Vol 87, No 4 (2017)
- Year: 2017
- Articles: 41
- URL: https://journals.rcsi.science/1070-3632/issue/view/13594
Article
Complex amidoboranes M2[M1(NH2BH3)4] (M1 = Al, Ga; M2 = Li, Na, K, Rb, Cs)
Abstract
Structural, spectral, and thermodynamic characteristics of complex amidoboranes M2[M1(NH2BH3)4] (M1 = Al, Ga; M2 = Li, Na, K, Rb, Cs) were calculated by the B3LYP/def2-SVPD quantum-chemical method. The procedure for the synthesis of these compounds by reactions of alkali metal amidoboranes with aluminum and gallium chlorides was suggested and experimentally tested. Reaction products were characterized by the NMR and IR spectroscopy and X-ray phase analysis.
Molecular structure of hexatomic heteronuclear (AlFe) metal clusters as determined by the DFT quantum-chemical calculation
Abstract
Geometric parameters of molecular structures of hexatomic heteronuclear (AlFe) clusters with various number of aluminum atoms (Al2Fe4 and Al3Fe3) were calculated using the density functional hybrid method in the OPBE/TZVP approximation. It was found that the first of these clusters is able to exist in nine and the second in twenty structural modifications substantially differing from each other in their stability and geometric parameters. The values of bond lengths, planar and dihedral (torsion) angles for some of these modifications are given.
Synthesis of manganese oxide sols by KMnO4 reduction with polyvinyl alcohol in an aqueous medium
Abstract
Manganese oxide sols were synthesized using the chemical condensation method by KMnO4 reduction with polyvinyl alcohol in an aqueous medium. The resulting gels were characterized by the manganese oxide content of 0.07–0.19 wt %, pH 9.5–10.2, and ζ-potential of–(20.3–42.9) mV. Spectrophotometric, turbidimetric, and dynamic light scattering methods were employed to determine how the particle size, ζ-potential, pH, and manganese oxide content in the resulting sols were affected by the KMnO4 concentration and the KMnO4 : polyvinyl alcohol ratio. The most stable sols preserved stability for over180 days and remained stable up to 0.5 M KCl, CaCl2, and AlCl3 concentrations.
Synthesis and structure of phosphates M0.5Ti2(PO4)3
Abstract
Phosphates M0.5Ti2(PO4)3 (M = Ni, Zn) were synthesized by the sol-gel method and characterized by the methods of X-ray diffraction, IR spectroscopy, and electronic microprobe analysis. Structures of Ni0.5Ti2(PO4)3 and Zn0.5Ti2(PO4)3 were studied by Rietveld method using the X-ray powder diffraction data.
The effect of the medium polarity on the mechanism of the reaction of hydroxybenzenes with hydrazyl radical in aprotic solvents
Abstract
Mechanisms of the reaction of di- and trihydroxybenzenes with 2,2′-diphenyl-1-picrylhydrazyl (stable radical) in aprotic media of different polarity have been elucidated by experimental and quantum-chemical methods. Kinetic, stoichiometric, and activation parameters of the reaction have been determined. In benzene (nonpolar solvent), the studied reaction occurs via the hydrogen atom transfer mechanism; in the polar solvent with weak ionizing ability (i.e. DMSO), the reaction predominantly occurs via the faster mechanism of coupled electron and proton transfer.
Interaction of hydrogen peroxide and thiourea or its oxides with terephthalic acid
Abstract
The suitability of thiourea and its oxides for the hydroxylation of terephthalic acid in aqueous solutions was explored. Allsulfur-containing compounds tested were found to favor the formation of hydroxyterephthalic acid. It was shown that thiourea and its di- and trioxides can act as both traps and promoters of hydroxyl radicals in aqueous solutions.
Hydroethoxycarbonylation of α-olefins at low pressure of carbon(II) oxide in the presence of the PdCl2(PPh3)2–PPh3–AlCl3 system
Abstract
High catalytic activity of the PdCl2(PPh3)2–PPh3–AlCl3 system containing AlCl3 as promotor has been demonstrated in the reaction of hydroethoxycarbonylation of hexene-1 and octene-1 at low pressure of carbon(II) oxide (≤25 atm). The reaction yields linear and branched products. The optimal conditions of the process have been elaborated. The target products yield is 84.6–93.8%.
