No abstract

The Jones-Dole B coefficients of the electrolyte Lithium bromide (LiBr), reference salts tetra butyl ammonium tetra phenyl borate (BU 4 NBPh 4 ), tetra butyl ammonium bromide (BU 4 NBr), and potassium chloride (KCl) in dimethylsulfoxide (DMSO), water, and DMSO-water mixtures were obtained at different temperatures range from 25 to 45°C For this, the relative viscosities were measured for Lithium bromide (LiBr) and reference salts in DMSO, water, and DMSO-water mixtures at above-mentioned temperatures. The B coefficients of these electrolytes were behaved as structure makers in DMSO, while in H 2 O and DMSO-H 2 O mixtures, the B-coefficient values were less positive showing the weak structure-making effect. Ionic viscosity B coefficients allow us to assess the behavior of ions in the solvent mixtures. In this study it was observed that all the values of ionic B coefficient of (Li + ) were positive and small showing the weak structure-making effects. It was also observed that Br − ions maintain negative B coefficient values in all DMSO-H 2 O mixtures, except in 60% DMSO mole fraction. From this it can be concluded that Br − ion behaved as a structure breaker in water and in all DMSO-H 2 O mixtures except in 60% DMSO mole fraction mixtures. The low B ± values of alkali metal ions and Br − ions in water are due to the breakdown of the tetrahedral structural of water and the formation of strongly structured solvated ion. It is also observed that the values of the energy of activation of the flow for LiBr are greater in DMSO-water mixtures and in pure water than in DMSO. This may be due the presence of a network of hydrogen bonds which cause the hindrance in the flow of the solution of LiBr in DMSO-water mixtures and in pure water than in DMSO.

The relative viscosities and densities for lithium bromide (LiBr) and sodium bromide (NaBr) were measured in dimethylsulfoxide (DMSO), water, and DMSO + water at temperatures from (25 to 45) °C. The estimated uncertainty of the measurements was ± 0.003 for relative viscosities and ± 0.0004 for densities. The data have been analyzed using the Jones−Dole equation. The Jones−Dole B-coefficients of these electrolytes were derived and the estimated uncertainty was ± 0.002. The values of the B-coefficients indicated that the salts behave as structure makers in DMSO, while in H2O and DMSO + H2O mixtures, the B-coefficient values were less positive showing a weaker structure-making effect.

A new alkaloid, “papilicine”, has been isolated from the leaves of Buxus papilosa to which structure (1) has been assigned on the basis of spectroscopic studies.