DEPENDENCE ACTIVATION ENERGY OF THE ELECTROREDUCTION OF PALLADIUM(II) BIS-HYDROXYETHYLIMINODIACETATE COMPLEXES ON THE OVERPOTENTIAL

The kinetic (exchange currents, apparent elect-ron transfer coefficients) and energetic (activation energies of diffusion and electron-transfer reaction) parameters of electroreduction of palladium (II) bis-hydroxyethyliminodiacetate complexes from an ele-ctrolyte containing an excess of free ligand have been determined. A method is proposed for calculating the actual activation energy of the electrode process that is controlled by mixed kinetics, based on the dif-fusion activation energy, transition reaction and the ratio of surface and volume concentrations of potenti-al-determining ions in the solution under study or the ratio of the limiting diffusion current jd and dischar-ge current jk of palladium (II) hydroxyethyliminodi- acetate complexes. The actual activation energy Af of the electrode process, which is controlled by mixed kinetics, is calculated based on the diffusion activati-on energy, transition reaction and the ratio of the li-miting diffusion current jd and discharge current jk of palladium (II) bis-hydroxyethyliminodiacetate com-plexes. The contribution of the activation energy of the transition stage (slow discharge) and the diffusion activation energy of bis -hydroxyethyliminodiacetate palladium (II) complexes to the actual activation ener-gy of the electrode process limited by mixed kine-tics is determined. The dependence of actual activation energy on electrode process overpotential has been stu-died. The actual activation energy Af of the electro-de process varies from the value of the activation ener-gy of the transition reaction At (63.4 kJ×mol–1) to the value of the diffusion activation energy Ad (22.5 kJ ×mol–1). The activation energy calculated according to Tyomkin can be considered as the actual activation energy Af of the discharge stage at a given polarizati-on DE only with a purely kinetic control of the pro-cess rate. The activation energy experimentally deter-mined by the temperature-kinetic method according to the Arrhenius equation and calculated by the pro-posed method is the actual activation energy Af of the electrode process, controlled by mixed kinetics. There is a coincidence of the experimentally determi-ned by the Gorbachev method and the actual Af acti-vation energy of electrode process controlled by mi-xed kinetics calculated by the proposed method. A good agreement between the calculated and experi-mentally determined values of the actual activation energy of the electrode process is observed.

Synthesis of Aluminium Hydroxide and Alumina by Hydrothermal and Solvothermal Methods

The paper describes some work done on the SEM and XRD characteristic studies of aluminium hydroxide and alumina synthesized by the solvothermal and hydrothermal methods. Hydrothermal process produced boehmite phase aluminium hydroxide while the solvothermal process produced gibbsite phase aluminium hydroxide. Transition reaction study by in-situ XRD shows that the gibbsite is transformed into boehmite before it is converted into alumina. This transformation stage involves a dissolution-recrystallization process. The SEM results show the changes in morphology of the crystals as a result of both these processes.

Spectrophotometric study of time stability and acid-base characteristics of chelerythrine and dihydrochelerythrine

Time stability, acid-base and UV-VIS spectral properties of dihydrochelerythrine (DHCHE) were studied spectrophotometrically in water:methanol and water:ethanol media. DHCHE is stable in strongly acid milieu (pH HCl, HNO3, H2SO4, H3PO4 and their mixtures. Remarkable shifts of formation parts of absorbance-pH (A-pH) curves to the alkaline medium were observed depending on the type and concentration of inert electrolyte (most remarkable for HNO3 and HCl). The corresponding equilibrium constants pKR+ of the transition reaction between charged iminium Q+ and uncharged QOH (pseudo-base, 6-hydroxy-dihydro derivative) forms of chelerythine were calculated using a numerical interpretation of A-pH curves by a SQUAD-G computer program which ranged from 8.51–9.31. The highest changes of ΔpK R+ (0.75 and 0.53) were observed for H3PO4 and H2SO4, respectively. The priority effect of ionic species and ionic strength was confirmed in the presence of additions of NaCl and KCl. The strength of interaction of CHE with biomacromolecular compounds (i.e., peptides, proteins, nucleic acids etc.) may be affected because of the observed influence of both cation and anion of the inert electrolyte on acid-base behavior.

Acid-base behaviour of sanguinarine and dihydrosanguinarine

Acid-base and optical properties of sanguinarine and dihydrosanguinarine were studied in the presence of HCl, HNO3, H2SO4, H3PO4, CAPSO and acetic acid (HAc) of different concentrations and their mixtures. The equilibrium constants pKR+ of the transition reaction between an iminium cation Q+ of sanguinarine and its uncharged QOH (pseudo-base, 6-hydroxy-dihydroderivative) form were calculated. A numerical interpretation of the A-pH curves by a SQUAD-G computer program was used. Remarkable shifts of formation parts of absorbance-pH (A-pH) curves to alkaline medium were observed. The shifts depend on the type and concentration of inert electrolyte (the most remarkable for HNO3 and HCl). The corresponding pKR+ values ranged from 7.21 to 8.16 in the same manner (ΔpKR+ = 0.81 and 0.73 for HNO3 and HCl, respectively). The priority effect of ionic species and ionic strength was confirmed in the presence of NaCl and KCl. The strength of interaction of SA with bioactive compounds (i.e. receptors, transport proteins, nucleic acids etc.) may be affected because of the observed influence of both cations and anions of the inert electrolytes.

ANALYSIS ON TWO-NEUTRON CORRELATION THROUGH DALITZ PLOT OF COULOMB BREAKUP REACTION FOR 6He

A new method to describe the three-body decaying states is developed. In this method, the Lippmann–Schwinger equation is combined with the complex scaling method to take the correct boundary condition into account. For the application, the E1 transition strength of 6 He is investigated. The energy and Dalitz distributions of the E1 transition are calculated, and the internal correlation of 6 He is discussed. As results, it is found that the 6 He → 5 He (3/2-)+n → 4 He +n+n sequential decay process is dominant in the E1 transition reaction of 6 He .