Diazomethane Without Tears. Or Explosions.

Here's a neat paper from Oliver Kappe's group on diazomethane flow chemistry. They're using the gas-permeable tube-in-tube technique (as pioneered by Steve Ley's group). Flow systems have been described for using diazomethane before, but this looks like a convenient lab-scale method. Diazomethane is the perfect reagent to apply flow chemistry to. It's small, versatile, reactive, does a lot of very interesting and useful chemistry (generally quickly and in high yields). . .and it's also volatile, extremely toxic, and a really significant explosion hazard. Generating it as you use it (and reacting it quickly) is a very appealing thought. In this system, the commercial diazomethane precursor Diazald is mixed with a KOH flow in one tube, while a THF solution of the reactants flows past it on the other side of a gas-permeable membrane. Methyl ester formation, cyclopropanation, and Arndt–Eistert reactions all worked well. Aldrich or someone should work this up into a small commercial apparatus, a bespoke diazomethane generator for general use. I think it would sell. I suggest, free of charge, the brand name "Diazoflow".
Source: In the Pipeline - Category: Chemists Tags: Chemical News Source Type: blogs