Photo-assisted Oxidation of Anilines and Other Primary Aromatic Amines to Azo Compounds Using Mercury(II) Oxide as a Photo-Oxidant

Saeid Farhadi,^a* Parisa Zaringhadam^a and Reza Zarei Sahamieh^b
aDepartment of Chemistry, University of Lorestan, Lorestan, Khoramabad 68135-465, Iran.
^bFaculty of Science, University of Lorestan, Lorestan, Khoramabad 68135-465, Iran.
 E-mail: farhadi.s@lu.ac.ir

Abstract
An efficient and selective photochemical method for the oxidation of primary aromatic amines to the corresponding azoaromatic compounds with HgO as the photo-oxidant is reported. Aniline and substituted anilines were transformed to the corresponding azobenzenes by treatment with HgO in CH₃CN at room temperature in high yields. Under similar conditions, diamines such as o-, m- and or p-phenylenediamines gave the corresponding diaminoazo compounds. It was proposed that the photoactivated HgO effects the cleavage of one of the N–H bond of the amine to generate the aminyl radical which dimerizes to the hydrazobenzene via nitrogen-nitrogen coupling. The hydrazobenzene was then oxidized to azo product.

Keywords: Anilines, photoassisted oxidation, mercury (II) oxide, azo compounds.