Hexamethylazoxybenzene. Structure, Basicity, and Rearrangement

Abstract

2,2′,4,4′,6,6′-Hexamethylazoxybenzene (1) has been prepared and characterized. The u.v. spectrum is indicative of large distortion from coplanarity. 1 is only slightly more basic than azoxybenzene despite expectations due to electronic effect of the methyl substituents. Two factors are considered responsible for this: steric inhibition of resonance in the unprotonated species and steric hindrance to hydration in the conjugate acid.Rearrangement of 1 in moderately concentrated sulfuric acid gives rise to the alcohol 4-hydroxymethyl-2,2′,4′,6,6′-pentamethylazobenzene (6). A Bamberger type phenolic product which would result from methyl migration is not observed. Possible reaction mechanisms are given.

Catalytic oxidation of anilines into azoxybenzenes on mesoporous silicas containing cobalt oxide

“…Azoxymesitylene. 1 H NMR (300 MHz, CDCl 3 ) ı 2.18 (6H, s), 2.29 (3H, s), 2.35 (3H, s), 2.37 (6H, s), 6.81 (2H, s), 6.90 (2H, s) [16].…”