Room‐Temperature Swern Oxidations by Using a Microscale Flow System

Kawaguchi, Tatsuya; Miyata, Hiroyuki; Ataka, Kikuo; Mae, Kazuhiro; Yoshida, Jun‐ichi

doi:10.1002/anie.200462466

Cited by 216 publications

(61 citation statements)

References 34 publications

(1 reference statement)

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“…The Moffatt-Swern type oxidation, i.e., oxidation with dimethyl sulfoxide, is used for the conversion of alcohols to carbonyl compounds, which requires activation of DMSO by trifluoroacetic anhydride [99], Scheme 13.…”

Section: Swern Oxidationmentioning

confidence: 99%

Novel Process Windows – Gate to Maximizing Process Intensification via Flow Chemistry

2009

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Driven by the economics of scale, the size of reaction vessels as the major processing apparatus of the chemical industry has became bigger and bigger [1,2]. Consequently, the efforts for ensuring mixing and heat transfer have also increased, as these are scale dependent. This has brought vessel operation to (partly severe) technical limits, especially when controlling harsh conditions, e.g., due to large heat releases. Accordingly, processing at a very large scale has resulted in taming of the chemistry involved in order to slow it down to a technically controllable level. Therefore, reaction paths that already turned out too aggressive at the laboratory scale are automatically excluded for later scale-up, which constitutes a common everyday confinement in exploiting chemical transformations. Organic chemists are barely conscious that even the small-scale laboratory protocols in their textbooks contain many slow, disciplined chemical reactions. Operations such as adding a reactant drop by drop in a large diluted solvent volume have become second nature, but are not intrinsic to the good engineering of chemical reactions. These are intrinsic to the chemical apparatus used in the past. In contrast, today's process intensification [3][4][5][6][7][8][9][10][11][12] and the new flow-chemistry reactors on the micro-and milli-scale allow such limitations to be overcome, and thus, enable a complete, ab-initio type rethinking of the processes themselves. In this way, space-time yields and the productivity of the reactor can be increased by orders of magnitude and other dramatic performance step changes can be achieved. A hand-in-hand design of the reactors and process re-thinking is required to enable chemistry rather than subduing chemistry around the reactor [40]. This often leads to making use of process conditions far from conventional practice, under harsh environments, a procedure named here as Novel Process Windows. Starting Point: Novel Process WindowsIntensify Rather than OptimizeThe aim of the following introductory remarks, and the paper as whole, is to make sensible -while everyone in the field would agree that microstructured reactors and micro-process technology [3-12] form a major direction within process intensification -that the exploitation of such innovation can still profit considerably by joining both concepts. It is frequently thought that the use of a microstructured reactor automatically and implicitly results in process intensification; simply because this is a major direction within process intensification and since the latter is also concerned with apparatus developments. This is only partly true and actually ignores significant chances for process breakthrough. In many investigations, the use of a microstructured reactor is still more concerned with process optimization, which is involves a slight to moderate improvement of processes using classical paths, in particular with the same or similar chemical and processing protocol. Often, the most radical and innovative step is the

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Section: Swern Oxidationmentioning

confidence: 99%

Novel Process Windows – Gate to Maximizing Process Intensification via Flow Chemistry

2009

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“…Multistep syntheses including unstable intermediates using microreactors with enhanced desired product yield and selectivity have been conducted. Swern oxidation [1], synthesis of diarylethenes [2], and sequential Br-Li exchange reactions of p-, m-, and o-dibromobenzenes [3,4] are examples of such syntheses. In these syntheses, however, multiple micromixers are connected by tube, and the mixers and tubes are soaked in a cooling bath.…”

Section: Introductionmentioning

confidence: 99%

Microreactor for Synthesis Via Intermediates with Assembled Units Enabling Rapid Operations

et al. 2008

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This paper describes a reactor for multistep syntheses via intermediates with improved selectivity of the desired product. This reactor is referred to as an assembled reactor. It consists of mixing, residence time, and heat exchange units. Connection of these units forms a module for a single reaction. Repeated joints of these modules enable the reactor to be used in multistep syntheses. Mixing and the heat transfer rate of the assembled reactor were evaluated. This reactor enabled rapid mixing under the total flow rates of more than 30 mL/min and heat transfer efficiency of the order of 10 K per 10 ms in the heat exchange of fluids with a temperature difference of 20-40 K. This reactor was also applied to the synthesis of bromobenzene via p-bromophenyllithium and gave a product yield of more than 80 %.

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“…Kawaguchi et al investigated this reaction at temperatures between −20 to 20°C in a microreactor. 31 The results showed that the microreactor yields were much higher than the batch yields (from 20% to 89%) at a very short residence time of 0.01 s. Trachsel In the present work, the cycloaddition of PO and CO 2 to PC is chosen as a model reaction and was investigated in the microreactor using the HETBAB ionic liquid catalyst. The main aim is to verify the feasibility of the cycloaddition of PO and CO 2 to PC in the microreactor, decrease the reaction time from hours in batch reactors to seconds, and improve the process efficiency (TOF and STY) by process intensification.…”

Section: Etcmentioning

confidence: 92%

Highly efficient synthesis of cyclic carbonate with CO₂catalyzed by ionic liquid in a microreactor

et al. 2013

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The development of highly efficient processes for the cycloaddition of CO 2 with epoxides to produce five-membered cyclic carbonates is a very attractive topic. In this work, the cycloaddition of propylene oxide (PO) and CO 2 to give propylene carbonate (PC) is studied in a microreactor using a HETBAB ionic liquid catalyst. The microreactor performance is evaluated by studying the effects of different operating conditions, including reaction temperature, operating pressure, residence time, molar ratio of CO 2 /PO, and the catalyst concentration in PO. The process characteristics of the reaction concerning the gas-liquid mass transfer and the intrinsic kinetics perspectives are discussed. The results show that the residence time can be dramatically reduced from several hours in a conventional stirred reactor to about 10 s in a microreactor. The yield of PC at 3.5 MPa can reach 99.8% at a residence time of 14 s. The turnover frequency (TOF) value varies in the range of 3000 to 14 000 h −1 compared to 60 h −1 in the conventional stirred reactor. The space time yield (STY) or the overall reaction rate ranges from 650 to 4500 g prod. (g cat. h) −1 , which is much larger than the value [ca. 19 g prod. (g cat. h) −1 ] for the conventional stirred reactor. To some extent, the present study has also demonstrated the concept of 'Novel Process Windows'.

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Room‐Temperature Swern Oxidations by Using a Microscale Flow System

Cited by 216 publications

References 34 publications

Novel Process Windows – Gate to Maximizing Process Intensification via Flow Chemistry

Novel Process Windows – Gate to Maximizing Process Intensification via Flow Chemistry

Microreactor for Synthesis Via Intermediates with Assembled Units Enabling Rapid Operations

Highly efficient synthesis of cyclic carbonate with CO₂catalyzed by ionic liquid in a microreactor

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Room‐Temperature Swern Oxidations by Using a Microscale Flow System

Cited by 216 publications

References 34 publications

Novel Process Windows – Gate to Maximizing Process Intensification via Flow Chemistry

Novel Process Windows – Gate to Maximizing Process Intensification via Flow Chemistry

Microreactor for Synthesis Via Intermediates with Assembled Units Enabling Rapid Operations

Highly efficient synthesis of cyclic carbonate with CO2catalyzed by ionic liquid in a microreactor

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Highly efficient synthesis of cyclic carbonate with CO₂catalyzed by ionic liquid in a microreactor