Manganese dioxide primary arylamines

Aromatic azo compounds can be obtained by the oxidation of primary arylamines. The reagent most widely used for this purpose is activated manganese dioxide. This converts aniline and substituted anilines into the corresponding azo compounds in moderate to good yield. At room temperature the products are the n -azobenzenes, which are isomerized to the trans compounds on heating. It is probable that hydrazobenzenes are intermediates in the reaction, but these are more easily oxidized dim the starting anilines (Scheme 7). These oxidations are inhibited by electron-withdrawing substituents and some nitro-substituted anilines fail to react. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

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