A TPD‐MS study of the interaction of coumarins and their heterocyclic derivatives with a surface of fumed silica and nanosized oxides CeO2/SiO2, TiO2/SiO2, Al2O3/SiO2

The interactions between coumarins and the surface of fumed SiO₂, CeO₂/SiO₂, TiO₂/SiO₂ and Al₂O₃/SiO₂ were assessed by means of temperature‐programed desorption mass spectrometry. The different stages of the thermolysis of coumarin were identified and an analysis of the underlying reactions was performed. The kinetic parameters of the involved reactions were thus obtained. The decomposition of thiazolyl‐substituted coumarins was found to proceed through a ‘thiazole–thiazine’ ring expansion in the adsorbed state. A linear correlation between the sigma constants (Σσ) of the coumarin substituents and the activation energy of CO₂ formation was obtained. Copyright © 2010 John Wiley & Sons, Ltd.     

Thermodynamic properties of 5(nitrophenyl) furan-2-carbaldehyde isomers

Background

The aim of the current work was to determine thermo dynamical properties of 5(2-nitro phenyl)-furan-2-carbaldehyde, 5(3-nitro phenyl)-furan-2-carbaldehyde and 5(4-nitro phenyl)-furan-2-carbaldehyde.

Results

The temperature dependence of saturated vapor pressure of 5(2-nitro phenyl)-furan-2-carbaldehyde, 5(3-nitro phenyl)-furan-2-carbaldehyde and 5(4-nitro phenyl)-furan-2-carbaldehyde was determined by Knudsen’s effusion method. The results are presented by the Clapeyron–Clausius equation in linear form, and via this form, the standard enthalpies, entropies and Gibbs energies of sublimation and evaporation of compounds were calculated at 298.15 K. The standard molar formation enthalpies of compounds in crystalline state at 298.15 K were determined indirectly by the corresponding standard molar combustion enthalpy, obtained using bomb calorimetry combustion.

Conclusions

Determination of the thermodynamic properties for these compounds may contribute to solving practical problems pertaining optimization processes of their synthesis, purification and application and it will also provide a more thorough insight regarding the theoretical knowledge of their nature.

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Graphical abstract: Generalized structural formula of investigated compounds and their formation enthalpy determination scheme in the gaseous state

     

Structural and magnetic studies of tetranuclear heterometallic M/Cr (M = Co,Mn) complexes self-assembled from zerovalent cobalt or manganese,Reineckes salt and diethanolamine

Four novel heterometallic complexes [Co₂Cr₂(NCS)₄(HDea)₂(Dea)₂]·4dmf (1), [Co₂Cr₂(NCS)₄(HDea)₂(Dea)₂]·4dmso (2), [Mn₂Cr₂(NCS)₄(HDea)₂(Dea)₂(dmf)₂]·2dmf (3) and [Mn₂Cr₂(NCS)₄(HDea)₂(Dea)₂(dmso)₂]·4dmso (4) have been prepared using zerovalent cobalt (1, 2) or manganese (3, 4), Reineckes salt, ammonium thiocyanate and a non-aqueous solution of diethanolamine (H₂Dea) in air. The single X-ray analysis reveals that all compounds have similar centrosymmetric crystal structures based on a tetranuclear {M₂Cr₂(μ₃-O)₂(μ-O)₄} (M = Co, Mn) core. Variable-temperature magnetic susceptibility measurements of 1, 2 and 4 show antiferromagnetic coupling between the magnetic centers, while 3 exhibits a ferromagnetic behavior.     

Synthesis of new 5‐acetyl(arylmethyliden)‐4‐thiazolidones

A new approach to the synthesis of new heterocyclic compounds with triazine and 4‐thiazolidone fragments in one molecule is developed. The synthesis methods comprise [2+3]‐cyclocondensation reactions essential in the preparative synthesis of 4‐thiazolidone derivatives. The reactions of S,N‐nucleophiles with C₂‐cyclization agents for the synthesis of a number of biologically active 2‐triazin‐4‐thiazolidones were investigated. The interaction of thiosemicarbazone of sym‐triazine with derivatives of α‐halogencarboxylic acids and maleic anhydride resulted in correspondent (2‐[2‐(4,6‐dichloro‐1,3,5‐triazin‐2‐yl)hydrazino]‐5‐(3,4,5‐ R‐p‐phenyl‐methyliden)‐1,3‐thiazol‐4‐ones obtained in the one‐step synthesis. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:392–396, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20631     

Lyophilic properties of surfactant-rich phases of polyethoxylated alkylphenols formed at cloud point temperature

The influence of the concentration conditions, solutions acidity, and electrolyte additions on the lyophilic properties of the surfactant-rich phases of polyethoxylated alkylphenols OP-7 and OP-10 formed at cloud point temperature were studied. The lyophilic properties of surfactant-rich phases were determined by estimating of their effective hydration values and solvation free energy of methylene and carboxyl groups at cloud point extraction of aliphatic monocarboxylic acids. It was shown that the surfactant-rich phases formed from the dilute surfactant solutions have more hydrophobic properties than the phases formed from the high concentrated solutions. The possibility of changing the lyophilic properties of surfactant-rich phases by electrolyte additions was shown: complex formation between electrolyte cation and the polyoxyethylene chain of the surfactant increases the hydrophilic properties of the surfactant-rich phases. Calculations of the solvation free energy of methylene and carboxylic fragments of the aliphatic carboxylic acids at micellar extraction showed the uniqueness of the surfactant-rich phases which are able to energetically advantageously extract both hydrophilic and hydrophobic molecules of substrates.     

Intermetallic and metal-rich phases in the system Li-Ba-In-N

Three new intermetallic phases, BaLi_2.1In_1.9, BaLi_1.12In_0.98, and BaLi_1.06In_1.16 and two subnitrides Li₃₅In₄₅Ba₃₉N₉ and LiIn₂Ba₃N_0.83 have been synthesized and their crystal structures have been determined. According to single crystal X-ray diffraction data BaLi_2.1In_1.9 and BaLi_1.12In_0.98 crystallize with hexagonal symmetry (BaLi_2.1In_1.9: P6₃/mmc, a=10.410(2), c=8.364(2) Å, Z=6, V=785.0(2) Å³) and BaLi_1.12In_0.98: P6/mmm, a=17.469(1), c=10.6409(7) Å, Z=30, V=2813.5(8) Å³), while BaLi_1.06In_1.16 has a rhombohedral structure (R-3c, a=18.894(3), c=85.289(17) Å, Z=276, V=26368(8) Å³). BaLi_2.1In_1.9 is isostructural with the known phase BaLi₄. The phase BaLi_1.12In_0.98 is structurally related to Na₈K₂₃Cd₁₂In₄₈, while BaLi_1.06In_1.16 is isostructural with Li_33.3Ba_13.1Ca₃. A sample containing structurally similar BaLi_1.12In_0.98 and BaLi_1.02In_1.16 was also investigated by transmission electron microscopy. Li₃₅In₄₅Ba₃₉N₉ and LiIn₂Ba₃N_0.83 crystallize with tetragonal (I-42m, a=15.299(2), c=30.682(6) Å, Z=2, V=7182(2) Å³) and cubic (Fd-3m, a=14.913(2) Å, Z=8, V=3316.7(7) Å³) symmetry, respectively. While the first-mentioned subnitride belongs to the Li₈₀Ba₃₉N₉ structure type, the second extends the structural family of Ba₆In_4.78N_2.72. The structural features of the new compounds are discussed in comparison to the known phases and the results of total energy calculations.