Oxidation of Primary Amines at Nitrogen

Primary amines are oxidized to azo, azoxy, nitroso, or nitro compounds, depending on the oxidants used. Most of the examples include aromatic amines, because aliphatic amines that have hydrogens on the carbons carrying the amino groups may undergo dehydrogenations to carbonyl compounds, imines, and nitriles (see equations 508-514). 

The dehydrogenation of primary amines into azo compounds is achieved by sodium perborate, which converts A -acetyl-p-phenylenedi-amine into /3,p -diacetamidoazobenzene in 58% yield on heating at 50-60 °C with boric acid and acetic acid for 6 h [193], 

More common oxidation reagents are oxygen in the presence of cobalt peroxide [1136], manganese dioxide [Si3], barium manganate [S53], silver permanganate [897], and nickel peroxide [936] (equation 495). 

OXIDATION OF PRIMARY AMINES TO NITROSO AND NITRO COMPOUNDS 

Oxidants suitable for the partial oxidation of amines to nitroso compounds are peroxy acids Caro acid, which is prepared in situ from potassium persulfate and sulfuric acid [195, 199 potassium peroxysulfate (Oxone) [295] peroxyacetic acid [i53], and peroxybenzoic add [1186], 3-Nitro-o-toluidine [195] and 5-nitro-o-toluidine [199] in aqueous-alcoholic solutions, when treated with a mixture of potassium persulfate and concentrated sulfuric acid, give 3-nitro-2-nitrosotoluene and 5-nitro-2-nitrosotoluene in respective yields of 60 and 55-66%. Organic peroxy acids convert 2,6-dihaloanilines into 2,6-dihalonitrosobenzenes (equation 497) [753, 1186]. p-Phenylenediamine (1,4-diaminobenzene) is oxidized by Oxone (2KHS05 KHS04 K2S04) in an aqueous suspension at room temperature to p-dinitrosobenzene in a quantitative yield [205]. 

---