Direct Tetrakisazo Dyes

Cl Direct Black 22 [6473-13-8] (Cl 35435) is an example of a tetrakisazo dye, (4,4 -dianainodiphenylainine-2-sulfoiiic acid bisdiazotized and coupled to 2 mol gamma acid which is then bisdiazotized and coupled to 2 mol y -phenylenediamine) which had production of 552 t in 1985. 

Conventional directdyes include monoazo, disazo. trisazo. and tetrakisazo dyes. It is advantageous to subdivide them according to the nature of their chemical structure. Disazo dyes, for example, can be divided according to chemical synthesis principles into primary and secondary. Conventional azo direct dyes further include symmetric urea derivatives, dyes obtained by oxidation of amines, and triazinyl and copper-containing dyes. 

An evaluation of the macrocyclic ligand cucurbituril in powder form as a precipitant for direct dyes varying in molecular size, including Cl Direct Red 79 (disazo), Blue 71 (trisazo) and Red 80 (tetrakisazo), established the influence of pH and ligand concentration on adsorption [60]. The cucurbituril molecule contains six acetylenediurein units linked in... 

Polyazo Dyes. Azo dyes can be made with three, four, or more azo linkages. Those with three (trisazo) and four (tetrakisazo) are quite common. An example of a trisazo dye for cotton is Direct Black 80. It is made by the following sequence p-aminoacetanilide is diazotized and coupled alkaline to Gamma Acid, the acetyl group is removed by hydrolysis, and the resulting diamine is tetrazotized and coupled with 1,6 Cleve s Acid to Gamma Acid (alkaline). 

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