Synthesis and properties of aminomethoxy derivatives of 1-(butylsulfanyl)pentane
Abstract
New aminomethoxy derivatives of 1-(butylsulfanyl)pentane have been synthesized. The structure of the synthesized compounds was studied by elemental analysis, IR and 1Н NMR spectroscopy, and mass spectrometry. Some specimens of the synthesized compounds were tested as antimicrobial additives to lubricant oil, and as aseptic compounds against bacteria and fungi.
Mechanism of the zinc-catalyzed addition of azide ion to unsaturated compounds: Synthesis of 5-substituted 1Н-tetrazoles from nitriles and of 1-substituted 1Н-tetrazole-5-thiols from isothiocyanates
Abstract
The mechanism of the formation of 5-substituted 1H-tetrazoles from organic nitriles and thiocyanates in the presence of NaN3 and ZnCl2 in aliphatic alcohols was studied. The results of this study allowed efficient methods of synthesis of substituted tetrazoles from nitriles, thiocyanates, and isothiocyanates to be proposed.
Synthesis and NMR spectroscopy of 1,3,3,5,5-pentaalkoxy-1-chlorocyclotriphosphazenes
Abstract
A series of pentaalkoxychlorocyclotriphosphazenes was synthesized. The spectral characteristics of the synthesized compounds (31Р, 1H, 13С NMR) were studied. It was shown that the complexity of the NMR spectra of pentaalkoxychlorocyclotriphosphazenes is associated with the magnetic nonequivalence of the phosphorus atoms in the triphosphazene cycle and the hydrogen and carbon atoms in the alkoxy groups on these phosphorus atoms, as well as the cis/trans isomerism of the latter groups.
Reaction of chloromethyl derivatives of ethyl 3-(furyl)-3-(diethoxyphosphoryl)acrylates with sodium azide and potassium thiocyanate
Abstract
Reaction of chloromethyl derivatives of ethyl 3-furyl-3(diethoxyphosphoryl)acrylates with sodium azide in acetonitrile in the presence of catalytic amount of potassium iodide proceeds with substitution of halogen with the azido group. The same chloromethyl derivatives react with potassium thiocyanate under analogous conditions to give a mixture of thiocyanates and isothiocyanates in (0.6–0.8) : 1 ratio save the case of ethyl 3-(3-chloromethylfur-2-yl)- and 3-(4-chloromethylfur-3-yl)acrylates when only thiocyanates are formed. Bromination of diethyl 5-methyl-2-furoyl phosphonate with N-bromosuccinimide afforded 5-bromomethyl-2-furoyl phosphonate. In the reaction with potassium thiocyanate it forms only thiocyanate.
Reactions of diiron(III) tris[(1-hydroxyethylidene)diphosphonate] tetrahydrate and iron(III) tris[(1-hydroxyethylidene)diphosphonate] tetrahydrate with p-aminobenzoic acid. Molecular structure of bis(4-carboxyphenylaminium) (1-hydroxyethylidene)diphosphonate
Abstract
Diiron(III) tris[(1-hydroxyethylidene)diphosphonate] tetrahydrate and iron(III) tris[(1-hydroxyethylidene) diphosphonate] tetrahydrate react with p-aminobenzoic acid in water to form diiron(III) pentakis(4-carboxyphenylaminium) tris(1-hydroxyethylidene)diphosphonate dihydrate and iron(III) hexakis(4-carboxyphenylaminium) tris(1-hydroxyethylidene)diphosphonate dihydrate. The crystal structure of bis(4-carboxyphenylaminium) (1-hydroxyethylidene)diphosphonate obtained by the reaction of (1-hydroxyethylidene)diphosphonic acid with p-aminobenzoic acid in methanol was established.
