Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor

• Pengcheng Li,
• Daniel Kowalczyk,
• Johannes Liessem,
• Mohamed M. Elnagar,
• Dariusz Mitoraj,
• Radim Beranek and
• Dirk Ziegenbalg

Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9

• operation of the reactor design concept of a guided inner circulation around the draft tube. Figure 4 shows the red channel values of ROIs for the mixing experiments with different stirring speeds (430, 560, 740, and 860 rpm). The mixing time in the draft tube only slightly depends on the stirring speed

• active materials. Experimental Reactor design The design parameters for the loop photoreactor are based on the optimal design parameters suggested by Blenke et al. [44]. The draft tube diameter is adjusted to achieve maximal mass transfer in the reactor [45][46][47][48]. The design parameters used in

• ) AQE for differrent photocatalyst loadings and stirring speeds. Reactor design: (a) CAD drawing of the loop reactor, (b) picture of the manufactured loop reactor. Assembled reactor and 3D printed parts: (a) the whole reactor setup, (b) 3D printed propellers. Photocatalytic reaction setup: (a) reaction

Anion–π catalysis on carbon allotropes

• M. Ángeles Gutiérrez López,
• Mei-Ling Tan,
• Giacomo Renno,
• Augustina Jozeliūnaitė,
• J. Jonathan Nué-Martinez,
• Javier Lopez-Andarias,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2023, 19, 1881–1894, doi:10.3762/bjoc.19.140

• , catalyst inactivation with 70 in formal complex 71 and product 69 in formal complex 72 supports anion-π catalysis but not autocatalysis. (B) Electric-field-induced anion–π catalysis on MWCNTs 3 in electrochemical microfluidic reactors, with reactor design (C) and notional transition states for ether

• International License, https://creativecommons.org/licenses/by/4.0). Electric-field-induced anion–π catalysis on MWCNTs 3 on graphite 76 in electrochemical microfluidic reactors, with reactor design (A) and notional transition states for ether cyclization of 68 at positive (XX) and zero voltage (XXI) on

Modern flow chemistry – prospect and advantage

• Philipp Heretsch

Beilstein J. Org. Chem. 2023, 19, 33–35, doi:10.3762/bjoc.19.3

• Philipp Heretsch Institute of Organic Chemistry, Leibniz Universität Hannover, Schneiderberg 1B, 30167 Hannover, Germany 10.3762/bjoc.19.3 Keywords: flow chemistry; method development; reactor design; Organic chemistry has shaped modern society by fulfilling the basic needs for pharmaceuticals

• application, rendering this technology rather a supportive tool than a general solution [15]. Still, having this option available significantly lowers the barrier of inventing novel technological solutions and allows for high-throughput optimization in reactor design. Since different types of reactions

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• flow [118]. The condensation of a range of aromatic aldehydes with acetone were again studied, with p-anisaldehyde (23) being used for scale-up. A simple reactor design based upon Teflon® tubing (8 mm inner diameter) was used in conjunction with static mixing elements as shown in Scheme 13, allowing

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

• sequestration [7]. Still, photochemistry has not been exploited much in industry since the distribution of light inside a photoreactor brings a lot of complexity to the reactor design. Unlike thermochemical reactions, it is not feasible to scale up photoreactions by increasing the dimensions of the reactor due

• c0 is the initial concentration, c the concentration at the end of the reaction, and τ the residence time. The comparison of the reaction rate constants for different reactor types, such as a photomicroreactor and a batch photoreactor are often used to point out how much the reactor design could

• successful scale-up strategies in literature. Design considerations The complexity of the photochemical processes leads to significant challenges in the photoreactor design. In addition to the general reactor design considerations, such as the selection of a suitable reactor material and geometry, the

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• some interesting reactor designs that could be implemented to enhance organic synthesis. Keywords: air purification; flow chemistry; heterogeneous photoredox catalysis; organic synthesis; reactor design; water purification; Review 1 Introduction 1.1 Scope of the review This review aims to be of

• , materials science, and physics, in addition to chemistry (Figure 1B). This reflects the multiplex nature of photocatalysis as it requires an advanced chemical and photophysical theory to rationalise its complex mechanisms, as well as skilled engineering and reactor design to overcome the limitations of

• mass transport limitations, the circumstance in which a process becomes diffusion-limited and independent of the catalyst efficiency [43]. This is often thought of as an “engineering problem” by chemists, which will be solved through the reactor design [52], but smart design of the HPCat structure and

