Meissenheimer complex

On heating primary amines form colored Meissenheimer complexes with trinitrobenzenesulfonic acid. 

Note The Meissenheimer conversion of 1,8-naphthyridine A-oxides into halo-geno-l,8-naphthyridines has been covered in Section 24.1 complexes of 1,8-naphthyridine 1-oxide with Cr,555 Cu,496 and Sr,462 and the lanthanide compounds429 have been reported and deoxygenation of an A-oxide is exemplified here. 

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