Search results for "SOLVENT"
showing 10 items of 1395 documents
Surprising solvent-induced structural rearrangements in large [N⋯I+⋯N] halogen-bonded supramolecular capsules
2018
Coordinative halogen bonds have recently gained interest for the assembly of supramolecular capsules. Ion mobility-mass spectrometry and theoretical calculations now reveal the well-defined gas-phase structures of dimeric and hexameric [N...I+...N] halogen-bonded capsules with counterions located inside their cavities as guests. The solution reactivity of the large hexameric capsule shows the intriguing solvent-dependent equilibrium between the hexamer and an unprecedented pentameric [N...I+...N] halogen-bonded capsule, when the solvent is changed from chloroform to dichloromethane. The intrinsic flexibility of the cavitands enables this novel structure to adopt a pseudo-trigonal bipyramida…
Organic solvent-soluble contents of nickel and cobalt in some algae
1990
In pursuit of our work on metal contents of lipid fractions isolated from plant material, we now show by means of highly sensitive analytical methods that nickel and cobalt are also present in organic extracts of algae in detectable amounts
Isobaric Vapor−Liquid Equilibria for Water + Acetic Acid + Potassium Acetate
2004
Isobaric vapor−liquid equilibria for water + acetic acid + potassium acetate at different salt concentrations as well as for solvent + potassium acetate binary mixtures have been obtained at 100 kPa. Potassium acetate is more effective in the salting-out effect (on water) than lithium and sodium acetates. The eNRTL-CT model, which is a combination of electrolyte nonrandom two-liquid and chemical theory models, has been used to fit the experimental data. The binary parameters of the model have been obtained from the experimental binary vapor−liquid equilibria which have been used to suitably reproduce the vapor−liquid equilibria (VLE) for water + acetic acid + potassium acetate ternary syste…
Soluble/MOF-Supported Palladium Single Atoms Catalyze the Ligand-, Additive-, and Solvent-Free Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids.
2021
Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cystein…
Can the absence of solvation of neutral reagents by ionic liquids be responsible for the high reactivity in base-assisted intramolecular nucleophilic…
2005
[reaction: see text] The kinetics of the rearrangement of the Z-phenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (1a) into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole (2a) induced by amines have been studied in two room-temperature ionic liquids (IL-1, [BMIM][BF4] and IL-2, [BMIM][PF6]). The data collected show that the reaction occurs faster in ionic liquids than in other conventional solvents previously studied (both polar or apolar, protic or aprotic). Presumably, this could depend on their peculiar ability to minimize the strong substrate-solvent, amine-solvent and amine-amine interactions occurring in conventional solvents.
The effect of the cation p-surface area on the 3D organization and catalytic ability of imidazolium-based ionic liquids
2011
The dichotomic nature of ionic liquids (ILs, simple solvents or supramolecular fluids) induced us to carry out a structural investigation of some mono-and dicationic ionic liquids using 1D and 2D NMR, resonance light scattering, and UV/Vis spectroscopy. Ionic liquids with different cation π-surface areas were used, namely [bmim][NTf2], [Bzmim][NTf 2], [Bzbim][NTf2], [p-Xyl-(bim)2][NTf 2]2, and [m-Xyl-(bim)2][NTf2] 2 [bmim = 1-butyl-3-methylimidazolium, Bzmim = 1-benzyl-3- methylimidazolium, Bzbim = 1-benzyl-3-butylimidazolium, NTf2 = bis(trifluoromethansulfonyl)imide]. In order to verify to what extent the structural investigation, coupled with the determination of solvent parameters, could…
LU un RSU iegūtās izglītības loma žurnālistu profesionālās identitātes veidošanā: programmu analīze, un mācībspēku un absolventu vērtējumi
2016
Bakalaura darba "LU un RSU iegūtās izglītības loma žurnālistu profesionālās identitātes veidošanā: programmu analīze, un mācībspēku un absolventu vērtējumi" mērķis ir noskaidrot, kā atšķiras dažādu augstskolu žurnālistikas programmas saturiski un absolventu vērtējumā. Teorētiskajā daļā aprakstīts izglītības jēdziens, definēta žurnālistu profesionālā identitāte un raksturota žurnālistikas vide Latvijā. Metodoloģijā aprakstīta daļēji strukturētā intervija, anketēšana un kontentanalīze. Pētnieciskajā daļā anketēti abu augstskolu absolventi un salīdzinātas mācību programmas. Rezultāti liecina, ka trešdaļa no abu augstskolu respondentiem uzskata, ka izglītība žurnālistikas nozarē nav vajadzīga.
Maģistra studiju programmas "Bibliotēkzinātne un informācija" 2013.-2018. gada absolventu profesionālās karjeras
2019
Bakalaurs darbs tika izstrādāts, lai noskaidrotu maģistra studiju programmas “Bibliotēkzinātne un informācija” 2013.-2018. gada absolventu profesionālās gaitas. Galvenie pētījuma jautājumi – kādas ir šī brīža darba vietas, apmierinātība ar tām, vai pēc viņu domām maģistra grāds paver plašākas iespējas darba tirgū, kā arī atalgojuma izmaiņas pēc maģistra grāda iegūšanas. Darba teorētiskā bāze – pragmatisms un sociālā kapitāla teorija. Izmantotās datu ieguves metodes – absolventu anketēšana un daļēji strukturētās intervijas. Pamatojoties uz veiktā pētījuma rezultātiem, var secināt, ka lielākā daļa absolventu strādā bibliotēkās, kopumā ir ļoti apmierināti ar darba vietām, maģistra grāds biblio…
Convergent results from experimental and theoretical DFT studies of the intramolecular rearrangement of Z-hydrazones of 3-acetyl-1,2,4-oxadiazoles
2004
A combined kinetic and theoretical study of the monocyclic rearrangements of heterocycles (MRH) has been carried out. The interconversion of the Z-hydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole into the corresponding triazole has been experimentally investigated in dioxane/water in the pS(+) range 5.5(5)-13.9. The uncatalyzed region has been examined at the DFT level using a model system formed by the Z-hydrazone of 3-formyl-1,2,4-oxadiazole and one or two water molecules. The environmental effect of the solvent has been emulated using a continuum model (COSMO) approach. The kinetic data suggest a concerted process where the magnitude of the activation barrier is determined by the interpl…
All-Organic Waveguide Sensor for Volatile Solvent Sensing
2019
This work was supported by ERDF 1.1.1.1 Activity Project Nr. 1.1.1.1/16/A/046 “Application assessment of novel organic materials by prototyping of photonic devices”. We acknowledge Igors MIHAILOVS for valuable discussions.