Search results for "Ammonium hydroxide"

showing 4 items of 14 documents

Analytical characterization of diterpenoid resins present in pictorial varnishes using pyrolysis–gas chromatography–mass spectrometry with on line tr…

2005

Abstract A procedure based on the technique of the pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) has been applied, in this work, in order to determine the composition of diterpenoid resin employed in art works. The method is based on the on line derivatization of these resins using hexamethyldisilazane (HMDS). Results obtained were compared with those previously reported in literature from Venice turpentine, Strasbourg turpentine, colophony, sandarac and Manila copal using this same method and with those others from in situ thermally assisted hydrolysis and methylation with tetramethylammonium hydroxide (TMAH). Canada balsam, copper resinate and Copaiba balsam have been also ana…

Tetramethylammonium hydroxideChromatographySilylationOrganic ChemistryVarnishSandaracGeneral Medicineengineering.materialSensitivity and SpecificityBiochemistryGas Chromatography-Mass SpectrometryAnalytical ChemistryPyrolysis–gas chromatography–mass spectrometrychemistry.chemical_compoundchemistryCanada balsamvisual_artPaintengineeringvisual_art.visual_art_mediumOrganic chemistryGas chromatographyDiterpenesDerivatizationJournal of Chromatography A
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Reduction of tris(benzene-1,2-dithiolate)molybdenum(VI) by hydroxide ions in dry tetrahydrofuran solution.

2001

Tris(benzene-1,2-dithiolate)molybdenum(VI) reacts rapidly and quantitatively with tetrabutylammonium hydroxide to yield the corresponding Mo(V) and Mo(IV) complexes and hydrogen peroxide; the reaction has been executed in dry tetrahydrofuran where the reaction rate shows a fair dependence on complex and OH2 concentrations. Cervilla Avalos, Antonio, Antonio.Cervilla@uv.es ; Perez Pla, Francisco, Francisco.Perez@uv.es ; Llopis Jover, Elisa, Elisa.Llopis@uv.es

UNESCO::QUÍMICAInorganic chemistrychemistry.chemical_element:QUÍMICA [UNESCO]CatalysisReaction ratechemistry.chemical_compoundMaterials ChemistryReduction ; Hydroxide ions ; Tetrahydrofuran solution ; Hydrogen peroxide ; OH2Hydrogen peroxideBenzeneTetrahydrofuranReductionUNESCO::QUÍMICA::Química inorgánicaTetrabutylammonium hydroxideMetals and AlloysGeneral ChemistryHydrogen peroxide:QUÍMICA::Química inorgánica [UNESCO]Surfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsHydroxide ionschemistryOH2MolybdenumYield (chemistry)Ceramics and CompositesHydroxideTetrahydrofuran solutionChemical communications (Cambridge, England)
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Effect of ammonium hydroxide addition in the anodizing electrolyte on the electronic properties of anodic oxides on Niobium

2010

ammonium hydroxide addition in the anodizing electrolyte electronic properties anodic oxides Niobium
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O-Alkylation of a lignite humic acid by phase-transfer catalysis

2006

A mild phase-transfer catalytic reaction has been conducted to O-alkylate the acidic functions of a lignite humic acid (HA), using tetrabutylammonium hydroxide as the phase-transfer catalyst. The HA acidic functional groups were made to react, in tetrahydrofuran, by nucleophilic substitution with several alkyl halides-methyl iodide, and ethyl, propyl, and butyl, and benzyl bromide. The occurrence of the O-alkylation reaction was assessed by elemental analysis and 1H NMR, CPMAS 13C NMR, and FTIR spectroscopy. Bonding of alkyl groups increased the carbon and hydrogen content and the H/C ratios of all the humic reaction products. Increased nitrogen in the reaction products suggested incomplete…

chemistry.chemical_classificationSettore AGR/13 - Chimica AgrariaEtherAlkylationCarbon-13 NMRBiochemistryAnalytical ChemistryCatalysischemistry.chemical_compoundchemistryProton NMRNucleophilic substitutionHumic acidOrganic chemistrylipids (amino acids peptides and proteins)Humic substances O-Alkylation Phase-transfer catalysis Tetrabutylammonium hydroxide NMR FTIRAlkylAnalytical and Bioanalytical Chemistry
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