Acyl Azide Synthesis and Curtius Rearrangements in Microstructured Flow Chemistry Systems
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The synthesis and utilisation of acyl azides in a flow apparatus combined with an automated extraction unit is described. This process safely provides multi-100 g quantities of a labile diacyl azide (3) as an intermediate that could not be generated safely by classic batch methods. Its subsequent conversion to the desired amine (4) represents an example for process intensification. The same set-up with an output capacity of >30 g/h was used for the unattended synthesis of benzoyl azide as the final product in solution (tert-butyl methyl ether (TBME), 0.5 M).
Keywordsacyl azide synthesis Curtius rearrangement continuous extraction process safety
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- 10.The glass microreactor type S02 is available with the Sigma-Aldrich Microreaction Explorer Kit, article number 19979. Also see www.sigmaaldrich.com/mrt/mrt.
- 11.Impedance glass probe SGK 180/40 and control unit MIL 8130 were purchased from Aquasant Messtechnik AG (Bubendorf, Switzerland).Google Scholar
- 12.For United Nation criteria on chemical products, see http://www.unece.org/trans/danger/publi/manual/manual_e.html
- 13.Sigma-Aldrich product numbers: 4, 726184; optical pure isomers 726311 and 726338; 6, 778486. For further information and other azides, see www.sigmaaldrich.com.