# How exactly does the oxidation of TEMPO by NaOCl/KBr work?

I would like to understand the exact process by which TEMPO is oxidized to the nitrosonium cation by NaOCl, as in the part of the mechanism shown in the diagram (1) surrounded by the red box:

The confusion for me is that TEMPO clearly needs to donate 1 electron to $\ce{OCl-}$ in order to form the neutral, nonradical nitrosonium cation, but we also get a $\ce{Cl-}$ anion, so there must also be a 2 electron process involving the $\ce{Br-}$ "co-catalyst" coming into play. How do I reconcile these 1 electron and 2 electron processes so as to draw a formally appropriate mechanism for this part of the reaction?

What exactly happens to the $\ce{OCl-}$ oxygen, and how does it happen?

(1) Org. Synth. 2005, 81, 195. DOI:10.15227/orgsyn.081.0195.

• Are you referring to the total mechanism? One specific step within it? Not sure what you're asking here. Feb 13 '17 at 0:31
• Just the oxidation of TEMPO to the nitrosonium cation. Feb 13 '17 at 4:40
• Can you show me where you found this mechanism? This might be a case of a poorly drawn mechanism. Feb 21 '17 at 14:50
• @MrFlux it doesn't matter. I just want to know the details of the oxidation of the TEMPO radical by NaOCl. Here is another picture: pubs.rsc.org/services/images/… some of then say the stoichiometry is 1/2 NaOCl, but I don't really see how this works either. Feb 21 '17 at 18:46
• A simple google search tells me you found this mechanism off Sigma-Aldrich page on TEMPO oxidation, not exactly a reliable source. Looks like poorly drawn mechanism. Feb 23 '17 at 1:06