Use In Continuous-flow Reactors Research Articles

Carbon-Supported and Shape-Controlled PtPd Nanocrystal Synthesis in Flowing Deep Eutectic Solvents for the Methanol Oxidation Reaction

Practical applications of advanced nanocrystals are limited by the lack of low-cost, scalable, and environmentally friendly manufacturing methods with consistent shape and size control. To address this challenge, we demonstrate here the use of continuous-flow reactors and environmentally benign deep eutectic solvents for the shape-controlled synthesis of intermetallic PtPd nanocrystals with almost exclusive octahedral shape and an average size of 12.8 nm within only 6 min of reaction time, much faster than conventional methods. The critical roles of solvent species were elucidated using a family of deep eutectic solvent combinations. We further demonstrate the direct growth of these shaped nanocrystals on carbon using a one-step process by harnessing their strong interactions with a Co- and N-codoped carbon surface, thus avoiding the mandatory additional catalyst separation and loading steps with conventional methods. The produced PtPd nanocrystals exhibited outstanding performance toward the electrooxidation of methanol and reached an activity of 201 mA mg–1 along with improved stability, confirming the promise of our method for scalable and low-cost manufacturing of shape-controlled electrocatalyst materials.

Scalability of U-Shape Magnetic Nanoparticles-Based Microreactor–Lipase-Catalyzed Preparative Scale Kinetic Resolutions of Drug-like Fragments

The production of active pharmaceutical ingredients (APIs) and fine chemicals is accelerating due to the advent of novel microreactors and new materials for immobilizing customized biocatalysts that permit long-term use in continuous-flow reactors. This work studied the scalability of a tunable U-shape magnetic nanoparticles (MNPs)-based microreactor. The reactor consisted of a polytetrafluoroethylene tube (PTFE) of various inner diameters (ID = 0.75 mm, 1.50 mm, or 2.15 mm) and six movable permanent magnets positioned under the tube to create reaction chambers allowing the fluid reaction mixture to flow through and above the enzyme-loaded MNPs anchored by permanent magnets. The microreactors with various tube sizes and MNP capacities were tested with the preparative scale kinetic resolution of the drug-like alcohols 4-(3,4-dihydroisoquinolin-2(1H)-yl)butan-2-ol (±)-1a and 4-(3,4-dihydroquinolin-1(2H)-yl)butan-2-ol (±)-1b, utilizing Lipase B from Candida antarctica immobilized covalently onto MNPs, leading to highly enantioenriched products [(R)-2a,b and (S)-1a,b]. The results in the U-shape MNP flow reactor were compared with reactions in the batch mode with CaLB-MNPs using similar conditions. Of the three different systems, the one with ID = 1.50 mm showed the best balance between the maximum loading capacity of biocatalysts in the reactor and the most effective cross-section area. The results showed that this U-shaped tubular microreactor might be a simple and flexible instrument for many processes in biocatalysis, providing an easy-to-set-up alternative to existing techniques.

Studies on the Continuous-Flow Synthesis of Nonpeptidal bis-Tetrahydrofuran Moiety of Darunavir

The use of continuous-flow chemistry has shown to be an important tool in improving API manufacture. In the present paper, we report the use of continuous-flow reactors in the synthesis of the bicyclic side chain of antiretroviral Darunavir.

Residence time distribution, a simple tool to understand the behaviour of polymeric mini-flow reactors

A simple method for the determination of the residence time distribution (RTD) of different polymer-based mini-flow reactors has been developed. The flow patterns have been adjusted employing the axial dispersion model, allowing a quantitative comparison of the flow patterns of the different structures. The use of different pulse tracer experiments highlights the differences in reactor behaviour depending on the nature (gel vs. macroporous) and shape (beads vs. monoliths) of the polymeric materials used in the reactor preparation. Thus, reactors based on monolithic columns showed a superior performance in terms of flow distribution when compared to commercial bead-shaped packed polymers of different sizes and backbone structure, confirming previous experimental results. These differences can help to understand the different catalytic efficiency detected for these mini-flow fixed-bed reactors. The model presented can help to properly design new processes based on the use of continuous flow reactors facilitated by functional materials, which is becoming an essential goal nowadays, in particular in the context of developing new efficient and clean technologies.

Improving chemical synthesis using flow reactors

Owing to the competitive nature of the pharmaceutical industry, researchers involved in lead compound generation are under continued pressure to identify and develop promising programmes of research in order to secure intellectual property. The potential of a compound for therapeutic development depends not only on structural complexity, but also on the identification of synthetic strategies that will enable the compound to be prepared on the desired scale. One approach that is of present interest to the pharmaceutical industry is the use of continuous flow reactors, with the flexible nature of the technology being particularly attractive as it bridges the changes in scale required between the initial identification of a target compound and its subsequent production. Based on these factors, a significant programme of research is presently underway into the development of flow reactors as tools for the synthetic chemist, with the transfer of many classes of reaction successfully reported to date. This article focuses on the application of continuous flow methodology to drug discovery and the subsequent production of pharmaceuticals.

Highlights in organic Chemictry [ Flow Reactors for Organic Synthesis

This review focuses on the use of continuous flow reactors as tools in synthetic organic chemistry and aims to highlight their many advantages, including their ability to synthesise products in high yield, purity and, where relevant, selectivity. Keywords: Gas Phase Reactions, Biphasic Reactions, Stereoselective Synthesis, Rapid Reaction Optimisation, micro channel

A new type of highly active polymer-bound rhodium hydroformylation catalyst

A new route of attaching phosphites to a (co)polymer chain is described. These copolymers are used for the preparation of a rhodium phosphite hydroformylation catalyst. The catalytic activity of this polymer-bound system is identical to that of the low molecular weight analogue. The catalysts show a high activity towards the hydroformylation of the otherwise unreactive cyclooctene. From spectroscopic and kinetic data, it was found that only one phosphite is coordinated to the rhodium complex in its active form. An equilibrium between this complex and an inactive complex without phosphite ligands, prohibits its use in continuous flow reactors.