Search results for " Synthesis"
showing 10 items of 1625 documents
Using Sandelowski and Barroso's Meta-Synthesis Method in Advancing Qualitative Evidence.
2016
The purpose of this article was to iteratively account for and discuss the handling of methodological challenges in two qualitative research syntheses concerning patients’ experiences of hospital transition. We applied Sandelowski and Barroso’s guidelines for synthesizing qualitative research, and to our knowledge, this is the first time researchers discuss their methodological steps. In the process, we identified a need for prolonged discussions to determine mutual understandings of the methodology. We discussed how to identify the appropriate qualitative research literature and how to best conduct exhaustive literature searches on our target phenomena. Another finding concerned our statu…
Asymmetric hydrogenation of ethyl pyruvate over aqueous dispersed Pt nanoparticles stabilized by a cinchonidine-functionalized β-cyclodextrin
2021
International audience; Cinchonidine-functionalized β-cyclodextrin was used as stabilizing agent for platinum nanoparticles dispersed in water, but also as chiral modifier for the asymmetric hydrogenation of ethyl pyruvate at 30 °C under 40 bar of hydrogen. This functionalized cyclodextrin allowed getting more stable, more catalytically active and also more enantioselective Pt nanoparticles compared to control catalytic systems. NMR and MALDI-MS analyses clearly showed the reduction of the vinyl group of the cinchonidine graft during the nanoparticles preparation. Under hydrogen pressure, the hydrogenation of the quinolinic moiety was also proven and can be responsible for the difficul…
Stability of biogenic metal(loid) nanomaterials related to the colloidal stabilization theory of chemical nanostructures
2018
In the last 15 years, the exploitation of biological systems (i.e. plants, bacteria, mycelial fungi, yeasts, and algae) to produce metal(loid) (Me)-based nanomaterials has been evaluated as eco-friendly and a cost-effective alternative to the chemical synthesis processes. Although the biological mechanisms of biogenic Me-nanomaterial (Bio-Me-nanomaterials) production are not yet completely elucidated, a key advantage of such bio-nanostructures over those chemically synthesized is related to their natural thermodynamic stability, with several studies ascribed to the presence of an organic layer surrounding these Bio-Me-nanostructures. Different macromolecules (e.g. proteins, peptides, lipids…
Template-controlled synthesis of chiral cyclohexylhemicucurbit[8]uril
2015
Enantiomerically pure cyclohexylhemicucurbit[8]uril (cycHC[8]), possessing a barrel-shaped cavity, has been prepared in high yield on a gram scale from either (R,R,N,N')-cyclohex-1,2-diylurea and formaldehyde or cycHC[6]. In either case, a dynamic covalent library is first generated from which the desired cycHC can be amplified using a suitable anion template.
The first metamagnetic one-dimensional molecular material with nickel(ii) and end-to-end azido bridges
2001
A novel single azido bridged one-dimensional Ni(II) chain, which represents the first metamagnetic one-dimensional metal–azido system with only end-to-end azido bridges, has been synthesised and characterised by a low temperature magnetic study. Lloret Pastor, Francisco, Francisco.Lloret@uv.es
Synthesis of the phytohormone [11C]methyl jasmonate via methylation on a C18 Sep Pak? cartridge
2005
[11C]labeled (±)-methyl jasmonate was synthesized using a C18 Sep Pak™ at ∼100°C to sustain a solid-supported 11C-methylation reaction of sodium (±)-jasmonate using [11C]methyl iodide. After reaction, the Sep Pak was rinsed with acetone to elute the labeled product, and the solvent evaporated rendering [11C]-(±)-methyl jasmonate at 96% radiochemical purity. The substrate, (±)-jasmonic acid, was retained on the Sep Pak so further chromatography was unnecessary. Total synthesis time was 25 min from the end of bombardment (EOB) which included 15 min to generate [11C]methyl iodide using the GE Medical Systems PET Trace MeI system, 5 min for reaction and extraction from the cartridge, and 5 min …
Automated synthesis and purification of [18F]fluoro-[di-deutero]methyl tosylate
2013
Automated synthetic procedures of [ 18 F]fluoro-[di-deutero]methyl tosylate on a GE TRACERlab FX F-N module and a non-commercial synthesis module have been developed. The syntheses included azeotropic drying of the [ 18 F]fluoride, nucleophilic 18 F-fluorination of bis(tosyloxy)-[di-deutero]methane, HPLC purification and subsequent formulation of the synthesized [ 18 F]fluoro-[di-deutero]methyl tosylate (d2-[ 18 F]FMT) in organic solvents. Automation shortened the total synthesis time to 50min, resulting in an average radiochemical yield of about 50% and high radiochemical purity (>98%). The possible application of this procedure to commercially available synthesis modules might be of signi…
On the Shape-Selected, Ligand-Free Preparation of Hybrid Perovskite (CH3NH3PbBr3) Microcrystals and Their Suitability as Model-System for Single-Crys…
2021
Hybrid perovskite materials are one of the most promising candidates for optoelectronic applications, e.g., solar cells and LEDs, which can be produced at low cost compared to established materials. Although this field of research has seen a huge upsurge in the past decade, there is a major lack in understanding the underlying processes, such as shape-property relationships and the role of defects. Our aerosol-assisted synthesis pathway offers the possibility to obtain methylammonium lead bromide (MAPbBr3 ) microcrystals from a liquid single source precursor. The differently shaped particles are aligned on several substrates, without using a directing agent or other additives. The obtained …
Improved Regioselectivity in Pyrazole Formation through the Use of Fluorinated Alcohols as Solvents: Synthesis and Biological Activity of Fluorinated…
2008
The preparation of N-methylpyrazoles is usually accomplished through reaction of a suitable 1,3-diketone with methylhydrazine in ethanol as the solvent. This strategy, however, leads to the formation of regioisomeric mixtures of N-methylpyrazoles, which sometimes are difficult to separate. We have determined that the use of fluorinated alcohols such as 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as solvents dramatically increases the regioselectivity in the pyrazole formation, and we have used this modification in a straightforward synthesis of fluorinated analogs of Tebufenpyrad with acaricide activity. Fil: Fustero, Santos. Universidad de Valencia; España Fil…
On the reaction of some 5-polyfluoroaryl-1,2,4-oxadiazoles with methylhydrazine: synthesis of fluorinated indazoles
2009
The reaction of 5-polyfluoroaryl-1,2,4-oxadiazoles with methylhydrazine has been studied and the synthesis of fluorinated N-methylindazoles has been realized. Rearrangement reactions showed predominantly formation of N(1)-methylindazole regioisomers. Starting compounds were preliminarily functionalized at the polyfluoroaryl moiety through fluorine displacement with nucleophiles (methanol, methylamine, dimethylamine), allowing the obtainment of target indazoles substituted at the C(6) position.