Electrooptical properties of multidomain liquid crystal structures

A physical model of the surfactant-assisted formation of multidomain structures is proposed, and a method of formation of planarly and homeotropically aligned regions on the same substrate is developed. The method makes it possible to form the following multidomain structures: homeotropic-hybrid, homeotropictwisted, hybrid-planar, hybrid-hybrid, and homeotropic-planar. The electropptical properties of multidomain liquid crystal cells are experimentally studied. The director deformation and the phase delay in multidomain structures in an electric field are calculated taking into account the boundary conditions for the director orientation angles on substrates, and results of calculations are compared with experiment. Possible applications of multidomain liquid crystal structures are discussed.     

Radical-chain reactions of CCl4 with hydrocarbons in the presence of silica-immobilized copper-containing catalysts

The activities of two catalytic systems toward the exchange reaction of CCl₄ with hydrocarbons are compared: a copper chloride complex with DMF and polycopperphenylsiloxane (PCPS). PCPS is a very stable catalyst. It completely preserves its catalytic activity after six catalytic cycles. Competitive reactions with the pairs of hydrocarbons suggested a radical-chain mechanism for the title reaction for both catalysts.     

Potentiometric Titration of Some Sulphide Forming Ions by Dithiopyrilmethane

Dithiopyrilmethane (DTPM) is the sulphur containing derivative of pyrazolone. This reagent forms active mono- or biprotonated form giving stable, often colored complexes with sulphide forming metal ions. It is the most common that the reagent as a bidentate neutral ligand exists in these complexes giving cation or neutral complexes. This reagent is used in spectrophotometric and extractive spectrophotometric methods of analysis of sulphide forming metal ions.     

Current approaches to the synthesis of pyrrolo[2,1-a]isoquinolines (microreview)

Chemistry of Heterocyclic Compounds - This microreview considers methods for the synthesis of pyrrolo[2,1-a]isoquinolines, published from year 2014 until 2018.     

Effect of vanadium content on the character of acidic sites on V2O5/Al2O3 catalysts

By IR spectroscopy and TPD the effect of vanadium content on the relative proportion of strongly acidic sites of V₂O₅/Al₂O₃ catalyst was studied.

---

- - V₂O₅/Al₂O₃.

     

Prediction of Potentialities and Practical Using of Potassium Diheptyldithiophosphate as a Potentiometric Titrant

Only one of the dithiophosphoric acid derivatives was used for potentiometric titration before our investigation. It was nickel diheptildithiophosphate which was used for the cupric ions determination. Reagents of this class form difficulty soluble complexes with sulphide forming ions.     

Catalytic Activity of Polymetalorganosiloxanes Supported on Silica in the Metathesis of a C–Cl Bond

The catalytic activity of structurally different Cu- and Ni-containing polymetalorganosiloxanes supported on silica was studied using the reaction of C–Cl bond metathesis in the carbon tetrachloride–saturated hydrocarbon (n-decane) system as an example. Catalysts with low metal contents were found to exhibit the highest activity; an increase in the metal content resulted in a decrease in both conversion and specific activity. At the initial portions of kinetic curves, the reaction was described by first-order rate equations with respect to n-decane; the reaction was of fraction order with respect to CCl₄and catalyst. The activation energy of the process in the n-decane–carbon tetrachloride system on a copper-containing network catalyst was 23 ± 2 kcal/mol. The mechanism of catalysis on immobilized catalysts from the above class is discussed.