Possibilities of tetra-, penta-, and hexacoordination in quantum-chemical simulation of mechanism of formation and stereoisomerization of bisligand azomethine complexes of Zn(II), Cd(II), and Hg(II)
Abstract
The competition between tetra-, penta-, and hexacoordination with the MN2O2, MN2O2X, and MN2O2X2 (X = S, Se) coordination nodes, respectively, during the formation of bisligand Zn(II), Cd(II), and Hg(II) complexes with bi- and tridentate heterocyclic azomethines has been studied by means of quantumchemical DFT simulation of the complex formation and further stereoisomerization. It has been found that pentacoordination was favorable for the Cd(II) and Hg(II) complexes, whereas the Zn(II) complexes are tetracoordinate.
Synthesis, structure, and photoluminescence properties of 4-methyl-N-{2-([1-alkyl-2-[2-(p-tolylsulfonylamino)phenyl]benzimidazol-5-yl]iminomethyl)phenyl}benzenesulfonamides and their zinc complexes
Abstract
4-Methyl-N-{2-([1-alkyl-2-[2-(p-tolylsulfonylamino)phenyl]benzimidazol-5-yl]iminomethyl)phenyl}-benzenesulfamides (H2L) and zinc complexes on their basis Zn2L2 have been synthesized. The structure of the ligands and complexes has been studied by IR, UV, 1Н NMR spectroscopy, X-ray absorption spectroscopy, and X-ray diffraction analysis.
Water-soluble cobalt phthalocyanines containing azo chromophores
Abstract
Sulfo derivatives of 4-[(Z)-(R)-diazenyl]phthalonitriles were synthesized by diazotization and azo coupling of 4-aminophthalonitrile and used as precursors for the corresponding cobalt phthalocyanines. The latter were obtained by template synthesis in boiling polychlorinated benzenes. The spectral properties of the products were studied.
Reaction of apple pectin modified by pharmacophores, with copper(II) cations
Abstract
The reaction of apple pectin modified by organic pharmacophores (nicotinic, salicylic, 5-aminosalicylic, and anthranilic acids) with Cu(II) cations was studied by spectral methods. The compositions of the complexes were determined and their stability constants, as well as the thermodynamic parameters (ΔH0, ΔG0, ΔS0) of the complex formation were calculated. The structure of the drug in the polymeric ligand was found to affect certain physicochemical properties of the metal complexes.
Physicochemical properties of aqueous solutions of L-aspartic acid containing chitosan
Abstract
Physicochemical properties of aqueous solutions of L-aspartic acid with and without addition of chitosan have been studied by conductometry, potentiometry, refractometry, tensiometry, and viscosimetry. It has been shown that aspartic acid molecules take a cyclic configuration stabilized by hydrogen bonds in aqueous solution at c > 0.04 g/dL (298 K). The interaction of chitosan with aspartic acid results in the formation of the polymeric salt that dissociates in aqueous solution to give chitosan polycation [~(NH3)+] and aspartate counterions. The addition of chitosan to solutions of L-aspartic acid results in progressive increase in the surface tension, absorbance, and refractive index as well as the change in hydrodynamic properties of the macromolecules. The polymeric salt exhibits polyelectrolyte properties in dilute aqueous solutions. The increase in temperature impairs the thermodynamic quality of the solvent for chitosan leading to the shrinkage of the polymer coils and, hence, to the decrease in the intrinsic viscosity of the system.
Spectrophotometric study of melting of double stranded Poly[A]·Poly[U] in the aqueous solution
Abstract
Experimentally observed changes in the electronic absorption spectrum of sodium salt of synthetic polyadenyl–polyuridyl acid (Poly[A]·Poly[U]) in the aqueous solution (pH = 7.0, I = 0.15 mol/L) with the change in temperature were explained in terms of co-existence of two different forms of the Poly[A]·Poly[U] strands. Chemometrics analysis of full set of melting curves measured at 120 wavelengths in the UV spectral range has been performed using evolving factor analysis (EFA) and KALS designed for the calculation of equilibrium constants from spectrometry data without a priori set model of the system. Using the Van’t Hoff equation, we have determined thermodynamic constants of the biopolymer transition from the double stranded helix into the random coil conformation (helix–coil transition), they can be further used to quantify the possibility of these structures to be involved in biochemical processes. Molecular model of partially denatured Poly[A]′·Poly[U]′ complex has been biult by means of molecular mechanics.
