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.
Authors:Y. Li, H. Xingen, L. Ruisen, and X. Guiying
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, hxy, 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.
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.
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.
Authors:R. Verma, L. Verma, M. Ranjan, B. Verma, and S. Mojumdar
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.
Authors:K. Varshney, V. Jain, A. Agrawal, and S. Mojumdar
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.
Authors:Z. Lu, S. Chen, Y. Yu, J. Sun, and S. Xiang
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.
Authors:L’. Fortunová, M. Reháková, S. Nagyová, S. Dolinská, S. C. Mojumdar, and E. Jóna
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
Authors:Agnieszka Jabłońska–Wawrzycka, Małgorzata Zienkiewicz, Maciej Hodorowicz, Patrycja Rogala, and Barbara Barszcz
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