water in an acidic medium. Removing water from reaction mixtures due to evaporation and a topochemical reaction increases the yield of esterified 1-germatranol. [ABSTRACT FROM AUTHOR]

Extraction of rare earths(III) from hydrochloric acid solutions with mixtures of new tridentate carbamoylmethylphosphine oxides Ph2P(O)CH2CON(R)CH2CH2P(O)Ph2 (R = Me, Bu, Oct) and 4-benzoyl-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one in organic solvents has been studied. The observed strong synergistic effect has been attributed to the formation of hydrophobic mixed-ligand rare earth complexes in the organic phase. Stoichiometry of the extractable complexes has been determined, and extraction constants have been calculated. The effect of organic solvent and composition of the aqueous phase on the extraction efficiency has been analyzed. [ABSTRACT FROM AUTHOR]

Exploration (factor, cluster, and decision tree), regression (multiple linear regression), and neural network (regression, classification) models of clustering, approximation and prediction of the stability constants of cation complexes with ionophore antibiotics (nonactin, monactin, dinactin, trinactin, ennatin B, monensin A, and valinomycin) according to the properties of organic solvents (methanol, ethanol, acetonitrile, and nitrobenzene) and cations (Li+, Na+, K+, Rb+, Cs+, Tl+, Ag+, NH4+, Mg2+, Ca2+, Sr2+, Ba2+, and Mn2+) have been developed. It has been shown that neural network performance is better than that of multiple linear regression (the correlation coefficient on the training sample 0.756 compared to 0.697). The neural network classifier and the classification tree has confirmed the clustering of stability of ionophore–cation complexes carried out by the exploratory k-means method by 97.2%. The prognostic capabilities of the constructed multilayer perceptron have been demonstrated. [ABSTRACT FROM AUTHOR]

The reaction of sulfoxides with peroxy acids in various organic media was studied. The reaction mechanism involves the rapid formation of a sulfoxide-–peroxy acid intermediate which decomposes in the second stage to form carboxylic acid and the corresponding sulfone. The second stage is the rate-limiting step. The reaction medium significantly affects the rate of oxidation. The calculated activation parameters of the oxidation process indicate a compensation effect in the investigated reaction. Correlations between the main physicochemical parameters of solvents and the effective rate constants (k) of dimethyl sulfoxide oxidation with peroxy acids were found. Depending on the reaction conditions, the main factors affecting the k values are specific and nonspecific solvation of the reactants and structural factors. [ABSTRACT FROM AUTHOR]

Extraction of rare-earth elements(III) ions from chloride solutions with mixtures of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone and phosphoryl-containing podands in organic solvents has been studied. The observed significant synergistic effect is associated with the formation of hydrophobic mixed-ligand complexes of rare-earth elements(III). The stoichiometry of the extracted complexes has been determined, and the extraction constants have been calculated. The influence of the phosphoryl-containing podand structure, the organic solvent nature, and the aqueous phase composition on the efficiency of the extraction of rare-earth element(III) ions into the organic phase has been considered. [ABSTRACT FROM AUTHOR]

The association of N-[3-(dimethylamino)propyl](meth)acrylamides in tetrachloromethane, tetrahydrofuran, and N, N-dimethylformamide has been studied by means of IR spectroscopy and quantum-chemical simulation at the B3LYP/6-31+G(d,p)/PCM level. The effect of the hydrogen bonding capacity of the solvent on the degree of participation of N-[3-(dimethylamino)propyl](meth)acrylamides in hydrogen bonding with the formation of the amide-solvent type self-associates and heteroassociates has been elucidated. [ABSTRACT FROM AUTHOR]

Models of multiple linear regression and multilayer artificial neural network have been developed for modeling and predicting the stability constants of sodium and potassium coronates basing on the properties of aqueous-organic solvents (water-methanol, water-propan-2-ol, water-acetonitrile, and water-acetone). The values of the coronates stability constants in water-ethanol solvents have been predicted, and the predictions of the models of multiple linear regression and an artificial neural network models have been compared. The contributions of electrostatic, cohesive, and electron-donating interactions to the increase in the stability of the coronates have been quantitatively assessed basing on the models of multiple linear regression and the principle of free energies linearity. Neural network models based on unsupervised (multilayer perceptrons) and supervised (Kohonen networks) learning algorithms have been developed to classify the stability of sodium and potassium coronates. The neural network classifiers have fully confirmed the classification of the coronated stability via the k-means exploration method. [ABSTRACT FROM AUTHOR]

