title: Laboratory-Scale Membrane Reactor for the Generation of Anhydrous Diazomethane.
abstract: 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.
authors.affiliation: Institute of Chemistry, University of Graz, NAWI Graz , Heinrichstrasse 28, 8010 Graz, Austria.
authors.forename: Doris
authors.initials: D
authors.lastname: Dallinger
authors.affiliation: Institute of Chemistry, University of Graz, NAWI Graz , Heinrichstrasse 28, 8010 Graz, Austria.
authors.forename: Vagner D
authors.initials: VD
authors.lastname: Pinho
authors.affiliation: Research Center Pharmaceutical Engineering GmbH (RCPE), Inffeldgasse 13, 8010 Graz, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Gutmann
authors.affiliation: Institute of Chemistry, University of Graz, NAWI Graz , Heinrichstrasse 28, 8010 Graz, Austria.
authors.forename: C Oliver
authors.initials: CO
authors.lastname: Kappe