Explosive Carbonyl Diazide Safely Made

A team of chemists based in Canada and Germany has developed a safe way to prepare and handle explosive carbonyl diazide, OC(N₃)₂, going against decades-old advice that it’s never wise to isolate it and that the high-energy compound should only be used in situ in small quantities (Inorg. Chem., DOI: 10.1021/ic1015143). Azides are compounds containing N₃ groups, which are prone to violently decompose to form N₂. They are challenging to synthesize but useful as reagents in organic synthesis and as precursors in materials science. The team, led by Michael Gerken of the University of Lethbridge, in Alberta, and Helge Willner of Bergische University, in Wuppertal, Germany, synthesized OC(N₃)₂ by treating FC(O)Cl with NaN₃, a salt commonly used as a propellant in automobile air bags. The reaction took place over four days at room temperature in a sealed glass ampule, after which the researchers used vacuum-line techniques to isolate and fully characterize the compound for the first time. They found that OC(N₃)₂ is a “rather shock sensitive” white solid that melts at about room temperature (16 °C), but it has remarkable thermal stability in the gas, liquid, and solid states. Carbonyl diazide is not likely to become commercially available, Gerken says, but, if handled with care, chemists can now explore its full potential as a synthetic reagent.