Scale-Up of Microwave-Assisted Reactions in a Multimode Bench-Top Reactor

Dallinger, Doris; Lehmann, Hansjörg; Moseley, Jonathan D.; Stadler, Alexander; Kappe, C. Oliver

doi:10.1021/op200090k

Cited by 60 publications

(46 citation statements)

References 114 publications

(159 reference statements)

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“…5 However, since microwaves have a limited penetration depth, the possibility of scaling up reactions using microwaves is somewhat limited. Large multimode applicators 3,13,14 or flow/stop approaches 3,11 are some of the alternatives that have been used to circumvent this problem.…”

Section: ■ Introductionmentioning

confidence: 99%

Evaluation of a Nonresonant Microwave Applicator for Continuous-Flow Chemistry Applications

Öhrngren

Fardost

Russo

et al. 2012

Org. Process Res. Dev.

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The concept of a nonresonant microwave applicator for continuous-flow organic chemistry is introduced and evaluated. The frequency of the incident microwave radiation can be adjusted between 2.4 and 2.5 GHz to optimize the energy absorbance. The temperature of the reaction is monitored by five IR sensors, and their signals can be used to automatically adjust the power output from the microwave generator. The heating of several different solvents up to 20°C above the standard boiling point has been explored. Several different organic reactions have been successfully carried out using a 200 mm × ⌽ 3 mm tubular borosilicate reactor and a flow between 47 and 2120 μL/min. The microwave heating pattern was visualized with an IR camera. The transformations include palladium-catalyzed coupling reactions (oxidative Heck and Suzuki reactions), heterocyclic chemistry (oxathiazolone and Fischer indole synthesis), rearrangement (Claisen), and a Diels−Alder cycloaddition reaction. A scale-out to 57 mmol/h was performed with the Fischer indole reaction.

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Section: ■ Introductionmentioning

confidence: 99%

Evaluation of a Nonresonant Microwave Applicator for Continuous-Flow Chemistry Applications

Öhrngren

Fardost

Russo

et al. 2012

Org. Process Res. Dev.

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“…The scale-up of microwave synthesis from the laboratory to process and production scale is a challenging area. Two different approaches for microwave synthesis on a larger scale have emerged: batch synthesis in larger multimode reactors or continuous/stop flow techniques [5].…”

Section: Energy Environment and Molecular Chemistrymentioning

confidence: 99%

New activation methods used in green chemistry for the synthesis of high added value molecules

Veitía

Ferroud

2014

Int J Energy Environ Eng

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In the chemical and pharmaceutical industry, molecular organic chemistry is undergoing a green revolution in order to avoid waste by developing a cleaner and safer chemistry. This change is subject to the new European regulation REACH. One of the major goals of organic synthesis is to design molecules with high added value by developing synthetic methods highly selective, economical and environmentally friendly. To satisfy the societal expectation new activation methods must be developed in order to shorten the synthesis, to respect the principle of atom economy and to substitute pollutants or toxic organic solvents. In this context, our group focuses its research on the synthesis of biologically active molecules, developing new environmentally friendly synthetic strategies and more energy-efficient alternatives such as microwaves, ultrasound, photochemistry or biotransformation. We present here how various activation methods used for the preparation of several high-value compounds can dramatically enhance yields and selectivity. First, we describe microwave-assisted syntheses of precursors of [ 11 C] PIB, a tracer used in PET imaging and amides intermediates of natural products. We describe also the selective reduction of nitro compounds using ultrasound activation and a facile pathway to obtain b 3 -chiral aminoacids by biotransformation using purified nitrilases. Finally the results concerning the alkylation of a-aldehydes, using visible light and dyes as catalysts without transition metal are discussed. Some general considerations concerning the activation methods and their impact on the environment and the energy saving are given.

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“…In the last 5-10 years, several papers have been published with examples of scale-up under microwave-assisted conditions [94][95][96][97][98][99][100][101][102][103][104][105]. Of special interest were the topics of reaction optimization, the energy efficiency of microwave heating, and the challenge of scale-up.…”

Section: Enterprises' Productsmentioning

confidence: 99%