نتایج جستجو برای: complexation reaction
تعداد نتایج: 418327 فیلتر نتایج به سال:
abstract in aggregate, active forms of reactive silica with mineral names are sometimes associated with sand and gravel in concrete mixture. alkali hydroxides originated from alkalis in the cement or other resources form an alkaline silica gel with this reactive silica which becomes swallowed and expanded during time causing damage to concrete. there have been growing researches on alkaline r...
The tannin fractions isolated from hazelnuts, walnuts and almonds were characterised by colorimetric assays and by an SE-HPLC technique. The complexation of Cu(II) and Zn(II) was determined by the reaction with tetramethylmurexide, whereas for Fe(II), ferrozine was employed. The walnut tannins exhibited a significantly weaker reaction with the vanillin/HCl reagent than hazelnut and almond tanni...
A novel simple kinetic spectrophotometric method for the determination of N-acetyl-L-cysteine (NAC) has been developed and validated. The proposed method is based on a coupled redox-complexation reaction, the first step of which is the reduction of Fe(3+) by NAC; the second one includes the complexation of Fe(2+), resulting from the preceding redox reaction, with 2,4,6-trypyridyl-s-triazine (TP...
The Front Cover shows the influence of reaction solvent on purin-2-yl Grignards with carbonyl compounds. In ether (THF), gives 8-carbinol products due to a rapid isomerisation purin-8-yl, whereas performing in dichloromethane stops and yields 2-carbinols good yields. contrast aldehydes, reactions ketones require prior complexation LaCl3.2LiCl before addition Grignard reagent. More information c...
Simulating adsorption of U(VI) under transient groundwater flow and hydrochemistry: Physical versus chemical nonequilibrium model" (2011). [1] Coupled intragrain diffusional mass transfer and nonlinear surface complexation processes play an important role in the transport behavior of U(VI) in contaminated aquifers. Two alternative model approaches for simulating these coupled processes were ana...
In the presence of iron (Fe), dissolved organic matter (DOM) may bind considerable amounts of arsenic (As), through formation of Fe-bridged As-Fe-DOM complexes and surface complexation of As on DOM-stabilized Fe-colloids (collectively referred to as As-Fe-DOM complexation). However, direct (e.g., chromatographic and spectroscopic) evidence and fundamental kinetic and stability constants have be...
the dependence on ionic strength of protonation of l-aspartic acid and its complexation withdioxouranium(vi) is reported in sodium perchlorate solution as a background salt. the measurementshave been performed at 25 ± 0.1 °c and various ionic strengths in the range 0.1 to 1.0 mol dm-3, using acombination of potentiometric and spectrophotometric techniques. the overall analysis of the present an...
in this thesis, a better reaction conditions for the synthesis of spirobarbiturates catalyzed by task-specific ionic liquid (2-hydroxy-n-(2-hydroxyethyl)-n,n-dimethylethanaminium formate), calcium hypochlorite ca(ocl)2 or n-bromosuccinimide (nbs) in the presence of water at room temperature by ultrasonic technique is provided. the design and synthesis of spirocycles is a challenging task becaus...
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