NOPR Collection:

Volumetric properties of binary mixtures of some n-alkoxyethanols with 2-pyrrolidinone and N-methyl-2-pyrrolidinone at 298.15 K

Tue, 01 Oct 2002 00:00:00 GMT

Title: Volumetric properties of binary mixtures of some n-alkoxyethanols with 2-pyrrolidinone and N-methyl-2-pyrrolidinone at 298.15 K Authors: Pal, Amalendu; Kumar, Anil; Kumar, Harsh Abstract: The excess molar volumes (V^E) for binary liquid mixtures of n-alkoxyethanol + 2-pyrrolidi none or N-methyl-2-pyrrolidinone have been measured with a continuous dilution dilatometer at 298.15 K and atmospheric pressure as a function of composition. The alkoxyethanols are 2-methoxyethanol (CH₃OCH₂CH₂OH), 2-ethoxyethanol (C₂H₅OCH₂CH₂OH), and 2-butoxyethanol (C₄H₉OCH₂CH₂OH). In all mixtures the excess molar volumes are negative across the entire composition range. In each case the excess molar volumes decrease as the alkyl chain length of the alkoxyethanol increases while it increases, from 2-pyrrolidinone to N-methyl-2-pyrrolidinone. The results have been used to estimate the excess partial molar volumes _i^E of the components. The change of V^E and _i^E with composition and the number of alkyl chain-length in the alkoxyethanol molecule is discussed with a view to understand some of the molecular interactions present in alkoxyethanol-cyclic amide mixtures. Page(s): 2017-2024

Photooxidation of substituted purines in presence of peroxydisulphate in aqueous solution

Tue, 01 Oct 2002 00:00:00 GMT

Title: Photooxidation of substituted purines in presence of peroxydisulphate in aqueous solution Authors: Swaraga, Midudhula Sudha; Adinarayana, Mundra Abstract: Photooxication of purine bases, viz .. caffeine, theobromine, theophylline, xanthine, hypoxanthine, adenine and guanine in aqueous solution has been carried out in presence of peroxydisulphate (PDS). Peroxydisulphate is activated to SO₄^- at 254 nm. The reactions are followed by measuring the absorbance of purine bases at their respective λ_max. The rates of reactions are calculated under different experimental conditions. The light intensity is measured using peroxydisulphate solution as standard chemical actinometer. Using reaction rate and light intensity at 254 nm, the quantum yields are calculated. The rates of photooxidation of purine bases are found to increase with increase in [PDS] and independent of [purine]. The increase of light intensity has been found to increase the rate of oxidation. The quantum yields are found to depend on [purine] but independent of [PDS] and light intensity. On the basis of experimental results a probable mechanism is suggested in which peroxydisulphate on photolysis gives sulphate radical anion which initiates the reaction by capturing an electro n from C8 position of purine to form purine radical cation. This radical cation deprotonates and undergoes further oxidation to give C(8) hydroxy purine. Page(s): 2096-2100

Synthesis, characterization, thermal decomposition and kinetic parameters of Ni(II) and Cu(II) terephthalate-8Hq complexes

Tue, 01 Oct 2002 00:00:00 GMT

Title: Synthesis, characterization, thermal decomposition and kinetic parameters of Ni(II) and Cu(II) terephthalate-8Hq complexes Authors: Mishra, A P; Tiwari, V K; Singhai, R Abstract: Ni(II)-8Hq terephthalate and Cu(II)-8Hq terephthalate complexes have been synthesised and characterized by elemental analysis, magnetic measurements, IR spectra and UV - Visspectra. The complexes have also been analysed thermogravimetrically for the evaluation of their decomposition kinetic parameters. The thermal decomposition of the compounds occurs mainly in two steps. Kinetic parameters, (E*,Z and ΔS*) have been determined by using three different methods. Page(s): 2092-2095

Ternary complexes of nickel(II) involving 6-aminopenicillanic acid and some potentially bidentate or tridentate ligands

Tue, 01 Oct 2002 00:00:00 GMT

Title: Ternary complexes of nickel(II) involving 6-aminopenicillanic acid and some potentially bidentate or tridentate ligands Authors: Nair, M Sivasankaran; Neelakantan, M A Abstract: Multiple equilibrium studies by pH-metric and visible spectral measurements in the ternary nickel(II) complexes with 6-aminopenicillanic acid (6apa) as ligand A and diamines [1,2- diaminopropane(dp), and 1,3-diaminopropane(tp)] and diaminocarboxylic acids [DL-2,3-diaminopropionic acid(dapa), DL-2,4- diaminobutyric acid(daba) and DL-2,5-diaminovaleric acid(dava)] as ligands B show the presence of NiABH₂, NiABH or NiAB ternary complex species. The ligand, 6apa binds the metal ion via 6 amino and 7 carbonyl oxygen atoms in both the NiABH and NiAB species, and the binding of ligand B in NiAB complexes is exactly similar to their binding in the respective binary species. The results indicate the site of protonation in the NiABH species to be with the terminal amino group of the ligand B. In the NiABH₂ complexes, one proton is attached to the ligand A and other to the ligand B. The computer simulated distribution of the complexes in solution has been evaluated. Page(s): 2088-2091