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Base Hydrolysis (base + hydrolysis)
Selected AbstractsAntituberculosis Agents and an Inhibitor of the para -Aminobenzoic Acid Biosynthetic Pathway from Hydnocarpus anthelminthica SeedsCHEMISTRY & BIODIVERSITY, Issue 8 2010Jun-Feng Wang Abstract Investigation on the extracts of Hydnocarpus anthelminthica seeds led to the isolation of three new compounds, anthelminthicins A,C (1,3, resp.), and two known ones, namely chaulmoogric acid (4) and ethyl chaulmoograte (5). Their structures were determined mainly by using spectroscopic techniques. The absolute configuration at the cyclopentenyl moiety of compound 2 was rationalized by quantum calculations. Base hydrolysis, followed by optical-rotation comparison, allowed assignment of the configuration of chaulmoogric-acid moiety of compounds 3 and 5. Biological assays revealed that compounds 1,5 significantly inhibit Mycobacterium tuberculosis (MTB) growth with MIC values of 5.54, 16.70, 4.38, 9.82, and 16.80,,M, respectively. Compound 3 was found to inhibit the pathway between chorismate and para -aminobenzoic acid (pAba) with a MIC value of 11.3,,M, representing a new example of pAba inhibitor isolated from a natural source. All compounds were not toxic to Candida albicans SC5314 at a concentration up to 100,,M. [source] Optimization of an Iron Intercalated Montmorillonite Preparation for the Removal of Arsenic at Low Concentrations,ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 1 2007D. Masih Abstract A series of iron intercalated montmorillonites (Fe-Monts) were prepared using (i) ion exchange of native sodium and calcium ions with iron ions, (ii) base hydrolysis of inserted iron ions in montmorillonite suspension, and (iii) insertion of pre-hydrolyzed iron colloid in montmorillonite. The materials were characterized by X-ray diffraction and gas adsorption-desorption techniques. The basal d(001)-spacing and BET specific surface area increased after the intercalation of iron species in montmorillonite. Local iron structure studied by X-ray absorption fine structure (XAFS) spectroscopy showed an unsaturation of the Fe···Fe coordination number (N 2.5) of the intercalated iron species as compared to the bulk iron oxyhydroxides (N 6). The Fe-Monts were employed for arsenic removal from aqueous solutions at low concentration (0.2,16 mg/L). Among the Fe-Monts, the one prepared by the hydrolysis of inserted iron ions, was the best in performance. The saturation adsorption amount of the optimized iron-montmorillonite was 4 and 28 times higher for the removal of arsenite and arsenate, respectively, as compared to bulk iron oxyhydroxide (goethite). Compared with bulk iron oxyhydroxide, the Fe-Monts were superior for arsenate uptake and comparable for arsenite. In addition, arsenite adsorbed on the Fe-Monts was found to be oxidized to arsenate based on XAFS spectroscopy. [source] Equilibrium and kinetic investigation of the interaction of model palladium(II) complex with biorelevant ligandsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 10 2010Mohamed M. Shoukry Pd(DME)Cl2 complex was synthesized and characterized, where DME is 2-{[2-(dimethylamino)ethyl]-methylamino}ethanol. Stoichiometry and stability constants of the complexes formed between various biologically relevant ligands (amino acids, peptides, DNA constituents, and dicarboxylic acids) and [Pd(DME)(H2O)2]2+ are investigated at 25°C and at constant 0.1 M ionic strength. The effect of dielectric constant of the medium on the stability constant of Pd(DME)-CBDCA complex, where CBDCA is cyclobutanedicarboxylate, is also reported. The concentration distribution diagrams of the various species formed are evaluated. The kinetics of base hydrolysis of amino acid esters coordinated to Pd(DME)2+ complex is investigated. The effect of the temperature on the kinetics of base hydrolysis of glycine methyl ester complex is studied. