http://nopr.niscair.res.in/handle/123456789/793 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/998 Title: Kinetics and mechanism of the oxidation of some ⍺-hydroxy carboxylic acids by [bis(trifluoroacetoxy)iodo]benzene <br/> <br/>Authors: Banerji, Jayshree; Sharma, Pradeep K; Banerji, Kalyan K <br/> <br/>Abstract: The oxidation of ⍺-hydroxy carboxylic acids by [bis(trifluoroacetoxy)iodo]benzene (TFAIB), to the corresponding oxoacids is first order with respect to each, the hydroxy acid, TFAIB and hydrogen ions. The oxidation of ⍺-deuteriomandelic acid (PhCDOHCO₂H) exhibits the presence of a substantial pri-mary isotope effect confirming the cleavage of the ⍺ – C – H bond in the rate-determining step. The rate of oxidation of substi-tuted mandelic acids correlates well with Brown’s ⍺⁺ values with large negative reaction constants. A mechanism involving transfer of a hydride ion from the hydroxy acid to the oxidant has been postulated. <br/> <br/>Page(s): 445-448 Mon, 26 Feb 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/992 Title: Theoretical studies on supramolecular complexes of anthyridone with various diaminopyridine derivatives <br/> <br/>Authors: Chen, X; Teng, Q; Wu, S; Xu, L <br/> <br/>Abstract: At the ground state, the complexes formed by anthyridone (A) and 2,6-diaminopyridine-3,5-dialdehyde (B) derivatives have been studied using the AM1 method to obtain information on the binding energies. The UV, IR and NMR spectra for the complexes have been calculated with the INDO/CIS, AM1 and B3LYP/6-31G methods, respectively. The results demonstrate that the complexes can be formed by the two monomers owing to the negative binding energy. The binding energy increases with the decrease in the intramolecular hydrogen bonds, but decreases with the increase in electron density on monomer B. The bulky group next to the hydrogen bond in monomer A is unfavorable, whereas the electron-donating group without the steric effect is favorable for formation of the hydrogen bonds. The first absorption in the UV spectrum of the complex is red-shifted relative to those of the two monomers. On formation of the hydrogen bonds the stretching vibrations of the N-H bonds are weakened and shift to lower frequencies in the IR spectra. In the NMR spectra, the chemical shifts move downfield. <br/> <br/>Page(s): 391-395 Mon, 26 Feb 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/990 Title: Apparent molar volumes of oxalic acid in wa-ter and in aqueous solutions of fructose at 293.15, 303.15, 313.15 and 323.15K <br/> <br/>Authors: Gupta, Radha Rani; Singh, Mukhtar <br/> <br/>Abstract: Apparent molar volumes (Vφ) of oxalic acid in water and in aqueous solutions of fructose of varing concentrations (0.5-2.6) mol kg⁻¹ have been determined as a function of molality by meas-uring the densities at 293.15, 303.15, 313.15 and 323.15K. From these data, the limiting apparent molar volume (V⁰φ) , which is equal to the partial molar volume of oxalic acid at inifinite dilu-tion (V⁰₂), has been obtained at different temperatures. The partial molar volumes have been used to calculate the partial molar vol-umes of transfer (V⁰φ ) of oxalic acid from water to aqueous fructose solutions. The values of limiting apparent molar expansi-bilities, (φ⁰E ) and that of have also been de-termined from temperature-dependence of at various concen-trations of the fructose solutions. The results have been discussed in terms of various interactions operating in oxalic acid, water and fructose systems. <br/> <br/>Page(s): 455-458 Mon, 26 Feb 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/985 Title: Kinetics, thermodynamics and sorption characteristics of an inorganic ion exchanger, titanium phosphate, towards first row transition metal ions <br/> <br/>Authors: Maheria, Kalpana; Chudasama, Uma <br/> <br/>Abstract: Amorphous titanium phosphate, an inorganic ion exchanger of the class of tetravalent metal acid salt, has been synthesized by sol-gel method, and characterized for elemental analysis (ICP-AES), spectral analysis (FT-IR), thermal analysis (TGA, DTA, DSC) and X-ray diffraction studies. Chemical resistivity of the material has been assessed in various media, i.e., acids, bases and organic solvents. The Na⁺ ion exchange capacity has been deter-mined and effect of heating on the ion exchange capacity has been studied. The sorption/ion exchange behaviour of the exchanger towards Cu(II), Mn(II), Ni(II) and Zn(II) has been studied at dif-ferent temperatures (313 K, 323 K and 333 K). Kinetic and ther-modynamic parameters have been evaluated and adsorption iso-therms have been studied. Based on the above studies the selectiv-ity order is found to be: Mn(II) > Ni(II) > Cu(II) > Zn(II). <br/> <br/>Page(s): 449-454 Mon, 26 Feb 2007 22:58:59 GMT