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Search for "packed bed" in Full Text gives 40 result(s) in Beilstein Journal of Organic Chemistry.

Investigating the continuous synthesis of a nicotinonitrile precursor to nevirapine

  • Ashley R. Longstreet,
  • Suzanne M. Opalka,
  • Brian S. Campbell,
  • B. Frank Gupton and
  • D. Tyler McQuade

Beilstein J. Org. Chem. 2013, 9, 2570–2578, doi:10.3762/bjoc.9.292

Graphical Abstract
  • included two columns: a packed-bed of Al2O3 to catalyze the reaction and a packed bed of 3 Å molecular sieves to absorb water before the addition of DMF-DMA (Scheme 4). The mass of each solid used (2.00 g of Al2O3 and 1.50 g molecular sieves) was chosen based on the size of the available columns. Assuming
  • the acetic anhydride and DMF-DMA (Scheme 4). While the higher the concentration the better, our prior efforts have revealed that packed-bed catalyst stability can rapidly decline at high concentrations while at lower concentrations can run for an extended length of time [44]. With this in mind, we
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Published 20 Nov 2013

Biosynthesis of rare hexoses using microorganisms and related enzymes

  • Zijie Li,
  • Yahui Gao,
  • Hideki Nakanishi,
  • Xiaodong Gao and
  • Li Cai

Beilstein J. Org. Chem. 2013, 9, 2434–2445, doi:10.3762/bjoc.9.281

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  • stable immobilized A. tumefaciens DPEase system containing borate [33]. It could generate 441 g/L D-psicose from 700 g/L D-fructose for one batch, and the reaction performed in a packed-bed bioreactor could continuously produce 325 g/L D-psicose from 500 g/L D-fructose over a long time period. Zhang et
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Published 12 Nov 2013

Flow synthesis of phenylserine using threonine aldolase immobilized on Eupergit support

  • Jagdish D. Tibhe,
  • Hui Fu,
  • Timothy Noël,
  • Qi Wang,
  • Jan Meuldijk and
  • Volker Hessel

Beilstein J. Org. Chem. 2013, 9, 2168–2179, doi:10.3762/bjoc.9.254

Graphical Abstract
  • aldolase (TA) from Thermotoga maritima was immobilized on an Eupergit support by both a direct and an indirect method. The incubation time for the direct immobilization method was optimized for the highest amount of enzyme on the support. By introducing the immobilized TA in a packed-bed microreactor, a
  • flow synthesis of phenylserine was developed, and the effects of temperature and residence time were studied in particular. Calculations of the Damköhler number revealed that no mass transfer limitations are given in the micro-interstices of the packed bed. The yield does not exceed 40% and can be
  • support. In continuation of our previous work [48], this paper includes further investigation of the thermal stability of TA on Eupergit by a so-called direct and indirect method. Also, a flow synthesis of Eupergit-immobilized TA in a packed bed microreactor was established and compared to the use of free
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Published 22 Oct 2013

Flow synthesis of a versatile fructosamine mimic and quenching studies of a fructose transport probe

  • Matthew B. Plutschack,
  • D. Tyler McQuade,
  • Giulio Valenti and
  • Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 2022–2027, doi:10.3762/bjoc.9.238

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  • flow chemistry challenge. The output from the oxime step contains excess hydroxylamine and salts carried from the first step that poisoned the packed-bed catalyst we screened. In theory, continuous purification could remove these materials but existing strategies do not enable removal of water soluble
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Published 07 Oct 2013

Gallium-containing polymer brush film as efficient supported Lewis acid catalyst in a glass microreactor

  • Rajesh Munirathinam,
  • Roberto Ricciardi,
  • Richard J. M. Egberink,
  • Jurriaan Huskens,
  • Michael Holtkamp,
  • Herbert Wormeester,
  • Uwe Karst and
  • Willem Verboom

Beilstein J. Org. Chem. 2013, 9, 1698–1704, doi:10.3762/bjoc.9.194

Graphical Abstract
  • . a) with a packed-bed microreactor, where the catalyst is attached to a polymeric material enclosed in the microchannel [5], and b) when the catalyst is covalently connected to the inner walls of a glass microreactor [6]. Although the former approach has advantages such as high catalyst loading and
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Published 16 Aug 2013

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

  • Rahat Javaid,
  • Shin-ichiro Kawasaki,
  • Akira Suzuki and
  • Toshishige M. Suzuki

Beilstein J. Org. Chem. 2013, 9, 1156–1163, doi:10.3762/bjoc.9.129

Graphical Abstract
  • thin (1–2 μm) palladium (Pd), platinum (Pt), and rhodium (Rh) layers by an electroless plating procedure [10][11]. These tubular reactors combined the merit of flow reaction processing with the catalytic properties of various metals. Unlike packed-bed catalysts, hollow tubular reactors can minimize the
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Published 14 Jun 2013

