Efficient synthesis of diarylidene octahydroacridines by one-pot multi-component tandem reactions

A one-pot multi-component reaction is developed for the efficient synthesis of 4,5-dibenzylidene octahydroacridines in high yields. The reaction is performed by the tandem reaction of three molar equivalent aromatic aldehydes with two molar equivalent 4-alkylcyclohexanone in the system of NH₄OAc/HOAc under microwave irradiation.      

Calorimetric study of melts in the System KF - K<Subscript>2</Subscript>NbF<Subscript>7</Subscript>

The relative enthalpies of melts in the system KF - K₂NbF₇ were measured by drop-calorimetry at the temperatures 1058, 1140 and 1208 K as a function of composition. Heat capacities of melted mixtures and enthalpies of mixing were determined using the experimental data. The molar heat capacity of melts diverges slightly from additivity. The molar enthalpy of mixing of melts shows small negative deviation from ideality which decreases with decreasing temperature. The thermal effect at mixing was assigned predominantly to association reactions producing more complex fluoroniobate anions.      

The binary system PbO - BiVO4

Phase equilibria established in the PbO - BiVO₄ system over the whole component concentration range up to 1000°C have been investigated. A phase diagram has been constructed using DTA and XRD.      

Ionic liquid promoted synthesis of bis(indolyl) methanes

1-benzyl-3-methyl imidazolium hydrogen sulphate [bnmim][HSO₄] was found to be an effective catalyst for the condensation reaction of indoles and derivatives with benzaldehydes in microwave irradiation with lower reaction time and higher yields to give bis(indolyl) methanes.      

Spectral study of coumarin-3-carboxylic acid interaction with human and bovine serum albumins

Fluorescence spectroscopy and circular dichroism (CD) spectroscopy were used to investigate the interaction of coumarin-3-carboxylic acid with human serum albumin (HSA) and bovine serum albumin (BSA) under physiological conditions in a buffer solution of pH 7.4.      

Methylcellulose/SiO<Subscript>2</Subscript> hybrids: sol-gel preparation and characterization by XRD,FTIR and AFM

Methylcellulose (MC) / SiO₂ organic / inorganic hybrid materials have been prepared from MC and methyltriethoxysilane or ethyltrimethoxysilane, and characterized by XRD, FTIR and AFM. XRD showed peak shifts. FTIR shows intermolecular hydrogen bonding between MC and SiO₂. AFM depicts surface roughness which depends on the silica precursor and MC content.      

Calorimetric study of melts in the system KF - K2TaF7

Enthalpy increment measurements on melts in the system KF-K₂TaF₇ were carried out by drop calorimetry at temperatures between 298 K and 1063, 1103 and 1143 K for selected compositions. Heat capacities of the melted mixtures and enthalpies of mixing have been determined. Careful calorimetric experiments showed small but distinct non-ideality of the melt. The molar heat capacity of melt exhibits small positive divergence from additivity. The molar enthalpy of mixing shows negative deviation from ideality which decreases with increasing temperature. The thermal effect at mixing was assigned predominantly to association reactions producing more complex fluorotantalate anions. The formation of complex anions with lower coordination number of Ta may not be excluded.      

Ceramic materials made of CdTe and Cd-Zn-Te nanocrystalline powders

In the present study newly produced semiconductor ceramic nanopowder materials made of CdTe and Cd_1−xZn_xTe (CZT) are considered. Common features and differences in microstructures, phase transformations, grain growth and properties of the ceramic materials of the binary and ternary compositions are studied.      

Equilibrium and kinetic study of the proton transfer reactions between nitroalkanes and strong organic bases — phosphazenes in tetrahydrofuran solvent

Proton transfer reactions rates between carbon acids 1-nitro-1-(4-nitrophenyl)ethane (NPNE), 2-methyl-1-nitro-1-(4-nitrophenyl)propane (MNPNP)) and phosphazenes (BEMP, BTPP, P₁-t-Oct) in tetrahydrofuran have been measured, and the activation parameters were determined. The results are compared with those previously obtained for P₁-t-Bu phosphazene, guanidines and amidines.      

A hydroxyaminophosphane derived from 2-imidazolidone and its unusual structure in solution

A novel hydroxyamino phosphane was synthesised through the reaction of 2-imidazolidinone with ClPPh2 and subsequently reaction of the resulting bisphosphino derivative with the Grignard reagent BrMgC₅H₁₁. The interaction of the pentyl substituent with one of the two phosphino groups and the structure in solution is shown by multinuclear NMR-spectroscopy..      

