Direct Dyes with a Urea Bridge

Other examples of symmetrical direct dyes with a urea bridge are shown in Table 3.2 (3.3.6.6). 

Direct Dyes with a Urea Bridge (see Section 3.3.4). 

Direct Dyes with a Urea Bridge. By the end of the 19th century, it was discovered at BASF that the reaction of aminoazo dyes with phosgene in aqueous solution in the presence of soda resulted in valuable symmetrical urea azo dyes [11] ... 

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