# Complete mechanism of benzotriazole synthesis from o-phenylenediamine

Does my suggested mechanism for benzotriazole synthesis look correct? Are the arrows for the cyclization in the right place?

Chemdoodle (which I drew this with) makes the curly arrows look a bit weird.

• Too many steps, amino could substitute H2O, then deprotonation. Jan 16 at 23:54
• You mean the intermediate with the pendant hydronium would cyclize with expulsion of water? Jan 16 at 23:55
• Your solution is plausible but I am bothered by the use of structure 7 the way you have. Its too far to reach! If you do an electrocyclization of 7 to form the benzene ring and a 4-membered ring bearing vicinal nitrogens, then you can have the remaining nitrogen as a neutral "nitrene" ready for 1,2-shift of nitrogen and ring expansion. OTOH, acid-catalyzed cyclization of structure 2 followed by dehydration gets you there. Jan 16 at 23:58
• When I was drawing it I figured the electrocyclization through the electronegative N wouldn't work but ended up drawing it anyway. So I was right to be concerned. Jan 16 at 23:59
• Jacob, you are free to like what you like. I'm not convinced. I'll post an answer. Jan 17 at 0:45

Cyclization of 5 $$\rightarrow$$ 6 and dehydration via 7 gets the job done. Perhaps @Mithoron knows something that I am not aware of.