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Abstract  

The enthalpies of dilution of aqueous solutions for pyridine and methylpyridine isomers have been determined with a 2277-Thermal Activity Monitor at 298.15 K. The results have been treated using the excess function concept and homotactic interaction coefficients have been obtained. The homotactic enthalpic pairwise interaction coefficients are discussed qualitatively in terms of substitution effects of methyl group introduced into the pyridine ring.

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Abstract  

Enthalpies of dilution of aqueous L-serine, pyridine and methylpyridine solutions and their enthalpies of mixing have been determined by a mixing-flow microcalorimeter at 298.15 K. The data have been analyzed in terms of McMillan-Mayer formalism to fit to virial polynomials from which the heterotactic enthalpic pairwise interaction coefficients, h xy, betweenL-serine and pyridine and methylpyridine isomers have been evaluated. The results obtained in the present paper are compared with those reported in the earlier paper about glycine and L-alanine in the same organic solvent aqueous solutions, giving a global insight of the interaction mechanism between the a-amino acids and pyridine and methylpyridine from the point of view of solute-solute interactions and substituent effects of methyl groups introduced into the pyridine ring.

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Pyridine based cerium(IV) phosphate hybrid fibrous ion exchanger

Synthesis, characterization and thermal behaviour

Journal of Thermal Analysis and Calorimetry
Authors: K. Varshney, A. Agrawal, and S. Mojumdar

Abstract  

A new phase of the hybrid fibrous ion exchanger, pyridine based cerium(IV) phosphate (PyCeP), has been synthesized in the form of a sheet like paper by mixing ceric sulphate, phosphoric acid and pyridine in a particular ratio to get the material of the optimum ion exchange characteristics. This material has been characterized with the help of ion exchange capacity, elution and concentration and pH titrations behaviour in addition to some physicochemical studies like X-ray diffraction, IR, TG, DTG and SEM studies. The SEM study confirms the fibrous nature of the material while amorphous nature is revealed by its X-ray spectrum.

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Abstract  

TG, DTA and other analytical methods were applied to investigate the thermal behaviour and structures of the compounds Mg(ClAc)2(Py)22H2O (I), Mg(Cl2Ac)2(Py)H2O (II), Mg(Cl3Ac)2(Py)6H2O (III) and Mg(SCN)2(Py)32H2O (IV), where ClAc=ClCH2COO, Cl2Ac=Cl2CHCOO, Cl3Ac=Cl3CCOO and Py=Pyridine. The compositions of the complexes and the solid-state intermediates and products of thermolysis were identified by means of elemental analysis. Possible schemes of destruction of the complexes are suggested. The final products of the thermal decompositions were MgO (I–III) and MgS (IV). The IR data suggest unidentate coordination of the carboxylate ions to Mg(II) in complexes I–III. Py is coordinated to the Mg(II) through the nitrogen atom of its heterocyclic ring.

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Abstract  

A series of ternary complexes of the types M2L′2L″2;ML′2L″2 (M=Fe, Cu, Zn; L′=2-oxocyclopentane dithiocarboxylate; L″=pyridine, morpholine) and CuL′2H2O was prepared afresh. Except the iron complex, all are dimer and complexation is through the dithio moiety of the ligand L′. Their thermal decomposition was carried out in air at heating rate 10°C min−1 and it revealed that the dehydration of the aqua complex follows the same path as the carboxylates and the pyridine complexes have the tendency to follow one-step decomposition. The copper complexes are less thermally stable. The overall thermal stability of the 2-oxocyclopentanedithiocarboxylato complexes of the three metals with the volatile ligands was found to be in the order: (CuLmorph)2< CuL2H2O<(CuLpy)2<(ZnLmorph)2<(ZnLpy)2<FeL2py2. The thermogravimetric properties of the complexes have been studied and the data were subjected to kinetic analysis. The values of n, E, A and ΔS# have been approximated and compared. Any formation of bridged structure is not indicated in the first step case.

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Journal of Thermal Analysis and Calorimetry
Authors: K. Varshney, V. Jain, A. Agrawal, and S. Mojumdar

Abstract  

Pyridine based zirconium(IV) phosphate (PyZrP) and tin(IV) phosphate (PySnP) have been synthesized as new and novel intercalated ion exchangers. These materials have been characterized using X-ray, IR spectra, TG, DTG and DTA studies in addition to their ion exchange capacity, elution, pH titration, concentration and distribution behaviour. The distribution studies towards several metal ions in different media/concentrations have suggested that PyZrP and PySnP are selective for Hg(II) and Pb(II), respectively. As a consequence some binary separations of metal ions involving Hg(II) and Pb(II) ions have been performed on a column of these materials, demonstrating their analytical and environmental potential.

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Abstract  

Thermal behaviour of tri(O,O'-diisopropyldithiophosphate)cobalt(III), Co(dptp)3 and bis (O,O'-diethyldithiophosphate)nickel(II), Ni(detp)2 and its adducts with pyridine, Ni(detp)2(py)2 or 4-methylpyridine, Ni(detp)(mpy)2 in a dynamic nitrogen atmosphere was investigated by TG-DTG and DSC techniques, which showed a medium endothermic peak for the evolution process of pyridine(or 4-methylpyridine) and a strong exothermic peak for that of O,O'-diethyldithiophosphate. The thermal stability and decomposition patterns for these compounds were compared and interpreted in terms of structural features such as bond character and steric effects. The kinetic parameters and mechanisms of every decomposition stage involved for all these complexes were obtained employing the non-isothermal kinetic analysis method suggested by Malek et al., which showed the kinetics mechanism for pyrolysis of pyridine(or 4-methylpyridine) is an S-B empirical model with lower activation energy, while that of O,O'-dialkyldithiophosphate is a diffusion model. These results are in accord with the fact that two ligands are of different type.

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Introduction The study of the sorption of pyridine derivates by copper forms of synthetic zeolite ZSM5 and natural zeolite of the clinoptilolite type (CT) is a continuation of our previous study of copper forms of zeosorbents

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Journal of Thermal Analysis and Calorimetry
Authors: Agnieszka Jabłońska–Wawrzycka, Małgorzata Zienkiewicz, Maciej Hodorowicz, Patrycja Rogala, and Barbara Barszcz

Introduction Pyridine 2,3-, 2,4-, 3,4-, 2,5-, 2,6-dicarboxylic acids have proved to be interesting and versatile ligands and may exhibit various coordination modes. Pyridine-2,3-dicarboxylic acid (2,3pydcH 2 ), being a

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Pathobiology Janero DR, Hreniuk D, Sharif HM, Prout KC: Hydroperoxide-induced oxidative stress alters pyridine nucleotide metabolism in neonatal heart muscle cells. Am. J. Physiol. 264

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