Eriochrome black A as reagent for spectrophotometric microdetermination of cobalt in presence of nickel

Summary Eriochrome black A has been found to be a suitable reagent for the spectrophotometric determination of microgram quantities of cobalt in pure cobalt solutions and in the presence of nickel and some other cations by measuring the decrease in the absorbance of Eriochrome black A at p_H 10, caused by the presence of cobalt.Many foreign cations especially nickel were completely masked by EDTA. Amounts as low as about 0.9 to 3 g were determined with fair accuracy.     

Synthesis of novel 1,3,4-trisubstituted pyrazole derivatives and their evaluation as antitumor and antiangiogenic agents

Several 1,3,4-trisubstituted pyrazole derivatives were synthesized and screened for their cytotoxic effect in a primary 3 tumor cell line test at 10(-4) M drug concentration. Compounds 19 and 20 reduced the growth of one or more of these cell lines to less than 32% and escalated up to evaluation in the full panel of 60 human tumor cell lines at a minimum of 5 concentrations at 10 fold dilutions. Compound N'-(1-[1-[4-nitrophenyl]-3-phenyl-1H-pyrazol-4-yl]methylene)-2-chlorobenzohydrazide 19 proved to be the most active of these derivatives with full panel median growth inhibition (GI50), total growth concentration (TGI) and median lethal concentration (LC50) mean graph mid-point (MG-MID) of 3.79, 12.5 and 51.5 microM, respectively. In addition, compounds 19, 39, 40, 41, 43, 45, 47 were tested for their antiangiogenic properties by testing their ability to inhibit human umbilical vein endothelial cells (HUVECs) proliferation, cord formation and migration in response to chemoattractant. 3-Acetyl-2-(1-(4-nitrophenyl)-3-phenylpyrazol-4-yl)-5-(4-pyridyl)-1,3,4-oxadiazoline 39 showed significant antiangiogenic profile at non-cytotoxic doses, with HUVEC proliferation inhibition IC50 of 7.60 microM, chemotaxis IC50 of 0.86 microM and was superior to the reference celecoxib 2 in both tests. Furthermore, in contrary to the references TNP-470 and celecoxib, all the tested compounds interfered with the migratory function of HUVECs in response to vascular endothelium growth factor (VEGF) rather than the endothelial cells proliferation.     

Evidence for the intermediacy of arylbenzylnitrenium ions in the thermal rearrangement of isoxazolidines derived from C,N-diarylnitrones and 2-morpholin-4-yl-acrylonitrile

In contrast to the diaryl, dialkyl, alkylaryl, and parent series, nothing is known about the generation and chemical behavior of arylbenzylnitrenium ions. Herein, we report that these species can be generated by a process involving an unprecedented thermal rearrangement of isoxazolidines derived from C,N-diarylnitrones and 2-morpholin-4-yl-acrylonitrile. The products from these reactions are dramatically dependent upon the nature of the nitrone. Most of the observed chemistry originates from the singlet state.     

Numerical study of the axially symmetric motion of an incompressible viscous fluid in an annulus between two concentric rotating spheres

The research reported herein involved the study of the transient motion of a system consisting of an incompressible Newtonian fluid in an annulus between two concentric, rotating, rigid spheres. The primary purpose of the research was to study the use of a numerical method for analysing the transient motion that results from the interaction between the fluid in the annulus and the spheres which are started suddenly by the action of prescribed torques. The problems considered in this research included cases where: (a) one or both spheres rotate with prescribed constant angular velocities and (b) one sphere rotates due to the action of an applied constant or impulsive t?orque. In this research the coupled solid and fluid equations were solved numerically by employing the finite difference technique. With the approach adopted in this research, only the derivatives with respect to spatial variables were approximated with the use of the finite difference formulae. The steady state problem was also solved as a separate problem (for verification purposes), and the results were compared with those obtained from the solution of the transient problem. Newton's algorithm was employed to solve the algebraic equations which resulted from the steady state problem, and the Adams fourth-order predictor–corrector method was employed to solve the ordinary differential equations for the transient problem. Results were obtained for the streamfunction, circumferential function, angular velocity of the spheres and viscous torques acting on the spheres as a function of time for various values of the system dimensionless parameters.     

Potentiometric PVC membrane sensor for the determination of scopolamine in some pharmaceutical formulations.

A novel PVC membrane electrode for the determination of scopolamine ion based on the formation of an ion-association complex of scopolamine with the phosphotungstate counter anion as an electroactive material dispersed in a PVC matrix is described. The sensor shows a fast, stable, near-Nenstian response for 1 x 10(-2) mol dm(-3) to 1 x 10(-6) mol dm(-3) scopolamine at 25 degrees C over the pH range of 3 - 7 with a cationic slope of 54.5 +/- 0.5 mV/decade. The lower detection limit is 8 x 10(-7) mol dm(-3) and the response time is 15 -45 s. The selectivity coefficients for scopolamine relative to the number of interfering substances were investigated. There was negligible interference from the studied cations, anions, and pharmaceutical excipients. The determination of scopolamine in aqueous solution shows an average recovery of 100.0% and a mean relative standard deviation (RSD) of 1.5% at 500 microg/cm3. The direct determination of scopolamine in some formulations (scopolamine injection and eye drops) gave results that compare favorably with those obtained by the United State of Pharmacopoeia method. Potentiometric titration of scopolamine with sodium tetraphenylborate and phosphotungstic acid as a titrant was monitored with the developed scopolamine electrode as an end point indicator electrode.     

Palladium(II) acetate catalyzed efficient synthesis of N‐aryl‐α,β‐unsaturated amides via carbonylative addition of aniline derivatives to aromatic alkynes

A series of new N‐aryl‐α,β‐disubstituted amides (gem or E1; trans or E2) were synthesized in good yields by carbonylative addition of aniline derivatives 1a–f to aromatic alkynes 2a,b catalyzed by Pd(OAc)₂ and 1,3‐bis(diphenylphosphino)propane. The catalytic synthesis of tertiary α,β‐unsaturated amides was also successfully achieved. Traces of products were observed in the absence of p‐toluenesulfonic acid used as an additive. The reaction is sensitive to the type of phosphine ligand and solvent. Copyright © 2002 John Wiley & Sons, Ltd.     

Thermal analyses of mono- and divalent montmorillonite cationic derivatives

DTA and TG analyses were carried out for mono- and divalent cationic derivatives of Jelsovy-Potok montmorillonite. A certain relation between the charge density and the highest dehydration DTA peak was established for both series, since the two variables are a function of the magnitude of binding the hydrated water molecules. According to the charge density levels the cationic derivatives can be classified into three categories: (i) the single peak group falls in the range of charge density lower than 1 C m^?2; (ii) the double peak group falls between 1 and about 2 C m^?2; and (iii) for the higher charge densities three peaks are observed. The Ba derivative presents the only exception in this series. As the charge density increases, not only the number of dehydration peaks increases, but also the isolation between them becomes better, i.e., the overlapping of these peaks decreases in the order Ca > Li > Mg.The slopes of the TG curves in the temperature range 200–500°C increase with increase in charge density on the cationic derivative. This indicates that the rate of dehydration differs by changing the exchangeable cation of the surface, whereas the rate of dehydroxylation for all derivatives is the same since they all have the same origin.