Laboratory-Scale Membrane Reactor for the Generation of Anhydrous Diazomethane

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• 作者：Doris Dallinger ; Vagner D. Pinho ; Bernhard Gutmann ; C. Oliver Kappe
• 刊名：Journal of Organic Chemistry
• 出版年：2016
• 出版时间：July 15, 2016
• 年：2016
• 卷：81
• 期：14
• 页码：5814-5823
• 全文大小：529K
• 年卷期：0
• ISSN：1520-6904

文摘

A configurationally simple and robust semibatch apparatus for the in situ on-demand generation of anhydrous solutions of diazomethane (CH₂N₂) avoiding distillation methods is presented. Diazomethane is produced by base-mediated decomposition of commercially available Diazald within a semipermeable Teflon AF-2400 tubing and subsequently selectively separated from the tubing into a solvent- and substrate-filled flask (tube-in-flask reactor). Reactions with CH₂N₂ can therefore be performed directly in the flask without dangerous and labor-intensive purification operations or exposure of the operator to CH₂N₂. The reactor has been employed for the methylation of carboxylic acids, the synthesis of α-chloro ketones and pyrazoles, and palladium-catalyzed cyclopropanation reactions on laboratory scale. The implementation of in-line FTIR technology allowed monitoring of the CH₂N₂ generation and its consumption. In addition, larger scales (1.8 g diazomethane per hour) could be obtained via parallelization (numbering up) by simply wrapping several membrane tubings into the flask.