http://nopr.niscair.res.in/handle/123456789/4682 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/4692 Title: Partial molar volumes of oxalic acid and its salts in water-rich binary aqueous mixtures of methanol <br/> <br/>Authors: Parmar, M L; Guleria, M K <br/> <br/>Abstract: Partial molar volumes of oxalic acid and its salts, viz., ammonium oxalate, sodium oxalate and potassium oxalate, have been determined in different compositions of water-rich binary aqueous mixtures of methanol (3, 6, 9, 12, and 15 wt. percent of methanol) from solution density measurements at 298.15 K and in 3% (<i>w/w</i>) methanol + water at different temperatures. The data have been analysed by using Masson equation and the obtained parameters have been interpreted in terms of ion-solvent and ion-ion interactions. The partial molar volumes vary with temperature as a power series of temperature. Structure making/breaking capacities of the electrolytes have been inferred from the sign of ([∂²φ⁰_v / ∂T²)_p, i.e. the second derivative of partial molar volume with respect to temperature at constant pressure. Oxalic acid and its salts act as structure breakers in binary aqueous mixtures of methanol. <br/> <br/>Page(s): 806-811 http://nopr.niscair.res.in/handle/123456789/4691 Title: Simultaneous kinetic determination of paracetamol and caffeine using Cu(II)-neocuproine in presence of dodecyl sulfate by H-point standard addition method <br/> <br/>Authors: Tavallali, H; Sheikhaei, M <br/> <br/>Abstract: A simple, feasible and selective kinetic spectrophotometric method for simultaneous determination of paracetamol and caffeine using H-point standard addition method is described. The method is based on difference in the rate of oxidation of the compounds with Cu(II)-neocuproine system and formation of Cu(I)–neocuproine complex, which is monitored at 453 nm and at <i style="">p</i>H 5.0 in the presence of sodium dodecyl sulfate. Experimental conditions such as <i style="">p</i>H, reagents concentrations, ionic strength and temperature have been optimized. Paracetamol and caffeine can be determined in the range 1.5-7.0 and 0.1-3.0 μg ml^-1respectively. The proposed method has been applied for the determination of paracetamol and caffeine in pharmaceutical samples with satisfactory results. <br/> <br/>Page(s): 812-816 http://nopr.niscair.res.in/handle/123456789/4690 Title: Linear solvation energy relationship in the reaction between phenacyl bromide and N-methyl aniline <br/> <br/>Authors: Ramesh, B; Bharathi, D Vijaya; Kavitha, B; Manikyamba, P <br/> <br/>Abstract: The reaction between phenacyl bromide and N-methyl aniline has been studied conductometrically in 17 different protic and aprotic solvents. The reaction is overall second order, being first order with respect to each reactant. Correlation of the second order rate constants with different solvent parameters indicates that the solvation of the reactants and the transition state is due to non-specific polarity of the solvent, hydrogen bond donor ability, solvent nucleophilicity, and electrophilicity of the solvent. By statistical analysis, a linear solvation energy relationship is derived and the percentage contribution of each type of solvation is estimated. <br/> <br/>Page(s): 801-805 http://nopr.niscair.res.in/handle/123456789/4689 Title: Kinetics and mechanism of oxidation of formic and oxalic acids by bis(pyridine) silver permanganate <br/> <br/>Authors: Banerji, Jayshree; Kotai, Laszlo; Banerji, Kalyan K <br/> <br/>Abstract: Kinetics and mechanism of oxidation of formic and oxalic acids by bis(pyridine) silver permanganate in aqueous acetic acid have been studied. The main product of oxidation is carbon dioxide. The reaction is first order each with respect to the permanganate and the reductant. The reaction is catalyzed by hydrogen ions. The oxidation of a‑deuterioformic acid exhibits a substantial primary kinetic isotope effect (<i style="">k</i>_H/<i style="">k</i>_D = 3.69 at 298 K). Suitable mechanisms have been proposed. <br/> <br/>Page(s): 797-800