Specificities of using differential characteristics of organic compounds for their group identification
Abstract
The possibility of group identification of organic compounds, specifically their assignment to the corresponding homologous series) on the basis of differential quantities, such as differences in their physicochemical characteristics or analytical parameters, is considered. The first example of using difference in the refractive indices at different wavelengths for the determination of the overall concentration of aromatic hydrocarbons in gasoline fractions is described. Various methods for the assignment of unknown compounds to homologous series are analyzed, in particular those based on the limiting values of refractive indices and relative densities, differences in gas chromatographic retention indices on stationary phases of different polarities, combinations of gas chromatographic retention indices with partition coefficients for heterogeneous organic solvent systems, and two versions of combinations of mass spectrometric and GC parameters, namely molecular retention indices and homologous increments of retention indices. The latter version (as the most important) is illustrated in detail by a particular example.
Simulation and synthesis of graphene oxide from expanded graphite
Abstract
Expanded graphite oxide and multilayered graphene oxide have been synthesized. The processes of thermal expansion of intercalated graphite and oxidation of graphene have been simulated. Thermal expansion of intercalated graphite and its oxidation into graphite oxide have been studied by a set of physico-chemical methods. Quantum-chemical simulation has revealed that the edge atoms of the graphene layers appearing during thermal expansion are the most active in the reactions of graphene oxidation.
One-pot synthesis of 9-arylxanthenediones and 9-pyrazoloxanthenediones using [DBU]OAc
Abstract
The synthesis of 9-aryl-1H-xanthene-1,8(2H)-dione derivatives starting from benzaldehydes or synthesized pyrazolcarbaldehydes and dimedone in the presence of 2,3,4,5,7,8,9,10-octahydropyrido[1,2-a]-[1,3]diazepin-1-ium acetate in high yields is reported. The synthesis provides several advantages, including short reaction time, simple work-up, and environmental friendliness.
NO2-Fe(III)PcCl@C -catalyzed one-pot synthesis of tetrahydropyridine derivatives
Abstract
A highly efficient, one-pot synthesis of functionalized tetrahydropyridines by multicomponent condensation of ethyl acetoacetate, two equivalents of aromatic aldehyde, and aromatic amine in the presence of a catalytic amount of NO2-Fe(III)PcCl@C is reported. In this way, a series of pharmacologically interesting substituted pyridine derivatives were obtained in moderate to good yields.
Synthesis and antibacterial activity of novel pyrano[2,3-d]pyrimidine-4-one–3-phenylisoxazole hybrids
Abstract
A series of ethyl 2,7-dimethyl-4-oxo-5-phenyl-3-[(3-phenylisoxazol-5-yl)methyl]-3,5-dihydro-4H-pyrano[2,3-d]pyrimidine-6-carboxylates was synthesized and screened for antibacterial activity against Gram positive and Gram negative bacterial species. All new compounds were characterized by 1H, 13C NMR, IR, and mass spectra. The results of the antibacterial study indicated that all compounds exhibited good to excellent antibacterial activity.
An efficient reduction of nitro and bromine naphthalene derivatives
Abstract
Reduction of 1,5-dimethoxy-4-nitronaphthalene by hydrazine hydrate was optimized in the course of current study. Influence of metals, temperature and solvents upon the process was tested. Yield of the reaction was the highest in the presence of Zn powder in DMF. Moderate heating made the process slightly more efficient than that at room temperature, whereas high temperature led to a decreased yield. The current approach made it possible to exclude high pressure and diminish experimental costs.
4-Bis(triphenylphosphonium)-2-butene peroxodisulfate as an efficient oxidizing agent for one-pot synthesis of ethyl pyrimidin-2(1H)-one-5-carboxylates
Abstract
An efficient one-pot synthesis of pyrimidin-2(1H)-ones via three-component condensation of aldehyde, ethyl acetoacetate and urea using 1,4-bis(triphenylphosphonium)-2-butene peroxodisulfate [BTPBPDS] as an oxidant is described.
