Monopermaleic acid

Owiag to the lower basicity of the parent amines, aromatic amine oxides cannot be formed directiy by hydrogen peroxide oxidation. These compounds may be obtained by oxidation of the corresponding amine with a peracid perbenzoic, monoperphthaUc, and monopermaleic acids have been employed. 

The order of reactivity of the peroxy acid increases with the pKa value, i.e. peroxytrifluoroacetic > monopermaleic > />-nitroperbenzoic > m-chloro-perbenzoic > performic > perbenzoic > peracetic. 

The hydroxyl proton in the intermediate 3 can migrate intramolecularly only with acylperoxo-type oxidants. Hence, acylperoxo-type oxidants are more effective than allq lperoxo oxidants. Additionally, it was observed that the presence of electron-withdrawing substituents on the peroxy acid increased the reaction rate because they made the conjugate base a better leaving group. Therefore, the reactivity of oxidants follows this order CF3CO3H > monopermaleic... 

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