A concise flow synthesis of indole-3-carboxylic ester and its derivatisation to an auxin mimic

• Marcus Baumann,
• Ian R. Baxendale and
• Fabien Deplante

Beilstein J. Org. Chem. 2017, 13, 2549–2560, doi:10.3762/bjoc.13.251

• reactor – Cambridge Reactor Design). The system pressure was controlled using a 75 psi inline back pressure regulator. The flow stream was quenched by mixing with a solution of hydrochloric acid (1 M) at a flow rate of 2 mL/min within a glass microreactor (1 mL, Little Things Factory). The biphasic

• Reactor Design, residence time 40 min). A 100 psi inline back pressure regulator was positioned prior to the exit. Collection of the reactor output allowed isolation of the title compound in 81% isolated yield following column silica chromatography (DCM/MeOH 9:1). 1H NMR (400 MHz, DMSO-d6) δ 11.42 (br. s

• two stock solutions were pumped (0.65 mL/min each channel) from their respective reservoirs to combine at a PEEK T-piece and were then directed through a FEP flow coil (52 mL maintained at 100 °C using a Polar Bear Plus reactor – Cambridge Reactor Design, residence time 40 min). A 100 psi inline back

One-pot multistep mechanochemical synthesis of fluorinated pyrazolones

• Joseph L. Howard,
• William Nicholson,
• Yerbol Sagatov and
• Duncan L. Browne

Beilstein J. Org. Chem. 2017, 13, 1950–1956, doi:10.3762/bjoc.13.189

• . thanks Cambridge Reactor Design for a Ph.D. award to J. L. H., the Bolashak International Scholarship of the President of the Republic of Kazakhstan for a Scholarship award to Y. S., the EPSRC First Grant Scheme for funding (D.L.B. EP/P002951/1) and the School of Chemistry at Cardiff University for

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

• Carmen Moreno-Marrodan,
• Francesca Liguori and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• to August 2016 are discussed in terms of reactor design. A comparison with batch and industrial processes is provided whenever possible. Keywords: alkynes; heterogeneous catalysis: hydrogenation; flow; liquid-phase; Introduction The catalytic partial hydrogenation of alkynes to alkenes in the

• different variables, i.e., the metal catalyst involved, the type of support material, the reactor design or the hydrogen source. We decided to break down the manuscript on the basis of the substrates examined in order to allow an easier comparison among different reactors performance and highlight the

• from a diffusion-controlled to kinetic-limited regime [163][181]. The non-accumulation of co-products adsorbed on the catalyst surface may also significantly contribute to the minimization of active site inhibition under the conditions of continuous flow [27]. Flow reactor design. Performance

3D printed fluidics with embedded analytic functionality for automated reaction optimisation

• Andrew J. Capel,
• Andrew Wright,
• Matthew J. Harding,
• George W. Weaver,
• Yuqi Li,
• Russell A. Harris,
• Steve Edmondson,
• Ruth D. Goodridge and
• Steven D. R. Christie

Beilstein J. Org. Chem. 2017, 13, 111–119, doi:10.3762/bjoc.13.14

• system and reactor design necessitated the generation of an idealised set of reaction conditions, allowing effective comparison of data sets. This reaction was the conversion of (R)-(−)-carvone (1) to its corresponding semicarbazone 2, using semicarbazide and sodium acetate (Scheme 1). This reaction was

• optimization. Reactor design 1 (RD1) By mimicking the internal dimensions of the DAD compartment within an Agilent HPLC system, an inline spectroscopic flow cell could be realised (Figure 1). RD1 was therefore fabricated using a 3D Systems Viper si2 SL system from Accura 60 photoresin, with external geometries

• device (see RD2 below). Reactor design 2 (RD2) Agilent HPLC systems are equipped with two programmable temperature controlled column compartments, which allow temperatures to be independently heated up to 100 °C and simultaneously selected by the user. This will allow a bespoke chemical reactor to be

Flow carbonylation of sterically hindered ortho-substituted iodoarenes

• Carl J. Mallia,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1503–1511, doi:10.3762/bjoc.12.147

• -liquid unit was attached to a commercial flow system; Vapourtec R2+ Series along with an R4 heating unit. Having established the reactor design, we next used 2-chloro-1-iodobenzene (4) as a model substrate for screening and identification of a set of general reaction conditions (Scheme 2). Initially, a