Synthesis and characterization of some novel 1,3-diaryl pyrazole bearing 2-oxopyridine-3,5-dicarbonitrile derivatives
Abstract
A series of new 1-{[1-(3-chlorophenyl)-3-(4-methoxyphenyl)-1H-pyrazol-4-yl]methyleneamino}-6-amino-1,2-dihydro-4-(substitutedphenyl)-2-oxopyridine-3,5-di carbonitrile derivatives (4a–4i) were synthesized and characterized via cyclization of the key intermediate (E)-N'-([1-(3-chlorophenyl)-3-(4-methoxyphenyl)-1H-pyrazol-4-yl]methylene}-2-cyanoaceto hydrazide with different 2-arylidenemalononitrile.
Microwave assisted one-pot synthesis of linear and angular furo chromanone scaffolds and their in vitro antimicrobial activity
Abstract
A new series of linear and angular alkyl substituted furochromanone derivatives have been synthesized in one pot microwave irradiation assisted process from ortho-hydroxy acetyl (linear and angular) benzofurans and aliphatic aldehydes in the presence of pyrrolidine. Various alkyl substituted furochromanones were synthesized with high yields. The in vitro antimicrobial activity of the products was tested. The structures of the compound have been elucidated on the basis of elemental analysis, IR, 1H and 13C NMR, and MS spectral data.
Solvent-free microwave assisted synthesis of substituted (E)-phenyl{3-(2-[1-phenyl-3-(thiophen-2-yl)-1H-pyrazol-4-yl]vinyl)benzofuran-2-yl}methanones and their antimicrobial activity
Abstract
New substituted (E)-phenyl{3-(2-[1-phenyl-3-(thiophen-2-yl)-1H-pyrazol-4-yl]vinyl)benzofuran-2-yl}methanones have been synthesized from substituted (E)-1-(2-hydroxyphenyl)-3-[1-phenyl-3-(thiophen-2-yl)-1H-pyrazol-4-yl]prop-2-en-1-ones and 2-bromo-1-phenylethanone under conventional and microwave irradiation conditions. The structures of the compounds were elucidated by IR, 1H and 13C NMR, and mass spectra. The synthesized compounds were screened for their antibacterial and antifungal activities.
Efficient one-pot synthesis of some new pyrimido[5′,4′:5,6]pyrido[2,3-d]pyrimidines catalyzed by magnetically recyclable Fe3O4 nanoparticles
Abstract
The study is devoted to one-pot reaction of 1,3-dimethylbarbituric acid with aromatic aldehydes and ammonium acetate using Fe3O4 nanoparticles as efficient and magnetically recyclable catalysts. Aromatic aldehydes substituted with electron-withdrawing groups or none, reacted successfully with 1,3-dimethylbarbituric acid and ammonium acetate to give new pyrimido[5′,4′:5,6]pyrido[2,3-d]pyrimidine derivatives (can be also named as pyrido[2,3-d:6,5-d′]dipyrimidines) in high yields over relatively short reaction time. The Knoevenagel condensation products were isolated using aromatic aldehydes bearing electron-donating substituents. The catalyst could be efficiently used for four times without substantial reduction in its activity. The new products were characterized on the basis of FT-IR, 1H NMR and 13C NMR spectral data.
Synthesis of some new pyrazolyl-thiazolidinone derivatives starting from 1-(3-chlorophenyl)-3-(4-methoxyphenyl)-1H-pyrazole-4-carboxaldehyde
Abstract
A novel synthetic approach to (E)-1-{[1-(3-chlorophenyl)-3-[(4-methoxyphenyl-1H-pyrazol-4-yl)- methylene]hydrazono}-3-phenylthiazolidin-4-one starting from the key intermediate thiosemicarbazone derivative is presented. The latter compound reacted with some aromatic and heterocyclic aldehydes to give (1-{[1-(3-chlorophenyl)-3-(4-methoxyphenyl)-1H-pyrazol-4-yl]methylene}hydrazono)-5-(substituted benzylidene)-3-phenylthiazolidin-4-one derivatives.
