Pyrimidine derivatives and related compounds VI. A novel synthesis of 3,5-diacetamidopyrazole and of 2-aminopyrazolo [1,5-α] pyrimidines

3,5-Diaeetamidopyrazole (2) could be prepared via arylazo group decoupling from 3,5-diamino-4-arylazopyrazoles ( 1a-c ) by the action of acetic acid-sulfuric acid mixture. Arylazo group removal could also be effected when 2-amino-5-melhyl-7-oxo-6,7-dihydro-3-phenylazopyrazolo-[1,5-α]pyrimidine ( 5 ) was similarly treated. The 2-aminopyrazolo[1,5-α]pyrimridine derivative was obtained in this case. On the other hand, under the same experimental conditions compounds 7a-c and 8 were recovered almost unaffected. The mechanism of the reaction is discussed.     

Characterization of similarities between two n-frames of projectors

An n-frame on a Banach space $\text{X}$ is E=(E₁,?, E_n) where the E_j's are bounded linear operators on $\text{X}$ such that E_j≠0,

$\text{∑}\text{j=1}\text{n}\text{E}{}_{\mathrm{j}}$

, and E_jE_k=δ_jkE_k (j, k=1,?, n). It is known that if two n-frames E and F are sufficiently close to each other, then they are similar, that is, F_j=TE_jT^-1 with T a bounded linear operator. Among the operators which realize the similarity of the two frames, there is the balanced transformation U(F, E)=(Σⁿ_j=1F_jE_j)(Σⁿ_j=1E_jF_jE_j)^{$\text{-1}\text{2}$}. One of our main results is a local characterization of the balanced transformation. Another operator which implements the similarity between E and F is the direct rotation R(F, E). It comes up in connection with the study of the set of all n-frames as a Banach manifold with an affine connection. Finally, it is shown that for quite a large set of pairs of 2-frames, the direct rotation has a global characterization.     

Synthesis and antagonist activities of 4-aryl-substituted conformationally restricted cyclopentenyl and cyclopentanyl-glutamate analogues

The conformationally restricted glutamate analogues, 4-aryl-1-amino-2-cyclopentene-1,3-dicarboxylates and their cyclopentane analogues have been prepared in a diastereoselective manner. Biological studies of 12a and 12b indicates that both compounds are modest antagonists at mGluR2.     

Phytochemical study,potential cytotoxic and antioxidant activities of selected food byproducts (Pomegranate peel,Rice bran,Rice straw & Mulberry bark)

Abstract

The aim of the study is to evaluate common food by-products (Pomegranate peel, Rice bran, Rice straw & Mulberry bark) to screen out their medicinal importance such as cytotoxic & antioxidant activities. HPLC revealed that all tested samples were rich in phenolics. Tested samples exerted significant antioxidant activity with high potency to Pomegranate peel. All tested extracts were able to reduce cell viability of tested cell lines in a dose-response manner after treatment. In most cases, the IC50 values were under 30 μg/ml except IC50 of pomegranate peel against breast cell line (42.4?ug/ml). The antioxidant and cytotoxic properties of pomegranate peel, rice bran, rice straw and mulberry bark have been attributed to synergetic effects of phenolic phytochemicals.     

Additivity of resonance energy in benzenoid hydrocarbons

A simple method is described for the calculation of resonance energies (RE ) of linear acenes based on their number of Kekulé structures. The values obtained for the first five linear acenes are used to graph–theoretically calculate RES of a wide variety of benzenoid hydrocarbons. Excellent linear relationships are found between RES and each of A-II, graph-theoretical (GT ), Hess–Schaad (HS ), and Dewar resonance energies (SCF ). These relations apply to 42 hydrocarbons and lead to the following equations: A-II = 0.084RE + 0.080 (0.9999); GT = 0.072RE + 0. 135 (0.9832); HS = 0. 106RE + 0. 169 (0.9889); and SCF = 0.316RE + 0. 166 (0.9899). Correlation coefficients are shown in parentheses. A linear relation also exists between RES and the square roots of the wavelengths of the UV spectra of hydrocarbons of the linear acenes and phene series. Least-squares analysis of the data leads to the following equation: RE = 0.412(λ)^½ ?15.479, with a correlation coefficient equal to 0.9903, in which λ is the wavelength of the β band of the UV spectra of these hydrocarbons. The method predicts no resonance energies for both open chain polyenes and the radialenes.     