Four complexes [Ni(DMA)2(H2O)4]Cl2·2H2O, [Ni(DMF)2(H2O)4]Cl2·2H2O, and [Ni(DMA)6][NiCl4], [Ni(DMF)2(H2O)2Cl2] were isolated from ternary water-organic saline systems containing nickel chloride and N, N-dimethylacetamide-water and N, N-dimethylformamide-water binary solvents. The obtained complexes were studied by X-ray structural analysis. The formation of hydrogen bonds between water molecules of the nickel ion solvate sphere, chloride ions, and non-coordinated water molecules located in the cavity of the crystal structure was detected. [ABSTRACT FROM AUTHOR]

4,5-bis[(4-phenoxy)phenoxy]phthalonitrile was obtained by the reaction of 4,5-dichlorophthalonitrile with 4-phenoxyphenol. On its basis 2,3,9,10,16,17,23,24-octakis-[(4-phenoxy)phenoxy]phthalocyanine and its single- and double-decked complexes with erbium were synthesized. Spectral-luminescent properties of resulting phthalocyanines were studied. The tendency of phthalocyanines to association in dichloromethane depends on the structure of their molecules. [ABSTRACT FROM AUTHOR]

The possibility of using spectrophotometric method for the evaluation of ozone solubility in highly concentrated solutions by measuring absorption in the Chappuis band directly in the liquid phase has been demonstrated. The solubilities of ozone in various organic solvents have been determined, and its limiting solubility has been calculated. The molar absorption coefficient in the long-wavelength band of ozone has been found to depend on the solvent nature. [ABSTRACT FROM AUTHOR]

The metal-exchange reaction between Cd(II) octa-(4-bromophenyl)porphyrinate and cobalt chloride in DMF and DMSO was studied by UV-Vis spectroscopy. The kinetic parameters of the metal-exchange reaction were calculated. A possible mechanism of the reaction was established. An effect of the nature of the solvent and metal salt on the reaction rate was revealed. Comparative analysis of the apparent rate constants of the metal exchange reaction between CoCl2 and Cd(II) octa-(4-bromophenyl)porphyrinates and Cd(II) octa-(4-bromophenyl)tetraazaporphyrinate in DMF and DMSO was performed. [ABSTRACT FROM AUTHOR]

О′,О′-Diethyl-[2-(3,4-dicyanophenoxy)phenyl]phosphonate has been synthesized for the first time and introduced in template condensation on lithium and zinc cations to prepare a series of new neutral and acidic phthalocyanines containing four fragments of 2-oxyphenylphosphonic acid. A scheme of modification of the peripheral substituents at the phosphoryl group was developed allowing a targeted synthesis of phthalocyanine ligands and complexes soluble in organic solvents or aqueous media. [ABSTRACT FROM AUTHOR]

On the way to solving the problem of developing an ecofriendly technology for preparing hydrophobic protective coatings to replace the existing technology involving casting from polymer solutions in toxic organic solvents, amphiphilic organosilicon oligomers, promising emulsifiers for preparing aqueous emulsions of organosilicon polymers, were synthesized. The synthesized oligomers were used to obtain stable aqueous emulsions of a film-forming silicone block copolymer. The resulting emulsions can be used to form hydrophobic protective coatings on the surface of construction materials. It was shown that the contact angle of wetting depends on the specific features of the preparation of the emulsion and reaches a maximum of 134°. [ABSTRACT FROM AUTHOR]

New metal-containing polymers, poly(salicylidene azomethines) containing metal atoms (Co, Ni, Cu) in the backbone, were synthesized from aromatic carbazolediamine derivatives. It was found that the polymers with a decyl substituent in the carbazole fragment are soluble in organic solvents (chloroform, methanol, DMSO, DMF) and exhibit film-forming and semiconductor properties. IR and NMR spectroscopy was used to show that the semiconductor properties of the new polymers are associated with the presence in the polymer backbone of transannular polyconjugation zones formed by intramolecular donor-acceptor interactions of the metal and nitrogen valence shells. [ABSTRACT FROM AUTHOR]

Predictive correlation-regression and neural network models for description of the properties of aqueous-organic solvents on the strength of acetic and benzoic acids have been developed. Significant descriptors affecting the dissociation equilibrium of the acids have been found. The features of the solvation (reflected in the electrostatic, cohesion, and electron accepting interactions) on the acids strength have been disclosed. Prediction of the dissociation constants of acetic and benzoic acids has been successfully performed using a three-layer perceptron. Prospects of the neural network modeling for prediction of organic acids strength in aqueous-organic media have been demonstrated. A neural network classifier of acetic and benzoic acids strength based on the aqueous-alcoholic solvents descriptors has been developed and trained. [ABSTRACT FROM AUTHOR]