Investigation of coordination ability of Mn(II), Fe(III), Co(II), Ni(II), and Cu(II) with metronidazole, the antiprotozoal drug, in alkaline media: Synthesis and spectroscopic studies
Abstract
Mn(II), Fe(III), Co(II), Ni(II), and Co(II) complexes of metronidazole drug (Met) were synthesized in alkaline media at 60°C and characterized on the basis of elemental, molar conductance, magnetic, spectral (FT-IR, Raman, ESR, and solid reflectance), and thermal analyses. Metronidazole formed stable 1 : 2 molar ratio complexes with Mn(II), Co(II), Ni(II), and Cu(II). Fe(III) complex was obtained with 1 : 3 molar ratio. IR spectra of the solid complexes indicated that the Met dug behaved as a monodentate chelate through the oxygen atom of deprotonated–OH ethanol terminal group. According to the physical spectroscopic parameters (Racah repulsion, crystal field splitting, and nepheloauxetic) and magnetic susceptibility, the complexes had an octahedral geometry, except Cu(II) complex that was square planar. Thermo gravimetric and differential thermo gravimetric analyses (TG–DTG) techniques demonstrated thermal degradation mechanisms of Met free drug and its metal complexes. Activation thermodynamic parameters, ΔE*, ΔH*, ΔS*, and ΔG*, were calculated for thermal decomposition steps of Met and its metal complexes.
Letters to the Editor
On the possibility of homolytic addition of N-bromohexamethyldisilazane to the triple carbon–carbon bond
Abstract
By an example of a reaction of N-bromohexamethyldisilazane with phenylacetylene the possibility of its homolytic addition to the triple carbon-carbon bond with the formation of a mixture of the corresponding E- and Z-isomers in the ratio of 1.2 : 1 was shown.
Imines derived from 4-methyl-4-diphenylphosphorylpentan-2-one and potassium salts of aminocarboxylic acids
Abstract
An effective procedure for the preparation of imines based on 4-methyl-4-diphenylphosphorylpentan-2-one, aminoacetic, aminopropionic, and aminobutyric acids with yields of 90–95% was developed. Reaction of dimephosphone (4-methyl-4-dimethoxyphosphorilpentan-2-one) with potassium salts of these amino acids led to methylation of the carboxy group of the amino acid to form potassium salt of 2-methyl-4-oxopentylphosphonic acid methyl ester.
Synthesis of 6-chlorotetrazolo[1,5-a]quinazoline and 6-chloro-4,5-dihydrotetrazolo[1,5-a]quinazoline
Abstract
Reaction of 5-aminotetrazole triethylammonium salt and 2-fluoro-6-chlorobenzaldehyde resulted in the formation of 6-chlorotetrazolo[1,5-a]quinazoline instead of the expected azomethine. Hydrogenation of the obtained quinazoline afforded 6-chloro-4,5-dihydrotetrazolo[1,5-a]quinazoline.
3,3,6-Trimethyl-2-chlorocyclohexeno[1,2-d]-1,2-oxaphosphol-4-ene-2-oxide as a convenient precursor for the synthesis of dimephosphone analogs
Abstract
A convenient approach to the synthesis of 3,3,6-trimethyl-2-chlorocyclohexeno[1,2-d]-1,2-oxaphosphol-3-ene-2-oxide was developed based on the reaction of the naturally occurring terpenoketone pulegone with methyl dichlorophosphite. Treatment of oxaphospholene-2-oxide with water or ethanol yielded γ-phosphoryl ketones, dimephosphone analogs. The studied hydrolysis and alcoholysis processes differ in stereoselectivity.
Synthesis, structure, and thermal behavior of the complex {Co2[N(CH2CH2OH)3]2Cl2}Cl2
Abstract
Complex {Co2[N(CH2CH2OH)3]2Cl2}Cl2 was obtained for the first time by the reaction of triethanolamine with cobalt chloride. It was characterized by the thermal analysis method. Its crystal structure was determined by the X-ray diffraction analysis.
Sulfur- and oxygen-containing platinum(II) complex
Abstract
Mixed-ligand platinum(II) complex with ethylenedithiodiacetic acid (HSSH) and thioglycolic acid has been synthesized. Ethyleneditiodiacetate is coordinated to platinum through the sulfur atoms in the bidentate mode, whereas thioglycolic acid acts as a unidentate ligand which is coordinated to platinum in the cis position through the sulfur atom. The carboxylic group of thioglycolic acid is not involved in coordination. The complex exhibits cytotoxic properties.