Number Of Catalytic Processes Research Articles

C(sp3)-CF3 Reductive Elimination from a Five-Coordinate Neutral Copper(III) Complex.

The reductive elimination from a high-valent late-transition-metal complex for the formation of a carbon-carbon or carbon-heteroatom bond represents a fundamental product-forming step in a number of catalytic processes. While reductive eliminations from well-defined Pt(IV), Pd(IV), Ni(III)/Ni(IV), and Au(III) complexes have been studied, the analogous reactions from neutral Cu(III) complexes remain largely unexplored. Herein, we report the isolation of a stable, five-coordinate, neutral square pyramidal Cu(III) complex that gives CH3-CF3 in quantitative yield via reductive elimination. Mechanistic studies suggest that the reaction occurs through a synchronous bond-breaking/bond-forming process via a three-membered ring transition state.

Radical coupling from alkyl amines

Radical intermediates are key species in many chemical transformations. Recent advances have provided a new suite of selective radical alkylation reactions. This Comment highlights pioneering studies using alkyl amines that act as radical precursors in a number of catalytic processes by their conversion to alkylpyridinium salts.

Variation of SMSI with the Au:Pd Ratio of Bimetallic Nanoparticles on TiO2(110)

Au/Pd nanoparticles are important in a number of catalytic processes. Here we investigate the formation of Au–Pd bimetallic nanoparticles on TiO2(110) and their susceptibility to encapsulation using scanning tunneling microscopy, as well as Auger spectroscopy and low energy electron diffraction. Sequentially depositing 5 MLE Pd and 1 MLE Au at 298 K followed by annealing to 573 K results in a bimetallic core and Pd shell, with TiOx encapsulation on annealing to ~ 800 K. Further deposition of Au on the pinwheel type TiOx layer results in a template-assisted nucleation of Au nanoclusters, while on the zigzag type TiOx layer no preferential adsorption site of Au was observed. Increasing the Au:Pd ratio to 3 MLE Pd and 2 MLE Au results in nanoparticles that are enriched in Au at their surface, which exhibit a strong resistance towards encapsulation. Hence the degree of encapsulation of the nanoparticles during sintering can be controlled by tuning the Au:Pd ratio.

Methanol Reactivity on Silica-Supported Ceria Nanoparticles

Ceria (CeO2) has been used in a number of catalytic processes, either as a support or promoter. For a better understanding of the factors that control the reactivity of ceria, we have used well-ordered CeO2(111) films and ceria nanoparticles supported on an ordered SiO2 film, as model catalysts. The systems were examined in the dehydrogenation of methanol to formaldehyde as a test reaction by using the techniques of infrared spectroscopy and temperature programmed desorption. The results revealed low-temperature reactivity (below 450 K) for supported ceria particles that is not present on ordered films, which show reactivity at 565 K. The results indicate that low-coordinated sites play an important role in the methanol reactivity on ceria.

Poly(3-hydroxyoctanoate) depolymerase from Pseudomonas fluorescens GK13: Catalysis of ester-forming reactions in non-aqueous media

Abstract Several industrial processes based on lipase catalysis have been established. However, since there are still a vast number of catalytic processes that lack a suitable enzyme, the discovery of new biocatalysts is required to fulfil this purpose. The potential of using the medium-chain-length (mcl)-PHA depolymerase from Pseudomonas fluorescens GK13 in anhydrous media to catalyze ester-forming reactions has been investigated and compared with that of Novozyme 435. The mcl-PHA depolymerase catalyzes the ring-opening polymerization of racemic β-butyrolactone (β-BL), l - and d -lactide (LLA, DLA) with high yield resulting in low molecular weight polymers. On the other hand, ɛ-caprolactone and pentadecalactone, which show high polymerizability using Novozyme 435 as catalyst, were not polymerized by mcl-PHA depolymerase. Besides, the activity of mcl-PHA depolymerase toward transesterification and esterification of ethyl-3-hydroxyoctanoate, lauric acid, ( R , S )-β-BL, LLA and DLA has been studied.

Carbon nanotubes for catalytic applications

The unique properties of carbon nanotubes, a new class of nanomaterials, make them usable as catalyst supports for various reactions. A pilot reactor has been constructed for producing nanotubes. The nanotubes obtained in this reactor have displayed high performance in a number of catalytic processes. A continuous laboratory-scale reactor for the synthesis of binary and mixed oxide nanosized catalysts has been tested. Russia has everything necessary for organizing nanotube production.

Stereoselective Synthesis of Isoxazolidines through Pd‐Catalyzed Carboetherification of N‐Butenylhydroxylamines

Stereoselective Synthesis of Isoxazolidines through Pd‐Catalyzed Carboetherification of <i>N</i>‐Butenylhydroxylamines

Application of neutral amidines and guanidines in coordination chemistry

The aim of this perspective is to highlight the continued development and application of amidines and guanidines as neutral, N-based donor ligands in coordination chemistry. From a sporadic interest dating back to the 1980s, work on these two closely related classes of compounds has steadily grown, with examples of evermore sophisticated substitution about the common ligand framework being developed to address specific problems in a number of fields of chemistry. These compounds have shown varied coordination modes at metals from across the periodic table, and examples of their application in a number of catalytic processes are emerging as the field matures.

Catalysis by Gold/Platinum Group Metals

The recent surge of new interest in catalysis by gold (–) has led researchers to investigate the effects of adding other metals to the gold. As a result, there are a number of reactions with potential for industrial application where combinations of gold with a platinum group metal (pgm) have been shown to have advantages over either gold or the pgm alone. These findings are expected to lead to applications in chemical processing, pollution control and fuel cell applications. Here, a number of catalytic processes that have benefited from the synergy between a pgm and gold are described, and some interesting reports from recent conferences are highlighted.