Oxidation of aromatic amines Boyland-Sims reaction

2 Oxidation of aromatic amines Boyland-Sims reaction) 

This oxidation is similar to the Elbs reaction, except that ortho substitution of sulphate normally occurs, e.g. 

The yield of o-amino aryl sulphate is generally 10-40 %. If both ortho positions are blocked then para substitution results. For preparative purposes the sulphate is hydrolysed by acid, as with the Elbs reaction. Behrman studied the oxidation of 2-amino-pyridine, and showed that the kinetics are second -order for the major part of reaction, viz. 

The pH dependence of the rate shows that the free amine is the reactive species. For the reaction in 0.475 M potassium hydroxide, 2 expressed by 

The salt effect is small and positive, consistent with the attack of an ion on a neutral molecule. Allyl acetate has no effect on the rate or yield of product. Electron-releasing substituents accelerate the reaction. Thus the features of the reaction are similar to those of the Elbs reaction, and point to a mechanism involving nucleophilic attack of the amine on peroxide oxygen. In order to determine whether attack occurred by nitrogen or carbon, Behrman compared the rates of oxidation of amines such as 2-amino-5-methyl-pyridine and 2-amino-6-methyl-pyridine, and found that in all cases the order of reactivity is consistent with attack by nitrogen. Furthermore, the rate of oxidation of 3,5-dideutero-2-amino-pyridine is the same as for the normal material, and the yield of product is the same. Behrman proposed the reaction scheme 

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