Nitro derivatives of azoxybenzene

Nitration of azoxybenzene may lead to the formation of various nitro derivatives, differing in the number of nitro groups. 

when nitrated with nitric acid alone (sp. gr. 1.45) azoxybenzene yields a mixture of 2- and 4-nitroazoxybenzenes (I) and (II) (Zinin [3] Werner and Stias- 

The 4-isomer has two crystalline forms Ha and lib (Angeli and Alessandri [4] Angeli and Valori [5]). 

More vigorous nitration with nitric acid of specific gravity 1.48 and at temperatures up to 100°C results in the formation of 2,6-dinitroazoxybenzene (III) (Va-lori [6]). 

Even more vigorous nitration, with boiling nitric acid of specific gravity 1.51, leads to the formation of a mixture of trinitroazoxybenzenes 2,4,2 - (IV) 2,4,3 -(V) and 2,4,4 - (VI)  

---

Tetranitro, CjjH NjO, and higher nitro derivS of azoxybenzene-monocarboxylic acid were not found in Beil or in CA through... 

---