Benzidine, preparation transformation

Nucleophiles, when they are used in the presence of cupric perchlorate, capture the cation-radicals initially formed. Instead of benzidines, the para-substituted dialkylanilines were obtained. In this a manner, A,A-dialkylanilines with halo or thiocyanato moieties in para positions were prepared in good yields under the same (simple) conditions. Scheme 7.13 illustrates the sequence of the transformations observed. The products are useful intermediates in the synthesis of dyes, drugs, and color cinema formulations. 

C-labelled Direct Blue 6 (17) and Acid Red 114 (18), bis-azo biphenyl dyes, possible human carcinogens2 3b, needed in order to study their distribution and biological transformations in animals, have been prepared24 from uniformly ring-labelled 14C-benzidine and 14C-3,3 -dimethylbenzidine according to equations 7 and 8. 17 has been prepared by reacting the diazotized benzidine with two equivalents of H acid under basic conditions to insure the occurrence of the attack of the electrophilic species at the ortho... 

In this method, a polymer is prepared which has certain struc-tiiral features which can be chemically transformed to dye structures in one or more steps. Perhaps the most common class of dyes that have been so synthesized on a polymer backbone is the azo dyes, which are simply formed by the coupling of a polymeric aryl diazon-ium salt with an activated aromatic system. The former are prepared from polymeric aromatic amines by diazotization. Thus polymers and copolymers of 2,2 -di vinyl benzidine (XVl) have been diazotized and coupled with sodium naphthionate, sodium anthranilate and sulfanilic acid to give polymeric azo dyes which act as pH indicators,... 

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