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 608,618, 2010 [source] Kinetics of base hydrolysis of ,-amino acid esters catalyzed by the copper(II) complex of N,N,N,,N,-tetramethylethylenediamine (Me4en)INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 12 2006Mahmoud M. A. Mohamed The kinetics of base hydrolysis of glycine-, histidine-, and methionine methyl esters in the presence of [Cu-Me4en]2+ complex is studied in aqueous solutions and in dioxane,water solutions of different compositions at T = 25°C and I = 0.1 mol dm,1. The kinetics of base hydrolysis of glycine and methionine methyl esters is studied at different temperatures. The kinetic data fits assuming that the hydrolysis proceeds in one step. The activation parameters for the base hydrolysis of the complexes are evaluated. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 737,745, 2006 [source] Wet chemical synthesis of low bulk density aluminium hydroxide powderJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2003JK Pradhan Abstract Fine, low bulk density aluminium hydroxide powdered gel was prepared by the mild base hydrolysis of an aqueous solution of aluminium sulfate with hydrazine hydrate. Parameters such as method of addition of reactant, initial concentration of Al3+, mole ratio, final pH and hydrolysis temperature have a profound effect on the lightness and particle size of the powder. Optimized conditions showed that the final pH, Al3+ concentration and method of addition of reactant have a major contribution on the formation of lighter grade powder. Experiments conducted using other bases also produced lighter particles under similar conditions. Deviation from the optimized conditions led to formation of a higher bulk density product. Copyright © 2003 Society of Chemical Industry [source] 1,1,-Fc(4-C6H4CO2Et)2 and its unusual salt derivative with Z, = 5, catena -[Na+]2[1,1,-Fc(4-C6H4CO2,)2]·0.6H2O [1,1,-Fc = (,5 -(C5H4)2Fe]ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2010John F. Gallagher The neutral diethyl 4,4,-(ferrocene-1,1,-diyl)dibenzoate, Fe[,5 -(C5H4)(4-C6H4CO2Et)]2 (I), yields (II) (following base hydrolysis) as the unusual complex salt poly[disodium bis[diethyl 4,4,-(ferrocene-1,1,-diyl)dibenzoate] 0.6-hydrate] or [Na+]2[Fe{,5 -(C5H4)-4-C6H4CO}2]·0.6H2O with Z, = 5. Compound (I) crystallizes in the triclinic system, space group , with two molecules having similar geometry in the asymmetric unit (Z, = 2). The salt complex (II) crystallizes in the orthorhombic system, space group Pbca, with the asymmetric unit comprising poly[decasodium pentakis[diethyl 4,4,-(ferrocene-1,1,-diyl)dibenzoate] trihydrate] or [Na+]10[Fe{,5 -(C5H4)-4-C6H4CO}2]5·3H2O. The five independent 1,1,-Fc[(4-C6H4CO2),]2 dianions stack in an offset ladder (stepped) arrangement with the ten benzoates mutually oriented cisoid towards and bonded to a central layer comprising the ten Na+ ions and three water molecules [1,1,-Fc = ,5 -(C5H4)2Fe]. The five dianions differ in the cisoid orientations of their pendant benzoate groups, with four having their ,C6H4, groups mutually oriented at interplanar angles from 0.6,(3) to 3.2,(3)° (as ,..., stacked C6 rings) and interacting principally with Na+ ions. The fifth dianion is distorted and opens up to an unprecedented ,C6H4, interplanar angle of 18.6,(3)° through bending of the two 4-C6H4CO2 groups and with several ionic interactions involving the three water molecules (arranged as one-dimensional zigzag chains in the lattice). Overall packing comprises two-dimensional layers of Na+ cations coordinated mainly by the carboxylate O atoms, and one-dimensional water chains. The non-polar Fc(C6H4)2 groups are arranged perpendicular to the layers and mutually interlock through a series of efficient C,H..., stacking contacts in a herringbone fashion to produce an overall segregation of polar and non-polar entities. [source] | ||||||||||