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• to the related batch scenarios which were difficult to control. Owing to the importance of efficient micro-mixing attainable in continuous processing another interesting reactor design coined as a ‘continuous oscillatory baffled reactor’ (COBR) was introduced. In this set-up the reactor stream being

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• process costs are the major requirement for potential large scale implementation. Some parameters that influence these costs are current efficiency, reactor design, electrode material and reactant costs. Electrocarboxylation setups All electrochemical processes involve an anodic and cathodic reaction in

One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor

• Mark C. Bagley,
• Vincenzo Fusillo,
• Robert L. Jenkins,
• M. Caterina Lubinu and
• Christopher Mason

Beilstein J. Org. Chem. 2013, 9, 1957–1968, doi:10.3762/bjoc.9.232

• microwave flow chemistry, is realizing its potential towards the next evolutionary step in synthetic chemistry [43]. In 2005 we described a new continuous flow reactor design for microwave-assisted synthesis that operates in the optimum standing-wave cavity of a proprietary instrument [44]. The principal

• favourably with microwave-heated batch experiments. For dihydropyrimidinone 8, a flow rate of 2 mL min–1 delivered a very respectable processing rate of 25 g h–1. Following the success of this reactor design in delivering pyridine and pyrimidine heterocycles, albeit from very different processes, and the

Camera-enabled techniques for organic synthesis

• Steven V. Ley,
• Richard J. Ingham,
• Matthew O’Brien and
• Duncan L. Browne

Beilstein J. Org. Chem. 2013, 9, 1051–1072, doi:10.3762/bjoc.9.118

• amination reactions [53][54], photodimerization studies [55], MnO2 oxidations [56] and during phase-transfer reactions [57]. The use of high-resolution cameras to specifically examine physical effects during the merging of sonochemistry and microfluidic techniques, leading to improved reactor design, was

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• emission from most common light sources. Even LEDs, which can be considered as planar light sources, often have a beam width wider than the actual channels; however, this issue could easily be addressed by a more directed reactor design. As a result microflow reactors are often inefficient at capturing

Continuous gas/liquid–liquid/liquid flow synthesis of 4-fluoropyrazole derivatives by selective direct fluorination

• Jessica R. Breen,
• Graham Sandford,
• Dmitrii S. Yufit,
• Judith A. K. Howard,
• Jonathan Fray and
• Bhairavi Patel

Beilstein J. Org. Chem. 2011, 7, 1048–1054, doi:10.3762/bjoc.7.120

• previous direct fluorination reactions using this reactor design. The hydrazine solution was added by a syringe pump, via a T-piece at Input C, into the liquid flow, which was carried along the flow reaction channel by the pressure of the accompanying nitrogen gas. The crude reaction mixture was then

Flow through reactors for organic chemistry: directly electrically heated tubular mini reactors as an enabling technology for organic synthesis

• Ulrich Kunz and
• Thomas Turek

Beilstein J. Org. Chem. 2009, 5, No. 70, doi:10.3762/bjoc.5.70

• reactor design it is necessary to know the specific electric resistance. A value of 0.724 Ω mm2 m−1 was measured at 25 °C. Before the reactor was used for reaction experiments the electric power consumption was estimated. For this purpose a flow of 10 mL water per min was pumped through the tube and the

Gold film- catalysed benzannulation by Microwave- Assisted, Continuous Flow Organic Synthesis (MACOS)

• Gjergji Shore,
• Michael Tsimerman and
• Michael G. Organ

Beilstein J. Org. Chem. 2009, 5, No. 35, doi:10.3762/bjoc.5.35

• very large quantities is not yet attainable with the current reactor design, the device is very suitable for preparing library collections of 50–750 mg of product for evaluation in medicinal chemistry or materials science applications. Conclusion Glass capillaries internally-lined with thin-metal films

Polyionic polymers – heterogeneous media for metal nanoparticles as catalyst in Suzuki–Miyaura and Heck–Mizoroki reactions under flow conditions

• Klaas Mennecke and
• Andreas Kirschning

Beilstein J. Org. Chem. 2009, 5, No. 21, doi:10.3762/bjoc.5.21

• 397/6-1). We are grateful to U. Kunz (Institute of Chemical Engineering, Technical University of Clausthal, Germany) for supporting us in all issues concerning flow reactor design. Note added in proof In a detailed study McQuade and coworker demonstrated that PdEnCat 30 also behaves as heterogeneous