Synthesis and anthelmintic activity of benzopyrano[2,3-c]pyrazol-4(2H)-one derivatives

Molecular Diversity - A series of benzopyrano[2,3-c]pyrazol-4(2H)-one derivatives were synthesized from readily available 1-phenyl- and 1-methyl-1H-pyrazol-3-ols by sequentially employing...     

Comparative Lipophilicity of Morphine Derivatives

JPC – Journal of Planar Chromatography – Modern TLC - Lipophilicity is an important physicochemical characteristic of compounds having potential use in the treatment of humans and...     

Mass transfer examination in electrodialysis using limiting current measurements

The impact of electrodialysis module characteristics on mass transfer was examined using the limiting current method. The current-voltage curves of different electrodialysis modules were measured and limiting currents were determined using the derivative method. The mass transfer coefficients were calculated and the parameters of their dependence on linear flow velocity were estimated. From these the impact of spacer thickness, spacer net type, membrane type, and module geometry were evaluated. It was found that the impact of spacer thickness was almost negligible within the examined range, but a decrease in the mass transfer coefficient could be expected in the case of thicker spacers. By contrast, the spacer net type and type of membrane were found to be very important parameters able to significantly influence the mass transfer. By modifying the module geometry, the mass transfer coefficient could also be altered and, only in this case, the exponential parameter of the dependence was changing. The parameters thus determined may be used to calculate the limiting current in a wide range of operational conditions and may help predict the performance of different electrodialysis module types.     

Study and application of the complex of Sn(II) with glycerol in volumetric analysis

The preparation of standard Sn(II) solutions in glycerol and ethanol media was studied and the most suitable conditions were found for their standardization using dichromate and potassium hexacyanoferrate. Further, the long-term stability of standard Sn(II)-glyc solutions was studied and it was found that the titer of 0.1 N Sn(II)-glyc does not change in an inert atmosphere over a period of 4 months. The solution undergoes partial oxidation in the air (Fig. 1). It was demonstrated polarographically and voltammetrically that the studied redox system is irreversible. The formal redox potential value E_f⁰ = 0.80 V (SCE) 0.1 N Sn(II)-glyc can be back-titrated with 0.1 N K₂Cr₂O₇ in a sat. Na₂CO₃ solution under an inert atmosphere. Generally it is possible in sat. Na₂CO₃ medium to determine with great precision dichromate and potassium hexacyanoferrate, iodine, chloramine-T, chlorine lime, hydrogen peroxide, inorganic peroxides, and silver (Table 2). Equilibrium potentiometry, bipotentiometry, and biamperometry can be used for indication of the equivalence point.     

7-Aminoheptanoic and 8-Aminooctanoic Acid Esters

A procedure was developed for preparing esters of secondary alcohols with 7-aminoheptanoic and 8-aminooctanoic acids.