Thermal synthesis and characterization of Al χ La1-χ P3O9

New binary lanthanum-aluminum triphosphates were synthesized by thermal-condensation method from H₃PO₄, La₂O₃ and Al(OH)₃. These pigments could be potentially used as special inorganic pigments; their corrosion-inhibition properties were widely studied. Synthesis conditions were determined on the basis of DTA and TG measurements. The products were also characterized by X-ray diffraction analysis. Physical properties — density by pycnometric method, particle size distribution, oil number and critical pigment volume concentration (CPVC), pH and specific conductivity of their aqueous extracts were also determined.      

ZrOCl<Subscript>2</Subscript> · 8H<Subscript>2</Subscript>O: An efficient catalyst for rapid one-pot synthesis of 3-carboxycoumarins under ultrasound irradiation in water

In this report, a rapid, efficient and environmental friendly synthesis of 3-carboxycoumarins under ultrasound irradiation in water media is described. The Knoevenagel condensation of Meldrum’s acid with substituted benzaldehydes in the presence of zirconium oxide chloride (ZrOCl₂·8H₂O) and ultrasonic irradiation in water gave the corresponding 3-carboxycoumarins in good to excellent yields.      

<Emphasis Type="Italic">N</Emphasis>-Alkylation of benzimidazoles with ketonic Mannich bases and the reduction of the resulting 1-(3-oxopropyl)benzimidazoles

Benzimidazole, benzimidazoles diversely substituted at position 2, and 5,6-dimethylbenzimidazole have been alkylated at N ¹ with ketonic Mannich bases derived from acetophenones, acetylnaphthalenes, 2-acetylthiophene and 1-tetralone to afford a series of novel 1-(3-oxopropyl)benzimidazoles. The reduction of these transamination products with NaBH₄ in methanol produced the corresponding 1-(3-hydroxypropyl)benzimidazoles in excellent yields.      

Bi(NO3)3 · 5H2O mediated synthesis of 4,4′-diaminotriarylmethane leuco malachite compounds under solvent-free conditions

In this report, we described the synthesis and characterization of a variety of diaminotriarylmethane derivatives with dimethylamino functional groups. These compounds were synthesized by the tandem regio-selective electrophilic aromatic substitution reaction of N,N-dimethylaniline with aryl aldehydes to form the corresponding diaminotriarylmethane compounds. In our strategy, Bi(NO₃)₃ was used as a catalyst under solvent free conditions to afford the desired products in good to excellent yields.      

Photo-induced chemical reduction of silver bromide to silver nanoparticles

This paper discusses the experimental results of the production of nanocolloidal silver using photoreduction method. Ultrafine crystalline gelatine-stabilised aqueous suspensions of silver bromide were used as a substrate for the synthesis of silver nanoparticles (Ag NPs). The influences of the reductant to substrate molar ratio, the medium’s pH, the type of the source of actinic radiation and the time of exposure to the efficient production of the Ag NPs were studied. A typical reaction was suggested, which involves the photo-induced reduction of silver bromide nanocrystals in the presence of ascorbic acid under specified physicochemical conditions. The properties of resultant silver particles were examined using UV-Vis spectroscopy and Dynamic Light Scattering (DLS). In addition, Transmission Electron Microscopy (TEM) was used for imaging the silver nanoparticle suspensions.      

Ugi products containing boronate esters

The Ugi reaction with formylphenylboronic acid derivatives as the carbonyl component proceeds to give the corresponding boron-containing dipeptide derivatives (Ugi products) in good yields.      

Ionic liquids - deanol derivatives as the Diels-Alder reaction solvents

The Diels-Alder reaction between cyclopentadiene and dienophiles in deanol derivatives containing bis(trifluoromethylsulfonyl)imide anion as media have been studied. The effect of the substituents attached to the cation on the endo:exo selectivity as well as the reaction yield have been evaluated in the absence and presence of Lewis acid catalyst - Y(OTf)₃. Catalytic activity of metal triflates and the recycling of chosen catalytic systems have also been investigated      

Metathesis transformations of unsaturated derivatives of β-diketones

Selected β-diketones bearing unsaturated derivatives have been demonstrated to undergo homo-metathesis and cross-metathesis with selected olefins in the presence of Grubbs catalysts. The reactions led to respective homo- and cross-metathesis products mainly with good yields and selectivities.      

Theoretical determination of the favorable mechanism of the reaction between AlX and HX (X = Br, Cl, and F)

The reaction mechanism between AlX and HX (X = Br, Cl, and F) have been characterized in detail using DFT as well as the ab initio method. The reaction yielding AlX₃ and molecular hydrogen was calculated to be highly exothermic. The present calculations also show that the possible routes to the trihalides species start more favorable with the primary insertion product AlX₂H than with the biadduct AlX(HX)₂ one.