Continuous proline catalysis via leaching of solid proline

  • Suzanne M. Opalka,
  • Ashley R. Longstreet and
  • D. Tyler McQuade

Beilstein J. Org. Chem. 2011, 7, 1671–1679, doi:10.3762/bjoc.7.197

Graphical Abstract
  • homogeneous catalyst can be prepared continuously via reaction with a packed-bed of a catalyst precursor. Specifically, we perform continuous proline catalyzed α-aminoxylations using a packed-bed of L-proline. The system relies on a multistep sequence in which an aldehyde and thiourea additive are passed
  • through a column of solid proline, presumably forming a soluble oxazolidinone intermediate. This transports a catalytic amount of proline from the packed-bed into the reactor coil for subsequent combination with a solution of nitrosobenzene, affording the desired optically active α-aminooxy alcohol after
  • reduction. To our knowledge, this is the first example in which a homogeneous catalyst is produced continuously using a packed-bed. We predict that the method will not only be useful for other L-proline catalyzed reactions, but we also foresee that it could be used to produce other catalytic species in flow
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Published 14 Dec 2011

Continuous-flow enantioselective α-aminoxylation of aldehydes catalyzed by a polystyrene-immobilized hydroxyproline

  • Xacobe C. Cambeiro,
  • Rafael Martín-Rapún,
  • Pedro O. Miranda,
  • Sonia Sayalero,
  • Esther Alza,
  • Patricia Llanes and
  • Miquel A. Pericàs

Beilstein J. Org. Chem. 2011, 7, 1486–1493, doi:10.3762/bjoc.7.172

Graphical Abstract
  • Franqués, 1. E-08028, Barcelona, Spain 10.3762/bjoc.7.172 Abstract The application of polystyrene-immobilized proline-based catalysts in packed-bed reactors for the continuous-flow, direct, enantioselective α-aminoxylation of aldehydes is described. The system allows the easy preparation of a series of β
  • -aminoxy alcohols (after a reductive workup) with excellent optical purity and with an effective catalyst loading of ca. 2.5% (four-fold reduction compared to the batch process) working at residence times of ca. 5 min. Keywords: α-aminoxylation; continuous flow; packed-bed reactors; polystyrene
  • chemistry with solid-supported catalysts allows the advantages inherent to both technologies to be added together. Thus, the physical immobilization of the catalyst in a packed-bed reactor allows it to be submitted constantly to the reaction conditions, avoiding possible degradation of the catalyst during
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Published 31 Oct 2011

Coupled chemo(enzymatic) reactions in continuous flow

  • Ruslan Yuryev,
  • Simon Strompen and
  • Andreas Liese

Beilstein J. Org. Chem. 2011, 7, 1449–1467, doi:10.3762/bjoc.7.169

Graphical Abstract
  • ). The coupled reaction is carried out in a continuously operated packed-bed microreactor. As compared to the batch-mode experiments, higher concentrations of H2O2 were applied without detectable catalyst deactivation after 24 hours. At 100% conversion, a space-time yield of 646 g L−1 day−1 was obtained
  • . Lozano and coworkers reported on a continuous, chemoenzymatic dynamic kinetic resolution (DKR) process for the production of (R)-1-phenylethyl propionate (24) from (rac)-1-phenylethanol (22) and vinyl propionate (23) (Scheme 8) [29][30][31]. In a multiphase packed-bed reactor, commercially available
  • chemocatalyst from the lipase by spatial separation in a single column [29] or in consecutive packed-bed reactors [31], however, similarly allowed the process to be efficiently run with high enantiomeric excesses of up to 99%, but with a reduced yield of 60%. A reaction sequence for the continuous synthesis of
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Published 24 Oct 2011

Multistep flow synthesis of vinyl azides and their use in the copper-catalyzed Huisgen-type cycloaddition under inductive-heating conditions

  • Lukas Kupracz,
  • Jan Hartwig,
  • Jens Wegner,
  • Sascha Ceylan and
  • Andreas Kirschning

Beilstein J. Org. Chem. 2011, 7, 1441–1448, doi:10.3762/bjoc.7.168

Graphical Abstract
  • good yield. The third step involves the formation of vinyl triazoles by a copper-catalyzed Huisgen-"click" cycloaddition. The required heat is generated by electromagnetic induction based on copper. Copper serves both as heatable as well as catalytically active packed-bed material inside the flow
  • conditions. Results and Discussion Synthesis of vinyl azides Our study commenced with the preparation and utilization of polymer-bound iodate(I) complex 5 as packed-bed material in a flow device. Here, the polymer served as an electrophilic reagent for the mild 1,2-azidoiodination of alkenes under flow
  • employing two functionalized polymers that served as a packed-bed material inside the reactor. Additionally, we showed that copper-catalyzed vinyl triazole formation of these vinyl azides in the presence of alkynes is possible by using elemental copper as an inductively heatable material. The method avoids
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Published 20 Oct 2011

Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

  • M. Isabel Burguete,
  • Eduardo García-Verdugo and
  • Santiago V. Luis

Beilstein J. Org. Chem. 2011, 7, 1347–1359, doi:10.3762/bjoc.7.159

Graphical Abstract
  • . Since an excess of vinyl acetate was used, all of the PEG 1500 was also acylated. A different approach was developed by Lozano et al. In their case, a thin layer of an IL phase containing the enzyme was created on the surface of silica and the resulting material was used in a packed-bed reactor, using
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Published 30 Sep 2011

Evaluation of a commercial packed bed flow hydrogenator for reaction screening, optimization, and synthesis

  • Marian C. Bryan,
  • David Wernick,
  • Christopher D. Hein,
  • James V. Petersen,
  • John W. Eschelbach and
  • Elizabeth M. Doherty

Beilstein J. Org. Chem. 2011, 7, 1141–1149, doi:10.3762/bjoc.7.132

Graphical Abstract
  • the ThalesNano H-Cube®, a commercial packed bed flow hydrogenator, was evaluated in the context of small scale reaction screening and optimization. A model reaction, the reduction of styrene to ethylbenzene through a 10% Pd/C catalyst bed, was used to examine performance at various pressure settings
  • run-to-run reproducibility of the H-Cube® reactor for screening and reaction optimization is discussed. Keywords: catalyst leaching; CatCart®; H-Cube®; packed bed flow hydrogenation; Introduction The potential advantages of heterogeneous catalytic flow hydrogenation over traditional batch reactor
  • hydrogenators, such as a Pd-immobilized 200 micron glass channel [2], a simple Pd/C packed bed bubble column reactor [3] and, more recently, a unique glass column packed bed system that introduces hydrogen across a Teflon-AF membrane [4]. In 2004, ThalesNano Inc. [5] was the first manufacturer to commercialize
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Published 22 Aug 2011

From discovery to production: Scale- out of continuous flow meso reactors

  • Peter Styring and
  • Ana I. R. Parracho

Beilstein J. Org. Chem. 2009, 5, No. 29, doi:10.3762/bjoc.5.29

Graphical Abstract
  • ) based on 4-bromoanisole. However, the TOF was significantly reduced from the reaction carried out at half the flow rate (1.5 h−1). It should be noted that the TOFs in flow reactors are lower than in batch as we are dealing with small flows through a packed bed reactor and hence the catalyst
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Published 09 Jun 2009

The development and evaluation of a continuous flow process for the lipase- mediated oxidation of alkenes

  • Charlotte Wiles,
  • Marcus J. Hammond and
  • Paul Watts

Beilstein J. Org. Chem. 2009, 5, No. 27, doi:10.3762/bjoc.5.27

Graphical Abstract
  • conducted by pumping a pre-mixed solution of the alkene 6 and UHP (3) through the packed-bed using a syringe pump. The reaction products were collected in a sample vial containing EtOAc (1 ml) over a period of 10 min, and analysed by GC-MS in order to quantify the conversion of 1-methylcyclohexene (6) to 1
  • oxidation of 1-methylcyclohexene (6) had occurred, albeit in low conversion (5.1%). Varying the flow rate of the reactant solution through the packed bed between 0.1 and 50 μl min−1, at 27 °C, enabled us to identify 0.1 μl min−1 (4.3 h residence time) as the optimum flow rate for the synthesis of 1
  • result of employing a packed-bed reactor and to exclude the possibility that the reaction was continuing within the collection vial, as only the hydrolysis and perhydrolysis steps were enzyme catalysed, five samples were analysed immediately and then subjected to re-analysis 5 h later. Analogous results
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Published 02 Jun 2009

A biphasic oxidation of alcohols to aldehydes and ketones using a simplified packed- bed microreactor

  • Andrew Bogdan and
  • D. Tyler McQuade

Beilstein J. Org. Chem. 2009, 5, No. 17, doi:10.3762/bjoc.5.17

Graphical Abstract
  • characterization of a simplified packed-bed microreactor using an immobilized TEMPO catalyst shown to oxidize primary and secondary alcohols via the biphasic Anelli-Montanari protocol. Oxidations occurred in high yields with great stability over time. We observed that plugs of aqueous oxidant and organic alcohol
  • entered the reactor as plugs but merged into an emulsion on the packed-bed. The emulsion coalesced into larger plugs upon exiting the reactor, leaving the organic product separate from the aqueous by-products. Furthermore, the microreactor oxidized a wide range of alcohols and remained active in excess of
  • potential as continuous flow processes. Realizing this, we developed a catalytic packed-bed microreactor that could be used for the continuous flow oxidation of alcohols to aldehydes or ketones. Oxidations that do not require transition metal catalysts are particularly appealing since there is neither
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Published 29 Apr 2009
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