http://nopr.niscair.res.in/handle/123456789/5794 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/5813 Title: Oxidative cleavage of gabapentin with <i style="">N</i>-bromosuccinimide in acid medium: A kinetic and mechanistic study <br/> <br/>Authors: Bhandarkar, P M Ramdas; Mohana, K N <br/> <br/>Abstract: The kinetics of oxidative degradation of gabapentin with <i style="">N</i>-bromosuccinimide in HClO₄­ medium has been studied at 308 K. The experimental rate law obtained is <i>d</i>[NBS] /<i>dt</i> = [NBS][GBP]^x[H⁺]^y, where x and y are less than unity. The reaction was subjected to changes in concentration of succinimide, the reduction product of NBS, concentration of the added neutral salt, dielectric permittivity and ionic strength of the medium. Solvent isotope effect has been studied using D₂O. The stoichiometry of the reaction has been found to be 1:1, and oxidation products have been identified and characterized by FTIR and ¹H NMR spectral studies. Activation parameters for the overall reactions have been computed from Arrhenius plot. (CH₂CO)₂N⁺HBr has been postulated as the reactive oxidizing species. The oxidation reaction fails to induce polymerization of the added acrylonitrile. The proposed mechanism and the derived rate law are consistent with the observed kinetic data. <br/> <br/>Page(s): 1107-1112 Wed, 29 Jul 2009 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/5812 Title: Syntheses, crystal structures and antibacterial activities of two end-on azido-bridged copper(II) complexes with Schiff bases <br/> <br/>Authors: Hui, Rui-Hua; Zhou, Peng; You, Zhong-Lu <br/> <br/>Abstract: Reactions of 4-bromo-2-[(2-diethylaminoethylimino)methyl] phenol and 1-[(2-ethylaminoethylimino)methyl]-naphthalen-2-ol with copper acetate and ammonium thiocyanate, respectively, afford two centrosymmetric azido-bridged dinuclear copper complexes, [Cu(L1)₂(μ_1,1-N₃)₂] (<b style="">1</b>) and [Cu(L2)₂(μ_1,1-N₃)₂] (<b style="">2</b>). Each Cu atom in the complexes is five-coordinate in a distorted square-pyramidal geometry. The antibacterial activities of the Schiff base and the two complexes have been tested. <b style=""></b> <br/> <br/>Page(s): 1102-1106 Wed, 29 Jul 2009 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/5811 Title: Thermal decomposition of CF₃CFClO radical – A computational study <br/> <br/>Authors: Singh, Hari Ji; Mishra, B K; Gour, N K <br/> <br/>Abstract: A theoretical study on the decomposition pathways of haloalkoxy radical formed from 2-chloro-1,1,1,2-tetrafluoroethane has been reported. Structures of all the reactants, products and transition states involved in the decomposition pathways have been optimized and characterized at MP2(full)/6-31G(d,p) level of theory. Single point energy calculations have been performed using MP4, QCISD(T) and CCSD(T) levels of theory. Critical energy barriers have been calculated for C-C bond scission and Cl elimination, the two prominent decomposition channels considered in the present investigation, and found to be 8.4 and 1.5 kcal mol^-1 respectively. Results show that Cl elimination is the dominant path involving a lower barrier height. Using transition state theory, rate constants for the decomposition pathways, viz., Cl-elimination and C-C bond scission, calculated at 298 K and 1 atm pressure are found to be 4.6×10⁵ and 5.1×10⁴ s^-1, respectively. The existence of transition states on the corresponding potential energy surface has been ascertained by performing Intrinsic Reaction Coordinate calculations. <br/> <br/>Page(s): 1096-1101 Wed, 29 Jul 2009 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/5810 Title: Density functional theory investigation of electrophilic addition reaction of chlorine to 3,4-benzobicyclo[3.2.1]-octadiene <br/> <br/>Authors: Abbasoglu, Rza; Magerramov, Abel <br/> <br/>Abstract: Full geometric optimization of 3,4-benzobicyclo[3.2.1]- octadiene (BBOD) has been carried out by DFT/B3LYP method using the 6-311G(d), 6-311G(d,p) and 6-311+G(d,p) basis sets. The double bond is endo-pyramidalized and its two faces are not equivalent. The BBOD-Cl₂system have been investigated by B3LYP/6-311+G(d,p) method and stable configurations determined. The stable configurations of the BBOD-Cl₂system correspond to BBOD…Cl₂(<i style="">exo</i>) and BBOD…Cl₂(<i style="">endo</i>) molecular complexes which are formed by the exo and endo orientation respectively of Cl₂molecule to the double bond of BBOD in axial position. <i style="">Exo</i>-complex is relatively more stable than the <i style="">endo</i>-complex. <i style="">Exo</i>-chloronium cation was found to be more stable than <i style="">endo</i>-chloronium cation by the DFT method. <i style="">Exo</i>-facial selectivity is expected in the addition reaction to BBOD of chlorine. The non-classical delocalized chlorocarbonium cation(IV) is the most stable ion among the cationic intermediates, and the ionic addition reaction occurs via this cation.<b style=""> </b>The mechanism of the addition reaction is also discussed. <br/> <br/>Page(s): 1091-1095 Wed, 29 Jul 2009 22:58:59 GMT