Decisive rule for classification and prediction of benzoic acid strength from dielectric constant and Kamlet-Taft parameter of the mixed solvents (water-methanol, water-ethanol, and water-2-propanol) has been elaborated basing on the results of multivariate exploratory analysis. The rule has been verified using the independent experimental data on dissociation constant of benzoic acid in water-dioxane and water-dimethylsulfoxide mixtures. Two-parameter linear regression model of the Gibbs energy of benzoic acid dissociation as a function of the properties of aqueous-alcoholic solvents has been built, and the contributions of dielectric and cohesion medium properties to the decrease in the acid strength have been shown. [ABSTRACT FROM AUTHOR]

Phthalocyanines containing gallic acid moieties were synthesized and investigated by the method of electron absorption spectroscopy. It was shown that in organic solvents the prepared phthalocyanines exist predominantly in associated form. [ABSTRACT FROM AUTHOR]

In this article, the first use of silicotungstic acid (HSiWO) as a catalyst for the synthesis of octahydroxanthene-1,8-diones by the reaction of 5,5-dimethylcyclohexane-1,3-dione (dimedone) with various aldehydes under thermal solvent-free conditions is described. The obtained results showed that the catalyst has a high catalytic activity, and the desired products were obtained in high yields. Moreover, the catalyst was found to be reusable, and a considerable catalytic activity still could be achieved after the fifth run. Easy work-up and avoidance of using harmful organic solvents are the other advantages of this simple procedure. [ABSTRACT FROM AUTHOR]

Choline tetrachloroferrate with a magnetic response property is applied in multicomponent one-pot synthesis of 2-amino-4 H-chromenes as effective catalyst. The catalyst is characterized by the UV-Vis and Raman spectroscopies and by the electrospray ionization mass spectrometry. [ABSTRACT FROM AUTHOR]

Solubility of salts in the systems MCl-HO-Solv (M = Co, Ni) and CoBr-HO-Solv (Solv = dimethyl sulfoxide, dimethyl formamide, and dimethyl acetamide) at 25°C was measured experimentally. Dominating species of cobalt and nickel halides existing in various concentration regions were identified by analysis of electron absorption spectra. It was shown that the major factor defining solubility is the interaction of halocomplexes of metal ions with solvent molecules. [ABSTRACT FROM AUTHOR]

Solubility at 25°C has been determined in the MSO-HO-Solv systems (M = Co, Cu, or Cd; Solv = dimethyl sulfoxide, dimethyl formamide, dimethyl acetamide, tetrahydrofuran, or dioxane) via the isothermal saturation method. Analysis of the solubility as function of the permittivity and donor power of solvents along with the information on the cations radius leads to the conclusion that ion-ion association dominates over solvation interactions in the studied systems. [ABSTRACT FROM AUTHOR]

The interaction of a series of acrylic and cinnamic acid amides with bis(pentafluorophenyl)-phosphinic acid proceeds vigorously at room temperature without any catalyst in the presence of the organic solvents providing for a high fraction of the >P-OH tautomer of the phosphinic acid. The reactions have afforded (2-carbamoylethyl)bis(pentafluorophenyl)phosphine oxides in a high yield. [ABSTRACT FROM AUTHOR]

The metal-exchange reaction between Cd(II) octa(4-bromophenyl)tetraazaporphyrinate and cobalt chloride in dimethylformamide and dimethyl sulfoxide was studied by spectrophotometry. Kinetic parameters of the metal-exchange reaction were determined. A possible stoichiometric mechanism of the reaction was proposed. Cobalt(III) octa(4-bromophenyl)tetraazaporphyrinate was synthesized and characterized. [ABSTRACT FROM AUTHOR]

Oxidation of ferrocenylboric acid with hydrogen peroxide in organic solvents and in aqueous solutions in the presence and in the absence of acids and bases has been investigated by electron absorption spectroscopy. Kinetics of FcB(OH) oxidation in neutral, acidic, and basic media has been studied; possible mechanisms of the reactions accounting for the substituent acting as the Lewis-type acidic center have been suggested. [ABSTRACT FROM AUTHOR]

The organic bismuth compounds PhBi(OCCH=CHCH) and PhBi(OCEt) decompose under scattered light in the presence of spin traps (2-methyl-2-nitrosopropane and C-phenyl- N- tert-butylnitrone) in organic solvents (acetonitrile, benzene, toluene) to form adducts of phenyl radicals with the traps. [ABSTRACT FROM AUTHOR]

It was proved by the IR spectroscopy that the first coordination sphere of nickel cations in the NiCl·2DMSO·9HO, NiCl·5DMSO·4HO, and NiCl·4DMSO·2HO compounds contains dimethyl sulfoxide and water ligands. According to X-ray structural analysis, in crystals of the NiCl·4DMSO·2HO compound, noncovalent contacts between sulfur atoms of neighboring dimethyl sulfoxide molecules are realized in the inner sphere of the complex. [ABSTRACT FROM AUTHOR]