Search results for "Catalysis"

ChemInform Abstract: Asymmetric Synthesis of Fluorinated Isoindolinones Through Palladium-Catalyzed Carbonylative Amination of Enantioenriched Benzyl…

2015

The asymmetric synthesis of fluorinated isoindolinones has been achieved by a palladium-catalyzed aminocarbonylation reaction of the corresponding α-fluoroalkyl o-iodobenzylamines. A base-mediated anti β-hydride elimination process was suggested to explain the partial erosion of the optical purity observed in some cases. This mechanistic rationale enabled the minimization of this partial racemization by fine-tuning the pKa of the base.

Strong donor–acceptor couplings in a special pair-antenna model

2010

A special pair model composed of two cofacial zinc porphyrins (acceptor) linked to a free base (donor) acts as an energy transfer dyad. Despite the absence of conjugation, ππ*/charge transfer excited states and ultrafast energy transfer (∼5 ps) are noted.

Book Review: Guidelines for Achieving High Accuracy in Isotope Dilution Mass Spectrometry (IDMS) Edited by Mike Sargent, Chris Harrington and Rita Ha…

2003

Determination of Platinum-Group Elements (PGE) from catalytic converters in soil by means of docimasy and INAA.

1996

The nickelsulfide fire assay (docimasy) for the enrichment of platinum-group elements (PGEs) has been modified for the use with small samples and combined with instrumental neutron-activation analysis (INAA). This procedure has been applied to the determination of PGEs exhausted from catalytic converters and deposited in soil near the Wiesbadener Kreuz (highway A3, Frankfurt-Koln). Our results show a considerable enhancement of the Pt (up to 330 ng/g), Pd (6.6 ng/g) and Rh (7.5 ng/g) contents close to the highway.

Synthesis of flexible nanotweezers with various metals and their application in carbon nanotube extraction

2018

Bisporphyrin-based flexible nanotweezers with various metals were synthesized and applied to the extraction of single-walled carbon nanotubes. Homo- and hetero-metallic bisporphyrins containing Co2+ were found to afford higher SWNT-extraction ability, while no or a little amount of SWNTs were extracted by bisporphyrins with other metals.

Synergistic effect of ligating and ionic functions, prearranged on a calix[4]arene.

2006

The covalent attachment of two CMPO-functions and two anionic Cosan groups to the narrow rim of tert-butylcalix[4]arene leads to a dramatic increase of the extraction efficiency for the cone isomer; Am(3+) is removed from 5 x 10(-8) M solution to more than 99% by a single extraction step with a 3 x 10(-6) M solution of the calixarene.

Extraction of lanthanides and actinides by a magnetically assisted chemical separation technique based on CMPO-calix[4]arenes

2001

A novel particulate system carrying CMPO ligands pre-organised on a calixarene scaffold has been synthesised and demonstrated to extract Eu3+, Am3+ and Ce3+ at high efficiency from simulated nuclear waste streams.

Cover Feature: Visible Light‐Induced Sulfonylation/Arylation of Styrenes in a Double Radical Three‐Component Photoredox Reaction (Chem. Eur. J. 38/20…

2019

Cover Feature: Triplet–Triplet Annihilation Upconversion in a MOF with Acceptor‐Filled Channels (Chem. Eur. J. 5/2020)

2019

Stabilizing Lead Cathodes with Diammonium Salt Additives in the Deoxygenation of Aromatic Amides

2014

Lead is efficiently protected against cathodic corrosion by the addition of diammonium salts in the electrolyte. The cationic coating of the cathode allows the efficient electroreduction of benzamides to benzylamines. The electrochemical deoxygenation of the amide is achieved without the use of oxophilic agents or sacrificial anodes. The surface of the lead cathode stays smooth and the cathode can be reused for multiple runs, providing <2.5 ppm of the crude product. Cyclic voltammetry studies reveal a shift in the onset potential of the hydrogen evolution reaction by −157 mV.