Development and Applications of a Practical Continuous Flow Microwave Cell

Wilson, Noel S.; Sarko, and Christopher R.; Roth, Gregory P.

doi:10.1021/op034181b

Cited by 115 publications

(74 citation statements)

References 9 publications

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“…Several other similar continuous organic synthesis microwave reactors have been reported. [152][153][154][155] There are few examples of continuous microwave reactors for the synthesis of inorganic materials, namely porous oxides such as zeolites. Braun et al [156] described the synthesis of AlPO 4 zeolites using a continuous tube reactor.…”

Section: Continuous Processingmentioning

confidence: 99%

Microwave Synthesis of Nanoporous Materials

2006

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Studies in the last decade suggest that microwave energy may have a unique ability to influence chemical processes. These include chemical and materials syntheses as well as separations. Specifically, recent studies have documented a significantly reduced time for fabricating zeolites, mixed oxide and mesoporous molecular sieves by employing microwave energy. In many cases, microwave syntheses have proven to synthesize new nanoporous structures. By reducing the times by over an order of magnitude, continuous production would be possible to replace batch synthesis. This lowering of the cost would make more nanoporous materials readily available for many chemical, environmental, and biological applications. Further, microwave syntheses have often proven to create more uniform (defect-free) products than from conventional hydrothermal synthesis. However, the mechanism and engineering for the enhanced rates of syntheses are unknown. We review the many studies that have demonstrated the enhanced syntheses of nanoporous oxides and analyze the proposals to explain differences in microwave reactions. Finally, the microwave reactor engineering is discussed, as it explains the discrepancies between many microwave studies.

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Section: Continuous Processingmentioning

confidence: 99%

Microwave Synthesis of Nanoporous Materials

2006

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“…The high-temperature continuous-flow conditions introduced herein for the Suzuki-Miyaura cross-coupling involving an aryl chloride compare favourably with the throughput achieved in previous continuous-flow Suzuki-Miyaura reactions. [21,22] For the selective reduction of the nitro group in 4'-chloro-2-nitrobiphenyl (3) we have envisaged a heteroA C H T U N G T R E N N U N G geneous transition metal-catalyzed hydrogenation protocol as these methods generally can be easily transformed into a scalable continuous-flow process employing a fixed-bed catalyst reactor. [23] To the best of our knowledge, in the context of the synthesis of Boscalid such an approach has never been considered, and most of the published methods employ more traditional reducing agents such as SnCl 2 [10,12] or Fe/NH 4 Cl.…”

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confidence: 99%

Toward a Continuous‐Flow Synthesis of Boscalid^®

2010

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A two-step continuous-flow protocol for the synthesis of 2-amino-4'-chlorobiphenyl, a key intermediate for the industrial preparation of the fungicide Boscalid is described. Initial tetrakis(triphenylphosphine)palladium-catalyzed high-temperature Suzuki-Miyaura cross-coupling of 1-chloro-2-nitrobenzene with 4-chlorophenylboronic acid in a microtubular flow reactor at 160 8C using the tertbutanol/water/potassium tert-butoxide solvent/base system provides 4'-chloro-2-nitrobiphenyl in high yield. After in-line scavenging of palladium metal with the aid of a thiourea-based resin, subsequent heterogeneous catalytic hydrogenation is performed over platinum-on-charcoal in a dedicated continuous-flow hydrogenation device. The overall twostep homogeneous/heterogeneous catalytic process can be performed in a single operation providing the desired 2-amino-4'-chlorobiphenyl in good overall yield and high selectivity.

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“…Gram quantities of the products were obtained by flowing reaction mixtures through a single capillary for about 90 min. Another interesting study was described by Wilson (Wilson et al, 2004), who developed a continuous microwave reactor that eliminates the potential reaction parameter reoptimization (time and temperature) typically required when methods are transferred from small-volume, single-mode systems to larger (but limited)-volume multimode systems ( Figure 6). The representative chemistries explored include S N Ar, esterification, and the Suzuki cross-coupling reaction, all of which were successfully and safely scaled up to multigram quantities using a home-made continuous flow microwave cell (Scheme 19).…”

Section: Scale-up In Continuous Flow Systemsmentioning

confidence: 99%