Applications of caterpillar trees in chemistry and physics

The relations of caterpillar trees (which are also known as Gutman trees and benzenoid trees) to other mathematical objects such as polyhex graphs, Clar graphs, king polyominos, rook boards and Young diagrams are discussed. Potential uses of such trees in data reduction, computational graph theory, and in the ordering of graphs are considered. Combinatorial and physical properties of benzenoid hydrocarbons can be studied via related caterpillars. It thus becomes possible to study the properties of large graphs such as benzenoid (i.e. polyhex) graphs in terms of much smaller tree graphs. Generation of the cyclic structures of wreath and generalized wreath product groups through the use of caterpillar trees is illustrated.     

Effect of solvents on the electronic absorption spectra of some substituted diarylformazans

Summary The electronic absorption spectra of some substituted diarylformazans in organic solvents of varying polarities are studied. The absorption bands are assigned to the corresponding electronic transitions in the molecules. The solvent effects on the intramolecular charge transfer bands are discussed using various solvent parameters. The charge transfer nature of the bands was also confirmed by the solvent effects on the absorption spectra of some formazans. Molecular orbital calculations using MNDO-PM3 were performed and indicate atrans configuration as the favoured geometry.

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Lösungsmitteleinflüsse auf die Absorptionsspektren einiger substituierter Diarylformazane

Zusammenfassung Die Absorptionsspektren einiger substituierter Diarylformazane werden in organischen Lösungsmitteln unterschiedlicher Polarität untersucht. Die Absorptionsbanden werden den entsprechenden Elekronenübergängen in den Molekülen zugeordnet. Die Lösungsmitteleffekte auf die intramolekularencharge-transfer-Banden werden unter Verwendung verschiedener Lösungsmittelparameter diskutiert. Diecharge-transfer-Natur der Banden wurde durch den Einfluß der Lösungsmittel auf die Absorptionsspektren einiger Formazane bestätigt. MO-Rechnungen (MNDO-PM3) wurden durchgeführt und bestätigen einetrans-Konfiguration als bevorzugte Geometrie.

     

Squarate complexes of some lanthanide ions in aqueous solution

The squarate complexes of Eu³⁺, Tb³⁺ and Tm³⁺ in aqueous solutions of 0.05M, 0.075M and 0.1M ionic strength are studied using the solvent extraction method. Effects of changes in the ionic strength on the stability constants of the complexes formed are discussed.     

Temperature effects on the extraxtion of divalent cobalt,zinc, cadmium and mercury by salicylaldoxime in carbon tetrachloride

The effect of temperature on the extraction of Co²⁺, Zn²⁺, Cd¹⁺ and Hg²⁺ by salicylaldoxime diluted with carbon tetrachloride was investigated radiometrically. It is found that the extraction constants at 25°C increase linearly with l/r, where r is the effective coordination radius of the metal cation. The thermodynamic data calculated from the effect of temperature on the extraction showed that, 1) the extraction process is endothermic, 2) the dehydration of the metal cation in the extraction process is the predominating factor in determining the enthalpy variation and 3) the entropy variation is a contribution of the degree of order caused by the hydration of the proton and the highly ordered chelate structure of the extracted species.     

Determination of trace elements of egyptian crops by neutron activation analysis

Neutron activation analysis, NAA, a high resolution Ge(Li) gamma ray spectrometer was used to determine the concentration of Al, As, Au, Br, Ca, Cd, Co, Cr, Cu, Fe, La, Mn, Mo, Sb, Se, W, and Zn in Cumin, coriander, carrots, and Daucus carrota (Umbelliferae Family), alfalfa, Kidney bean, Phaseolus sativus, Phaseolus vulgaris, bean, lenses, and fenugreek (Legumirosae Family). Multielement determination technique on destructive and nondestructive samples was followed. This method is simple, precise and sensitive to 17 trace elements.